An Investigation Into Rational Strategies for the Design of a Near Zero Energy Commercial Office Building in the United Kingdom

AN INVESTIGATION INTO RATIONAL STRATEGIES FOR THE DESIGN OF A NEAR ZERO ENERGY COMMERCIAL OFFICE BUILDING IN THE UNITED KINGDOM

A thesis submitted to The University of Manchester for the degree of Doctor of Philosophy (PhD) in the Faculty of Engineering and Physical Sciences

2013

ALEXANDER JOHN MITCHELL

SCHOOL OF MECHANICAL, AEROSPACE AND CIVIL ENGINEERING

Contents

1. Introduction ...... 20

1.1 Problem Statement ...... 20

1.2 Objectives ...... 24

1.3 Research Methodology...... 26

1.3.1 A review of literature ...... 26

1.3.2 Emulating the design process ...... 26

1.3.3 Identification of case studies ...... 26

1.3.4 Application of design methodologies ...... 26

1.3.5 Testing of the design solutions ...... 27

1.3.6 Evaluation of the design methodologies, the proposed solutions and the investigative process ...... 27

1.4 Summary of thesis ...... 28

1.5 Case Study Buildings ...... 29

2. Literature Review ...... 32

2.1 Background ...... 32

2.1.1 Building Services Engineering ...... 32

2.1.2 Heat and mass transfer ...... 33

2.1.3 Design and simulation tools ...... 33

2.1.4 Dynamic simulation in commercial practice...... 36

2.2 Emissions and Energy Demand ...... 40

2.2.1 Defining “zero carbon” building performance ...... 40

2.2.2 Defining “near Zero Energy Building” performance ...... 42

2.2.3 On-site renewables ...... 43

2.2.4 Compliance and Accreditation ...... 44

2.2.5 Simulation and design ...... 50

2.3 Demand reduction and energy efficiency ...... 52

2.3.1 Introduction ...... 52

2.3.2 Building Orientation ...... 52

2.3.3 Form and Fabric ...... 54

2.3.4 Space conditioning ...... 56

2.3.5 Ventilation ...... 57

2.3.6 Lighting ...... 60

2.3.7 Renewable and LZC Technologies ...... 61

2.4 A review of design strategies ...... 64

2.4.1 A review of the Green Building Council and Target Zero ...... 64

2.4.2 A review of Annex 44 International Energy Agency’s Energy Conservation in Buildings and Community Systems Program...... 72

2.4.3 Naturally ventilated office spaces ...... 80

2.4.4 Passivhaus ...... 81

3. Simulation Theory...... 84

3.1 Geometry ...... 84

3.2 Weather ...... 84

3.2.1 Location ...... 84

3.2.2 Daylight ...... 85

3.2.3 Future Weather ...... 86

3.3 Heat Transfer ...... 87

3.4 Internal Gains ...... 87

3.4.1 Lighting and Equipment...... 87

3.4.2 Occupancy ...... 88

3.5 Ventilation ...... 88

3.5.1 Natural Ventilation ...... 88

3.5.2 Mechanical Ventilation and Air Conditioning ...... 88

3.5.3 Mixed Mode Ventilation ...... 89

3.6 Heating and Cooling ...... 90

3.6.1 Concept Design ...... 90

3.6.2 Detail Design ...... 90

3.7 Domestic Hot Water ...... 90

3.8 Dimming Controls - Radiance Calculations ...... 91

4. Methodology ...... 92

4.1 Research Methodology...... 92

4.1.1 Introduction ...... 92

4.1.2 Emulating the design process ...... 94

4.1.3 Identifying building design strategies ...... 96

4.2 Design Methodologies ...... 110

4.2.1 The “Incremental improvement” strategy ...... 110

4.2.2 The “Natural ventilation” strategy ...... 112

4.2.3 The “Dynamic building” strategy ...... 114

4.2.4 The “Passivhaus” strategy ...... 116

4.2.5 Available Technologies ...... 119

4.2.6 Key Performance Indicators (KPIs) of an nZEB Building ...... 120

5. Results ...... 124

5.1 Pre-design Analysis ...... 124

5.1.1 Choosing building form ...... 124

5.1.2 Building Fabric ...... 128

5.1.3 Daylight analysis ...... 129

5.1.4 Loads ...... 131

5.1.5 Climate Data ...... 133

5.2 Incremental Improvement Case ...... 134

5.2.1 Concept Design ...... 134

5.2.2 Model geometry ...... 134

5.2.3 ‘Base’ case design concept ...... 136

5.2.4 Incremental improvements to concept design ...... 138

5.2.5 Best combination of improvements ...... 143

5.2.6 Detail Design...... 145

5.2.7 Detailed design simulation - Results ...... 147

5.2.8 Case Summary ...... 148

5.3 Natural Ventilation Case ...... 150

5.3.1 Introduction ...... 150

5.3.2 Model geometry ...... 150

5.3.3 Concept design – ‘base’ case ...... 152

5.3.4 ‘Base’ case – Results...... 157

5.3.5 Concept design – ventilation alternatives ...... 158

5.3.6 Ventilation alternatives – Results ...... 162

5.3.7 Final ventilation strategy – Results ...... 164

5.3.8 Detail Design – Under-floor heating system...... 167

5.3.9 Detailed design simulation – Results ...... 168

5.3.10 Case Summary ...... 169

5.4 Dynamic Building Case ...... 170

5.4.1 Thermal Mass Activation using Hollow Core Slabs ...... 170

5.4.2 Active Integrated Façade ...... 172

5.4.3 Case Summary ...... 173

5.5 Passivhaus Case ...... 174

5.5.1 Introduction ...... 174

5.5.2 Building Form ...... 174

5.5.3 Geometry ...... 175

5.5.4 Concept design - Basic parameters ...... 176

5.5.5 Concept Design – Results ...... 178

5.5.6 Detail design - earth coupling ...... 180

5.5.7 Results – Detail design option...... 184

5.5.8 Case Summary ...... 185

5.6 Summary of Results ...... 185

5.7 Post-design Analysis ...... 188

5.7.1 Introduction ...... 188

5.7.2 Overheating ...... 189

5.7.3 Energy Consumption ...... 190

5.7.4 Conclusions ...... 195

6. Discussion ...... 196

6.1 Findings ...... 196

6.2 Assessment of design methodologies and building concepts ...... 198

6.2.1 Incremental improvement ...... 198

6.2.2 Natural ventilation ...... 198

6.2.3 Dynamic building ...... 199

6.2.4 Passivhaus ...... 199

6.3 Limitations of commercial design and simulation process ...... 200

6.4 Limitations of research methodology...... 201

7. Conclusions ...... 202

7.1 Recommendations for further work ...... 207

References ...... 208

Selected bibliography ...... 229

APPENDIX A – IESVE Simulation Inputs ...... 230

APPENDIX B –Case Study Simulation Outputs ...... 248

APPENDIX C – Parameter Sweep Simulation Outputs ...... 265

Word count: 71,620

List of Figures

Figure 1: A breakdown of chapters and subchapters contained within the thesis ...... 28

Figure 2: Heat and mass transfer processes in a building (image created by A Mitchell - 2012)...... 34

Figure 3: RIBA Stages for design, with 'Green Building' Overlay and annotation [29] [30]...... 37

Figure 4: BREEAM credit distribution for CO2 emissions [48]...... 48

Figure 5: Percentage reduction in annual carbon dioxide emissions (kgCO2/m2/year) [34] ...... 70

Figure 6: Pre-design investigation of building form, orientation and location for design case studies...... 98

Figure 7: Common concept design phase for all case studies...... 99

Figure 8: Standard occupancy profile for the office spaces in thermal simulation [148]...... 100

Figure 9: Common detail design phase for all case studies ...... 102

Figure 10: "mixed-use office" occupancy profile...... 103

Figure 11: "Extended hours" occupancy profile...... 104

Figure 12: "Public office" occupancy profile...... 104

Figure 13: "Shift office" occupancy profile...... 105

Figure 14: "24 hour call-centre" occupancy profile...... 105

Figure 15: Range of building orientations examined in the post-design testing phase of program research...... 107

Figure 16: "Incremental improvement" design methodology ...... 111

Figure 17: "Natural ventilation" design methodology ...... 113

Figure 18: "Dynamic building" design methodology ...... 115

Figure 19: "Passive house" design methodology ...... 118

Figure 20: Comfortable office temperature range [160]...... 121 8

Figure 21: Floor layout and zoning scheme for deep plan building ...... 125

Figure 22: Glazing and cladding configuration of south facade of Deep Plan Building...... 126

Figure 23: Floor plan and zoning scheme for shallow plan building...... 127

Figure 24: Glazing configuration of south facade of Shallow Plan Building ...... 128

Figure 25: Daylight factor calculation for office space of deep plan building form .... 130

Figure 26: Daylight factor calculation for office space of shallow plan building form 131

Figure 27: Rendered image of deep plan building used in the Incremental Improvement case study...... 135

Figure 28: Wireframe image of the deep plan building used in the Incremental improvement case study...... 135

Figure 29: Distribution of primary energy demand per m2 floor area for 'base' case concept ...... 137

Figure 30: Percentage reduction in primary energy consumption through fabric improvements ...... 140

Figure 31: Percentage reduction in primary energy consumption through glazing improvements ...... 141

Figure 32: Percentage reduction in primary energy consumption through lighting and shading improvements ...... 141

Figure 33: Percentage reduction in primary energy consumption through improvements to heating, cooling and domestic hot water systems ...... 142

Figure 34: Percentage reduction in primary energy consumption through ventilation system improvements ...... 142

Figure 35: Distribution of primary energy demand per m2 floor area for ‘base' case and 'final' case building designs as generated by the ApacheSim dynamic simulation module (kWh/m2.year) ...... 144

Figure 36: Apache HVAC 'multiplex' model of the VRF system used in the final model of the Incremental Improvement case study...... 146

Figure 37: Distribution of primary energy demand per m2 floor area for ‘final' case and 'final' case with VRF Apache HVAC model as generated by the ApacheSim dynamic simulation module (kWh/m2.year) ...... 147

Figure 38: Cross-section of thermal model zoning of natural ventilation case study. .. 150

Figure 39: Rendered image of shallow plan building as used in the Natural ventilation case study...... 151

Figure 40: Wireframe image of deep plan building used in the Natural ventilation case study...... 151

Figure 41: Ventilation strategy for cross-ventilation with trickle vents...... 153

Figure 42: Glazing layout per office space 'zone' for natural ventilation strategy ...... 155

Figure 43: Distribution of primary energy demand per m2 floor area for 'base' case concept ...... 157

Figure 44: Modes of natural ventilation considered for the 'Natural ventilation' case study ...... 159

Figure 45: Ventilation strategy for cross-ventilation with change-over mechanical supply air ...... 159

Figure 46: Rendered image of natural ventilation case study with internal glazed atrium space...... 160

Figure 47: Rendered image of Natural ventilation case with wind-catchers ...... 161

Figure 48: Primary energy consumption for 'mixed-mode' design alternatives for Natural ventilation case study ...... 162

Figure 49: Primary energy consumption for 'wind-catcher' design alternatives for Natural ventilation case study ...... 163

Figure 50: Primary energy consumption for 'atrium' design alternatives for Natural ventilation case study ...... 163

Figure 51: Primary energy consumption for 'base' and 'final' design concepts for Natural ventilation case study ...... 166

Figure 52: Primary energy consumption for 'final' design concept and 'final with under- floor heating' design concept for Natural ventilation case study ...... 168

Figure 53: Airflows within a 'Termodeck' unit from an IESVE test case model ...... 171

Figure 54: Apache HVAC schematic of 'Termodeck' test case model ...... 171

Figure 55: Rendered image of the shallow plan building as used in the Passivhaus case study ...... 175

Figure 56: Wireframe of Passivhaus case study including 'earth tube' geometry ...... 181

Figure 57: Detail view of earth tube in operation, showing Macroflow air flow direction ...... 182

Figure 58: MVHR and distribution schematic in Apache HVAC module of the IESVE ...... 183

Figure 59: Distribution of primary energy demand per m2 floor area for 'final' concept of Passivhaus case study...... 184

Figure 60: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a changing climate (Manchester) ...... 191

Figure 61: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of location within the UK ...... 192

Figure 62: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of building orientation ...... 193

Figure 63: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of building usage ..... 194

Figure 64: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of building occupancy ...... 195

List of Tables

Table 1: BREEAM Energy efficiency and carbon criteria [46] [49] [35] ...... 49

Table 2: Technologies available to the 'design team' for each of the case study building ...... 119

Table 3: Peak heating and cooling loads for building forms used for case study buildings ...... 132

Table 4: Minimum specifications used for the 'base case' building in the IESVE model ...... 137

Table 5: Total energy consumption for 'base' building concept...... 137

Table 6: Part L assessment results for 'base' case building design as generated by the IESVE Compliance module ...... 138

Table 7: Incremental improvements applied to base case design...... 139

Table 8: Improvements applied to the 'final' case of the Incremental improvement case study ...... 143

Table 9: Total energy consumption for 'base' and ‘final’ building concepts ...... 144

Table 10: Part L assessment results for 'base' case and 'final' case building designs as generated by the IESVE Compliance module ...... 144

Table 11: Total energy consumption for 'final' and ‘final’ + VRF Apache HVAC model building concepts ...... 148

Table 12: Material properties of building fabric for natural ventilation case study (admittances from CIBSE Guide A Table 3.55 [179])...... 154

Table 13: Glazing properties for 'base' case of natural ventilation case study ...... 155

Table 14: Total energy consumption for 'base' building concept...... 157

Table 15: Part L assessment results for 'base' case building design of the Natural ventilation case study as generated by the IESVE Compliance module ...... 157

Table 16: Total energy consumption for design alternatives for Natural ventilation building case study ...... 164

Table 17: An assessment against comfort criteria of the design alternatives of the Natural ventilation case study ...... 164

Table 18: Total energy consumption for 'base' and ‘final’ building concept of Natural ventilation case study ...... 166

Table 19: Part L assessment results for 'base' case and 'final' case building designs of the Natural ventilation case study as generated by the IESVE Compliance module ...... 166

Table 20: Part load data for air source heat pump used in under-floor heating model for Natural ventilation case study ...... 168

Table 21: Total energy consumption for 'final' design concept and 'final with under-floor heating' design concept for Natural ventilation case study ...... 169

Table 22: Fabric properties for construction materials used in Passivhaus case study . 176

Table 23: Glazing properties for Passivhaus case study ...... 177

Table 24: Properties of 'Maxi' 6001DC MVHR units used in Passivhaus case study .. 178

Table 25: Primary energy per m2 floor area for the 'base' concept of the Passivhaus case study ...... 179

Table 26: Energy consumption for the 'base' concept of the Passivhaus case study .... 179

Table 27: Part L assessment results for 'base' case of Passivhaus case study ...... 179

Table 28: Total energy consumption for 'base' and ‘final’ building concept of Passivhaus case study...... 184

Table 29: Comparison of Primary Energy Consumption per metre squared of floor area across case study buildings...... 185

Table 30: Overheating checks for parameter sweeps of the Natural ventilation and Passivhaus case studies ...... 189

ABREVIATIONS

AIF – Active Integrated façade ASHRAE - American Society of Heating, Refrigerating and Air Conditioning Engineers BER/TER – Building Emissions Rate / Target Emissions Rate BMS – Building Management System BRE – Building Research Establishment BREEAM – Building Research Establishment Environmental Assessment Method BS – British Standard BSRIA - Building Services Research and Information Association CCHP – Combined Cooling, Heat and Power CFD – Computational Fluid Dynamics CHP – Combined Heat and Power CIBSE- Chartered Institution of Building Services Engineers

CO2 – Carbon dioxide DSF – Double Skin façade DSM – Dynamic Simulation Method DSY – Design Summer Year EPBD – Energy Performance of Buildings Directive GBC – Green Building Council GSHP – Ground Source Heat Pump HVAC – Heating, Ventilation and Air Conditioning IEA ECBCS – International Energy Agency’s Energy Conservation in Buildings and Community Systems IES VE – Integrated Environmental Solutions Virtual Environment KPI – Key Performance Indicator LEED – Leadership in Energy Efficient Design LZC – Low and Zero Carbon MEP – Mechanical, Electrical and Plumbing MVHR – Mechanical Ventilation and Heat Recovery NCM – National Calculation Methodology NPV – Net Present Value nZEB – near Zero Energy Building

PCM – Phase Change Material PHPP – Passivhaus Planning Package PV – Photovoltaic RBC – Responsive Building Concept RBE – Responsive Building Element RIBA – Royal Institute of British Architects SAP – Standard Assessment Procedure SEER – Seasonal Energy Efficiency Ratio SLL – Society for Light and Lighting SBEM - Simplified Building Energy Model TMA – Thermal Mass Activation TRY – Test Reference Year UKCIP – United Kingdom Climate Impacts Program VRF – Variable Refrigerant Flow

ABSTRACT

Alexander John Mitchell, The University of Manchester, Doctor of Philosophy (PhD), September 2012 An investigation into rational strategies for the design of a near zero energy commercial office building in the United Kingdom The United Kingdom government has set the target that all new non-domestic buildings should be ‘zero carbon’ in operation by 2019. The challenge of implementing this vision of a more energy efficient and less emissions intensive building stock is both technological and organizational in nature. While exemplar buildings have achieved this level of performance in the UK the proliferation of such designs within the building stock at large has not been realised, due to the drive to meet interim emissions targets at the minimum of cost premium. In order to achieve the necessary performance improvement in commercial buildings at large to meet this target a step change in the design methodologies applied to these buildings is required. An extensive review of the literature available to the non-domestic building design team was used to identify four distinct design strategies which aspired to levels of operational efficiency beyond the current standards. These strategies were then developed into methodologies which could be applied to case study buildings. The testing of these methodologies was conducted through the emulation of a dynamic building simulation led design process with the target of optimal operational energy efficiency. The comparison and evaluation of these test case buildings and the design methodologies which were applied to them offered an insight into rational strategies for near zero energy buildings going forward. The robustness of both the final design concepts and the methodologies themselves were tested through a series changes to the external and internal conditions under which the buildings were expected to operate. The result of these investigative measures was a demonstration that the performance improvement of commercial office buildings beyond what is currently typical is possible using a commercial design process if the depth of investigation is sufficient. It also identified significant risks associated with these design methodologies and in particular the response of highly specified building designs to changes in use and local climate.

Declaration

It is hereby declared that no portion of the work referred to in the thesis has been submitted in support of an application for another degree or qualification of this or any other university or other institute of learning. Copyright Statement

i. The author of this thesis (including any appendices and/or schedules to this thesis) owns certain copyright or related rights in it (the “Copyright”) and s/he has given The University of Manchester certain rights to use such Copyright, including for administrative purposes. ii. Copies of this thesis, either in full or in extracts and whether in hard or electronic copy, may be made only in accordance with the Copyright, Designs and Patents Act 1988 (as amended) and regulations issued under it or, where appropriate, in accordance with licensing agreements which the University has from time to time. This page must form part of any such copies made. iii. The ownership of certain Copyright, patents, designs, trademarks and other intellectual property (the “Intellectual Property”) and any reproductions of copyright works in the thesis, for example graphs and tables (“Reproductions”), which may be described in this thesis, may not be owned by the author and may be owned by third parties. Such Intellectual Property and Reproductions cannot and must not be made available for use without the prior written permission of the owner(s) of the relevant Intellectual Property and/or Reproductions. iv. Further information on the conditions under which disclosure, publication and commercialisation of this thesis, the Copyright and any Intellectual Property and/or Reproductions described in it may take place is available in the University IP Policy (see http://www.campus.manchester.ac.uk/medialibrary/policies/intellectualproperty. pdf ), in any relevant Thesis restriction declarations deposited in the University Library, The University Library’s regulations (see http://www.manchester.ac.uk/library/aboutus/regulations ) and in The University’s policy on presentation of Theses.

Acknowledgements

Many thanks to my supervisor Dr. Rodger Edwards for his guidance, encouragement and excellent lunch conversation.

Many thanks to Graham Hirst and Tom Edge of Clancy Consulting for taking an interest in my project and for sharing their expert opinions.

My deepest thanks to my parents, for their constant encouragement and support and to Charlie, who brought me cups of tea.

Finally, the author would like to thank the Joule Centre, The School of Mechanical, Civil and Aerospace Engineering and The University of Manchester for their financial support of this project.

1. Introduction

1.1 Problem Statement

It has become apparent in recent years that the current strategy for world energy provision is no longer viable. There are three main factors which contribute to this situation. The first is the depletion of fossil fuel resources such as coal and oil. The burning of these fuels is the mainstay of the electrical power industry and alternatives must be provided and implemented before they run out. The second factor is the increased demand for centrally distributed energy that runs counter to the struggle to meet it. The final factor is the damage that traditional methods of power generation (in addition to other devices which use such fuel, for example cars or planes) are doing to the environment, in particular the generation of gases (CO2 being the most high profile example) which contribute to climate change.

The existence of these problems has led to an interest in the two related disciplines of sustainable energy systems and low energy design. Sustainable energy is that which can be obtained either by exploiting energy that is naturally released (solar, wind, tidal, geothermal) or else by tapping a resource which can be readily replaced (for example biofuel, biomass, and hydrogen). Low energy design aims to create a product which provides the same (or better) functionality than its traditional counterpart while requiring less energy to operate, either through system efficiency or integration with the energy sources outlined above. The correct implementation of this approach to phase out traditional means of generation and the level of demand which perpetuates their use would result in a reduction of the harmful emissions as a consequence.

The design, construction and operation of buildings have a significant role to play within this new culture of demand reduction and integration of renewable energy sources into the energy supply infrastructure. The operational energy demand of the UK non-domestic building stock accounts for 17% of the nation’s carbon emissions, with domestic stock accounting for a further 27% [1], the significance of these figures is supplemented by the viability of buildings as a route to both demand reduction and a change in energy provision.

The challenge of implementing this vision of a more energy efficient and less emissions intensive building stock is both technological and organizational. The design of buildings, particularly large scale commercial projects and modern housing developments, is a multi-disciplinary process. It involves a large group of actors and stakeholders as well as a traditional set of design criteria which overlap with the drive for energy efficiency to varying degrees dependent on the nature of the project in question. A need was identified for drivers for industry to consider the operational performance of buildings, whether in terms of efficiency, emissions or some combination of both, as a design constraint of equal importance to traditional requirements such as longevity, safety, comfort and cost.

One initiative that was put in place to encourage the use of these practices was the passing of a new legislation by the British Government in response to the Energy Performance of Buildings Directive(EPBD). The target was to achieve the objective of zero carbon emissions in operation in all new dwellings by 2016. This would be followed by the same requirement for commercial projects by 2019 [2].

This target differed in its choice of metric from the overarching EU directive; which designated the development of ‘Near Zero Energy Buildings’ as the ultimate goal of the legislation [3]. The difference between these two metrics and any impact that it might have on the design process is fundamental to any research into design strategies which has the target of being building industry relevant.

The drive to meet these performance targets, in whichever terms they are couched, is defined by these legislative deadlines. After 2019 it will not be commercially viable to fail to deliver to this high standard of performance. Therefore the progress towards these standards must be made in the interim period; with innovative designs given time to be occupied, used and, if necessary, modified so that when the deadline arrives the building industry can furnish this requirement to the same standard as it currently furnishes requirements of its clients.

The methodology by which a building may be constructed to attempt a “zero carbon” standard is varied and dependent of the traditional design constraints associated with the industry in addition to this new and demanding target. While detailed investigation has been carried out into commercially viable methods of designing a carbon neutral dwelling, direct research into rational strategies for non-domestic buildings are less well

developed. Due to the scale and complexity of most large commercial buildings it can, however, be assumed that they would pose a greater challenge to the designer than a typical family home.

The core requirement of any design solution generated in response to this research problem is that the strategies must be commercially viable methods of producing the required standard of performance. The design choices that define the building must be demonstrated to be robust and any technologies included must be demonstrated to be mature and functional. Within both the building industry and the research community the use of building physics and its sister discipline of dynamic thermal modelling are increasingly leading the way in the design and testing of buildings which seek performance beyond what is considered typical. As such it is essential that the use of these principles form the foundation for any investigation into viable strategies for the design of high performance buildings and as such the identification of the correct simulation tools and detail level will form a necessary component of the research. In addition to identifying the commercial and theoretical constraints of the research problem, the relationship between the concepts and the environment must also be explored. The impact of climate change is a core driver of this branch of engineering research but its relationship with the industry is reciprocal in nature. The emissions produced by building energy consumption are affecting the climate but the climate change is also affecting building performance. The response of building to future changes in climate is an essential area of investigation for any research that seeks to move forward the level of understanding surrounding energy efficient building design.

As the terms ‘commercial’ ‘non-domestic’ buildings encompass an array of different products with disparate uses, layouts and dimensions this research problem required further reduction. In order to narrow the focus of this investigation towards a more manageable yet suitably varied number of potential case studies a decision was made to concentrate on speculative office spaces in their various forms, with the identification of the appropriate building size and form representing a facet of the research. Due to the need for flexibility of use, speculative offices were considered to be a more complex problem than company specific projects as well as offering the potential for more wide reaching findings.

The defining feature of this program of research would be the identification, formalization and testing of those strategies for the performance improvement of buildings in operation which are currently available to the building designer. The contribution to knowledge would therefore be an interrogation and comparison of these design concepts which are typically selected outright or overlooked entirely during a typical design process. In this way an assessment of the ‘state-of-the-art’ can be made which demonstrates which of these approaches is likely to yield successful building concepts and also identifies the challenges facing both the design team and the thermal modelling professional in their testing of these concepts.

1.2 Objectives

Problem: The disparate metrics used to assess the performance of building design concepts lead to a lack of clarity and accuracy in the assessment method.

Objective 1: To identify the most appropriate performance metrics for the assessment of building performance when designing for a sustainable future.

Problem: If designers target the ‘neutralization’ of non-domestic buildings (whether energy consumption or carbon emission) for 2019 then the level of innovation will not be sufficient to ensure a stable design process to this standard going forward.

Objective 2: To investigate the possibilities available to the design team for creating a zero carbon/energy building now with the expectation that the implementation of practical strategies will lead to informed design choices in the future.

Problem: The strategies available to the design team seeking this level of performance are varied and their selection can be based on external factors such as costing or corporate image rather than a reasoned examination of the options available.

Objective 3: To identify those design strategies for building performance improvement which have been publicized within the industry and formulate methodologies for their testing on appropriate case studies in a simulation led design environment.

Problem: The focus on emissions reduction cannot come at the cost of traditional building design requirements.

Objective 4: Identify the traditional key performance indicators (KPIs) for comfort and use that can be measured in a simulation led design process and implement parallel testing of these KPIs alongside the process of performance improvement.

Problem: There is a high level of design replication within the non-domestic sector, particularly non-bespoke office buildings which form part of larger commercial developments. This is tied to the related issue of change of use, whereby office space may be designed with a traditional working week in mind but be occupied under an alternative schedule.

Objective 5: To exploit the flexibility of the simulation driven approach to design to explore the potential risks associated with the replication of successful building designs under different external conditions as well as change of use.

Problem: Climate change scenarios suggest that any buildings designed to be zero energy/carbon should consider the potential impact that the changing UK weather conditions could have on their performance.

Objective 6: Identify climate change scenarios that can be integrated into the testing process and investigate the impact of these scenarios on the markers of building performance.

1.3 Research Methodology

1.3.1 A review of literature

A review of literature was used to define the key performance indicators which would best identify and quantify the sustainability credentials of a commercial building in operation. The review was widened from the research community alone to include design guidance, commercial consultation and UK Government consultancies. This review provided a set of Key Performance Indicators which were used to determine the success of the proposed case study buildings. The broadening of the review also facilitated the development of four distinct strategies for the performance improvement of commercial buildings in operation.

1.3.2 Emulating the design process

The design strategies identified by the review of literature were developed into design methodologies with clearly defined stages, parameters and performance goals dependant on the building fabric and services used and the internal condition sought.

1.3.3 Identification of case studies

The testing of the building design methodologies took was conducted through their application to case study buildings as part of a dynamic simulation led design process. An examination of successful low energy/low carbon buildings was made and appropriately ‘form neutral’ case studies (case studies which would be defined by the design measures enacted upon them rather than some extreme feature of architecture) were established.

1.3.4 Application of design methodologies

The design methodologies were applied to the case study buildings as a means of testing the performance of the methodologies themselves but also the limits of the investigative approach. This approach was itself an emulation of the best practice found within the commercial design environment with the addition of a more diverse set of design options resulting from the application of multiple strategies. This stage of the research was the opportunity to identify which strategies could be confirmed as successful by an approach to testing which is in turn constrained by the use of commercially recognized

and accredited software. The motivation behind this approach was to demonstrate design barriers to making an exemplar case into a rational design solution in regular use within the UK building stock.

1.3.5 Testing of the design solutions

The final designs for those case studies which met the requirements of the KPIs defined by the review of literature were examined under varying internal and external conditions in order to establish the robustness of the solutions put forward. This testing took the form of parameter sweeps encompassing a change in the location, orientation and usage of the building. This process acted as an evaluation of the response of the building designs to replication in conditions other than those found in the location of the original building. These tests were supplemented by the application of predicted future weather data in order to test the viability of the design solutions in a changing climate.

1.3.6 Evaluation of the design methodologies, the proposed solutions and the investigative process

The evaluation of the success of the case study buildings formed the foundation for the discussion of findings but the analysis also encompassed the success of the design methodologies themselves and the viability of the use of commercial software as a means of deepening the investigative capabilities of the commercial design process.

1.4 Summary of thesis

This thesis consists of seven chapters as described in Figure 1 below:

Figure 1: A breakdown of chapters and subchapters contained within the thesis Figure 1 also denotes the points in the thesis where the objectives of the research project are addressed. A red arrow denotes the identification of information, concepts or points

of best practice leading to the meeting of an objective. A blue arrow denotes the production of results data relating to the meeting of an objective.

The structure of the thesis is one of chapters which address the research process as applied to the problem and document the meeting of the research objectives. The chapters are broken into subchapters where necessary, and a summary is included at the start of that subchapter for reference.

1.5 Case Study Buildings

The focus of this research is the design of speculative commercial office spaces. These are buildings which are developed for rental or sale as generic office space which is then put to use by the client or tenant. This class of building was targeted due to the potential diversity of usage patterns and occupancy densities, combined with the need to design and build in a cost effective manner. The design and construction of marquee commercial buildings and individual exemplar buildings affords the design team more licenses for alternative solutions and capital investment. Cost effective design is implicit in the development of speculative office space. This allowed the research project to consider the potential benefits of applying a simulation led design process to buildings which were typical rather than extraordinary and replicable rather than unique (it should be noted that the term “replicable” used in this context throughout the thesis refers to facility to design a building solution for a client and subsequently adapt and reproduce that solution for future projects at a reduction in design cost and uncertainty).

For the purposes of the research, it was also necessary to define what constituted an office space and what constituted the required supplementary spaces in an office building. Due to the broad spectrum of specific solutions used in the commercial building market a set of existing offices of various types were investigated in order to extract some basic criteria. The buildings were selected on the basis of being identified as office buildings which had achieved some level of energy efficiency by exploiting one of the design strategies described and evaluated in the literature review. While cases such as the Interserve Passivhaus office [4] demonstrated a design strategy which ultimately formed one of the four case studies considered in this program of research, it was considered too small to form the basis of a generic case study building. Conversely, the building employed by the Target Zero [5] study was a prestige central London

headquarters building with little relationship in form to the simple layouts found in office parks. It was concluded that rather than sourcing an existing building layout it would be more useful to create a generic layout such as those used in the Green Building Council study [6]. The level of detail applied to these generic layouts needed to be increased in order to accommodate the more detailed design and simulation methodology that would applied in this program of research. Using accepted design data for offices that may employ natural or mixed mode ventilation a typical subdivision of open plan space of 8m x 8m x 3m was defined [7] [8], though this was modified where necessary to ensure the best simulation strategy.

2. Literature Review

2.1 Background

This subchapter introduces the core principles used in the design and thermal simulation of buildings. It reflects on the role these principles play in the design of the building form, fabric and systems and finally discusses how these principles are developed into methods of analysis of appropriate for design and research.

2.1.1 Building Services Engineering

Building services engineering is the umbrella term for all engineering practices associated with the mechanical and electrical performance of a building [9]. This includes the design of mechanical systems for the provision of key services as well as the associated practices of façade engineering, fire engineering, IT and communications services and sustainability and low and zero carbon (LZC) technologies. In the context of this research problem it is those aspects of building services which are concerned with the design and testing of the form, fabric and mechanical services as well as the implementation of low and zero carbon technologies which were of interest. The emulation of design strategies that are used in industry to implement the best practice within these subsectors of building design was outlined as core deliverable of the program of research (see Objective 3).

The design of lighting and plumbing is typically carried out in parallel to the design of the heating, domestic hot water, cooling and ventilation systems but often by a different engineer or engineers within the design team. This gives rise to the term Mechanical, Electrical and Plumbing (MEP) Engineers with reference to building services design. The relationship between these sectors traditionally results in close collaboration on projects [9] but a high level of transparency is necessary in order to facilitate design that can meet the intensive targets set by the Energy Performance of Buildings Directive [3].

The role of the building physicist is to provide the design engineers with information on the impact that their choices will have on the overall thermal, energy and emissions performance of the building as well as the investigation and testing of any design concepts which are novel or indeed new to the design team at large [10]. 32

2.1.2 Heat and mass transfer

The principles of heat and mass transfer are the foundations upon which building services design decisions are made. These principles lie at the heart of both mechanical building services engineering and Building Physics and as such any design of an energy efficient building must start with an understanding of how they impact on design. A successful building will create and maintain the desired internal condition through well- chosen form, fabric and building services. These choices must be informed by an understanding of the thermal properties of the components and the impact on the air space contained within the building.

Information on the relevant concepts and how they relate to this research project are included in this section of the thesis. For more detail on the specifics of heat transfer processes the reader is referred to Fundamentals of Heat and Mass Transfer (Incropera et al 2007 – 6th Edition) [11]. For more detail on the use of the principles of heat transfer in building design the reader is referred to CIBSE Guide A (CIBSE 2007) [12].

2.1.3 Design and simulation tools

2.1.3.1 Calculation

The design of building services is traditionally carried out through the use of sequential calculations backed up by empirical data gathered from real cases and laboratory research. This process begins with the calculation of the heat losses and heat gains for the building as these inform the size of the heating and cooling services respectively. The heat losses are defined by the sum of the losses through the fabric (walls, ground floor, roof, windows), infiltration (unintended air movement through the building fabric) and ventilation (designed air movement through the building fabric). Heat gains are determined by heat gained through the same phenomena but also from solar radiation and the presence of sources of heat within the building (artificial lighting, equipment, people).

Figure 2: Heat and mass transfer processes in a building (image created by A Mitchell - 2012).

CIBSE provide the UK industry standard practice for this approach to design and further details can be found within CIBSE Guide A, (CIBSE 2007) [12].

2.1.3.2 Steady-state simulation

The next level of detail for the design team seeking to understand the behaviour of the building and the prospective services is the use of a steady-state calculation tool. These tools are typically used in the testing of compliance with building regulations (UK SAP for housing [13] and Simplified Building Energy Model (SBEM) for non-domestic [14]) or design towards an accreditation standard (Passivhaus Planning Package (PHPP) [15]). They function as a collection of the linear calculations used in design but consider the behaviour of the building at a series of conditions (SBEM for example uses a day a month method [16] for a whole year analysis of energy consumption and carbon emissions).

These programs are computationally inexpensive and simple to use, however they have more in common with paper and pencil methods than with the more advanced dynamic models which have superseded them in the design and accreditation of complex buildings [17] [18].

2.1.3.3 Dynamic simulation

The modern building design team is increasingly likely to employ the use of dynamic simulation both as an aid to design and as a means of checking compliance with the UK building regulations. These simulations are conducted using software suites which are available for both the research and commercial markets, with some cross-over in usage when working on innovative design concepts (see Section 2.2.5 for further details on how a simulation package was selected for use in this research project).

This process varies fundamentally from the use of calculations or even steady-state simulation as the latter both consider the average thermal behaviour of the building over a period of time whereas dynamic simulation considers the varying thermal behaviour of the building over a period of time. Specifically, the dynamic simulation package considers the relationship between the characteristics of the model at the previous moment and at the current moment. It can also consider the relationship between several areas of a building at the same time, rather than modelling the isolated behaviour of each area in parallel. This last is called multi-zone building simulation and is the cornerstone of the modern simulation package [19]. It is these more complex, time dependant, relationships between the building systems and elements that give rise to the greater degree of accuracy in the output and allow the simulation package to examine the impact of phenomena such as thermal mass (see Section 2.3.3.4) and natural ventilation (see Section 2.3.5.1). The ability to identify points of interest within the period of building occupation after the fact, rather than pre-targeting certain external or internal conditions as points of interest allows the building designer to identify such phenomena as conflicting heating and cooling systems (where both heating and cooling are acting on a zone either directly or through a boundary surface) and overheating in non-cooled spaces (the internal temperature has exceeded the standard maximum for the activity to be performed within the space).

The accuracy of the dynamic thermal simulation method was explored by the IEA Annex 21 as early as 1994 [20] when the software available at that time was tested against a variety of case study buildings with inconclusive results attributed to failure of monitoring procedure and model instability. There has been significant progress in the field in the intervening years and the IESVE is now validated [21] by both CIBSE, through the application of Technical Manual 33 [22] and ASHRAE 140 [23] [24] [25].

It should be noted that while this validation has given strong credibility to the use of dynamic simulation packages, the quality of outputs remain dependant on accurate inputs, appropriate application and an understanding of the limitations of the software.

For more information on the underlying theory of building simulation the reader is referred to Energy simulation in building design (Clarke JA 2001 – 2nd Edition) [26] as this is widely regarded as the seminal text on the subject.

2.1.4 Dynamic simulation in commercial practice

The process of building design and construction in the UK is governed by the Royal Institute of British Architects (RIBA) Plan of Work and the associated RIBA Stages [27]. In the current best practice the building design team would collaborate to meet the needs of client, project and legislation as denoted at the current RIBA stage. In recent years, overlays have been provided to the RIBA Plan of Work to encourage the correct application of modern design tools and techniques, including but not limited to sustainable design [28]. The structure of the RIBA stages for Preparation and Design are included in Figure 3. The information for this figure was extracted from the RIBA Plan of Work [29] and the Green Building Overlay [30]. Also included is an annotation by this author which demonstrates the how the creation of a “simulation led design process“ (as required in Objective 4) was achieved in this research project and how it might translate to industry.

Figure 3: RIBA Stages for design, with 'Green Building' Overlay and annotation [29] [30].

In the typical application of the recommendations detailed in Figure 3, the impact of thermal simulation at the concept stage of the design would reflect the detail as specified by the architects and design engineers up to that point. The use of simulation would be primarily to explore the compliance of the building with Part L of the Building Regulations and to make some design recommendations.

The approach proposed and examined in this research project was to “move ahead” of the Concept Design stage and explore in more comprehensive detail the design options available, their impact on the energy consumption and thermal comfort of the building and the potential impact of changes in external and internal condition. The benefit of this approach in a research context was to demonstrate how effective the application of current design strategies for achieving near zero energy building status would be when applied to typical speculative commercial office buildings.

The potential benefit to industry would be to encourage more ambitious and rigorous design of buildings through the testing and feeding back of the projected performance of alternative designs. This would stand in contrast to the development of a single design which is then modified to meet the requirements of Part L or, in some cases a more stringent target set by Building Research Establishment Environmental Assessment Method (BRREAM) targets or client requirement.

2.2 Emissions and Energy Demand

This subchapter discusses the Key Performance Indicators (KPI) associated with emissions reduction and energy efficiency during the operating life of commercial buildings. It goes on to make the case for the near Zero Energy Building (nZEB) standard as the most appropriate for this study. It also examines the role of UK Building Regulations compliance, third party accreditation and the use of building simulation on the design process.

2.2.1 Defining “zero carbon” building performance

The use of emissions based criteria to define the success of a sustainable building is deeply ingrained in both the UK government legislation and the nomenclature of the research fields of sustainability and building physics. The difficulty with this target lies not with its comprehension as a lay term, but rather in its viability as a design metric or even as a scientific definition.

The CIBSE Guide L defines Zero Carbon (ZC) in operation within the field of building performance:

“The zero target relates to net emissions over the course of a year. It allows energy use on site giving rise to CO2 emissions as long as this is balanced by the export of energy that abates an equivalent quantity of CO2.” [31]

This definition is relatively clear in stating that “zero carbon” as a measure of building performance is defined annually and processes which are not carbon neutral can be offset by the provision of emission free generation at other times. In contrast to this, report by the UK Green Building Council in 2007 offers five potential definitions for “zero carbon” including the definition offered by CIBSE (option 2 below). These are reproduced as follows:

1. “Self-sustaining site (i.e. a site aiming to use no gas or electricity other than that generated on the site).

2. Annual zero carbon building balance. The building produces and exports sufficient zero carbon electricity (or possibly gas in the future) over the year to

compensate for the carbon emissions resulting from all electricity and other fuels used on the site.

3. Annual zero carbon with directly connected near-site renewables.

4. Annual zero carbon with UK off-site renewables.

5. Annual zero carbon with UK or international carbon offsetting.” [32]

This is significant as the report in question was the first stage of a wide reaching consultation process which led to the current 2010 Part L (conservation of fuel and power) of the Building Regulations for England and Wales. The Regulations themselves offer no specific definition of “zero carbon”: however, the output of the National Calculation Method (NCM 2010) for establishing successful emissions reductions is defined as a Building Emissions Rate (BER) which should be less than a Target Emissions Rate (TER) if compliance is to be demonstrated [33]. The Building Emissions Rate represents the projected performance of the actual building with fuel types of set emissions factors attributed to values for energy demand found through calculation or simulation. The Target Emissions Rate represents the performance of a building of like use and the same construction that represents a typical case (see section 2.2.4.1 for more detail on the UK Building Regulations) [33].

2 In this method the metric used for the BER/TER comparison is kgCO2/m yr. It would be logical to suppose, then, that the UK definition for “zero carbon” performance would be a BER of zero. This supposition has in fact been challenged, however, with commercial research projects demonstrating that a further 46% reduction in Building Emissions Rate is needed to make ‘true’ zero carbon, including small power emissions, which form 32% of this target but remain unregulated [34]. This ambiguity is further compounded by the use of standard carbon metrics for various fuels, which themselves are subject to debate and error.

As a result of this lack of clarity, the focus of this research was shifted to the European model of a ‘near Zero Energy Building’ (nZEB) [3]. This is a building which essentially achieves a net yearly energy demand of zero through the use of demand reduction strategies and appropriate renewable energy sources.

2.2.2 Defining “near Zero Energy Building” performance

Article 9 of the recast Energy Performance of Buildings Directivesets a requirement for near net zero energy buildings by 2020 with evidence of interim progression by 2015 in the commercial sector [3]. This target is in line with the long established UK targets for zero carbon but its adoption by CIBSE [3] and BREEAM [35] has defined it as the definitive metric going forward. Whilst emissions as assessed by the UK compliance procedure remain relevant for industry context and have been addressed throughout this research, the classification of the success through energy consumption per square metre of floor area was determined as the appropriate assessment criteria for this research.

It was also noted that the concept of ‘primary energy’ has been cited as increasingly relevant in the field of sustainability and particularly where buildings are concerned [35] [36].

Primary energy is the energy found in the raw fuel sources used for generation of heat and electrical power, rather than the ‘delivered energy’, which is the energy supplied to meet the demand.

In this instance the issue with primary energy comes from the fact that any energy generated on site (through renewable sources) or saved through energy efficiency measures is an absolute value, whereas the demand that is left to come from the grid assumes 100% efficiency of generation and supply, which could be extremely misleading. For example, in the context of localised versus centralised electricity generation, a combined heat and power (CHP) unit might generate electricity at an efficiency of approximately 35% when compared to primary energy input, in addition to heat at approximately 65% (values illustrative from industry data [35] [37]). In comparison, the true efficiency of a traditional coal fired power station would be approximately 40% [35], meaning that the efficiencies for electricity generation are comparable, neglecting the heat energy gained from the combined heat and power unit; which can used to meet space heating or domestic hot water demand. It was clear that this metric provided an increased degree of context to the value of on-site generation and would be a more prominent part of legislative decisions going forward and as such was addressed in the analysis of results in this research. It was noted, however, in Phase 3 of the Green Building Council report on non-domestic zero carbon buildings [36] that

simply replacing an emissions standard with a primary energy standard was repeating the same simplification process and risked leading the hand of design teams. The requirement for a KPI that demonstrated the ‘sustainability’ credentials of the buildings superseded this concern and the application of primary energy facilitated this without confusion between the emissions predictions of the Part L dynamic simulation and those that could be calculated from the more robust and detailed thermal models developed in this program of research. As such the use of primary energy in the analysis of any findings was used to offer context on design choices and the providence of energy consumed by the building.

Ultimately, by refocusing on energy consumption, the EPBD and BREEAM have targeted the reward of efficiency and build quality, rather than the simple application of renewable energy sources to buildings of middling performance in order to offset carbon emissions. The application of renewables should be considered, but after attempts to reduce the energy consumption have been made through the application of good design.

The improvement of building performance through the application of a series of thermal simulation driven design methodologies was the foundation of this research project. It was therefore considered useful to present and assess the performance of the case study buildings in a form which demonstrated the efficacy of the measures implemented.

2.2.3 On-site renewables

The use of on-site renewables is a necessary consideration when attempting to achieve near zero energy performance and indeed Article 6 of the recast EPBD has made its consideration mandatory [3]. It has been observed, however, that not all renewable energy systems need to be directly integrated within the building design, and that the constraints for their application are cost and planning based rather than architectural or building services design based. Several studies have used the output of wind turbines and photovoltaic panels as baseline assessment for the value of performance improvement measures; that is to ask the question - is it cheaper to acquire a low or zero carbon energy source than to improve the building beyond regulated standards? [34] [38]. The fact that these studies found that demand reduction was needed in order to size renewables cost effectively and the focus of the EPBD and BREEAM on demand

reduction and energy efficiency in building means that non-integrated renewable sources can be considered as a retrofitted measure and separate from this research. Systems which employ a renewable component, such as heating using solar hot water, combined heat and power units or heat pumps fall within the remit of the research as they form a reciprocal design relationship.

2.2.4 Compliance and Accreditation

2.2.4.1 L2A 2010

Part L of the UK Building Regulations for England and Wales is concerned with the ‘Conservation of fuel and power’. As stated in Section 2.1, this requires the setting of carbon emissions targets for new buildings and refurbishments in England and Wales. The current 2010 document is the latest stage in a sequence of progressively stringent regulatory requirements intended to achieve a required a so called ‘zero carbon’ standard (as stated above the exact definition of this metric has not been defined at the time of this research) by 2016 in residential buildings and 2019 in non-domestic buildings [39]. The document within Part L 2010 which is relevant to this research is Approved Document L2A 2010. This covers the requirements for new building non- domestic buildings (under which remit new commercial office spaces fall). The document contains a primary requirement that the design gives a Building Emissions Rate (BER) of less than a Target Emissions Rate (TER). The TER is defined by the modelling of a similar, notional building which is a

“………building of the same size and shape as the actual building, constructed to a concurrent specification” [33].

This assessment was enacted to allow the regulations to establish that an aggregated 25% emissions reduction (that is across all sectors, with some buildings required to achieve a higher performance improvement than others) had been achieved over typical designs that were compliant with the requirements of the previous version of Part L2A [40]. The secondary requirements of Approved Document L2A 2010 are limiting factors on the performance of fabric and systems within the building and a solar gain check [41]. The purpose of including these checks was to ensure that the performance improvement was produced by good design and not by an exploitation of the testing procedure. A building which meets these criteria should not exploit levels of heat loss or 44

solar gain which in reality would not represent good design (particularly with regard to occupant comfort) but rather should reach the energy efficiency standards through control of the internal condition with the minimum expenditure of fuel and power.

While the use of an accessible testing method for the performance of real building designs is an essential component in Part L 2010, the methods outlined above have several issues which suggest that using this ready provided set of tests for the assessment of building design performance in a research environment (even one which targets ‘rational’ commercial strategies) is not appropriate as they are comparative markers of performance designed to drive improvement rather than to test the success of a specific innovation or design feature.

The inaccuracy associated with a unified ‘carbon’ metric as a KPI has been addressed and designing to meet such a criterion (particularly when no definition of absolute ‘zero carbon’ is found within the documentation) could be expected to prove a distraction within commercial design practice. The desire to meet regulation and accreditation standards is strong within the construction industry, but there is little need to represent this in a research context, particularly as a driving force of the study, when the targeted level of performance is significantly beyond that which is required to meet the current standard.

2.2.4.2 The National Calculation Method (NCM) and Simplified Building Energy Model (SBEM)

The delivery of a unified standard of building energy and emissions performance for UK buildings is facilitated by the National Calculation Method [42]. While it has been established that there was little to be gained by taking on all the assumptions associated with this method of assessing buildings simply for convenience or even context it was also acknowledged that significant time and resources were placed into this system and much of the data and assumptions were well sourced and potentially relevant to this research.

The National Calculation Method takes the form of a simulation methodology which can either be applied to a set of empirical calculations (the Simplified Building Energy Model (SBEM)) or to a dynamic simulation package that has been accredited by the UK Government for use with Part L2A 2010 [33]. The former tool was designed with 45

simple buildings in mind and solely for the purpose of confirming compliance with Part L. In brief, SBEM generates the notional and actual building performance data using a series of monthly “design day” calculations for heating, cooling, domestic hot water, auxiliary energy values and lighting specification. The tool does not consider the effects of adjacent spaces or complex features such as the architectural design options that are addressed in this research [16]. It is the simplest and strictest interpretation of the National Calculation Method and was completely discarded from this research as being irrelevant to the design of commercial buildings of significant size and complexity. This is considered to be particularly valid when said buildings employ design strategies which are atypical and / or technologies which are dynamic in nature and intrinsic to building performance.

The application of the National Calculation Method to a dynamic simulation was considered of more relevance to the program of research as it uses the same tool set as is typically used in the design of large scale commercial projects; with models initially built for design testing imported into a “compliance checking” module within the suite in order to establish whether the design meets L2A criteria. In fact, in cases where the performance of a large building under L2A conditions is marked as the determining factor in the allocation of resources (that is, a building whose designers seek to achieve compliance with L2A, already being confident of comfort and behaviour and not interested in further performance improvement) there may only be a model for compliance checking purposes.

The opportunity for cross referencing between a design model and a compliance model was considered to be a useful line of enquiry (again, the influence of the compliance checking process on the pursuit of low energy demand and low emissions buildings was a recurrent theme throughout the review of literature). This comparison would allow the research to compare the performance of the design methodologies under testing with perceived carbon emissions as rated by Part L2A 2010 without using the NCM as the core testing methodology.

The data available within the National Calculation Method databases was also identified as material of value to the program of research. The minimum levels of performance that are set by L2A and found in the National Calculation Method for U-values, system efficiencies and occupier influence (occupancy of the building, internal gains from 46

lighting and equipment) were established through rigorous research and offer the opportunity to benchmark certain basic requirements. The constraint that compliance applies to the design process could therefore be exploited as a point at which to begin enquiry into the benefits of performance improvement. A building which has no extraordinary strategy for the manipulation of its thermal mass, for example, has no reason to violate the basic insulation requirements for a building envelope under L2A as defined by the U-value requirements set out in the documentation [41]. The value of improvement of U-values beyond current standard practice was considered an area of interest for the research as a whole and features to some extent in all of the design methodologies explored herein. The value of contesting the minimum standards of current practice was considered of less value and the National Calculation Method offered a level of benchmarking which is universally recognizable within the UK building industry. As such when there were instances within the research program where an assumption was required for a minimum value or data for the performance of a secondary space (for example the specific fan power of a toilet extract fan) the first point of address for this data was the National Calculation Method.

2.2.4.3 Accreditation schemes

It should be noted that constraint of compliance on commercial buildings in the UK does not originate solely from the need to meet the requirements set out in Part L2A 2010. There is also move towards the use of third party sustainability assessment schemes such as the Building Research Establishment Environmental Assessment Method (BREEAM) [43] and the Leadership in Energy and Environmental Design (LEED) method [44]. Whilst a detailed review of these schemes fell outside the remit of this study, the impact on the definition of KPIs for Near Zero Energy Buildings in the commercial sector was considered a relevant area of investigation. Lee et al [45] suggested that there was little difference in the impact of the scheme chosen, but rather that there was a benefit to following a scheme. These findings reflected the comparison of schemes using the 2004 issues and buildings seeking a level of sustainability (including energy performance) which would be desirable during that time frame. The current (2011) version of BREEAM has been significantly reworked to reflect the more stringent demands placed upon design teams and to make use of the evolving nature of compliance software [46].

The impact of BREEAM was considered particularly significant, both due to its popularity and the method of performance assessment found in the BREEAM 2011 requirements for new commercial buildings. The BREEAM credits allocated for energy (19% of which are determined by energy, with a further 5% available through innovation in energy [47]) are closely tied to the NCM methodology, which further drives the need in the building industry to follow the path of achieving compliance and then considering further benefits as a secondary issue. As has been established in this review, this approach is not viable for the testing of designs which hope to achieve high levels of performance: however the impact of a BREEAM assessment goes beyond the need to meet minimum targets. A building seeking sustainable credentials which can be advertised commercially will seek BREEAM and as such the National Calculation Method, which was designed in the first instance to represent the moderate performance improvement required by Part L2A 2010 would be required to represent a more extreme example of performance and furthermore to produce three forms of output rather than the typical overall carbon value. The energy credits (emissions) in BREEAM 2011 constitute 15 out of 30 credits for energy (plus 5 innovation credits) [47]. The BREEAM guidance chart has been reproduced in Figure 4.

Figure 4: BREEAM credit distribution for CO2 emissions [48].

The three values required from the NCM 2010 calculation in order to make this assessment are given in Table 1 [46] [49] [35].

Performance Original New NCM Output Units Indicator weighting weighting Actual and Notional Energy Energy Demand MJ/m2 0.28 0.25 Demand Actual and Notional Energy Energy Consumption kWh/m2yr 0.34 0.41 Consumption 2 CO2 emissions BER and TER kgCO2/m yr 0.38 0.34

Table 1: BREEAM Energy efficiency and carbon criteria [46] [49] [35]

This dependence on the National Calculation Methodology for a secondary set of data and particularly one which is highly significant in the current building market, further reinforced the need to account for its impact on the process within the research methodology. A further investigation by BRE in 2012 demonstrated that in order to comply with Article 9 of the updated Energy Performance of Buildings Directive [3] a change was made to the weightings used in assessing the value of the three performance criteria which shows an increased level of importance being placed on energy consumption over carbon emissions [35].

This approach also demonstrated that while a move was being made towards a more clearly defined energy based standard once again there was a clear lack of a definition 2 for ‘zero carbon’. Figure 4 clearly shows that a BER of 0kgCO2/m yr equates to ‘zero carbon’ within the BREEAM methodology, a statement that is not supported explicitly in the Part L2A 2010 documentation and is in fact contradicted in research [34].

The BREEAM assessment of emissions in its updated form draws attention to the perceived benefit of demand reduction and particularly consumption reduction as methods of reducing levels of CO2 and encouraging sustainable building practices. In this case ‘demand’ is characterised as the energy required to meet the comfort temperature requirements of the occupied spaces and ‘consumption’ [50] is the amount of energy consumed by systems when the building is in operation (this includes heating ventilation and air conditions systems, domestic hot water and lighting). The former is considered a test of good form and fabric design and the latter of good system selection and configuration.

The investigation into the impact of BREEAM 2011 as a constraint on the development of ‘zero energy’ buildings in the UK ultimately concluded that the need to emulate the ratings scheme directly in the research program was not apparent:, however, the motivation to encourage the investigation of multiple Key Performance Indicators for building performance was of definite value both to the program of research and the building industry. The main issue with this approach as a driver for change and as a consideration in a robust and forward thinking design process is the use of the National Calculation Methodology. The potential for this use to further the cause of seeking to meet targets set by a system designed to provide comparison with a typical design, rather than to rate success in absolute terms, is a risk to the progression of designs which seek to implement innovation whilst achieving compliance as a matter of course.

2.2.5 Simulation and design

The use of simulation software as a design tool has already been demonstrated as being intrinsic to the commercial building process due to its connection with compliance testing for Part L2A 2010 [33] and BREEAM [46]. The use of whole building thermal simulation models as a design tool is also gaining popularity due both to increasingly onerous statutory energy efficiency standards and to a growing interest in the exploitation of building physics and passive design strategies in the development of high quality buildings.

Thermal simulation software originated as a research tool, facilitating the exploration of alternative design strategies and component selection for individual building cases. The evolution of both the research software such as TRNSYS [51] and ESP-r [52] as well as more commercially aimed packages such as Energy Plus [53], IESVE [17] and TAS [18] permitted a more standardized process to be enacted which in turn increased the impact on the commercial building industry [54]. At the time of writing, the development of building simulation software is still on-going, with regular updates and user defined functions being made available to the research and building physics communities. The relative stability and popularity of the commercially orientated suites has however afforded the opportunity to establish cross over between commercial and research interests, and that was the case with this program of research.

The use of simulation in the design process offers the designer and researcher the opportunity to explore the performance of the building as a whole as well as addressing in some detail the impact of specific design choices. The design of building fabric and systems through the use of empirical calculation is a standard process in the building industry as the requirements of the occupants in particular must be considered at the most extreme conditions likely (in terms of heating, cooling, lighting, air quality and hot water requirements). The opportunity offered by dynamic simulation is to understand the relationship between these extreme conditions and the building as well as whether these levels of demand are a spike or representative of constant demand.

The investigation of the former offers the opportunity to identify areas of weakness in design so that the overall peak demand conditions can be reduced to a more acceptable level. The latter allows the building designer to understand the relationship between the requirements of the occupant and the requirements of the building and adjust controls and parameters accordingly. This ability to ‘tune’ a building design so as to achieve the required performance standard, rather than simply fitting it to handle worst case scenarios has been strongly linked with increased energy performance through demand reduction and more efficient delivery [55].

2.3 Demand reduction and energy efficiency

This subchapter considers the technologies and design choices available to the nZEB commercial building designer. It includes a review of the state of the art in form, fabric, space conditioning, ventilation and lighting. It also includes a review of the state of the art in those LZC technologies which fit into the remit of the research program.

2.3.1 Introduction

The technologies available to the building designer seeking to reduce the energy demand of a building are numerous, diverse in nature and variable in efficacy. In this research, consideration has been given to those which are believed to be commercially viable for the design of a net zero energy commercial office space. Research into the performance of individual measures and technologies within this field has been extensive and it was considered of importance to establish the perceived wisdom of those which play a fundamental role in some or all of the design methodologies under investigation. Those technologies which are specific to the case studies are explored in more detail in the results for that case study.

There is a cross over between good building design and energy efficiency which predates the desire to reduce emission rates. Exploiting technologies which suited this design remit was considered essential in order to achieve the required level of performance and to represent the commercial design process. The goal of this research project was to offer ‘rational’ strategies but also to offer a counterpoint to the drive to assess the success of those strategies against accreditation and compliance procedures which are simplified tools which risk failing to reward good design practice to the same degree as good component selection.

2.3.2 Building Orientation

The site and orientation of a building has significant impact on its thermal performance. It will define the nature of its relationship with daylight and weather conditions. Client preference, other buildings, natural features, access and architect and engineer insight can all have an influence on the building orientation.

Due to this multitude of influences, it cannot be assumed that complete control over the orientation of the building can be afforded to the design team at all, or with energy efficiency particularly in mind. However, conventional wisdom suggests that a commercial building seeking to maximise natural light should face south with shading at any east or west facing windows [56]. This classic design recommendation formed the basis for the investigation into the impact of orientation found within this research. This impact was anticipated to be far reaching and a defining constraint on the effectiveness of pre-designed archetypal solutions to the near zero energy building problem.

2.3.2.1 Daylight

A well-designed building will exploit daylight to its advantage, both as a source of free heat and of good quality illumination. The exposure to daylight within the building determines the behaviour of any dimming controls and has an impact on the thermal performance of the building. There has been extensive industry testing of the impact on building performance in this area that demonstrate that daylighting strategy should affect the choice of glazing allocation and building orientation rather than be examined reactively, after the fact [8].

This data has been supplemented by research into more advanced methods of exploiting daylight as a means of reducing energy demand from lighting and mechanical systems. These methods are themselves relatively mature within the industry with substantial research data available on their performance.

Altan et al [57] found that the inclusion of an active façade in a UK office building (university administration) resulted in a successful increase in both advanced natural ventilation performance (with solar gains driving the stack effect) and enhanced daylight performance. This was noted with the caveat that the design had a risk of glare, with traditional blinds not proving to be a sufficient solution.

A shallow plan office which exploited a daylight heavy design and attached an appropriate dimming control to its space lighting could expect to receive energy savings of up to 60% over a traditionally configured equivalent according to a simple daylight level design tool developed by Ihm et al [58]. The use of ‘daylight guidance systems’ (also known as light pipes and solar chimneys) to provide a similar level of performance

to the core areas of deep plan buildings was demonstrated to be feasible in terms of design but potentially non-cost effective by Mayhoub et al [59].

2.3.3 Form and Fabric

The improvement of the building form and fabric to maximise the impact of the desirable external conditions and minimize the impact of the undesirable is fundamental to good building design.

2.3.3.1 Building Fabric - Insulation

The thermal transmittance of construction materials (or its U-value) governs the movement of heat through the building fabric [60]. Building insulation is defined as materials placed within the construction for purposes of controlling the thermal transmittance of the building envelope [61]. The use of appropriate insulation is essential to the creation and maintenance of favourable thermal conditions within the building. A highly insulated building offers the designer more direct control over the internal temperature but also places increased responsibility on the designer to ensure that the temperature is appropriate. The maintenance of favourable conditions is offset by the risk of the creation and exacerbation of unfavourable conditions, for example overheating due to poorly controlled solar gains (see Section 2.3.2.1). The reduction of heating demand should not come at the expense of an increased level of cooling demand. Particularly undesirable is a situation whereby the addition of insulation results in a need for cooling where none was required before.

Insulation also has an impact on the hygrothermal regime within the building [56]. If a building has been designed with an insulation strategy that relies on mechanical ventilation to ensure the airflow required to prevent condensation then failure of systems can result in severe building damage (damp, mould, rot) [56].

2.3.3.2 Building Fabric - Glazing

Glazing carries the same design constraints as for any opaque building fabric; as any decrease in thermal transmittance within a window will similarly affect the retention of the current internal condition. Typically, the U-values of glazing are significantly higher than that of wall constructions; the standard L2A 2010 requirements for the U-values of external walls is 0.35W/m2K in contrast to 2.2W/m2K for windows (excluding blinds,

curtains or shutters) [41]. There is an additional property of interest which is the solar transmittance (determined by the G-value; BS EN 410) [62] which determines the amount of solar radiation that penetrates the window, which in turn determines the solar heat gains associated with daylight. This further demonstrates the impact of orientation and daylight strategy as discussed above, as there is a trade-off between heat losses through glazed constructions and heat gains as a result of solar radiation which must be balanced in order to minimize heating and cooling loads.

2.3.3.3 Building Fabric - Air tightness

Air infiltration through the building fabric is a vital performance parameter as it impacts upon the heating and cooling loads, ventilation demand and air quality within a building. The air permeability of a building is measured by a pressure test which is carried out on the completed building.

The building is sealed (both passive and mechanical ventilation openings as well as windows and doors) and any HVAC services shut down. Test fans are then used to supply air until the building reaches a pressure of between 50-100Pa. Finally, the pressure is increased incrementally by approximately 10Pa by an increase in fan speed. The fan power and the pressure difference between the outside and inside can be used to calculate the air permeability of the building [63]. Further information on the practical process of testing and the calculation method can be found at http://www.attma.org/ [63].

The volumetric flow rate of air leakage (given in m3 per hour) per m2 of exposed surface area is given as the parameter for air infiltration rate. The minimum performance for building regulation (L2A 2010 compliance is 5m3/m2.h @ 50Pa [64]) but it is the responsibility of the construction team to build to the required quality to meet the standard. The standard of airtightness required is usually defined by cost and going beyond typical best practice for a construction type must be justified. The Passivhaus standard is an exception as it holds a high level of air tightness as one of its core tenets, with infiltration rates as little as one tenth of that associated with typical best practice [65]. The impact of variations in air tightness can be investigated through dynamic building simulation.

2.3.3.4 Building Fabric – Thermal Mass

The consideration of thermal mass is fundamental to building design. The term thermal mass refers to the heat energy storage capacity of a material. The thermal mass of a construction is defined by its thermal capacity (J/K) but also its admittance:

“The admittance value of a construction element provides a useful indication of its thermal mass. High values indicate a high thermal mass and vice-versa. ‘Admittance’ describes the ability of a material or construction, such as a wall, to exchange heat with the environment when subjected to a simple cyclic variation in temperature, which for buildings is 24 hours.” [66]

This behaviour can be exploited by the building designer to create and preserve favourable conditions if the thermal mass is sufficient. Conversely, a building with low thermal mass will be more responsive to changes in air temperature, which might also be of benefit to the designer, particularly if the building in question has an unpredictable level of occupation or is used for a variety of activities.

It is important to note that thermal capacity is not the same as insulation and in fact most insulation has a low thermal capacity due to the entrapment of air or other gases. Equally it should be noted that thermally lightweight and structurally lightweight are not always analogous. A building with high thermal mass will usually be a heavyweight construction, unless non-structural mass is included after the fact, but only exposed materials can absorb heat from the air or radiation and the addition of false ceilings, finishes and carpets can result in a structure which is thermally lightweight regardless of building material [66].

2.3.4 Space conditioning

2.3.4.1 Heating

When considering a building in the UK climate the design of a suitable heating system is a major component of both the building services and sustainability strategies of the project. Oughton and Hodkinson state that the “..number of heating systems is almost unlimited if every combination... is considered” [67], meaning that it is more appropriate for the building designer to consider each system on a case to case basis before assigning one to a building. This was the course of action followed in this 56

research and detailed examinations of each heating system used can be found with the case study in question.

There are, however, certain concepts which were addressed with regard to the selection of systems for a given case. Oughton and Hodkinson also state that heating systems may be broadly broken up into two categories [67],

Namely Direct Systems which convert the source of energy acquired directly into heat in the place where it is required and indirect Systems, that convert the energy which has been acquired into heat and then send the required amount to the location of the demand. Typically, indirect systems are used in commercial settings due to economies of scale and workplace safety.

2.3.4.2 Comfort Cooling

Not to be mistaken with air conditioning (see below), comfort cooling is the treating of the air in a room in order to maintain a comfortable air temperature. The cooling device need not form a component of the centralized ventilation supply and indeed can be used in conjunction with a natural ventilation strategy. Comfort cooling systems can be room based or centralized depending on type and have become increasingly popular as efficient means of providing small amounts of cooling when ventilation and passive design is not sufficient [68].

2.3.5 Ventilation

As with space heating, correct design of ventilation provision is essential in any building for energy efficiency and comfort. Ventilation constrained by the geometry of the building but certain criteria must be met. A fresh air requirement of 10l/s/person is considered a minimum to ensure occupant health. Any required cooling effect that may be sought will require further supply. A poor ventilation strategy can account for up to half of energy wastage within a building [69].

2.3.5.1 Natural Ventilation

The provision of natural ventilation in a building is facilitated through the installation of purpose provided ventilation openings such as trickle ventilators into the building envelope as well as the use of doors, windows and other ventilation portals such as

louver [70]. The element of human control which natural ventilation offers can be considered favourable by occupants but can also lead to human error and associated wastage.

Due to the constraints of geometry (floor plan depth) and the desire to provide highly controlled indoor environment natural ventilation is rarely employed in commercial office buildings. If appropriately designed, however, it can provide cooling for no direct energy cost and with a negligible increase in the heating demand [69]. As such natural ventilation design strategy formed a key component of this research, whilst acknowledging its unsuitability in cases of high internal gains or external temperatures.

2.3.5.2 Mechanical Ventilation

When the building geometry or user requirements are unsuited to a natural ventilation strategy then a mechanical system is required to provide an acceptable air change for air quality and comfort. Unlike a natural ventilation strategy, mechanical ventilation requires energy to operate its fans, pumps and controllers. This is offset against greater control over the unwanted heat loss in the building and the opportunity to further reduce the heating demand.

The functions of a mechanical ventilation system can be divided as follows [69]:

Supply - Air is pushed into the space using fans and the increase in pressure in the room pushes the stale air through vents. The centralised gathering of the air supply allows for filtration and the slight pressurisation of the building reduces the ability of outside air to infiltrate. Supply systems can be local to a particular area or room or completely centralized and distributed throughout the building.

Extract - Air is sucked from the space using fans and the decrease in pressure pulls air in through vents. Centralised gathering of the air exhaust allows for the removal of moisture and reduces condensation risk to the building. Extract in isolation is used for rooms that require the removal of odours and contaminants (in commercial building context this is bathroom/WC areas and food preparation areas).

Balanced Systems - Employ the first two techniques in concert to offer the benefits of both as well as an overall increase in performance control. Balanced and centralised

ventilation systems are energy intensive and usually form the basis for an air conditioning system.

Heat Recovery - Employs the excess heat from the extract air to preheat the supply air; heat recovery is often essential in a balanced system if energy efficiency is sought [71].

This research examined the use of mechanical ventilation, both as the inevitable by- product of the building form and as an active component in the energy efficiency strategy for the building.

2.3.5.3 Mixed Mode and Hybrid Ventilation

Mixed mode, or hybrid, ventilation is ventilation which exploits both natural and mechanical ventilation dependant on which is most the most energy efficient method to provide comfort. BSRIA [72] defines four types of mixed mode ventilation dependant on strategy and usage:

 “Contingency: mechanical ventilation is installed to provide in use flexibility;

 Zoned: some areas, for example conference rooms, are supplied with mechanical ventilation;

 Changeover: such as using a mechanical system for summer/winter, and natural ventilation in spring and autumn;

 Parallel: both methods (natural and mechanical ventilation) in use simultaneously.”

Lomas et al [73] demonstrated that not only is a parallel system viable, even in climates which have more extreme heating and cooling loads than the UK, but that buoyancy driven natural ventilation can be the dominant component. This strategy was in place throughout the design of the building as it incorporated both exterior ventilation stacks and a central atrium space. The resulting mixed mode system was found to be capable of conserving favourable internal conditions and supplying them throughout the building, resulting in a significant saving in heating and cooling load as well as mechanical power demand. Ji et al [74] applied a similar method to an office building in sub-tropical China and demonstrated that even in these extreme summer conditions (well above predicted maximum temperatures for the UK) the passive cooling available 59

from a natural ventilation strategy could be used in conjunction with mechanical ventilation and cooling for an energy saving of 30-35% over the mechanical system alone. These findings, combined with the fact that both studies used a dynamic building simulation led approach that was quality controlled using Computational Fluid Dynamics, supported the eventual exploration of the potential benefits of mixed mode systems in this research.

2.3.5.4 Air Conditioning

Mechanical ventilation provides a redistribution of air with a variable amount of associated flexibility as to what the system can offer (fresh air, cooling, heat recovery). Air conditioning is the overarching name given to mechanical ventilation systems which actively vary the temperature and humidity of the air to meet comfort requirements [75] [76]. This differs from heating or cooling methods which directly treat the room air rather than the air supply, which requires that the supply volume be far greater than it would be for a fresh air requirement.

When seeking comfort and condition control in a building, there are cases where air conditioning is required and in such cases the appropriate system should be selected and calibrated to suit the specific demands of the building. For the purposes of this study, the need for air conditioning was examined but the intrinsic low energy efficiency made it an unappealing option in most cases.

2.3.6 Lighting

The artificial lighting scheme of a building has a major impact on its energy demand. In the first instance it is itself a source of demand, with the Society of Light and Lighting (SLL) stating that approximately 19% of total electricity consumed is through artificial light and that a well-designed task or daylight dependant lighting scheme can offer savings of up to 50% over a standard scheme, regardless of the efficiencies of the luminaires themselves [77]. This is supported by Debois et al, who stated that 10kWh/m2 per year was an appropriate lighting consumption target for what the authors termed a ‘North European office’ (with a typical value set at 21kWh/m2 per year) [78]. These targets were bettered by Roisin et al [79], who demonstrated that the potential savings could in fact be up to 61% in a daylight optimized office but still at a significant 45% in a building with comparably poor daylight design.

These findings should be qualified with the observation that they refer to the study of office spaces in which are kept typical day time operating hours and this research included the examination of 24 hour and shift based office occupancy. Linhart et al [80] suggest that, for evening usage at least, low energy lighting solutions at 3.9W/m2 that were designed for highly day lit offices can be viable. This is a significant gap in performance from the baseline low energy lighting data found in the NCM 2010 which specifies a maximum standard of 12W/m2 [81] [82] and the ‘Target Zero’ zero carbon office guidance which specifies a maximum standard of 10W/m2 [5] and an absolute best practice of 6W/m2 [34].

The artificial lighting strategy also has a relationship with the natural light strategy and subsequently the building form and orientation. Within this research the design strategies considered the lighting design and behaviour to a ‘concept’ level of detail. This meant that lighting was assigned by zone (considering the full range of performance cited above), with the appropriate internal gains and power consumption attributed. Ryckaert et al [83] produced a methodology for lighting concept design that offered a more accurate model of appropriate luminaire variation across multi-use spaces; however this technique was unnecessary for a standard office space.

The concept of daylight dimming and intelligent controls was addressed but individual luminaires and schemes were not specified as the client impact on any detailed selection is too great to make a final decision.

2.3.7 Renewable and LZC Technologies

Renewable energy and LZC technologies work towards reducing the demand on external energy sources by providing alternatives which are lower in carbon (or indeed carbon neutral). As has been stated previously, this research only considered technologies which were integrated with the building systems rather than those which provided zero carbon electricity supply such as photovoltaics (PV) and wind turbines.

2.3.7.1 Heat Pumps

Ground source and water source heat pumps use the ground or a body of water respectively to provide heating and cooling within a building [84]. Ground source heat pumps can, if correctly designed and constructed, offer an excellent method of

controlling the temperature of a building. They do, however, come with high associated costs due to the need to install an extensive underground component [84] [85]. This technology is a demonstration of the divergence that can occur between research and design; a system that is theoretically functional but possessed of complications in its practical execution. Air source heat pumps are a more widely used device which forms a component of both heating and comfort cooling devices [86]. Air source heat pumps formed a significant component of this research as they are a mature technology which allows for the energy efficient provision of heating and cooling through various means of delivery. Ground source heat pumps are not considered in this thesis due to their unsuitability as generic solution (they are extremely site-suitability dependant). The related principle of earth coupling, however, is addressed as the installation process is less involved. As such, the benefits of using ground temperature and mass to mitigate energy consumption were addressed in some form.

2.3.7.2 Solar Hot Water

Solar hot water systems are roof or façade mounted panels which contribute to the heating of the domestic hot water supply [87].The benefits must be weighed up against the potential effectiveness of photovoltaic panels which are more expensive but provide direct current electrical generation, as both technologies would ideally occupy the same space on a building façade. For the purposes of this research the benefit of meeting the established hot water demand through solar hot water production was considered as a design option for all cases.

2.3.7.3 Biomass, Combined Heat-Power (CH-P) and Tri-generation

These three technologies have developed from the same design concept, namely the use of low emission, heat based generation at the building and development level. Biomass boilers burn a low carbon fuel to heat boilers (individual buildings) or hot water for heating systems (district) and sit on the line between the improvement of existing heating systems and a true form of renewable energy generation. Combined Heat and Power (CHP) generation uses the waste heat from a gas or biomass fuelled generator to provide heating as well as electricity to a building or development [88]. The system can be chosen to meet either an electrical demand, with offsetting of heating demand, or conversely, it can be controlled to meet heating demand with electricity demand as the

offset. The latter mode is often more practical as electricity can be returned to the grid whereas surplus heat is wasted.

If correctly specified and installed combined heat and power can have a significant effect on the performance of a building [39] [89] and due to its ability to maximise the energy that it generates can be a cost effective option, even for higher priced units [90].

Tri-generation or combined cooling heat and power (CCHP) is the next stage in this process combining the provision of cooling. This is usually achieved through absorption chillers, which use some of the heat from the heat-power cycle to enact the absorption cycle; whereby the compressor used in a typical chiller is replaced by an absorbent and pump system [91]. The use of the heat when cooling requires theoretically permits the unit to run year round; furnishing a proportion of the electrical load as well as meeting the space conditioning loads of the building, whether they are heating or cooling. The design challenges and maintenance risks are significant for such a complex technology but for a building that is built around its functionality the effects can be significant [92].

This research project addresses the use of conventionally fuelled CHP units, but rejected biomass as the growing infrastructure and safety issues surrounding fuel supply could not be accurately quantified for generic case studies as they are a site dependant issue. The use of tri-generation was considered but ultimately found to be inappropriate for any of the case studies investigated, due to the need for constant demand to offset the low efficiency of the absorption chillers.

2.4 A review of design strategies

This subchapter contains a review of those design strategies available to the nZEB commercial design team. It begins by reviewing a method identified as typical of industry best practice when seeking to comply with UK Building Regulations which has been extrapolated to provide a further level of performance improvement. The review also considers three more radical approaches in the use of ‘responsive building elements’ (RBEs), a natural ventilation strategy and the use of the Passivhaus standard.

2.4.1 A review of the Green Building Council and Target Zero

As the target of the program of research was to determine “rational” strategies for more energy efficient (lower emissions) buildings the state of the art could not be confined to strictly academic research material. There have been a number of influential collaborative studies into methodologies for building performance improvement since 2007 which have had and continue to have an impact on how demand and emissions reduction are viewed in the building industry.

In the first instance there was the 2007 report into the reduction of emissions in non- domestic buildings commissioned by the UK Green Building Council [93] and produced as a collaborative effort between government, industry and academic research. This report formed the foundation of the 2010 update of Part L of the Building Regulations by predicting the level of performance improvement achievable by technologies readily available in the marketplace [92]. This approach was enacted using the SBEM empirical compliance tool in the first instance, followed by a more detailed approach using the dynamic simulation research tool ESP-r [94]. The contrasting nature of the findings supports the assertion of the author as expressed within this literature review (and indeed the designers of the software [14]) that SBEM is not suitable for use as either a design or a research tool for predicting year round building performance. Further than that however, the findings of the dynamic simulation model suggest that the incremental improvement strategy which focuses on demand reduction through improved efficiencies and the addition of on-site renewables to meet the deficit will not be sufficient. This conclusion was based upon the observation that, none of the case studies could achieve sufficiently low services power

demands to be matched by on-site renewables and, that if this had been achieved; the small power demand could not be met.

The issue of small power demand has been determined as outside the remit of this research, but a target of less than 15kWh/m2year for heating and cooling has been set as a KPI of a successful nZEB building design [94].

The influence of this report was felt in the 2010 Part L which used the 25% improvement in carbon dioxide emissions by 2010 target as the foundations to its new aggregated emissions targets [95].

The findings of this report demonstrated the risk of confusing compliance software used for the prediction of emissions rates with design tools used to analyse the dynamic behaviour of the building systems themselves (which offer a variety of outputs from which emissions and demand predictions can be extrapolated). While dynamic compliance simulation software such as that found in the IES and TAS simulation suites offers the opportunity for more complex strategies to be rated by the National Calculation Method there is still a significant amount of simplification and generalisation when compared to a model that is used solely to test design concepts for successful levels of performance.

The use of the National Calculation Method in research must come with the caveat that the data produced will represent how any design tested fits into the performance expectations of the UK government, rather than of the researcher alone, who has selected the simulation package and assumptions directly according to the level of detail specified in the research plan. The research that comprises the Target Zero technical guidance reports falls into this category.

The Target Zero report on commercial office buildings investigated carbon in operation, BREEAM score and embodied carbon with the objective of offering design guidance to architects and engineers seeking to produce low emission commercial office spaces [96]. As carbon in operation and secondarily, BREEAM score, are within the remit of thisthesis, the report was considered to be a significant marker of the advice available to the design team on how to achieve ‘sustainability’ and ‘emissions reduction’.

The viability of the NCM and carbon values as a KPI have been addressed but the methodology of the report and the design of the case study building were examined in order to determine the design strategy employed therein. The building modelled within the report was No.1 Kingdom Street, London; a city centre commercial office rather than an office park based speculative office. The report itself acknowledges that there were increased constraints on the case study building in terms of ventilation, orientation and footprint [97]. It was expected however, that there would be a similarity in design requirements, particularly in internal dimensions and conditions which would give insight into the cases found in this research.

The Target Zero methodology took recent constructions and reduced them to a level of specification barely compliant with Part L 2006 as a base case for testing improvement methods. The rationale was that designers would find this more relevant than following a design from the beginning and that it offered solutions that could be immediately put into practice. It also allowed for more a detailed costing analysis that would be possible through a theoretical process [96].

This resulted in base case data that was expressed as a Part L2A 2006 IES Dynamic Simulation Method (DSM) score and BREEAM 2008 rating, both of which were outdated metrics at the time of publication [98] [99]. The report acknowledged the limitations of the National Calculation Method and suggested that the figures required for a cost/benefit comparison meant that it was sufficient but that more accurate modelling would be required for true figures and optimal design decisions. That decision clearly set out the Target Zero research ethos as a corporate strategy report rather than a true engineering technical document despite the heavy design engineer involvement. While the method of assessment, and hence, to a certain extent any findings, could be considered less robust than the level required by this research, the method of selection of solutions was taken from what was deemed to be engineering best practice. As such the approach to the application of improvements matches the methods used in the 2007 GBC report [92]. The recurrence of this approach of selecting ‘higher performance’ components until demand is reduced sufficiently in two separate but high profile reports was enough to establish this approach as a design methodology going forward in the research.

The delivery of this approach to design, termed ‘incremental improvement’, in the Target Zero report is specified in greater detail than in the 2007 GBC report. This offered the opportunity to identify the expected performance of a traditional, large scale, office building when exposed to the design methodology (albeit with the caveat of a limited mode of performance assessment).

The building itself was designed to retain optimal air conditions rather than to exploit thermal mass through exposed construction elements [100].

The actual building design used a ground source heat pump (GSHP) as the primary heating and cooling system with coils located in the foundation piles. This is an example of an LZC technology that is often available to new build only due to issues of system integration and in this case into the construction itself. Conventional heating and cooling plants included in case of failure or maintenance. These were roof mounted chillers for cooling and gas powered condensing boilers for the heating. 116m2 of solar hot water panels were roof mounted in order to supply the domestic hot water. Lighting was provided by linear fluorescent tubes to provide 200lux [101].

This design was then modified to the base case used in the study by the removal of solar controlled glass and shading (and some windows to avoid overheating) from the facade, the Ground Source Heat Pump and a small (0.1) increase in air permeability. All systems efficiencies were also reduced to the minimum permitted for compliance under Approved Document L 2006 [96]. This base case would no longer be acceptable in the new 2010 Part L, either in terms of design criteria or in terms of overall performance. This makes the base case figures out of date, but that does not necessarily render the improvements out of date, particularly since the actual building was designed to a higher standard. The lighting efficiency was then set to 2.5W/m2 per 100lux in order to assure minimal L2A 2006 compliance [5].

This base case model was produced in the IESVE accredited Part L2 dynamic simulation compliance tool in order to test the incremental improvement methodology and extract findings for use in costing and life time carbon payback data as per the emissions results of NCM 2006 compliance through dynamic simulation [100]. The implication being that such a design strategy is a logical progression from the strategy

used to facilitate compliance with the current minimum standards, with cost as a key constraint.

Three packages of improvement offered over the 25% improvement that is required by 2010 regulations which are now in force [40]. A cost effective package offered a 42% improvement over the base case and a -£1,853,479 Net Present Value (NPV) 25 years (Net Present Value represents the relationship between the up-front cost of a design choice and the savings afforded through reduced demand over the period denoted. A negative NPV represented an overall saving over the period denoted, a positive NPV an overall premium over the period denoted) at an upfront cost premium of £172,400. Two more complex and expensive packages offered a higher premium and lower NPV but savings of 52% and 55% respectively. This data suggested that the now in place 2010 legislation can lead to long term savings in cost as well as carbon but also suggested that going beyond this target towards ‘zero carbon’ would result in increased lifecycle costs as well as a significant up-front cost premium using the design strategy implemented in the study [34].

Lighting design was found to be not only the most open to improvement as an energy saving measure but also to be one of the most design intensive measures due to the interrelationship between lighting, glazing, shading and internal gains. The pursuit of savings in the lighting design led to more complex and in depth modelling procedures.

The balancing of heating and cooling loads in the building is often desirable, particularly when fitting innovative HVAC systems and on-site generation: however this practice presented difficulties to the design team without changing the basic form of the building. The designers found little benefit to decreasing heating load at the expense of greater cooling or vice versa, rather it was how those loads were met that would determine the emissions from HVAC in the proposed packages. This highlighted a limitation in the methodology; which discounts building physics input in terms of the design of form and the specification of construction materials. The value of buildings with a high thermal response time is intrinsically linked to ability of the building to meet the demand spikes efficiently and retain the internal condition with minimum system intervention. The design team highlighted this issue within the building design but were unable to act on the situation. It should be observed that the relatively high air permeability values used in the simulation [5] (as well as the National Calculation 68

Method defined occupancies and gains) could be expected to have had an effect on this lack of retention of internal condition.

As has been referenced previously (See Section 2.2.1) Target Zero identified a definition of ‘zero carbon’ as a 146% reduction in carbon emissions over the value required for 2006 compliance (this would result in a negative BER but also factored in unregulated power at a figure of 32% of carbon emissions) and stated that no single Low or Zero Carbon technology available offered that level of improvement, with the most successful being an on-site CCHP plan that offered a 75% improvement but at a 10% cost increase and a positive NPV [34].

None of the combination packages considered for the Target Zero office case study achieved this definition of ‘zero carbon’: the study also observed that its parallel projects in other sectors yielded a wider range of feasible design options, which demonstrates the highly constrained problem being addressed in the commercial office sector.

The most successful viable package resulted in a 79% reduction in carbon emissions at a 7.4% cost increase that offered a near neutral NPV. This design uses ‘complex’ energy efficiency measures, a small roof mounted wind turbine, extensive PV and a CCHP plant. This is a highly demanding set up with reliability and maintenance issues attached due to the extensive use of renewable technologies [102].

Examination of the ‘successful’ solutions for Target Zero (those which achieved significant and cost effective performance improvement) suggested that most measures were as expected (It should be noted that the goal of the report was the best combination of accepted practices; that the process was only sporadically design and simulation driven and employed a highly constrained case study), however the use of a Seasonal Energy Efficiency Ratio (SEER) of 6 for cooling in the ‘Part L 2010 compliant’ bracket and of 8 in the ‘high performance’ bracket (the previously mentioned 79% carbon emissions reduction) appear on initial examination to be optimistically high.

Figure 5 shows the individual emissions reduction benefits of the design improvement measures. The findings were as expected with improved mechanical and electrical efficiencies and use of more efficient HVAC offering the largest improvements. The low impact of U-value improvements was more extreme than might have been

expected; but due to the highly glazed façade, the buffer spaces internally (including atria) and at the floor/ceiling the path of heat flow was likely to be dominated by glazing performance and indeed this was reflected in the findings.

Figure 5: Percentage reduction in annual carbon dioxide emissions (kgCO2/m2/year) [34]

The Target Zero method assessed the success of packages of solutions by considering the cost saving/premium over 25 years per kgCO2 saved. The findings of the report suggested that under current costing models the expense of creating a building that could meet the projected 2013 regulations [103] (still far short of ‘zero carbon’ by Target Zero definition) would be such that a more conservative package (achieving 2010 compliance) in combination with what are termed in the Regulations as ‘allowable solutions’ (the use of offsetting through off-site renewables) would actually be more cost effective in a built up area.

If these findings are indicative of a trend then it could have significant bearing on the design and construction of the next generation of commercial office buildings as the potential to construct something energy efficient, cost effective and compliant now and then consider the acquisition of renewables as and when it becomes financially viable could be demonstrated to be the universally favourable choice over the further refinement of building designs. This, however, could be a temporary solution, preventing the development of these new methods and technologies (and thus their adoption and eventual reduction in installation costs). Additionally, it is apparent that this study was limited both by the metrics employed and the design options made available. As a representation of that design strategy it suggests that without steps forward in building design and performance improvement combined with the meeting of demand there will be no ‘zero carbon’ or ‘zero energy’ buildings, particularly where the external environment is not favourable for renewable technologies.

On-site ‘LZC’ technologies were tested extensively in combination with successful energy efficiency measures. It should be noted that for the purpose of the Target Zero report heat pumps, CCHP and heat recovery were counted as ‘LZC’ technologies, in the case of the former two, this convention was is shared in this report, whereas heat recovery is better classified as a component of the HVAC system.

The design methodology as formally outlined suggested focussing on lighting design, then façade then finally material improvements in order to attain the best performance figures. In highly glazed commercial offices such as the one addressed in the Target Zero report this strategy is strong for both pure consumption reduction and for 2010 compliance. These findings were supported by the review of literature which exposed the significance that lighting design (both natural and artificial) can have on the thermal and energy performance of a commercial building (see Section 2.3.2.1 and Section 2.3.6) In a building with less glazing, high thermal mass and/or dominant atria using hybrid ventilation this assumption simply cannot be made.

The strategy considered sources of heating and cooling a high priority within the workflow which matches its costing findings which suggested typical low energy HVAC system is more cost effective than on-site renewables which are in turn more cost effective than hyper-efficient state-of-the-art HVAC systems [102].

A fundamental limitation which both the Green Building Council and Target Zero reports as definitions of a clear design strategy is that both ignore the impacts of end user requirements and the potential impact that can be made by a pre-design phase where all members of the design team have an impact on form, orientation and material, thus offering the opportunity for a clear and detailed energy balancing strategy. Regardless of these limitations, both studies remain significant as they have not only had an impact on the development of UK government policy (in the case of the GBC) but are also high profile examples of the ‘path of least resistance’ design approach to emissions reduction as assessed by that policy.

As a result of this significance the approach to design found in these studies formed the basis for a design strategy within this research project, however, this approach is not the only one available to a design team and several other routes to nZEB were also explored.

2.4.2 A review of Annex 44 International Energy Agency’s Energy Conservation in Buildings and Community Systems Program.

Annex 44 of the International Energy Agency’s Energy Conservation in Buildings and Community Systems Program (IEA ECBCS) approached the design of low and zero energy buildings in a significantly different manner to that found in either the GBC report [104] or Target Zero [34]. A research led investigation it explored the benefits of design buildings which create and preserve favourable internal conditions with the minimum amount of energy expended. This process involved multiple research threads which identified and examined four core types of Responsive Building Element (RBE).

The first is Heat Flux RBEs, which exploit variable (adaptive) insulation levels to control internal conditions. Examples include double skin façade and dynamic insulation. Thermal Energy Storage RBEs store heat at times of overheating and release at times of heat deficit. Examples include Phase Change Materials (PCM), earth coupling and thermal mass activation. These technologies are subdivided by storage time period; short (day), medium (week) and long (month-year) term storage. Transparency RBEs are materials which vary the level of transparency dependant on solar radiation and daylight levels. Examples are reactive window and glazed façade technologies. Finally, Permeability (Ventilation) RBEs are ventilation and façade

strategies which control heat flow through air flow rate. Examples include ventilated facades and embedded ducts. Pre-treatment of incoming air is sometimes employed and this, along with air flow rate, defines the performance of the RBE. This is an example of hybrid ventilation; where natural air movement is exploited by a more complex HVAC strategy [105].

The report clearly stated that the successful use of such technologies required for what was termed an ‘Integrated Design Process’ involving a collaborative process between architect, structural/civil engineers and building services (and sustainability) engineers [106]. This is in contrast to the approach emulated in the previous studies which more closely resembled the recommendation of technologies and improvements in a linear mode and selected by costing [92] [34]. The challenge for the researcher is to emulate this process, as it is not the same as giving the most importance to the area in which the research is carried out. This is true even if the area in question is that in which the most progress over standard practice must be made in order to achieve the specific goals of the project type. For example, giving complete license to the building services engineer to design the hypothetical buildings due to the value placed on nZEB performance does not equate to making nZEB a priority within an integrated design team.

The core benefit of this approach to integration both in design and in the building elements themselves was identified as the movement towards solutions which offer the transport and storage of energy which is already available with the minimum of extra actuating energy required to initiate it. This efficiency of storage and supply, combined with the extra level of control over internal conditions such methods could offer the building during its operational life, suggested a potential for double savings with a reduction in both gross demand and in energy wastage. This review has already identified the growing importance placed upon this approach by accreditation bodies (see Section 2.2.4.3) and it stands again in contrast to the ‘incremental improvement’ approach.

An integrated design process as defined by the Annex 44 research group used the standard process of demand reduction and then met the left over demand through the most efficient measures [55]. In this case the implementation was divided between the static choices (building form and orientation, standard building materials), RBEs and “low exergy systems” [55]. Exergy is defined by Hepbasli [107] as the transferable 73

portion of the energy in a system; in a building services context an electric panel heater would be a high exergy system (a high proportion of the electrical energy supplied is converted to heat, resulting in high temperature radiant heating) whereas a low exergy system would provide heat through a medium which is close in temperature to the space to be heated.

RBEs were considered a crossover point between demand reduction and the provision of renewable energy and “low exergy systems” were defined as systems which provide renewable energy while using the lowest possible fossil fuel content. It should be noted that here (as in the Target Zero report [108]) renewable energy was any device that takes in energy for the purpose of providing a desirable internal condition for the building while producing lower emissions than the grid electricity alternative. This included, but was not limited to, LZC generation of heat and electricity, heat recovery, solar collectors and heat pumps.

2.4.2.1 An integrated design process [55]

It was stated in the Target Zero report [16] that early choices in form and orientation can have huge impacts on the size and complexity of building services (a widely supported point within the industry [56]). In addition, without consideration at this stage, it would be very difficult to implement technologies such as thermal storage Responsive Building Elements that take the performance beyond strong traditional design.

Where the first stage of the design was about avoiding pit falls and offering a so called ‘blank canvas’ to the building services engineers in terms of their choice of building systems, the second stage was about demand reduction through good design. This was the stage in the design process where the report recommended considering passive measures that architects traditionally use (solar gains, daylight, shading, free cooling, natural ventilation and traditional thermal mass design). This was where the nature of the building was decided.

The third stage of the design process was the integration of building services into building elements in order to exploit and control their natural properties. A poorly planned building might struggle against the thermal behaviour of its fabric but a building that uses this strategy would actively exploit the interaction between services and structure.

The fourth stage of the design process was the design of what is defined as “low exergy systems”. This combined with stage three should identify a system which is both efficient in its consumption and delivery.

The fifth stage was the quantification of that part of demand that cannot be met by innovative, low carbon design solutions and the selection of the correct conventional systems to meet that demand. This area was identified as of great significance as a badly selected or calibrated system might be overused, thus negating the benefits of the lower consumption/emission system provided by stages three and four. This is a widely observed risk attached with any nZEB or ‘zero carbon’ building project with Clarke et al observing that:

“There are many examples where low-energy buildings have been monitored and their energy consumption shown to be substantially greater than expected” [90]

The sixth and final stage was tuning the performance of the selected systems to meet demand in the most efficient manner and also to be adaptable to the changes in demand that will be inevitable in the actual building.

2.4.2.2 Climate Data

The report set out a demanding requirement for climate data; suggesting that not only should the weather data for the area be considered by all parties from the planning stage onwards but that climate and radiant heat data from the site should be collected and analysed as well. This calls into question the method standardized by industry simulation tools such as the IESVE, associated compliance procedure (which uses the CIBSE weather data) and also the potential for replication of designs, even within a relatively small region such as the UK. This was identified as significant to this research as the recommendation of a building type (or types) as a pervasive strategy for ‘zero energy’ commercial offices would have to reject this highly specified design methodology. The alternative was to accept that this level of detail could only be implemented on a case by case basis (which would fall outside the development of generic case studies for use in research).

In its consideration of the impact of external climate on the building design the IEA ECBCS report identified two distinct internal climate strategies [109]. The first was

Exclusion, whereby the building maintains an internal climate that has as little interaction as possible with the external conditions. This would be used to cope with fluctuating weather conditions and create a stable load for building services to meet. The second was Selective, whereby the building is designed to exploit those external conditions which are beneficial to the desired internal climate and exclude those that are not. This is used to reduce the gross energy required to create a desirable internal condition.

In order for this ‘selective’ method to work it was determined that there must be a high level of responsiveness both in the building services and in the mechanisms that allow the entry of the external conditions [109].

There is a chain of effects associated with building performance, whereby the change in demand due to internal behaviours or external conditions demands a control strategy. This control strategy must be designed to meet the real changes that might occur on any given day, best modelled by a series of extreme cases. However, it is impossible to completely predetermine all possible real changes is and there must be some calibration of the building after completion. The inability to accurately model all permutations of real building behaviour and how control strategies will react to them is a limiting factor on whole building simulation as a reliable method of investigation.

This level of uncertainty and specificity was identified as increasingly significant the more ‘selective’ the building design becomes. It followed that the control strategy itself became integral to the design of any building using Responsive Building Elements as both an energy saving measure in its own right and the most effective way to fully exploit the Responsive Building Elements. As such, it was determined that any strategy developed from the findings of the IEA ECBCS would involve the consideration of comprehensive control strategies, albeit with the caveat that these would be case specific and would be unlikely to provide solutions that could be mapped onto buildings of significantly different geometry or use.

The design strategy and recommendations for implementation found in the IEA ECBCS differed significantly from those found in the ‘incremental improvement’ strategies used in the GBC and Target Zero reports; by proposing that solutions were identified earlier in the design process and integrated more completely into the form of the building.

However this divergence in approach also extended to the technologies used to achieve performance improvement. In addition to provision of guidance, the IEA ECBCS offered significant detailed information about the RBEs themselves.

2.4.2.3 Advanced Integrated Façade (AIF)

The report defines three core types of Advanced Integrated Façades [110] as transparent ventilated facades (of which double skin facades are an example), which are designed to provide natural light and often to facilitate air movement but that limit solar gains. Advanced fenestration systems are traditional windows in nature but with advanced states of control and placement that allow them to function as part of a hybrid ventilation strategy. Finally, opaque ventilated facades, which are divided by opaque/opaque and transparent/opaque (Trombe wall) which are designed primarily to condition and move air through natural means.

The report then goes on to define five types of air flow design found in Advanced Integrated Façades [110]. Three types of air flow interact with both the internal space and the external environment. These are, exhaust air; air which flows from inside to outside through façade, supply air; air which flows from outside to inside through the façade and reversible flow; which provides either of the above conditions when required. The Advanced Integrated Façades can also provide a one sided interaction with either the external or internal condition. This is facilitated by either an outdoor air curtain; air which flows from outside into cavity and out again or an indoor air curtain; air which flows from inside into cavity and then inside again.

The double skin façade (DSF) itself is divided in the IEA ECBCS [110] by the generally recognised industry classifications [111]. The simplest use of a double skin façade is as a Buffer Space where the double skin façade is only used as a thermal buffer, with a small connection to external conditions for pressure purposes. Alternatively the double skin façade can be used to provide one of the air flow strategies identified above as either a box window where each window of the double skin façade is individually partitioned a shaft box which is a double skin façade that is only partitioned horizontally across the façade or a Corridor which is a double skin façade that is only partitioned vertically across the façade.

Finally, there is an option for a Multi-Story configuration; a façade with no internal barriers across its cavity. In some cases the external skin is made of louvers which, when open, negate the properties of the double skin façade.

The reasons for using an Advanced Integrated Façade on a low energy building would be for the purpose of gathering solar energy to heat air where required, drive stack effect ventilation through solar heating of air where required and offer a superior thermal barrier than that offered by a traditional glazed and cladded façade. The findings of the IEA ECBCS were that these performance improvements were feasible if the design of the façade was linked with the design of both the building and its systems [112].

2.4.2.4 Thermal Mass Activation (TMA)

Thermal mass activation was defined as a design ethos whereby the thermal mass of the building constructions was actively exploited to create and preserve a desired internal condition; resulting in reduction in heating and cooling demand. Of particular interest to the IEA ECBCS was ‘core activation’. The thermal mass potential of a solid material is limited by the non-linear behaviour of the heat transfer process. The most efficient method of facilitating heat transfer into a material is to increase the surface area exposed to the medium that contains the heat energy.

In terms of envelope detail, this meant the exposure of the internal material to heat energy through the addition of hollow cores within the slab, or if the slab is not exposed at all, in the adjacent layer [113].

The findings of the IEA ECBCS research into core activation and thermal mass activation suggested design process which could offer demand reduction within the UK climate, but also one which could not offer a high degree of control over temperature range within the specified comfortable range. That is to say that the level of control over air temperature afforded by a heating and cooling system exploiting the thermal mass activation mechanic should be greater than a traditional natural ventilation arrangement but less than a traditional mechanical air conditioning system [114].

2.4.2.5 Earth Coupling

While earth coupling was identified as a Responsive Building Elements and formed a component of the IEA ECBCS design ethos, it must be noted that this is a widely

considered solution for low energy buildings. This is because of its proven performance, simplicity and its quantifiable performance (the heat transfer mechanics of earth tubes are well understood and ground temperature a readily available value for use by the designer [115]. The findings of the IEA ECBCS experimental data demonstrated that in moderate climates an earth tube system could replace standard cooling systems entirely [116] but also observed that despite being divorced from the building fabric design (this also set it apart from the other Responsive Building Elements) earth coupling methods are not suited to retrofit or refurbishment due to the need to conduct extensive works on either the foundations of the structure or the adjacent ground.

2.4.2.6 Phase Change Materials (PCM)

The use of Phase Change Materials to control the heating and cooling balance of a building was identified as a viable technology by the IEA ECBCS; which suggested that they can be used to store solar gains for dissipation at a later time. This could result in either a daytime ‘cooling’ effect (an absorption of solar gains without the fabric heating that results from solid thermal mass methods) or a ‘heating’ effect where heat due to solar gains is accumulated throughout the day and when the building cools down in the evening the energy is released; mitigating the demand peak during evening hours (this would be particularly useful in buildings with evening or night time occupations or heating systems not appropriate for frost protection) [117].

That said phase change materials are more suited for addressing specific issues with a building which is highly constrained in terms of design options available or cases where the usage patterns of the building are clearly defined. As a solution it must be highly specified in order to be of value, with the IEA ECBCS stating that it is essential that the Phase Change Materials be calibrated through detailed analysis to meet the requirements of the building usage pattern through the use of finite elements software and that while dynamic simulation can represent the behaviours of an understood specification it cannot be used to size the mass of Phase Change Materials required [117].

As a result of these stringent design requirements, the use of Phase Change Materials was excluded from this research as it could not be recommended as a strategy but rather a solution to a specific building physics problem.

2.4.2.7 Dynamic Insulation (DI)

The IEA ECBCS determined that dynamic insulation, the process whereby “insulation” is created by thermally activating a wall using controlled airflows through a cavity, is not viable. This was attributed to the lack of understanding of the behaviour of the system (whereas the other RBEs are the results of the application of well understood technologies and phenomena). The situation was further complicated by the potential risk of condensation under certain conditions with the traditional method of prevention in cavity walls through natural ventilation not viable due to the controlled and slow velocity of air flow that is intrinsic to the concept [118].

It should be observed, however, that the product has since been brought to market in the housing sector by Energyflo [119]. The lack of published performance data and current commercial building case studies resulted in Dynamic Insulation being rejected from this program of research. However, if this technology subsequently matures it may become significant in the future.

2.4.3 Naturally ventilated office spaces

The investigation of cross-disciplinary reports has yielded two distinct approaches to reimagining the traditional office building as an nZEB or “zero carbon” building. While the two approaches explored contrast with each other in terms of the level of adaptation and innovation required of the design team, if they are successfully implemented neither approach is expected to result in a building which differs greatly in its form or usage. The adaptability required of the developer and in particular the occupier is minimal. In contrast to this, another design option involving the use of natural ventilation was considered which was anticipated to significantly reduce the energy demand of the office space in comparison to a standard configuration, without the need for either expensive or innovative design measures. The use of natural ventilation, or mixed mode ventilation with dominant natural ventilation characteristics, would facilitate a significant reduction in energy demand for both ventilation and, if correctly designed, cooling [72]. As has already been outlined in this review (see Section 2.3.5.3); mixed mode ventilation has been demonstrated as viable for more climate extreme conditions than could be realistically anticipated in the UK.

The fundamental distinction between a naturally ventilated office and a more traditionally designed “air conditioned” office is similar to the distinction between the use of dynamic building components and a traditionally designed “air conditioned” office. In other words, the designer is sacrificing certainty of performance for the opportunity to achieve savings which are can only be achieved otherwise by massive capital investment. The distinction between the dynamic building and natural ventilation strategies manifests in their practical implementation. The design of naturally ventilated buildings is usually more conventional than the use of the Responsive Building Elements discussed in the previous section: however, the interaction of a natural ventilation strategy is directly with the occupant. Despite variations in delivery mechanism and the process driving the ventilation (wind, buoyancy) natural ventilation is the delivery of outside air to the internal environment. This means that there will be some inherent risk in terms of variation of ventilation rate, air temperature and air quality. Even in a mixed mode system of the type proposed the goal is to directly supply outside air to the building if possible, whereas an active façade is structured around the pre-treatment of the supply air, albeit by natural means, and the other options considered interact with fabric or systems rather than the internal air directly.

It is this risk of uncertain internal conditions, along with the constraints of form that are intrinsic to a natural ventilation strategy that prevent it from being a pervasive design solution. Whist these issues were considered, it was decided for the purposes of this research that the opportunity to examine the value of a naturally ventilated office could not be discarded This was on the grounds that it would offer a contrast to the other designs as low energy demand would be more assured but suitable comfort performance less so.

2.4.4 Passivhaus

The final design strategy considered in this review was the Passivhaus standard, and more specifically how its tenets could be applied to office design; an emerging area of interest in the UK; The Interserve Office (finished in 2011) was the first UK office building to meet the Passivhaus standard [4].

As with the proposed natural ventilation approach detailed in the previous section it was anticipated that the use of Passivhaus would apply constraints to the building form and

size due to the requirements for lightweight, highly insulated and airtight constructions. These limitations are offset by the important fact that Passivhaus is alone amongst the strategies examined in that is specifies a rigid set of performance criteria by which any design choices are tested. While these demands may vary when the method is taken outside its original housing based sphere of use the core requirements remain the same. BRE provides the official Passivhaus assessment in the UK and they define the following requirements to meet standards:

Passivhaus does not strictly prohibit the use of either heating or cooling, nor does it prohibit the opening of external windows (both are commonly held misconceptions). In reality, Passivhaus simply defines a design ethos, similar to those proposed in the IEA ECBCS Annex 44 report [120], but whereas those recommendations require that the designer define the criteria for success, those for successful Passivhaus performance are clearly outlined. It is also significant to note that Passivhaus rejects the idea that LZC technologies, and generation in particular, can be considered part of the solution, as the knowledge that they are available may reduce the drive to ensure that the low energy ethos of the building design and construction are carried through to conclusion [121].

In theory, the evidence of ratified Passivhaus buildings, particularly a commercial office, gives sufficient confidence that the design ethos can work under the right conditions and quality of design. The energy demand specification (demand in kWh/m2/year) was specifically set so as to result in a demand level that can be met by appropriately sized renewable energy sources [121] and, indeed, form the target of minimum success that was used in this research project. It was the rigid, assessment based approach to design and the differing building characteristics that the Passivhaus method follows that made it a valuable addition to this investigation.

Due to the limited availability of the Passivhaus design guide, as well as its targeting of residential rather than commercial buildings, some level of assumption was required within the emulated design process. These assumptions can be found at the appropriate points in the investigation of that case study and were not believed to significantly impact on the overall representation of a “Passivhaus” office within the dynamic simulation software.

3. Simulation Theory

This chapter outlines the principles of the dynamic simulation method used in the research methodology and how it represents to the various aspects of the building form, fabric, systems and external conditions. This includes outlining the general assumptions associated with a dynamic simulation method; with case specific assumptions identified in the relevant results chapters.

3.1 Geometry

The accurate rendering of building form in the simulation package is integral to a successful simulation. The modelling practices used in this study err towards representation of conditions to a high level of detail within the context of the design stage under investigation. There is value in a so called “sketch” simulation at the concept design phase, particularly in cases where the turnaround time is short and the building is typical in most respects.

However, in this research program it is the design methodology itself that is under investigation, and as such the simulation tool must act both as the design tool and the testing environment for the performance of the case building in question.

The subdivision of rooms, particularly large open plan offices and atrium spaces, was dealt with on a case to case basis in order to ensure that the ventilation strategy was modelled as accurately as possible and that the required temperature values for comfort analysis were available.

3.2 Weather

3.2.1 Location

The use of weather data files is fundamental to a dynamic simulation of building performance. The external conditions have a direct impact on the internal demands for energy and the ability of the building to maintain a favourable condition. Industry convention dictates that Test Reference Years are used for design. These are artificially generated weather files which employ a ‘typical’ month for each month of the year at 84

that location based upon a range of actual data sets (1983-2004) [122]. The test reference years are also employed in compliance simulation and are provided by CIBSE [123]. The 14 UK Test Reference Year sites are:

 Belfast  Birmingham  Cardiff  Edinburgh  Glasgow  Leeds  London  Manchester  Newcastle  Norwich  Nottingham  Plymouth  Southampton  Swindon

The testing of overheating performance is typically carried out through the use of Design Summer Years. These employ an example weather year for the periods January to March and October to December but feature a selection of temperatures from the collected weather data for use during the summer months of the data set, with the target of representing a “hot summer” [124].

The value of this test is to demonstrate that the building design can cope with heat waves or moderate climate change without requiring a change of ventilation or cooling strategy. The use of future weather data has allowed this investigation to be taken beyond short term considerations and consider the impacts of climate change scenarios.

3.2.2 Daylight

The use of a design suite such as the IES VE affords the designer access to a suite of secondary tools that can be used to add detail to the simulation process. In this study the use of the Suncast module [125] facilitates the use of building form and shading devices to control solar gain. 85

3.2.3 Future Weather

The use of future weather data as a means of exploring the ability of buildings to cope with climate change has been an area for extensive research. Jentsch et al [126] proposed that the UKCIP02 climate change data could be used to morph the existing TRY files used by dynamic building simulation and compliance so as to generate a variety of climate change scenarios [126]. This line of investigation was considered to be both relevant and valuable to this research project. The design of a building which meets nZEB standards under current climate conditions, but that would fail to meet comfort or energy efficiency criteria under even the most modest of climate change scenarios could not be considered a success. The need to address this aspect is further reinforced by the presence of climate change scenarios in commercial and governmental reports on building performance; if this data is informing policy it will have an impact on the design team regardless of any client driven desire to future proof the building.

It should be noted that the UKCIP02 data used by Jentsch et al [126] has since been superseded by the new UKCIP09 scenarios and that the work of Eames et al [127] has demonstrated that the new scenarios are less well suited to the data morphing procedure and that while the overall files are still viable for use in simulation, care should be taken when analysing the results to confirm that spikes in internal conditions are due to valid changes in climate rather than anomalous data within the files themselves.

Eames et al [127] go on to propose that a statistical weather generator using sets of past weather data was better equipped to implement the climate change predictions set out in UKCIP 09. To this end a program of research titled PROMETHEUS conducted by the University of Exeter [128] [129] has rendered an extensive set of future weather scenarios using this methodology. These weather files are accessible to both the research community and to industry (for investigative purposes only) and offer a more robust form of testing the impacts of climate change than other freely available sources.

There are alternative climate change models available with which to produce future weather data, such as the Hadley CM3 model used by Crawley [130] to explore the impact of urban heat islands on future weather data in the US. The decision to use the UKCIP model was founded on the availability of suitable weather data files and the demonstration in the literature review that the PROMETHEUS files offered a more

useful data set than the application of that model to the CIBSE weather files [127] [128].

3.3 Heat Transfer

As a dynamic simulation package, the IES VE employs a finite difference method for modelling heat transfer between the designated zones over the designated time steps [131]. This method has been widely accepted as the most accurate simulation methodology which is computationally inexpensive enough to be used for whole year analysis of the thermal performance of buildings [132].

In the context of this research, which includes the modelling of systems which exploit thermal mass, it should be observed that this method of simulation works under the assumption that the heat transfer through a construction element is perpendicular to the face of that construction element [133].

3.4 Internal Gains

3.4.1 Lighting and Equipment

The representation of lighting and equipment gains in the thermal modelling of buildings poses a challenge to the designer but an opportunity to the researcher. In the design process accurate data but is required but also brevity of reporting: however, in this research the target was to broaden the data set that the design strategies were exposed to from what is conventional in industry. As such it was possible to consider changes in activity and internal requirements after the design has been finalised as well as the control and mitigation measures which form part of all of the design methodologies. The baseline data for internal gains for lighting and equipment was defined, as in industry, by use of the CIBSE [81] and NCM [134] datasets where appropriate (copies of the latter are included in the installation of the IESVE as part of the accredited Part L calculation module [17]). The use of these values give context with industry and compliance process and, through the virtue of being extrapolated and averaged data, offer a midpoint for the parameter sweeps used to test the versatility of building designs.

3.4.2 Occupancy

As with the lighting and equipment gains, the occupancy pattern of the buildings could be varied in order to interrogate the ability of the solutions to adapt to change of use. The occupancy gains consisted of both a sensible and a latent component both at the design stage and the subsequent post-design testing stage.

3.5 Ventilation

3.5.1 Natural Ventilation

Natural ventilation in this research was represented through the use of the Macroflo bulk airflow model [135] which allowed the simulations to consider the movement of air through natural ventilation features and also the internal zones of the building models. While bulk airflow is less accurate in its representation of the ventilation characteristics than computational fluid dynamics, it offers the benefit of being fully integrated into the thermal simulation used in IES. In investigative terms this means that the air flow has an impact on the day-to-day energy demand of the building and the fluctuations in occupancy and external conditions have an impact on the air flow, thus emulating real-world conditions. This stands in contrast to the use of CFD, which is valuable for the creation of ‘snap shots’ of the behaviour of the natural ventilation strategy under certain conditions but is too detached and computationally expensive to be used to produce a whole-year representation of performance.

3.5.2 Mechanical Ventilation and Air Conditioning

Mechanical supply air is represented by the inclusion of convective heat transfer between the air in the room and air at the supply air temperature. In the ApacheSim module used in the concept stage the system itself is represented simply by an auxiliary energy value or specific fan power which uses the rate of supply to calculate energy consumption [136]. The temperature of the supply air may be set to outside (including an option for fan heat pick-up), tempered air (air conditioning) or supply from an adjacent zone (which can be useful for mixed mode – see below, as well as the effect of an extract system).

In the detail design stage the ApacheHVAC module of the IES VE offers a more detailed approach, with models in place for variable rate fans, duct losses and the connecting of spaces which are not directly adjacent (again this is useful for mixed mode system modelling but also for the modelling of earth coupling). It should be noted that the in-room convection model remains the same when ApacheHVAC is in use [137].

3.5.3 Mixed Mode Ventilation

The representation of mixed mode ventilation in the IES VE is essentially the same as the system in practice. the two component ventilation types (natural and mechanical) are represented, with the addition of control parameters that allow the best use of each function at any given time. The risk of inaccuracy comes under moderate internal conditions (when the internal temperature approaches the cooling set point for example), where there may be a risk for an inappropriate control strategy being implemented within the model (such as the repeated switching from mechanical to natural over short time periods) that would be designed out of a real building though careful programming of the BMS system. Equally, the risk of system failure or user interference cannot be accounted for in the overall simulation. It is possible, of course, to develop simulations specifically to test the consequences of failure; a logical extension of overheating tests and the parameter sweeps found within this research. As such a well-designed control strategy will in all likelihood result in a successful performance output. The use of uncertainty analysis in thermal simulation, and building design as a whole, is still in its early stages. It was identified in this case as a process likely to dominate the research methodology and, more so than sensitivity analysis, mark a departure from the drive for representation of the commercial design process. It is noted here as mixed mode ventilation was identified as a design option with a high risk of uncertainty but ultimately one which could be represented within this mode of research under the assumption of good control design.

3.6 Heating and Cooling

3.6.1 Concept Design

At the concept design stage heating and cooling loads are modelled as direct interactions with the air volume in the room. The elements of control over delivery are minimal, with the limiting of the maximum size of the unit and the definition of the radiant fraction the only options. The system and delivery efficiencies as well as the fuel type and auxiliary energy (pumps, fans and controls) are constant and set at system level. The use of Seasonal Energy Efficiency Ratio (SEER) allows for a simple rendition of part load behaviour: however a greater level of detail is required to accurately confirm that a chosen solution is viable.

3.6.2 Detail Design

At the detail design stage the use of the Apache HVAC [138] component based module allows for the detailing of not only room component types and sizes but also part load efficiencies and heat recovery. This level of complexity adds significant time to the construction and execution of the simulation however it offers a level of detail which permits an informed assessment of the value of choosing a specific space conditioning method. It also facilitates further investigation into the impacts of modification of control strategy and changes in climate and usage patterns, all of which were identified as areas of enquiry for this program of research.

3.7 Domestic Hot Water

While domestic hot water design can have a significant impact on services energy demand (and indeed cooling due to the internal gains from hot water pipe runs) in certain types of building, it was anticipated that in office spaces the load would be so low in comparison to other loads that it could addressed as a secondary design issue. The modelling of domestic hot water in the NCM includes pre-set levels of demand for the building type; in the case of offices it is determined by the occupancy of the office space itself and is set at 0.22l/person/hour for every occupied hour of the day [139]. This demand level was used for all cases in this research.

3.8 Dimming Controls - Radiance Calculations

The use of Radiance and other ray-tracing packages as a means of performing research quality lighting analysis has been recently drawn into question with more complex modes of considering the impact of light on the building design process being developed [79]. In this design process the role of the Radiance module of the IES VE is to facilitate a more accurate representation of dimming controls on the internal lighting [140]. As lighting falls within the energy consumption remit of this study (and the compliance process) and also has an impact on the internal gains of the simulated spaces, it was important to use the most accurate measure within the limits of the identified commercial process. As the Radiance simulations are providing data to be reacted to by further simulation (with further assumptions and simplifications applied) it was decided that it would suffice in this instance.

4. Methodology

4.1 Research Methodology

This subchapter outlines the methodology of the program of research. In particular it details how the design and simulation process found in industry was recreated in a research environment. It goes on to detail how the research approached those conditions and constraints which were constant across all case studies and which offered points of direct comparison during the analysis of findings. The flowcharts included in this subchapter were produced for this research project.

4.1.1 Introduction

The starting point for developing the research methodology used in this thesis was the identification of the near zero energy building standard as the most appropriate metric for determining energy efficiency and emissions reduction in a new commercial building. The review of technical and legislative information demonstrated that there was an array of methodologies available to assist in achieving both performance improvement and performance measurement. The methodology detailed in this section was structured to offer a comparison between the fundamentally different approaches available to the building design team. It begins with the need to identify the stages of the design process itself and the level of impact that the building physicist, building services engineers and sustainability engineers can have on the decision making process. In order to remove unwanted elements of uncertainty from the research data it was determined that all case studies would be driven primarily by the following key performance indicators (KPIs):

1. Thermal comfort – determined by an overheating test; 2. Demand reduction (system) – determined by load calculation and fabric design; 3. Demand reduction (lighting) – impacted by façade and lighting design; 4. Ventilation analysis – consideration (where necessary) of natural ventilation through bulk airflow model. 5. Energy consumption – determined by annual dynamic simulation;

6. Carbon emissions – determined by the IESVE accredited dynamic simulation L2A 2010 compliance check (while carbon has been rejected as a driver for design, Part L remains highly relevant to modern building design).

This set of metrics represents the relevant activities within a design team where those members concerned with energy efficiency have a high level of control and as such the responsibility for delivery of the required performance targets.

Four distinct design strategies were proposed as viable commercial choices for a design team attempting to meet these standards of performance:

1. Incremental improvement strategy; a commercial office building of the traditional type. The design team seeks to institute performance improvement by reducing the demand on otherwise traditional systems through a series of mitigation measures. Internal conditions are typical of a traditional air conditioned office building. 2. Natural ventilation strategy; a definitive change of internal condition priorities. This design strategy places a requirement for flexibility on the occupants by attempting to provide natural or mixed mode ventilation through conventional methods. This design offers a counterpoint to the ‘incremental improvement strategy’ as it is also a series of performance improvement measures but one which demands a much greater level of control over form and façade. 3. Dynamic building strategy; the use of dynamic control of the physical properties of the building materials to control heating, cooling and ventilation demand. This design strategy attempts to bridge the gap between the controlled internal conditions of the ‘incremental improvement’ strategy and the low baseline energy demands of the ‘natural ventilation strategy’ through the application of control measures. 4. Passivhaus strategy; a definitive method for demand reduction. This strategy offers a clear contrast to options 1-3 as it is an extrapolation of an existing design and accreditation scheme. This strategy will represent an attempt to follow the Passivhaus design ethos rather than a rigid attempt at creating a Passivhaus office building.

These strategies are contrasting in terms of their philosophy of performance improvement, of what materials and systems are appropriate for a building seeking a high level of energy efficiency and how a desirable internal condition should be provided. While these criteria are disparate, in each case the research methodology offers a structure for comparison as it was identified that the design process would have common ground in terms of the stage at which detail was applied to the design and at which simulations would be carried out.

The method of enquiry focussed on the need to first determine whether improvements of a particular type were leading the building towards performance improvement and then to quantify the level of success achieved by the final design. The question of whether a given design strategy will prove to be successful cannot be determined, however, by the performance of a single, specific building case. Previous studies, such as Simm et al [141], have explored the use of building simulation as a means of exploring multiple stages of the building design process. This approach allows the use of the research data to move beyond what might be offered by industry experience and consider whether any strategy currently in use has the flexibility of function to become a defining tenet of the design of future commercial developments in the UK, or equally, if any method possesses intrinsic flaws which prevent it from being designed on anything other than a case to case basis. In order to ensure that these diverse approaches to design shared common data points for comparison, the following research methodology was adopted.

4.1.2 Emulating the design process

4.1.2.1 Iterative Design

It is a widely acknowledged view that an iterative design process is essential to ensure a high quality finished product [142]. A risk in research is to consider all parameters and as such develop combinations of solution that are not viable in practice or create a negative condition which it is outside of the modelling software to detect such as “sick building syndrome”, which is a loosely defined combination of conditions which designers and clients are nonetheless extremely wary of causing [143]. In order to avoid this and to ensure that the study remained grounded in its industry context the design of the case studies developed in the research was carried out using an iterative design

process (the level of iteration does vary between methodologies as would be the case in practice). This does mean that the exploration of design options is not exhaustive, but rather takes the ideas set forth in the previous studies to their logical conclusion. The second benefit to producing a definitive “best case” for each of the buildings was that their versatility as occupied spaces and as replicable solutions could be tested parametrically.

4.1.2.2 Simulation

The use of a commercial software package in the IES VE was driven by two major factors. The first was its status as market leader within the commercial design environment in the UK and consequentially the level of support available to research carried out using the software [17] combined with its validation [21] by both CIBSE, through the application of Technical Manual 33 [22] and ASHRAE 140 [23] [24] [25]. The IES VE is also one of three software packages (along with EDSL TAS and Bentley Hevacomp) which are validated by CIBSE, BRE and the UK Government as suitable for the dynamic thermal simulation of buildings for the purpose of Part L compliance and the production of Energy Performance Certificates [144]. This commercial and legislative backing was reinforced by the cost effectiveness of the software selection as compared to the commercial pricing points of software such as TRNSYS, Design Builder and TAS.

Secondly, the suite itself offers versatility to the researcher, with a wide range of modelling and testing functions available, while being confident that the method used would not be too esoteric to be employed in the design process that the research seeks to emulate, a risk that was identified with research tools such as Energy Plus and ESP-r.

An exhaustive study by Crawley et al [54] which explored the versatility of the most significant building simulation packages suggests that IES VE is a tool of competitive detail in the modelling of fabric, glazing, system and gains performance and limited only with regards to the customization options and additions that come with a collaborative research tool. The limitations of the software and how they impact on the integrity of the study are addressed in this further detail in the theory chapter and form a section of the discussion of results.

4.1.2.3 Compliance

While this research seeks to address the potentially harmful impact of the ever tightening compliance procedure on the design of buildings attempting to achieve near zero energy performance it is essential that it forms a part of the research methodology. The impact of compliance on design is dominated by two factors; the use of carbon as a metric for performance and the use of a second layer of assumptions in the simulation process. Both of these constraints lie outside the control of the building designer as they are fixed features of the NCM software model [145]. The flaws in the first are addressed in the literature review, but the second has a far more direct impact on this study. The theory of compliance simulation itself formed a part of the investigation of the design process while the critical assessment of the data supplied and the risks of designing to compliance can best be assessed by testing the designs within the L2A 2010 [145] simulation in parallel with the core, detail driven, dynamic simulations.

4.1.3 Identifying building design strategies

The review of literature identified four strategies for the design of either “Zero Carbon” or “Zero Energy” commercial buildings (see Section 2.4). These four strategies share a common goal in that they focus on the mitigation and control of energy demand. The differences lie in the approach to design and the materials and components used to achieve the result. In order for a strategy to be thought of as rational it must not only be cost effective and practical but also accessible to the design community. These methodologies are accessible, and the goal of the research was to test their effectiveness. As a preamble to the testing of cases studies against the design methods, the processes themselves were examined in detail in order to identify their key targets and how they could be represented in a simulation driven, theoretical scenario.

4.1.3.1 Pre-design Testing

The pre-design testing phase of the research methodology focussed on the investigation of the impact of building form and orientation on the design process.

The target of this investigation was to identify characteristics that would impact performance and explore how they are simulated within the software environment. There has been extensive research conducted on the impact of ventilation and glazing

strategies on building performance [146] [147] [69], however the selection of case study geometries required a more structured approach than the selection of existing building types. As the investigation of the building form is the basis for selection of fabric and services strategy and that stage of the process could not be overlooked.

The value of exploring the impact of these stages of design from a simulation assessment perspective is discussed within the pre-design chapter. It also provided a counterpoint to the tests conducted in the parameter sweeps which followed on from the completion of the case study simulations by contrasting the optimal case with the potential constraints of a specific site or client requirement. The testing of the impact of form and orientation on so-called “un-populated” models (models which possess little to no detail of systems or use, with some baseline data provided where necessary for simulation) is a typical design practice, with pre-prepared data available for a variety of combinations but this is less true of the testing of designs after the fact [8]. Figure 6 depicts a flowchart of the pre-design methodology.

The differences between the replication of building forms associated with specific usage types and the replication of fully designed buildings with energy efficiency measures and building services fully detailed forms a section of the discussion of results.

Figure 6: Pre-design investigation of building form, orientation and location for design case studies.

4.1.3.2 Concept design

In the context of the research the concept design stage refers to the implementation of the design methodology in question and as such was the stage most fundamentally defined by the method employed in that case. The unification of the disparate approaches at this stage came through the fixed nature of the testing process. The concept design process offers the designer the opportunity to explore the design choices and variations which should ultimately lead to a low energy building concept. Figure 7 depicts the flowchart for the concept design methodology.

Figure 7: Common concept design phase for all case studies.

It should be noted that the iterative design process is factored into the testing procedure as detailed in Figure 7 , but that the exact nature of this process varies slightly for each design methodology as some form iteration is intrinsic to each approach.

The testing of these designs, regardless of how they were arrived at, must be against the criteria that will define success to the designer and the client. These have been identified in this study as energy demand, comfort and compliance. All three of these factors can be considered at the concept phase. In fact the level of detail provided by the simulations in the detail design phase surpasses the detail that can be accounted for in the compliance process, meaning that the concept design stage was the only stage of the

design at which compliance could be considered a factor. The internal gains and occupancy used at this stage in the research were the standard values established for an office space [148]. The modulating signal profile shown in Figure 8 has no units of its own but represents the pattern of usage of the office. This pattern of usage was applied to the values for occupancy, equipment and lighting in order to give an easily comparable baseline input across all cases that could then be modified in the post- design phase to examine the impact of variation of use.

Figure 8: Standard occupancy profile for the office spaces in thermal simulation [148].

The standard values used for internal gains in the office spaces were taken from CIBSE [81] and the National Calculation Method [134] [139] as these are well known industry standards and also gave a basis for comparison with any previous research which is impacted upon by UK compliance testing.

The gains which were attributed to this modulating profile were:

 Occupancy 75W sensible; 55W latent at 12m2/Person [149];  Lighting 12W/m2 or 3W/m2/100lux at 400lux [81] [82];  Equipment 10W/m2 (computers, appliances etc.) [81].

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The gains attributed to the core zones of the building models were taken from the NCM methodology (See “Compliance theory” section).

4.1.3.3 Detail design

The detail design stage is not detail design in the building services terminology as this is a purely industrial process that cannot be accurately represented within the context of this research due to its reliance on the constraints of quantity surveyor input and pre- agreed cost structures. In the case of the research presented, detail design refers to the increased level of input information on building services that can be derived from this process. It should be noted that the level to which detail design is part of the design methodology (rather than just a detailing of already determined design measures) varied from case to case. Regardless of this, including a detail design stage in the process offered several opportunities.

Primarily, it offered greater fidelity to the core results of the research; and allowed for a more detailed investigation of the performance of the design strategy as a whole. This was supplemented by the ability to accurately model features within the design which may have been poorly represented at the concept stage (and completely ignored in the Compliance simulations). Finally, it provided a more accurate dimension to the post- design analysis stage, as both the HVAC systems and any dynamic building elements were expected to be responsive to changes in location or use. Figure 9 depicts the flowchart of the detail design methodology.

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Figure 9: Common detail design phase for all case studies

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4.1.3.4 Post-design testing (comparative analysis)

The post design testing stage takes on the structure of a research process alone, rather than a representation of a process typically found in the commercial design environment as is the case with the previous stages of the research methodology. The focus of this section of the research was to explore how robust the building designs offered by the methodologies were in the face of changes of use and replication in sites other than the base case. The comparison between designs and the comparison of these findings with those of the pre-design stage are a feature of the discussion of results.

4.1.3.4.1. Occupancy

The standard occupancy patterns for the testing of the offices were established in the concept design stage (Section 4.1.3.2) as they form an integral part of that process. At this stage of the research a set of new occupancy patterns were established (see Figure 10 to Figure 14) which reflect changes of use and occupation density in order to explore the sensitivity of the designs to changes of use.

Figure 10: "mixed-use office" occupancy profile.

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Figure 11: "Extended hours" occupancy profile.

Figure 12: "Public office" occupancy profile.

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Figure 13: "Shift office" occupancy profile.

Figure 14: "24 hour call-centre" occupancy profile.

The option “mixed use office” displays a profile which reduces the set occupation density by half (for example. if office occupation is 12m2/person then at these times it will be set at 24m2/person).It was alternated with the standard “office” day over a week to explore the effect of fluctuating use. The “24 hour call-centre” was tested for 7 days a

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week and 5 days a week patterns to explore the effects of consistent occupation. The “public office” option represents an office where visiting clients form part of the regular occupation (such as sales or recruitment companies). All other daily patterns were used on a five day week. All tests were conducted at occupation densities of 8m2/person, 12m2/person (typical) and 16m2/person [148].

4.1.3.4.2. Internal gains

As with the occupancy profiles the internal gains were standardized (though lighting varied in practice due to the use of dimming and controls). As lighting is not only a gain but also a design measure which falls under energy efficiency it could not be arbitrarily modified in terms of intensity as part of the parametric tests. Therefore in this section the lighting gains were varied to match the occupation profiles only and the equipment gains were varied to match the occupation profiles but also in intensity to reflect change of activity and technology level within the office space.

Lighting and equipment patterns were set to match the duration of occupancy in the building (for example “office” and “mixed use office” would use the same profile as lighting would still be required in spite of reduced occupancy).

4.1.3.4.3. Orientation

The orientation of buildings is increasingly a factor that a building physicist (or specially trained architect) can impact on in real cases. As such the use of optimised orientations is a feature of all four of the case studies. The testing of what constitutes ‘optimal orientation’ was a feature of the pre-design stage and these tests were revisited using the final designs which offered an insight into the impact of last minute changes to façade layout and the risks associated with design replication on sites where the positioning of the structure is restricted. It is not uncommon to see commercial office parks that feature multiple, similar structures which have been orientated due to space constraints or site planning requirements relating to aesthetics or access rather than performance and as such the potential risk afforded by this practice meant that this was a viable line of inquiry for the research. It was accepted that any replicated building could conceivable be rotated as much as 90° from optimal positioning in either the easterly or westerly direction. Any further rotation would simply require the inversion of the façade design (there may be further design constraints that prevent such measures

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but it was considered beyond the scope of the research to explore specific cases where facades would be designed with no consideration of the optimal performance). Figure 15 demonstrates the pattern of rotation applied to each case in the investigation into variations of building orientation.

Figure 15: Range of building orientations examined in the post-design testing phase of program research.

4.1.3.4.4. Location

As observed above the risk of replication of a successful design without rigorous testing is a real one in a building market where margins are low and demand for performance is ever increasing. An investigation into variation of regional climate within the UK and how that could impact on the replication of any design solution was carried out. This investigation was facilitated through the use of a set of pre-chosen locations from within the CIBSE weather data range.

The original location of Manchester was selected as a result of the initial targets provided by the Joule Centre and the North West Development Agency and reflected both their interest and the focus of the scoping study that constituted the first year of the program of research. The subsequent locations were selected to give an appropriate range of conditions from within the overall UK climate.

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4.1.3.4.5. Climate change

The weather testing in the post-design phase was further supplemented by the use of future weather scenarios for the locations of the various case studies. Future proofing of low energy buildings (whether their design ethos is to minimize interaction with external conditions or maximise them) is an essential factor in long term design strategy and forms the final test in this stage of the research (see Section 3.2.3). The climate files found in this section of the analysis were generated using UKCIP 09 data [126] by the PROMETHEUS project [129] and were used in order to provide an appropriate range of potential climate change scenarios to the testing process.

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4.2 Design Methodologies

This subchapter defines the design methodologies examined in the research. It outlines the process of design and the points of iteration should any be required. It concludes with a summary of the design options identified as active for each of the case study buildings. The flowcharts included in this subchapter were produced for this research project.

4.2.1 The “Incremental improvement” strategy

The incremental improvement strategy as identified in the literature review is the typical method used in industry to improve a conventional building beyond the standards typically required (or, in certain cases, simply to meet L2 A 2010) [150]. It is primarily a linear method in its approach to identifying solutions, with a list of viable technologies created based upon cost, availability, client interest and suitability for incorporation into the building in question. Though it is a commercial method, borne of a need to hit demanding performance targets in a cost-effective and unobtrusive manner, the literature review also identified several studies which employed this procedure in an academic context, albeit with strong industry (Target Zero) and legislative (Green Building Council report) ties [96] [92]. While the literature review identified that neither of these methodologies were robust enough to be employed directly in this research (the use of the NCM 2006 dynamic modelling was both flawed and outdated as a measure of performance) the approach to component selection and testing was used form the basis of the design strategy.

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Figure 16: "Incremental improvement" design methodology

Figure 16 demonstrates the refined “incremental improvement” methodology as used in Case Study 1. The cornerstone of this design method was the identification of elements in a typical commercial office building that could be improved using market ready technologies with the minimum of reliance on interaction between said building elements. The appeal of such an approach from an industry perspective was the aforementioned ability to avoid high design costs and expensive and potentially unpredictable technologies. From a research perspective, this method offers a control subject for the other methods considered (all of which demand something unconventional, either of the designer, the client or both). This is a practice that is already common place, and indeed outmoded in some sectors, as such it forms the core of any analysis into the commercial viability of more complex strategies, which must be demonstrated to outperform it, regardless of any demonstrable shortcomings the method itself may possess.

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The improvements and technologies considered for this methodology were structured around the improvement of systems and design features which would be found on a typical commercial office building. Mixed mode ventilation systems were not considered and as such neither were atria or double skin facades. Improvements to the efficiency of core building services (ventilation, space conditioning, domestic hot water and lighting) were considered in addition to improvements to fabric performance (U- values and glazing type). The optimal use of mechanical controls was considered a component of improved efficiency of systems. The integration LZC technologies such as CHP and solar hot water which meet the energy demand of a building service (heating and domestic hot water) were considered as design options.

4.2.2 The “Natural ventilation” strategy

The use of natural ventilation as driving force for comfort and energy demand reduction in office design is not a new concept. As has been observed above there has been extensive research into the use of natural ventilation in office spaces [146] [151]. The core demand in this design strategy was to minimise the use of space air conditioning (preferably to heating only) while maintaining an internal condition which met the comfort criteria. The danger in such a strategy is the failure to control internal conditions to a significant degree; as failure to do so risk clients taking measures to provide ventilation or cooling, often resulting in inefficient options driven entirely by cost and convenience after the fact. As a result of this, the natural ventilation strategy, though it leads the designers hand towards simplicity and demands a level of flexibility from the end user, is in fact a simulation-heavy design method, as the design team must work to reduce the level of uncertainty surrounding performance.

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Figure 17: "Natural ventilation" design methodology

As a result of this very specific and potentially uncertain design process, the designer must be prepared to make some sacrifice of the minimalist approach; this was acknowledged in the case study with the option for some mechanical ventilation, as an office that cannot guarantee a certain level of comfort cannot be considered a successful design regardless of its energy efficiency credentials.

The technologies considered for this design methodology were structured around the support of the central concept of ensuring thermal comfort without the application of mechanical cooling and the provision, when possible, of natural ventilation. As such the

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control of solar gains and the use of thermal mass through exposed surfaces, night purge and appropriate control strategies were considered. The use of thermal mass was also considered during the winter months through the investigation of an under-floor heating solution. Alternative modes of natural ventilation were considered as potential design solutions, in particular the use of wind catchers and atria. Double skin facades were considered a complex mechanism more in line with the Dynamic Building case study. Internal shading was removed as a reliable solar control option for the natural ventilation case as it risked being under-used by building occupants due to an unpredictable interaction with the air movement through operable windows. The use of natural light where possible, in combination with a need to reduce internal gains in order to remove the need for cooling, led to daylight dimming controls being specified as a fixed design feature.

4.2.3 The “Dynamic building” strategy

The dynamic building strategy attempts something significantly different from either the incremental improvement or natural ventilation strategies in that it demands a distinct change in design approach rather than the concessions towards cost (incremental improvement) or comfort (natural ventilation) although in reality some compromise may be required on both fronts. The tenet of the dynamic building, or a building that uses Responsive Building Elements (RBEs), is that the building fabric and form can create and preserve favourable (or unfavourable) conditions and that with the correct implementation of control these can be harnessed [152]. This design method offers the opportunity to mitigate the need to artificially change the conditions of the building through direct action (heating, cooling, artificial lighting) when the natural conditions of the building can be retained or even ‘stored’.

The two forms of Responsive Buildings Elements that were identified as of most interest in this research were ‘façade systems’ and ‘storage systems’ (and, where the two concepts meet; atrium design). These technologies were selected as both have been used extensively in recent building design [153] [154] and thus while this more extreme implementation is experimental the manufacture and installation of the elements themselves is a well understood process.

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Figure 18: "Dynamic building" design methodology 115

The methodology presented in Figure 18 above focussed on the need to drive the RBEs as core demand mitigation measure of the building. The ultimate goal of any design team is a ‘successful’ building, though the definition of success may change from project to project (or even during a project due to cost or client requirements), however the ultimate goal of this research is to explore the strategies available and how they might be both rational (commercially successful) but also innovative in terms of the level of performance achieved. As such, for this case study the imperative to test the functionality of RBEs had to override the potential real world decision to reject them in favour of more standard concepts. This decision offered the opportunity to test this new approach against the two previous strategies and consider whether radical design changes are possible or whether the use of more traditional approaches is still the only viable option to the designer.

The technologies that were applied in this case were those which would act as the Responsive Building Elements (hollow core slabs and double skin facades) and those which would facilitate the control of their thermal behaviour. The use of thermal mass and controlled ventilation (either through mechanical supply or the control of façade openings) was fundamental to this building concept. The application of conditioned air (both heating and cooling) was considered as a design option in order to enhance the ‘free’ heating and cooling effects of the Responsive Building Elements. The highly glazed façade, in combination with a need to reduce internal gains in order to reduce the cooling load, led to daylight dimming controls being specified as a fixed design feature.

4.2.4 The “Passivhaus” strategy

The Passivhaus design strategy offered a final, contrasting approach to the provision of an nZEB building. Where the other approaches require the design team to work within constraints to identify combinations of performance improvements, the passive house method is fixed in its implementation. The dynamic building strategy seeks to create and ‘store’ favourable conditions within the building fabric and air volume, whereas a passive house methodology seeks to regulate the internal condition tightly within the local space. This results in two building types with a similar ethos of expending the minimum energy to create conditions but with opposing approaches to fabric and form. As a contrast the form of the natural ventilation and passive house buildings could be expected to be similar but the approach to providing internal condition is opposite, with

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the natural ventilation strategy seeking to mitigate the external condition and thus avoid using mechanical systems and the passive house seeking to control the internal condition mechanically and in doing so avoid applying heating and cooling. In each case some part of a traditional HVAC system is required and the case studies offer a contrast in which functions to use and which to omit and the benefits of each.

It is important to draw a distinction between a passive house method and the Passivhaus standard. The former is a method of building design which follows the design strategy laid out by the Passivhaus Trust [15] and supported by BRE [155]. The second is the ratification of a successful design which confirms that it meets the standards required. In this research the interest was in finding solutions which are viable in practice rather than in seeking validation in a particular scheme and as such the design methodology developed to represent this strategy focussed on the aim of using the core principles of Passivhaus to achieve a low level of energy consumption. These principles were defined as insulation, air tightness and advantageous use of external conditions through solar gain control and mechanical ventilation [156]. The selection of available technologies within this case study was structured around the application of these principles. The use of space conditioning was not considered in this case, but the use of earth tubes to pre- treat the supply air was examined as an alternative which was in keeping with the Passivhaus design ethos.

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Figure 19: "Passive house" design methodology

Figure 19 shows the design methodology as used in the case study and it reflects that fact that passive house design is less of an iterative process than the other strategies considered in this research and more a set of actions with some concessions and adaptations available in order to meet requirements.

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4.2.5 Available Technologies

The technologies and design features available are specific to each case study. is a collation of the options available across the research and whether they were included in the design process for a case as a definitive fixture or as an explored variation.

Incremental Natural Dynamic Feature Type Feature Passivhaus Improvement Ventilation Building Highly-glazed facade Double Skin Facade Form Atrium Open plan Low U-values Ultra-low U-values* Triple glazing Fabric Solar control glazing Thermal mass Air-tightness Ultra-airtight* Mechanical Natural Mixed-mode Ventilation Night purge Heat recovery Earth tubes Windcatchers Radiators Heated air Heating Under-floor (ASHP) Split system (VRF) Split system (VRF) Cooling Air conditioning Low energy Light Daylight dimming Internal Shading External Shading Ventilation Thermal mass Controls Windows Lighting Shading CH-P LZC Tech. Solar Hot Water *These design options are unique to the Passivhaus methodof design and procurement. KEY Fixed Option Unavailable Table 2: Technologies available to the 'design team' for each of the case study building

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4.2.6 Key Performance Indicators (KPIs) of an nZEB Building

The literature review explored the diverse methods available for the definition of a ‘successful’ sustainable building. Primarily, this review determined that there is no substitute for clear understanding of the various criteria and their implications and limitations. It is strongly recommended that any design team be familiar with the various metrics and their place within the regulatory and design process. The KPIs selected for use in this research are replicated together below in order to provide a clear point of reference for the data provided in the results chapters.

4.2.6.1 Energy Consumption

Two KPIs for annual energy consumption were used in the evaluation of the case studies:

Annual Energy consumption (MWh) is a fundamental design value that defines the total energy consumption of the core services of the system: Heating, Cooling, Ventilation, Domestic Hot Water and Lighting.

Energy consumption per unit floor area (kWh/m2year) was considered beneficial as a means of comparison between case studies of differing floor areas.

4.2.6.2 Occupier Comfort

Three occupancy densities were determined by examining suggested office layouts and accepted design data; they were 8m2/Person (dense occupation), 12m2/Person (typical occupation) and 16m2/Person (diffuse occupation).

Internal gains from office equipment were established at a conservative estimate of 10W/m2 without considering energy saving control measures or equipment selection [149].

A light level of 400lux for working space was determined as suitable for office work as an average of the design recommendations for open plan glazed offices (300lux) and deep plan office areas (500lux) [157]. The light levels in other areas (circulation, WC, storage) were set as 100lux [158].

The comfort criteria for office spaces was, in the first instance, taken as a heating set point of 19°C and a cooling set point of 23°C with no more than 1% occupied hours 120

over 28°C for naturally ventilated buildings [159]. The value of these definitions is explored within the research, with particular focus on the energy efficiency benefits of a more flexible comfort criterion. There have been extensive in-situ studies that have explored the true requirements for a comfortable working environment and which identify the point of change not only between comfort and discomfort (which is dependent on outside temperature) but also the point at which discomfort becomes severe and cannot be gained by a change in apparel or user interaction with the space (window opening and closing, use of blinds), this is demonstrated in Figure 20, which has been reproduced from CIBSE Knowledge Series 06 [160].

Figure 20: Comfortable office temperature range [160].

Number of occupied hours over 28°C determines the thermal comfort of the occupants in buildings which are not fitted with mechanical cooling [161]. Dry resultant temperature was used for this test as it represents the effects of air temperature, radiant temperature and any high velocity air movement and is thus a more accurate measure of ‘comfort’ than air temperature alone.

CO2 concentration in parts per million (ppm) determines the air quality in buildings which use natural ventilation, with a maximum acceptable value of 1000ppm used in this research.

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4.2.6.3 Sustainability Criteria

2 The Building Emissions Rate (BER) (kgCO2/m year) determines the carbon emissions generated by the building as assessed by the National Calculation Methodology. In this research the National Calculation Methodology values were not considered sufficiently robust to be used in the assessment of building performance, however evaluations of the design concepts using the IESVE compliance module were conducted and the results included in order to give context to the findings using a KPI which is highly significant in the commercial environment.

Primary Energy Consumption per unit floor area (kWh/m2year) was selected as the best alternative as a “sustainability” KPI to the Building Emissions Rate used in National Calculation Methodology. This decision was driven by the need to reflect the sustainability credentials of the building concepts while expressing the energy consumed rather than the CO2 produced. While both methods apply a factor to the energy consumption of the building based upon the fuel used, primary energy has the benefit of demonstrating to the design team the value of renewable energy solutions without allowing them to be used as a cure-all for poor building performance. The selection and specification of these systems lay outside the remit of this thesis but the metric remains the most informative sustainability KPI to the design team. The following conversion factors were established for primary energy [36]:

Natural Gas – 1.02

Grid Electricity – 2.92

In the context of this study, a total primary energy per unit floor area of 120kWh/m2 was set as an acceptable maximum value as this is the standard used by Passivhaus [121] and it was considered appropriate for a comparative study that all cases be tested against a uniform sustainability KPI.

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5. Results

5.1 Pre-design Analysis

5.1.1 Choosing building form

The form of each the four case studies was chosen through a review of existing buildings which either adhered to the standard set out in the specific methodology or represented the form required and possessed some level of green credentials.

The Incremental improvement strategy was primarily targeted as means of demonstrating the limitations of simply improving the performance of building components and systems as means of reaching nZEB performance. As such it was considered essential that the building represent a form which would not be constrained by its potential for performance improvement but would rather represent the target layout of a medium sized commercial office. If a design team are considering form factor for an office building (whether solitary or as part of a development) from a purely financial standpoint it becomes logical to build ‘out’ rather than ‘up’ and to maximise the floor area per unit rather than the construction of multiple units. As such the layout pictured in Figure 21 was used for this case study; the zoning strategy for the IESVE model is also displayed. The subdivision in this case was chosen to reflect the zoning of daylight dimming and to facilitate the inclusion of the thermal mass activation system explored in the Dynamic building case. Each office space zone is dimensioned at 8m by 8m (64m2 of the overall open plan office space).

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Figure 21: Floor layout and zoning scheme for deep plan building The deep plan nature of the office (and absence of any mitigating architectural features such as atria or light wells) precludes both natural ventilation and extensive natural light [8]; it was expected therefore that the building systems and their performance would become the defining characteristics of energy efficiency within this case study as required by the research methodology. This was reinforced by the decision to apply a curtain wall design to the external façade of the building and false ceilings with carpeted floors; resulting in thermally lightweight construction [66]. The façade selected for the deep plan building was therefore chosen with daylight in mind, rather than the control solar gain or the opening of windows. The façade was given a glazed area of 70% as displayed in Figure 22 (for a single ‘zone’, of which seven comprise the south façade).

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Figure 22: Glazing and cladding configuration of south facade of Deep Plan Building. The dynamic building strategy offered several opportunities for the consideration of more distinctive building forms, however it was ultimately established from the literature review that the most transferable and potentially effective RBEs were the Active Integrated Facades (AIFs) and Thermal Mass Activation (see Section 2.4.2). These technologies both present opportunities to include some of the demand reduction benefits of traditional natural ventilation [111] and exposed thermal mass [162] [163] in buildings with deep plans and highly glazed facades. As a result of this it was determined that the most beneficial approach for this program of research was to identify the potential benefits of these features as design alternatives to the conventional demand reduction and efficiency measures used in the Incremental improvement case study.

Unlike the Incremental improvement strategy, the Natural ventilation strategy must be, by its nature, constrained in terms of façade type and building depth. While the design strategy resulted in the exploration of several types of natural and mixed mode ventilation strategies it was considered essential to consider simple cross ventilation. This resulted in the limitation of the building depth to 16m [164]. Figure 23 displays the floor plan and zoning scheme for this shallow plan layout. The zoning scheme was carried over from the deep plan building with each office space zone representing 64m2 of the open plan floor space.

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Figure 23: Floor plan and zoning scheme for shallow plan building. The façade configuration was chosen in order to offer the opportunity for window opening and to maximise light without overheating (over use of solar gains was not considered a viable design choice for a building without a cooling system) [8]. The roof structure of the shallow plan building was considered a design variable, as was the addition of wind catchers, as both could be used as alternative means of driving natural ventilation.

While thermal mass activation was considered in the Dynamic building case study, there was the option for a more simple process within the natural ventilation strategy through the use of exposed, pre-fabricated concrete constructions and the office layout was designed to reflect that.

The value of the Passivhaus case study lay in both its consideration of the particulars of such a rigid design philosophy but also in its comparison with the other, more speculative approaches. In particular it was the comparison with the ‘natural ventilation’ strategy that was expected to yield the most interesting results. As with the Natural ventilation case, the Passivhaus case was constrained by the depth, façade and construction requirements of its methodology. Passivhaus buildings should look in the first instance to maximise solar gain, then mitigate it in the summer months to prevent overheating [156]. In order to achieve this, a relatively high proportion (50% façade area) of south facing glass and a shallow floor plan were required [8]. This also permitted the use of natural ventilation on extreme summer days. It was anticipated that the increased ratio of external surface area to floor area would result in proportionately higher heating loads in the shallow plan building, this would be offset by the increased 127

solar gain per unit floor area (as considered for cooling loads) that would also result from this increased ratio. The glazing configuration for the shallow plan building (for a single ‘zone’, of which seven comprise the south façade and six the north facade) is displayed in Figure 24.

Figure 24: Glazing configuration of south facade of Shallow Plan Building The number of floors employed in all cases was set to four, both as an attempt to retain point of comparison between the two building types and to permit the use of cross- ventilation in all floors without considering the increased wind speed issues experienced by tall buildings, which lay outside the remit of the program of research. The useable floor area of the shallow plan office was approximately 3300m2 and the floor area of the deep plan office building was approximately 6600m2 which ensured that the case studies represented offices of a substantial size. The Natural ventilation and Passivhaus cases in particular were significantly greater in floor area than that of the test case buildings on which they were based.

The decision to develop two building forms of relatively generic design allowed the research to bypass the unquantifiable variations available to the architect and demonstrate the efficacy of the fabric and mechanical solutions which would be required to meet the standards required regardless of form.

5.1.2 Building Fabric

The fabric of each case study building is detailed within the relevant sub-chapter, however it was necessary to determine a clear approach to material selection in order to provide the materials necessary to facilitate the required thermal performance in each case while avoiding deviation from current building practice.

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The selection of the construction method for a modern office building may ultimately be influenced by every major actor in the design process. A core purpose of this research project was to test the potential for near zero energy commercial buildings when sustainable design measures are given a high priority from an early design stage. As such it was assumed that the appropriate constructions from a thermal design standpoint would be available in each case.

The use of a concrete deck structure was considered uniform throughout all case studies (with the variation of Termodeck, a specific type of pre-cast slab, in the Dynamic Building case study) as this was deemed appropriate for the size of building under examination by the Whole Building Design Guide [165] and suited the requirements for exposed mass in the Natural Ventilation case study. The external skin of the building (walls and roof) were determined as appropriate for each case, with a cladding/glazing curtain wall system for the deep plan configuration, pre-cast concrete for the Natural Ventilation case study and Passivhaus specific constructions for the Passivhaus case study. All construction types were confirmed as case appropriate through consultation of the Whole Building Design Guide [166].

5.1.3 Daylight analysis

As a quality control measure to ensure that the literature on façade design was accurate [8] and that the desired lighting effect would be achieved for both building forms, a daylight analysis was performed on each of the case study building forms using the FlucsDL module of the IESVE. Figure 25 and Figure 26 display the daylight factor distribution for the deep and shallow plan building forms respectively.

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Figure 25: Daylight factor calculation for office space of deep plan building form Figure 25 demonstrates that as anticipated there would be significant areas of the office space which would benefit from the 5% plus daylight factor which would preclude the need for artificial light during daytime [167] but that there was also a larger portion of the floor area which would require artificial light at all times. This analysis justified the decision to subdivide the deep plan case (see Figure 19) in the IESVE as this would facilitate the use of daylight dimming and more accurately represent the thermal effect of the uneven distribution of both lighting and solar gains.

Figure 26 yielded less anticipated results as while the level of daylighting is significant across most of the occupied floor area the penetration is not complete even without any shading in place (shading being a design option for the natural ventilation case). This image suggested that daylight dimming would be viable and indeed highly effective as a demand mitigation device as anticipated when the building form was selected, however it also demonstrated that artificial light will usually have some part to play in even the most carefully designed building forms.

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Figure 26: Daylight factor calculation for office space of shallow plan building form 5.1.4 Loads

The use of load calculation to size HVAC equipment is a well-established convention of building services engineering (see Section 2.1.3.1). The focus of this research project was the reduction of energy demand through the implementation of design strategies. The meeting of heating and cooling loads forms a core part of these strategies and while it should be noted that the output of the ‘systems’ modelled by the ApacheSim module of IESVE are open ended it was considered valuable to ascertain the peak heating and cooling demand of both case study buildings under the National Calculation Method Notional fabric conditions. This would establish that the building forms were not inherently flawed and likely to artificially increase heating and cooling demand beyond what is typical. The inputs used for the calculations and the results obtained are detailed in Table 3, the loads were calculated using the CIBSE Method for heating and cooling loads and the Manchester TRY weather file.

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CIBSE Heating and Cooling Loads - Inputs FABRIC External Wall Roof Ground Floor Glazing U-value (W/m2K) 0.26 0.22 0.18 1.9 Glazing G-value 0.63 Infiltration rate (air changes/hour) 0.25 INTERNAL GAINS VENTILATION Occupancy 10m2/person Office fresh air rate (l/s/person) 10 Lighting 10W/m2 WC Extract (air changes/hour) 10 Equipment 10W/m2 Circulation Vent. N/A CIBSE Heating Load Calculation Deep Plan Building Conduction Losses (kW) Heating Infiltration Vent. Loss Total Heat ROOM Load Internal External Total Loss (kW) (kW) Loss (kW) 2 (W/m ) F01 Office -0.87 -21.37 -22.24 -9.30 -44.63 -76.17 47.39 Stair -0.05 -0.05 -0.10 -0.06 0 -0.16 32.00 WC -0.04 -0.04 -0.08 -0.04 -0.72 -0.84 140.00 Shallow Plan Building Conduction Losses (kW) Heating Infiltration Vent. Loss Total Heat ROOM Load Internal External Total Loss (kW) (kW) Loss (kW) 2 (W/m ) F01 Office -0.54 -12.31 -12.85 -5.45 -23.10 -41.4 49.76 Stair -0.05 -0.05 -0.10 -0.06 0 -0.16 32.00 WC -0.04 -0.04 -0.08 -0.04 -0.72 -0.84 140.00 CIBSE Cooling Load Calculation Peak Month August Time 15:00 ROOM F04 Office Vent. Solar Internal Total Cooling Building Conduction Infiltration Gain Gain Gain Gains Load Form Gain (kW) Gain (kW) (kW) (kW) (kW) (kW) (W/m2) Deep Plan 7.22 2.24 10.76 38.25 40.2 98.67 59.15 Shallow Plan 4.12 1.16 5.41 16.42 20.80 47.61 57.58 Table 3: Peak heating and cooling loads for building forms used for case study buildings All values were considered to be within an acceptable range and the building forms suitable for the application of the relevant design strategies. It was also established that the cooling loads were highest for the fourth floor offices.

It should be noted that, as anticipated, the shallow plan building experiences a slightly higher heating load per metre of floor area in the office space than that of the deep plan building. This is a result of the greater ratio of external surface area to floor area and therefore a larger conduction loss per unit floor area under identical wall U-values. In this case the ventilation heat loss is the dominant loss and as such, the divergence in gains is limited to approximately 5%. Similarly it was anticipated that the increased ratio of façade area to floor area for the shallow plan building would result in a higher solar gain per unit floor area and hence a higher cooling load. The decision to reduce the percentage of glazing on the façade of the shallow plan building over that chosen for the deep plan building prevented this, and resulted in a slightly higher cooling load per unit floor area for the deep plan building. Excessive solar gains can be problematic in 132

building cases which propose to avoid cooling and the control of solar gains is explored further within the Natural Ventilation and Passivhaus case studies.

5.1.5 Climate Data The case studies in the following chapter employ the CIBSE Test Reference Year files for the energy analysis and Part L compliance simulations. The CIBSE Design Summer Year files were used in all cases to test thermal comfort. The parameter sweep examining the impact of climate change (see Section 5.7.3) employed the PROMETHEUS weather data [129].

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5.2 Incremental Improvement Case

This subchapter contains the results of the application of the Incremental improvement design strategy. It demonstrates the process applied to the base case building in order to establish the most effective improvement measures. It goes on to produce a final design case using those improvements and increase the simulation detail through the modelling of a detailed space conditioning and ventilation system. Simulation input data for this case can be found in Appendix A1 and output data in Appendix B1.

5.2.1 Concept Design

The application of the Incremental improvement strategy was dominated by the concept design stage, which was used as an opportunity to test all of the potential improvement options individually. The sensitivity of a building to certain design improvements was expected to vary from case to case and as such it was not considered appropriate to simply apply the measures recommended by either the Target Zero [102] or the Green Building Council [32] reports but rather to test which were most suited to the case study building defined at the pre-design stage. The literature review also determined that the use of the National Calculation Methodology as the means to determine the success of these performance improvements was inappropriate and that a generic building simulation approach would yield more accurate results and offer more control over simulation parameters.

In keeping with the target of an nZEB standard, the percentage improvement in overall primary energy consumption was used as the KPI as the alternative to the NCM carbon metric.

5.2.2 Model geometry

The Incremental improvement case used the basic deep plan geometry established in the Pre-design analysis of the problem. The building was discretised as displayed in Figure 21 with a floor plate to floor plate height of 3.5m with a 0.5m false ceiling. This layout was chosen to ensure that this case study represented as closely as possible the typical speculative office building; divorced from distinctive architectural choices and exotic construction features. Figure 27 and Figure 28 display the model geometry as inputted into the IESVE simulation software.

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Figure 27: Rendered image of deep plan building used in the Incremental Improvement case study.

Figure 28: Wireframe image of the deep plan building used in the Incremental improvement case study.

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5.2.3 ‘Base’ case design concept

The first stage of the concept design process was to establish a ‘base case’ specification for the case study. The starting point for the energy efficiency and carbon emissions section of design for any non-domestic building must be compliance with the minimum standards found in the Building Regulations and their supporting documents. This was the approach that was used in both of the studies examined in the literature review [5] [92] and it was replicated here in order to offer a realistic starting point for the design process.

5.2.3.1 Specifications

The specifications for the base case model were obtained from the appropriate government literature. The fabric standards were obtained from Approved Document L2A 2010 [41]. The mechanical standards were obtained from The Non-Domestic Building Services Compliance Guide 2010, this included heating [168], cooling [169], mechanical ventilation and heat recovery [170] and domestic hot water provision [171]. The Lighting Standards were set using the SSL Handbook [172]. The air conditioning system selected was a variable refrigerant flow (VRF) system with supply air provided zonally.

Minimum Fabric Standards – Part L2A 2010 Roof 0.25 W/m2K Wall 0.35 W/m2K Floor 0.25 W/m2K Windows, roof windows, roof-lights, curtain walling and pedestrian doors 2.2 W/m2K Vehicle access and similar large doors 1.5 W/m2K High-usage entrance doors 3.5 W/m2K Roof ventilators (inc. smoke vents) 3.5 W/m2K Air permeability at 50 Pa (reduced from typical)1 5.0m3/h.m2 Minimum Mechanical Standards – Non-domestic Compliance Guide Specific Fan Power (SFP) 1.8W/l/s AEV (W/m2)2 0.39 W/m2 Heating - Co-efficient of Performance (COP) 2.2 Cooling - Seasonal Energy Efficiency Ratio (SEER) 2.5 Heat recovery efficiency (thermal wheel) 65% Domestic hot water efficiency 73% Lighting Standards – SLL Design Guide Lighting demand (per 100lux) 2.5W/m2 Glazing G-value 0.68

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1. Minimum air permeability is set as 10.0m3/h.m2 at 50Pa in L2A 2010 but accepted industry target is 5.0m3/h.m2 set at 0.2ac/h from CIBSE method [173]. 2. The ‘Auxiliary Energy Value is calculated using an inbuilt algorithm in the Apache systems module of the IESVE which produces a system specific constant demand representing the mechanical power demands of the system. More information can be found in the IES Knowledge Base [144]. Table 4: Minimum specifications used for the 'base case' building in the IESVE model 5.2.3.2 Primary energy consumption

This model yielded the distribution of primary energy consumption per m2 of floor area displayed in Figure 29.

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Figure 29: Distribution of primary energy demand per m2 floor area for 'base' case concept

Building Concept Energy Consumption ‘Base’ Total (MWh) 371.4 Total per unit floor area (kWh/m2) 56.3 Primary energy per unit floor area (kWh/m2) 155.7 Table 5: Total energy consumption for 'base' building concept

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5.2.3.3 L2A 2010 Compliance

Table 6 displays the results of the L2A 2010 dynamic simulation for the ‘base’ case building; it demonstrates that not only does this case fail to meet the targeted primary energy demand for nZEB standard but it also fails to meet the Part L of the 2010 Building Regulations.

L2A 2010 ‘Base’ model 2 Building Emissions Rate (BER) 33.8 kgCO2/m .year 2 Target Emissions Rate (TER) 19.3 kgCO2/m .year Pass/Fail (BER

The total energy consumed, as well as the total per floor area and the primary energy per floor area, are displayed in Table 5 for comparative purposes. The fact that the building is dominated by electrical demands in the form of space conditioning from the variable refrigerant flow system and the lighting means that the primary energy consumption per m2 floor area is significantly higher than the maximum target of 120kWh/m2year set out in the methodology. This ‘base’ case data demonstrated that some action would be required by the design team to meet the standards required. This is further supported by the results of the L2A 2010 dynamic simulation displayed in Table 6 above.

5.2.4 Incremental improvements to concept design

The ‘base’ case formed a starting point for the improvement measures developed from the review of literature to represent typical improvements offered in an attempt to reduce the energy consumption and carbon emissions of a commercial office building. These improvements were then applied individually to the ‘base’ case to establish the degree of positive (or otherwise) impact that they would have on the building energy performance.

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5.2.4.1 Specifications

Table 7 displays the improvements employed at this stage of the process. As in the Target Zero approach [34], percentage improvements were applied to the minimum requirements laid out in the Building Regulations and design guides (see Table 4).

The improvements represented a common best practice improvement and an ‘extreme’ improvement that was representative of idealized conditions of design, materials and construction. Percentage reductions were applied to U-values and G-values in order to reduce heating and cooling loads respectively. Percentage reductions in specific fan power and lighting demand were applied to represent the sourcing of more efficient components. Likewise percentage increases in system efficiencies represented the sourcing of more efficient systems.

Case Study “Incremental Improvement” Percentage Area of Improvement to Improved Characteristic Improvement Type Improvement characteristic Value value Air tightness -40% 3.0 (0.08ac/h) Wall U-value -20% 0.28 W/m2K Wall U-value -40% 0.21 W/m2K Floor U-value -20% 0.2 W/m2K Floor U-value -40% 0.15 W/m2K Fabric Roof U-value -20% 0.2 W/m2K Roof U-value -40% 0.15 W/m2K Glazing U-value -30% 1.8 W/m2K Glazing U-value -40% 1.6 W/m2K Glazing U-value -50% 1.4 W/m2K External Shading N/A 1m(horizontal, south) Internal Shading N/A Blinds* Glazing G-value -20% 0.56 Light Glazing G-value -40% 0.43 Lighting Efficiency -20% 2.0W/m2 per 100lux Lighting Efficiency -40% 1.5W/m2 per 100lux Daylight dimming N/A Light sensor Specific Fan Power -20% 1.44 W/l/s Air Distribution Specific Fan Power -30% 1.26 W/l/s Specific Fan Power -40% 1.08 W/l/s Co-efficient of Performance +40% 3.1 (kW/kW) Heating Co-efficient of Performance +60% 3.5 (kW/kW) Seasonal Energy Efficiency Ratio +40% 3.5 (kW/kW) Cooling Seasonal Energy Efficiency Ratio +60% 4.0 (kW/kW) Seasonal Energy Efficiency Ratio +80% 4.5 (kW/kW) Efficiency +20% 78% Heat Recovery Efficiency +40% 91% Boiler Efficiency +20% 86% DHW Solar Hot Water N/A 300m2 *Blinds set to lower at incident radiation greater than 300 W/m2 and to be raised again at incident radiation of less than 100W/m2. Table 7: Incremental improvements applied to base case design.

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5.2.4.2 Combined Heat and Power

Combined heat and power was considered as an option for this case, however it was established that there were insufficient hours of consistent heat demand (less than the 4500hrs recommended [174]) from the heating system to make it a viable alternative to heating via Variable Refrigerant Flow. The domestic hot water demand was not sufficient in volume to justify a CHP unit to meet its needs and this resulted in its non- use as a design option.

5.2.4.3 Primary energy consumption

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-3.50 Air Wall U Wall U Floor U Floor U Roof U Roof U Tightness 20% 40% 20% 40% 20% 40% 40% % 0.08 0.19 -0.11 -0.23 0.01 0.01 -3.14

Figure 30: Percentage reduction in primary energy consumption through fabric improvements

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Figure 31: Percentage reduction in primary energy consumption through glazing improvements

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Figure 32: Percentage reduction in primary energy consumption through lighting and shading improvements

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0.00 Solar DHW boiler eff seer40% seer60% seer80% cop20% cop60% % 2.03 0.73 4.70 6.72 7.84 0.70 3.34

Figure 33: Percentage reduction in primary energy consumption through improvements to heating, cooling and domestic hot water systems

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Figure 34: Percentage reduction in primary energy consumption through ventilation system improvements

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Figure 30 to Figure 34 above displays the impact on primary energy consumption that each improvement measure had in isolation. These results are displayed in the form of percentage improvements.

5.2.5 Best combination of improvements

Using the data generated by the parameter sweep displayed in the previous section a series of improvement measures were selected for use in a ‘final’ concept design case. It can be observed that fabric improvements have little benefit on this case and indeed often increase the primary energy demand. This was established as an increase in summer cooling demand as reflected by the inability of a thermally lightweight building to ‘normalize’ its temperature during unoccupied hours if starting from an extreme evening condition. In contrast, those measures which mitigated gains, both solar and internal, demonstrated strong positive results. The dominance of lighting was also demonstrated in the benefit of both increased efficiency and the application of daylight dimming. Finally, the improved efficiencies of the heating, cooling and ventilation systems yielded positive results as was to be expected given their direct reduction in the quantity of energy required to condition the space. Table 8 collects the improvements selected for the ‘final’ case study.

Improved Mechanical Standards – ‘Final’ case study Specific Fan Power (SFP) 1.08W/l/s AEV (W/m2)2 0.39 W/m2 Heating - Co-efficient of Performance (COP) 3.5 Cooling - Seasonal Energy Efficiency Ratio (SEER) 4.5 Heat recovery efficiency (thermal wheel) 91% Domestic hot water efficiency 86% Solar Hot Water 300m2 Improved Lighting Standards – ‘Final’ case study Lighting demand (per 100lux) 1.5W/m2 (dimming) Glazing G-value 0.43 External Shading 1m

Table 8: Improvements applied to the 'final' case of the Incremental improvement case study

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5.2.5.1 Primary energy consumption

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Figure 35: Distribution of primary energy demand per m2 floor area for ‘base' case and 'final' case building designs as generated by the ApacheSim dynamic simulation module (kWh/m2.year)

Building Concept Energy Consumption ‘Base’ ‘Final’ Total (MWh) 371.4 173.3 Total per unit floor area (kWh/m2) 56.3 26.3 Primary energy per unit floor area (kWh/m2) 155.7 73.9

Table 9: Total energy consumption for 'base' and ‘final’ building concepts 5.2.5.2 L2A 2010 Compliance

L2A 2010 ‘Base’ model ‘Final’ model 2 2 Building Emissions Rate (BER) 33.8 kgCO2/m .year 13.0 kgCO2/m .year 2 2 Target Emissions Rate (TER) 19.3 kgCO2/m .year 19.3 kgCO2/m .year Pass/Fail (BER

The combination of these improvements resulted in a significant improvement over the performance of the ‘base’ case. Figure 35 and Table 9 below demonstrate that the Incremental improvement approach can yield successful results, albeit with the use of 144

high performance components in both the fabric and mechanical and electrical systems of the buildings. The improvements also yielded a significant performance improvement within the dynamic compliance simulation as seen in Table 10. The building now passes Part L of the building regulations by a significant margin. The primary energy consumption per m2 floor area was found at this stage to be sufficiently low to progress to the detail design stage of the methodology, which targeted the refinement of the building concept to reflect the tangible benefits of the specific HVAC system used.

5.2.6 Detail Design

The incremental improvements applied to this case study have yielded a building design that offered a significant performance improvement over the base case generated using the minimum standards found in the government literature. This success would typically represent the point at which the information was disseminated to the design engineers as the required specification to meet the strived for energy consumption / carbon emissions for the building. The designers would aim to replicate these performance improvements through the sourcing of the correct components and materials.

It has been established in both the design and research methodologies (see Chapters 4 & 1.1) that in order to fully investigate the performance of the building cases (particularly in the post-design investigation) it was necessary to replicate the first stage of this design process. In this case it has been identified that the performance of the heating and cooling systems, along with the lighting design, mark the areas which most benefit from improvements to efficiency and control strategy. The lighting model used in the first set of simulations represented the most accurate method available; however the use of the Apache HVAC module of the IESVE afforded a more accurate examination into the performance of the heating, cooling and ventilation systems.

5.2.6.1 Variable refrigerant flow

Variable refrigerant flow is a variation on a traditional multi-split system. Indoor units (which can be directly connected to supply air or fitted as separate units) provide heating and cooling of the room air through refrigerant cycled from outdoor units. Unlike a traditional split system, however, the Variable Refrigerant Flow system is also capable of moving heat energy between zones rather than simply outside to inside and vice versa [175]. It is this ability to ‘dump’ heat from zones that require cooling to those

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that require heating that afford the energy performance benefit that results in its high efficiency rating. Li et al [176] demonstrated that in months of moderate external temperature, where solar gains might prove the difference between a zone requiring heat or cooling (and a conventional system may fight against itself) a Variable Refrigerant Flow system should provide a suitable and indeed highly efficient solution. It was this aspect of its functionality that led Variable Refrigerant Flow to be chosen as the most efficient conventional HVAC system available to this case study.

Figure 36: Apache HVAC 'multiplex' model of the VRF system used in the final model of the Incremental Improvement case study. Figure 36 displays the schematic used to represent the variable refrigerant flow system in the Apache HVAC simulation module of the IESVE. The image an individual indoor unit of the Variable Refrigerant Flow system and the air supply and extract system which accompanies it. The ‘multiplex’ facility of the ApacheHVAC module allows these features to be assigned globally to each of the office space zones in the simulation model. The model used in this case study used auto-sized components to meet the heating and cooling demand as in the less detailed Apache Sim model. The fundamental differences between the two modelling approaches were the ability to represent part load data and the ability to represent the simultaneous heating and cooling facility that

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provides Variable Refrigerant Flow systems with their performance improvement over conventional multi-split systems. The methodology used to model this performance enhancing feature is provided within the ApacheHVAC support documentation [177]. By permitting 100% heat recovery from the condenser on the chiller component for use by the heat source the model ensures that if cooling is occurring in one zone of the building and heating in another the heating will be met first by that which has been ‘removed’ from the cooled zone. While this does not directly represent the real behaviour of the Variable Refrigerant Flow system it has been demonstrated to provide valid results within the accuracy limits of the building simulation software [177]. It was used in this case where the research goal was to demonstrate the potential savings that an advanced heating and cooling system could provide over a traditional ducted system to best effect rather than examine in detail the effectiveness of specific components.

5.2.7 Detailed design simulation - Results

5.2.7.1 Energy

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Figure 37: Distribution of primary energy demand per m2 floor area for ‘final' case and 'final' case with VRF Apache HVAC model as generated by the ApacheSim dynamic simulation module (kWh/m2.year)

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Building Concept Energy Consumption ‘Final’ ‘Final’ + VRF Total (MWh) 173.3 160.6 Total per unit floor area (kWh/m2) 26.3 24.3 Primary energy per unit floor area (kWh/m2) 73.9 68.3

Table 11: Total energy consumption for 'final' and ‘final’ + VRF Apache HVAC model building concepts 5.2.8 Case Summary

The ‘Final’ model, with the more accurate Variable Refrigerant Flow model attached, demonstrated a building design which met the requirements set out in the design methodology. The building demonstrated a successfully conditioned internal space which does not exceed the cooling set point of 23°C or the CO2 concentration of 1000ppm. The primary energy consumption of the core building services was significantly lower than the target of 120kWh/m2year and a reduction of 56% over the ‘base’ case commercial office building.

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5.3 Natural Ventilation Case

This subchapter contains the results of the application of the Natural ventilation design strategy. It demonstrates the process applied to the base case building in order to establish the most appropriate ventilation method for comfort and energy efficiency. It goes on to produce a final design case using those improvements and increase the simulation detail through the modelling of an under-floor heating system. Simulation input data for this case can be found in Appendix A2 and output data in Appendix B2.

5.3.1 Introduction

The primary concept for this case study was a simple, naturally ventilated office space with hot water radiator heating. The most fundamental barrier to natural ventilation as a viable strategy for an nZEB building is that of preserving occupant comfort in both summer and winter temperatures. The lack of mechanical ventilation and cooling resulted, as expected, in a low baseline energy demand with the minimum of designer intervention required. The natural ventilation base case demonstrated the lowest energy demand of any base case considered in program of research and still presented the opportunity for further performance improvement.

5.3.2 Model geometry

The building model was subdivided to reflect the natural ventilation design strategy and the potential for uneven temperature distribution throughout the space. While comfort analysis considered a whole office space average of temperature this discretization improved accuracy and allowed for quality control of the models. Figure 38 demonstrates the nature of this subdivision.

Figure 38: Cross-section of thermal model zoning of natural ventilation case study.

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The occupied space and air space, as well as the north and south sectors of the office space, are divided by a “hole” element (a zone boundary of minimized thermal resistance and which permits the movement of air flow across it). It should also be noted that the under-floor slab zones marked in Figure 38 were added in order to facilitate the under floor heating option at the detail design stage.

Figure 39: Rendered image of shallow plan building as used in the Natural ventilation case study.

Figure 40: Wireframe image of deep plan building used in the Natural ventilation case study.

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5.3.2.1 Assumptions

This subdivision of the building form was predicated on the following assumptions relating to the thermal and bulk airflow within the model and the accepted best practice for achieving accurate and consistent results.

1. That the air space above the occupied height of the office would experience different thermal conditions, particularly during phases of natural ventilation, and as such should be subdivided in the Z axis. 2. That the daylight levels and solar radiation from the north and south facades would be significant to the design process (daylight dimming and solar gains respectively) and as such should be subdivided in the X and Y axes (as defined in Section 5.1.1). 3. That there will be some stack effect within the open plan reception area of the building and as such it should be subdivided in the z-axis to represent the temperature gradient.

5.3.3 Concept design – ‘base’ case

The ‘base’ case for this case study was simply a naturally ventilated office space of the most basic type; cross ventilation from operable windows to mitigate summer overheating and trickle vents to ensure sufficient fresh air supply year round. The selection of fabric, glazing, systems and lighting was determined by a drive to minimise energy consumption and control the risk of overheating within the office space during occupied hours through passive means.

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5.3.3.1 Cross-ventilation

Figure 41: Ventilation strategy for cross-ventilation with trickle vents. 5.3.3.2 Building fabric

The use of exposed thermal mass was essential in the control of internal temperatures. It was identified in the literature review as a design option for any building where the preservation of an internal condition was favoured over the continued conditioning of the internal air volume. While more exotic forms of thermal mass were explored elsewhere in the research the minimalist approach used in this case as well as the option for a natural ventilation driven night purge led to its inclusion in the core make-up of the building concept through the exposure of the ceiling slabs and the internal faces of the external walls. In the IES VE the ‘thermal mass’ of a construction element is calculated as the energy stored per square metre of surface area per degree of temperature difference, for the first 100mm of material depth. This property denotes the capacity for thermal storage within the material itself. The other property of significance when considering thermal mass is the surface admittance (or Y-value) of the material which forms the inner boundary of the construction element. Where ‘thermal mass’ denotes capacity, Y-value denotes the rate of heat transfer across the boundary condition between the air volume and the construction element [178]. The combination of these two characteristics determine the rate at which heat may be absorbed and discharged from a construction element, as well as the quantities of energy which can be stored and released assuming full activation of the thermal mass occurs. 153

Table 12 displays the material properties used in the building fabric.

Thermal Surface Construction Materials U-value Mass Admittance Element (outside to inside) (W/m2K) (KJ/m2K) (W/m2K) Render, EPS slab, External wall 0.26 176.4 5.43 exposed concrete. Internal Plaster, EPS slab, Plaster 0.4 70.0 0.61 partition Flooring, screed, EPS Internal 176.4 slab, exposed concrete 0.3 5.73 floor/ceiling (ceiling) (ceiling). Foundations, concrete, Ground floor EPS slab, screed, 0.18 40 1.39 flooring. Felt/Bitumen, EPS slab, 176.4 Roof exposed concrete 0.22 5.73 (ceiling) (ceiling). Table 12: Material properties of building fabric for natural ventilation case study (admittances from CIBSE Guide A Table 3.55 [179]). Thermal mass is denoted as the energy storage capacity per square metre of exposed surface per degree difference in temperature (known as ΔT) in kJ/m2K. The U-values were reduced below the minimum standards for L2A 2010 [41] in order to preserve the internal conditions created by the heating (winter) and natural ventilation (summer).

The observations of the Incremental improvement case study that extreme increases in U-values could potentially have a greater impact on cooling load (which could not be met mechanically in this case) than preservation of heat in winter (see Section 5.2.4) led to the reduction stopping short of the minimum achievable values. The impact of these extreme U-values on a building design which does not use comfort cooling is further addressed in the Passivhaus case study.

In this case insulation was also added to the internal floor to create a barrier between the screed layer and the concrete slab. This was included to create a thermal barrier between the under-floor heating system within the screed (see Section 5.3.8) and the exposed concrete slab. Similarly, the use of a thermal mass strategy is reliant on the retention of heat overnight in winter in order to be efficient. As such it was determined that rather than include the external core spaces in this strategy, where sufficient levels thermal mass may be difficult to expose and temperature set points are different, it would be more efficient to create a separate thermal envelope for these sections. This was

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achieved through the inclusion of insulation in the partitions dividing the external core areas from the office space.

5.3.3.3 Glazing

The glazing strategy for the building was determined as part of the selection of building form at the Pre-design stage. The layout of the window panes per office space ‘zone’ is displayed in Figure 42 below. The upper panes were set as operable, top hung windows while the lower panes were fixed.

Figure 42: Glazing layout per office space 'zone' for natural ventilation strategy Table 13 displays the material properties for the glazing strategy and as with the opaque construction elements the case employed best practice U-values rather than lowest achievable or highest permissible by regulation. The G-value of the glass was set at 0.62 in order to capitalise on winter solar gain as a source of heat. The comparison between retention of this value with and without shade or the use of a solar control glass with a lowered U-value forms a portion of the investigation into alternative design options below.

Construction Façade Materials U-value G-value % with frame South facing double glazing 50 6mm clear float with 1.8 W/m2K 0.62 10% PVC frame. North facing double glazing 50 6mm clear float with 1.8 W/m2K 0.62 10% PVC frame.

Table 13: Glazing properties for 'base' case of natural ventilation case study

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5.3.3.4 Air tightness

The air tightness of the building was taken as 5.0m3/hr.m2 at 50Pa; converted to an infiltration rate of 0.20ac/h using the CIBSE method (due to the natural ventilation strategy in place the peak value infiltration rate was used) [173].

5.3.3.5 Lighting

A best practice maximum lighting gain of 1.5W/m2 per 100lux at 400lux with daylight dimming to 100lux was set as standard due to need to reduce internal gains as a design priority in naturally ventilated offices [164].

5.3.3.6 Domestic Hot Water

The testing of alternative domestic hot water systems was not considered a part of the investigation for this case study and as such an 89% efficiency gas boiler was assigned for all cases, as used in the final iteration of the incremental improvement case study. The solar hot water panels were excluded as they fell outside the scope of this case study, which focussed on the reduction in energy consumption through a natural ventilation and thermal mass strategy.

5.3.3.7 Combined Heat and Power

Combined heat and power was considered as an option for this case, however it was established that there were insufficient hours of consistent heat demand (less than the 4500hrs recommended [174]) from the heating system to make it a viable alternative to heating via VRF. The domestic hot water demand was not sufficient in volume to justify a CHP unit to meet its needs and this resulted in its non-use as a design option.

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5.3.4 ‘Base’ case – Results

5.3.4.1 Energy

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Figure 43: Distribution of primary energy demand per m2 floor area for 'base' case concept

Building Concept Energy Consumption ‘Base’ Total (MWh) 198.4 Total per unit floor area (kWh/m2) 60.1 Primary energy per unit floor area (kWh/m2) 76.8 Table 14: Total energy consumption for 'base' building concept 5.3.4.2 L2A 2010 Compliance

L2A 2010 ‘Base’ model 2 Building Emissions Rate (BER) 13.5 kgCO2/m .year 2 Target Emissions Rate (TER) 16.3 kgCO2/m .year Pass/Fail (BER

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5.3.4.3 Analysis

Unlike the Incremental improvement case, the ‘base’ case Natural ventilation concept immediately demonstrates the credentials of a low energy building. While the energy demand is similar per m2 floor area to its counterpart in the previous case (see Table 14), the primary energy demand is 50% lower due to its use of natural gas as a primary heating source and lack of mechanical ventilation or comfort cooling. Also significant is that the building easily passes the L2A 2010 dynamic compliance check. These initial findings were tempered, however, by concerns with regard to model accuracy and realistic representation of thermal comfort.

5.3.5 Concept design – ventilation alternatives

The use of simple window design with opening and trickle vents yielded an acceptable thermal comfort all year round but raised questions of energy efficiency. It was observed, that the heating demand, particularly in winter, was extremely high and that there was a risk that the true effect of the trickle vents could in fact be more severe (the use of permanent natural ventilation is inherently unpredictable and a strategy which employs it leaves the building vulnerable to even mild fluctuations in climate and even changes in the surrounding building stock which may increase exposure [180]). The research requirement to pursue variation within the design strategies as well as to emulate the design process itself (good practice would include an investigation into the mitigation of this risk) led to the search for an alternative which met with the requirements.

Three alternative ventilation strategies were then developed in parallel in an attempt to produce a concept which would match the low energy demand of the base case without the inherent risk of a traditional natural ventilation strategy.

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Figure 44: Modes of natural ventilation considered for the 'Natural ventilation' case study The first of these concepts was simply to offer a mixed mode system whereby window opening was still employed to provide ‘cooling’ during high internal temperatures and to facilitate night purging of the office space but with a change-over system which provided sufficient fresh air mechanically to maintain air quality. This system was modelled using a simple supply air condition with passive heat recovery that ensured a significant reduction in heating demand but at the cost of a mechanical power demand from the supply air fan.

Figure 45: Ventilation strategy for cross-ventilation with change-over mechanical supply air

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The second concept modified the structure of the case study building to include a glazed atrium roof on the open plan reception area. The addition of louvres to this roof structure facilitated a stack ventilation approach rather than the cross ventilation used in the base case. As there is a risk of excessive ventilation from trickle vents so there is a risk with cross flow ventilation that the air speeds within the building will become uncomfortable (in excess of 0.5m/s). The use of single sided window opening and an atrium was explored as an alternative which could sufficient air without exposing the office space to these potentially unsatisfactory conditions.

Figure 46: Rendered image of natural ventilation case study with internal glazed atrium space. The final concept was the use of wind-catchers as a direct alternative to any kind of mixed mode strategy. Wind-catchers channel wind into the building, controlling air velocity and supply rate through controlled room units. This is in contrast to both windows and louver opening (which directly expose the internal environment to the external) or ducted ventilation which requires powered fans. The section of the windcatcher which is leeward permits a constant flow of warm air to escape through buoyancy in the absence of a wind driven downward flow.

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Figure 47: Rendered image of Natural ventilation case with wind-catchers All three concepts failed to meet the required comfort standards without some form of additional fabric design intervention and/or the inclusion of a night purge facility (night purge functionality is in-built to the wind catcher control scheme). Night purges are more favourable in buildings which offer an alternative means of natural ventilation than controlled window opening as this can offer a potential security risk if not designed and controlled correctly. For the purposes of this study it was assumed that the appropriate design measures had been taken and that a design option which featured night purging through window opening could be assessed on its merits as an occupier- friendly and energy efficient design.

The fabric additions which were made to the building design concepts were the addition of solar controlled glass (g-value 0.43) and/or external shading (1m fixed overhang). The atrium concept used solar control glass for both options due to the increased glazing area.

The use of conventional internal shading (curtains or blinds) was considered at odds with the desire to use passive systems or controls where possible and also with the use of cross ventilation which could result in significant disruption of the device at times when it might otherwise be required to mitigate solar gains.

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5.3.6 Ventilation alternatives – Results

The results for the testing of these design alternatives, as well as the overheating mitigation measures attributed to them were collated into Table 17 below in order to evaluate their viability as alternatives to the ‘base’ case option.

The criteria set to determine success were that the building design concept should not exceed the 1% occupied hours over 28°C or internal CO2 concentration of less than 1000ppm set out in the comfort criteria section of the methodology but should still compete with the ‘base’ case in terms of primary energy demand.

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Primary Energy consumptionperm Mixed Mixed Mode + Mixed Mode + Mode + Mode + Mode + LowG Mode LowG Shade + Purge Shade Glazing + Glazing Purge Purge Heating 10.47 10.46 11.10 12.86 13.12 11.35 DHW 4.38 4.38 4.38 4.38 4.38 4.38 Ventilation 1.7 1.7 1.7 1.7 1.7 1.7 Lighting 23.8 23.8 25.0 23.8 23.8 25.0

Figure 48: Primary energy consumption for 'mixed-mode' design alternatives for Natural ventilation case study

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Primary Energy consumption per m per consumption Primary Energy Shade LowG Glazing Heating 23.41 25.48 28.71 DHW 4.38 4.38 4.38 Ventilation 0.0 0.0 0.0 Lighting 27.2 29.3 27.2

Figure 49: Primary energy consumption for 'wind-catcher' design alternatives for Natural ventilation case study

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Figure 50: Primary energy consumption for 'atrium' design alternatives for Natural ventilation case study

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Energy Consumption Design Options Total/m2 PE/m2 Total (kWh/m2) (kWh/m2) Nat. Vent. + Trickle 198.4 60.1 76.8 Mixed Mode 76.8 23.3 40.3 Mixed Mode + Purge 80.2 24.3 42.1 Mixed Mode + Shade 84.6 25.6 42.7 Mixed Mode + Low-G Glazing 85.4 25.9 43.0 Mixed Mode + Low-G Glazing + Purge 81.0 24.5 42.4 Mixed Mode + Shade + Purge 76.9 23.3 40.3 Atrium + Purge 82.1 24.9 42.0 Atrium + Purge + Shade 92.9 28.2 45.9 Wind-catcher 120.6 36.6 55.0 Wind-catcher + Shade 129.7 39.3 59.1 Wind-catcher + Low- G Glazing 137.8 41.8 60.3

Table 16: Total energy consumption for design alternatives for Natural ventilation building case study

Comfort Criteria Percentage of Design Options occupied hours over CO2 Concentration 28°C internal (ppm) temperature Nat. Vent. + Trickle 1 914 Mixed Mode 3 888 Mixed Mode + Purge 1.3 888 Mixed Mode + Shade 1.2 888 Mixed Mode + LowG Glazing 1.3 889 Mixed Mode + LowG Glazing + Purge 0.7 889 Mixed Mode + Shade + Purge 0.6 888 Atrium + Purge 7.9 893 Atrium + Purge + Shade 3.7 895 Wind-catcher 3.8 1083 Wind-catcher + Shade 2 1214 Wind-catcher + LowG Glazing 1.8 1193 Table 17: An assessment against comfort criteria of the design alternatives of the Natural ventilation case study 5.3.7 Final ventilation strategy – Results

The investigation into design alternatives suggested that for the building form examined cross-ventilation remained the only viable option. The wind-catchers could not sufficiently control overheating or cycle air sufficiently to maintain a good standard to air quality. The atrium ventilation strategy was more successful at cycling air but the

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glazed roof area resulted in significant overheating, suggesting that for a building of this size an atrium space could not directly interact with the office space but would require a true hybrid ventilation system which was beyond the scope of this case study.

The mixed-mode ventilation was successful in both its control of internal temperature and its meeting of air quality requirements. In order to control the internal temperature it required night purging of the office space and either fixed external shading or a solar control glass. The ‘final’ design solution used the fixed external shading as it allowed the building fabric to absorb solar gains in winter and as such lowered the heating load of the building.

The mixed-mode change over system with cross ventilation was the most effective of any of the design concepts at exploiting the thermal mass through night-purging and as such controlling the gradual increase in morning temperatures during a working week. A further design option was proposed to attempt to exploit the thermal mass of the building to better effect during the winter months. Under-floor heating systems have the dual advantage of being low exergy (the water in the pipes is typically 30-40°C as opposed to up to 60°C in a hot water radiator system) and being directly coupled with the thermal mass of the building. The modelling of under-floor heating systems in the Apache Sim module of the IESVE is non-explicit and simply entails the setting of the heating profile to represent that of an under-floor heating system (constant 1st September to 30th April) rather than matching the occupancy and the setting of the COP to match that of the heat source, in this case an air source heat pump (COP 4.3).

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5.3.7.1 Energy

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Figure 51: Primary energy consumption for 'base' and 'final' design concepts for Natural ventilation case study

Building Concept Energy Consumption ‘Base’ ‘Final’ Total (MWh) 198.4 64.4 Total per unit floor area (kWh/m2) 60.1 19.5 Primary energy per unit floor area (kWh/m2) 76.8 48.8

Table 18: Total energy consumption for 'base' and ‘final’ building concept of Natural ventilation case study 5.3.7.2 Part L2A 2010 Compliance

L2A 2010 ‘Base’ model ‘Final’ model 2 2 Building Emissions Rate (BER) 13.5 kgCO2/m .year 12.1 kgCO2/m .year 2 2 Target Emissions Rate (TER) 16.3 kgCO2/m .year 18.4 kgCO2/m .year Pass/Fail (BER

The addition of the “under-floor heating” system successfully exploited the thermal mass in the building, resulting in a significantly lower Total Energy Consumption for 166

the Natural Ventilation case study when compared to the fully naturally ventilated ‘base’ case with radiators (see Table 18). It resulted in a primary energy value that was significantly lower than that of the ‘base’ case, with the more efficient heating strategy able to offset the electrical power demand from the change-over mechanical ventilation system. As in the case of the Incremental improvement strategy an opportunity for a deeper level of investigation was identified.

The model used in the ‘final’ case was little different from the application of an air-to- air heat pump in the occupied space; so that the thermal mass in the room was exploited but not the thermal mass of the floor itself. Additionally, the low exergy benefits of the under-floor heating were also neglected. Both of these factors could be expected to further reduce the energy consumption of the system in meeting the space heating requirements. In response to these inaccuracies within the model, a more detailed simulation was developed using the Apache HVAC module of the IESVE.

5.3.8 Detail Design – Under-floor heating system

The Apache HVAC module does not contain an explicit model for under-floor heating, however a solution has been proposed by Moore [181] and supported by IES [182] that permitted a more accurate representation of the behaviour and efficiency of an under- floor heating system.

The ‘slab’ elements pictured in Figure 38 were modelled with internal volumes of less than 1mm; the under floor heating coils embedded within the screed were represented by ‘radiators’ placed within these under floor zones. These ‘radiators’ were set to the mass of the water contained within the tubing (50 litres per office space zone) and given 100% convective heat transfer properties within the minimal zone space afforded by the internal volume of the slabs. This ensured that the heat transfer between ‘radiator’ element and the floor of the room zone represented the process of under floor heating rather than adjacent heated air spaces. In order to represent the fact that the surface area contact of the loops with the screed was less than the flat internal volume of the model the conductivity of the screed was reduced by 80% (this is the maximum reduction factor recommended by the Moore [181] and was confirmed by running a one room test). The loop temperature was set to 30°C with a 19°C set point based upon

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internal temperature; the pumping rate of the water loop was set to 0.02l/s [183]. The part load efficiencies of the associated heat pumps were set as stated in Table 20 below.

Unit Air Temperature COP Power (°C) (kW/kW) (kW) -10 2.43 5.30 Outdoor Unit 4 3.99 8.64 (one per floor) 12 5.64 12.17

Table 20: Part load data for air source heat pump used in under-floor heating model for Natural ventilation case study 5.3.9 Detailed design simulation – Results

5.3.9.1 Energy

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Figure 52: Primary energy consumption for 'final' design concept and 'final with under-floor heating' design concept for Natural ventilation case study

Building Concept Energy Consumption ‘Final’ ‘Final’ + UFH Total (MWh) 64.4 56.1 Total per unit floor area (kWh/m2) 19.5 17.0 Primary energy per unit floor area (kWh/m2) 48.8 41.4

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Table 21: Total energy consumption for 'final' design concept and 'final with under-floor heating' design concept for Natural ventilation case study 5.3.9.2 Analysis

The ‘final’ model for the Natural ventilation case displays a better primary energy consumption value when modelled; with further performance improvement demonstrated using the more accurate under-floor heating model. This improvement is distinct and quality control checks were performed on the model to ensure that the findings were robust. The internal temperature of the office space was controlled at 19°C throughout the heated hours of the year with a surface temperature at floor level not exceeding the recommended 27°C [183].

5.3.10 Case Summary

The ‘Final’ model, with the more accurate under-floor heating model attached, demonstrated a building design which met the requirements set out in the design methodology. The building successfully controlled summer internal temperatures to

28°C or below for 99.4% of occupied hours and the CO2 concentration did not exceed the designated limit of 1000ppm. The primary energy consumption of the core building services was approximately one third of the maximum allowable 120kWh/m2year and a reduction of 47% over the ‘base’ case conventional naturally ventilated building.

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5.4 Dynamic Building Case

This subchapter contains the results of the application of the Dynamic building design strategy. It demonstrates the unsuitability of the IESVE simulation software to the representation of the RBEs considered in this design methodology and the implications for their inclusion in a simulation led design process.

The Responsive Building Elements considered for this case study were thermal mass activation using hollow core concrete slabs (often known by the trade name “Termodeck”) and an active integrated façade (a form of double skin façade which directly interacts with the air space in the building to reduce heating and cooling demand and provide a source of natural ventilation). These technologies are both robust commercial products found on buildings targeting high levels of energy efficiency and low carbon emissions. It was the target of this research, however, to develop ‘rational’ strategies for the design of nZEB commercial buildings and part of that rationale was to find concepts which could be accurately tested by commercial design software in order to encourage their inclusion in an on-going design process as opposed to a pre- determined “make it work” requirement. In this respect both technologies were found not to be suitable.

5.4.1 Thermal Mass Activation using Hollow Core Slabs

The modelling of a test case simulation using hollow core slabs was conducted in order to establish the impact that their inclusion would have on the thermal performance of the occupied space. The modelling of the air pathway was successful through the use of the Macroflo bulk airflow module in combination with the Apache HVAC module, which was used to create a flow deficit which would drive supply air through the Termodeck into the room space (see Figure 53 and Figure 54 below).

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Figure 53: Airflows within a 'Termodeck' unit from an IESVE test case model

Figure 54: Apache HVAC schematic of 'Termodeck' test case model The result of this test was that there was no significant difference in heating or cooling energy consumption when compared to direct supply of the room space, bypassing the Termodeck itself and leaving it as simply exposed thermal mass. The ineffectiveness of

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the model in test case in combination with its extreme computational expense was sufficient grounds for rejection from the research program.

King [184] suggests that while the Thorpe Park green office building (Leeds, West Yorkshire), which employs Termodeck, was represented by an IESVE model, the Termodeck was tested by the use of proprietary Termodeck software which is unavailable to designers or researchers. Furthermore the Thorpe Park green office building project was developed as a tri-generation project, with the use of a CHP unit to power an absorption chiller [184]. The facility to model this system also lies outside the capabilities of the IESVE as well as the remit of this research as determined by the review of literature.

The work of Winwood et al [185] demonstrated that the modelling of hollow core slabs was best carried out through the application of computational fluid dynamics and validated this against actual building case studies. Barton et al [186] used finite element analysis to examine slab behaviour and concluded that the horizontal heat transfer between cores was the fundamental driver behind the ability of Termodeck to outperform conventional thermal mass solutions. These finding was determined while investigating the heat transfer properties of the corner joints of the Termodeck configuration; however it reinforces both the failure of the IESVE model and the conjecture within the industry design community that Termodeck installation is a specialist undertaking which is not suited to inclusion within an encompassing design strategy.

5.4.2 Active Integrated Façade

The modelling of the Active Integrated Façade presented a similar problem to the representation of the Thermal Mass Activation as it was found that the understood relationship between the building element and structure at large. As stated in the literature review the IEA ECBCS report [113] stated that the AIF was a viable mode of both providing advantageous solar gains through heating air in the cavity and mixed- mode ventilation through solar gain assisted stack ventilation. The report also expressed concerns [113] with regard to the representation of AIFs (and double skin facades in general) within a commercial dynamic simulation software tool.

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Høseggen et al [187] proposed that DSFs could be modelled accurately in thermal modelling software but that extensive modification of the wind pressure coefficients supplied would be required. Even in this case, which was facilitated through the use of the more malleable ESP-r research software, was of limited functionality, with unwanted airflow stagnation in the cavity that could not be directly attributed to either a flaw in the design or a flaw in the modelling practice. This issue was supported by Azarbayjani et al [188] who asserted that wind effects were definitive in the behaviour of a naturally ventilated double skin façade. The generation of a test case building using both sealed and naturally ventilated yielded inconclusive results and in combination with the extreme computational expense of the model when compared to those used to address the other case studies led to it been rejected as a rational strategy for conserving energy in a speculative commercial office.

5.4.3 Case Summary

The attempt to represent two dynamic building components in the IESVE failed to generate viable results and further review of the literature both supports the value of the technologies described and confirms their status as specialist systems, designed and specified by experts and unsuited to inclusion in an open ended design process for affordable, rational and replicable building concepts.

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5.5 Passivhaus Case

This subchapter contains the results of the application of the Passivhaus design strategy. It demonstrates the unsuitability of the IESVE simulation software and in particular the L2A Compliance module to the representation of a Passivhaus building. It demonstrates the need for the development of an Apache HVAC system to represent the MVHR units and the requirement for earth coupling in order to control overheating. Simulation input data for this case can be found in Appendix A3 and output data in Appendix B3.

5.5.1 Introduction

The Passivhaus design methodology differs significantly from the other cases examined in this program of research in that the concept is already in place. The requirements of the design are fixed and the challenge to the designer is how to ensure that the building meets the necessary comfort criteria without deviating from the energy consumption targets.

5.5.2 Building Form

The Passivhaus case shares a form with the Natural Ventilation case as this offered the opportunity for direct comparison and also facilitated the use of the glazed portion of the façade to provide winter solar gain, natural light and displacement ventilation when required.

The Natural Ventilation case saw several variations on the basic form in order to allow for variations on the basic ventilation strategy. The Passivhaus case used a fixed form, but with the addition of an exposed pitched roof space.

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Figure 55: Rendered image of the shallow plan building as used in the Passivhaus case study This feature was not selected for ascetic reasons but to afford additional air volume to the building structure. The high volume of air circulation in a Passivhaus building is designed to expel warm air during the summer months; however the use of the extreme U-values which are intrinsic to Passivhaus design in the Incremental improvement case (and the resultant spike in cooling energy demand) demonstrated the potential risks associated with such an approach. The inclusion of a sloped roof space, open to the fourth floor office allowed warm air to rise to the peak of the pitch, resulting in stratification above the occupied spaces. This assisted in the mitigation of overheating in the fourth floor of the building, which had been determined to have the highest cooling load (see Section 5.1.4, Table 3). The designer could also be confident that the high air change rates used in the ventilation strategy would prevent these temperatures reaching levels which would be problematic for the building as a whole A quality control test was performed on the simulations in order to confirm the veracity of this assumption which demonstrated that in the ‘final’ case the roof space did not exceed 32°C which within the upper limits of ‘comfort’ for an occupied space (see Section 4.2.6.2) and certainly acceptable for an open pitched roof space.

5.5.3 Geometry

The building was modelled using the same subdivision method as the natural ventilation case as displacement ventilation and solar gains were expected to play a role in the building performance.

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5.5.3.1 Assumptions

1. That the air space above the occupied height of the office would experience different thermal conditions, particularly during phases of natural ventilation, and as such should be subdivided in the Z axis. 2. That the daylight levels and solar radiation from the north and south facades would be significant to the design process (internal shading devices and solar gains respectively) and as such should be subdivided in the X and Y axes (as defined in Section 5.1.1). 3. That there will be some stack effect within the open plan reception area of the building and as such it should be subdivided in the z-axis to represent the temperature gradient.

5.5.4 Concept design - Basic parameters

5.5.4.1 Building Fabric

Construction Materials (outside to inside) U-value (W/m2K) External wall Cladding, EPS, natural fibre insulation, EPS, plaster 0.12 Internal partition Plaster, EPS, plaster 0.15 Internal floor/ceiling Carpet, screed, EPS, concrete, plaster 0.15 Ground floor concrete, EPS, screed, carpet 0.1 Roof Cladding, EPS, natural fibre insulation, EPS, plaster 0.1

Table 22: Fabric properties for construction materials used in Passivhaus case study

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The use of a Passivhaus insulation and heat recovery strategy is reliant on the retention of heat overnight in winter in order to be viable. In order to enact this strategy it was determined that rather than include the external core spaces in the same thermal envelope as the office, where internal gains would be lower and temperature set points are different, it would be more efficient to create a separate thermal envelope for these sections. This was achieved through the inclusion of insulation in the partitions dividing the external core areas from the office space. Similarly, the insulation at floor/ceiling level allowed each floor to control its internal temperature separately through the use of the MVHR system, allowing the building to adapt to changes in occupancy from office to office.

5.5.4.2 Air Tightness

Air tightness was taken as 0.6 air changes per hour at n50Pa; converted to 0.04ach model infiltration rate using the CIBSE method [173].

5.5.4.3 Glazing

Construction Façade Materials U-value with G-value % frame (W/m2K) South facing 50 6mm clear float with 0.85 0.56 Triple glazing PVC frame (argon filled) North facing 50 6mm clear float with 0.85 0.56 Triple glazing PVC frame (argon filled)

Table 23: Glazing properties for Passivhaus case study 5.5.4.4 Ventilation

Passivhaus buildings are designed to employ a mechanical ventilation and heat recovery unit (MVHR) which can provide the necessary volume of supply air as well as efficiency heat recovery. The supply air can be pre-treated in order to ensure a desirable internal temperature, though the reduction of heating and cooling loads to a minimum is a core tenet of the Passivhaus design methodology. In this case a Paul maxi 6001DC [189] (see Table 24) was used as the basis for the ventilation model at each floor of the case study building (for a total of 4 units).

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System type Mechanical Ventilation Heat Recovery Units Model Paul ‘Maxi’ 6001DC Max. supply rate 6000m3/h Power consumption (per fan) 3219W Heat Recovery (Plate exchanger) 91.1% Number of units installed 4 10l/s/person fixed Actual supply rate 40l/s/person dependant on internal temperature Supply profile 0800-1800 + NIGHT PURGE

Table 24: Properties of 'Maxi' 6001DC MVHR units used in Passivhaus case study 5.5.4.5 Domestic Hot Water

The domestic hot water demand was met in the first instance by a direct supply at 89% efficiency using natural gas as applied in the Natural ventilation case study. As in the case of the natural ventilation case study the solar hot water panels used in the incremental improvement case study were excluded.

5.5.4.6 Lighting

The Passivhaus design strategy requires a form that exploits natural light and materials which require careful consideration of internal gains. Therefore it was assumed that the most energy efficient lighting option available would immediately be included in the design, with a best practice maximum lighting gain of 1.5W/m2 per 100lux at 400lux was set as standard due to need to reduce internal gains.

5.5.5 Concept Design – Results

5.5.5.1 Overheating

The ‘base’ model of the Passivhaus suffered from extreme overheating until a full set of mitigation measures were applied to the building model. The addition of a night purge to the ventilation cycle, solar controlled venetian blinds and window opening during peak summer temperatures brought the overheating under control, but at 3% of occupied hours over 28°C it was still significantly above acceptable levels.

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5.5.5.2 Energy

90.0

80.0

70.0

floor area area floor

60.0

) 50.0 2

40.0 (kWh/m 30.0

20.0

10.0

Primary Energy consumption per m per consumption Primary Energy 0.0 BASE Heating 0 Cooling 0 Ventilation 23.4 Domestic Hot Water 4.38 Lighting 51.5

Table 25: Primary energy per m2 floor area for the 'base' concept of the Passivhaus case study

Building Concept Energy Consumption ‘Base’ ‘Final’ Total (MWh) 98.9 148.0 Total per unit floor area (kWh/m2) 30.0 44.9 Primary energy per unit floor area (kWh/m2) 79.4 122.8

Table 26: Energy consumption for the 'base' concept of the Passivhaus case study 5.5.5.3 Part L2A 2010 Compliance

L2A 2010 ‘Base’ model 2 Building Emissions Rate (BER) 10.2 kgCO2/m .year 2 Target Emissions Rate (TER) 39.2 kgCO2/m .year Pass/Fail (BER

Table 27: Part L assessment results for 'base' case of Passivhaus case study

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5.5.5.4 Analysis

The ‘base’ case model failed the overheating check with even the full complement of solar gain mitigation measures and an extended mechanical ventilation cycle. At this stage the suitability both of the Passivhaus standard for use on commercial offices (as has been noted this case study was significantly larger in floor area than the successful exemplar Passivhaus office) or that IES was not capable of representing the behaviour of buildings with extreme U-values. Additionally it was observed that the Passivhaus case achieved an extremely low BER given the use of mechanical ventilation and this drew attention to the issues associated with the NCM and both its representation of buildings which deviate from typical in their design and the lack of overheating assessment on buildings which have no cooling system installed.

5.5.6 Detail design - earth coupling

The issue of the representation of the design within the simulation software was explored through the continued examination of the design problem in further detail. It has already been demonstrated in the Dynamic building case study that the use of commercial simulation software to explore design options for innovative building concepts is ultimately limited by the viability of the modelling methods of the technology under investigation. The modelling of both the Variable Refrigerant Flow system used in the Incremental improvement case and the under floor heating system used in the Natural Ventilation case required substantial assumptions, however these assumptions have been supported by peer review and upheld by the results presented in this thesis. This did not hold true for the representation of either the hollow core slab or the double skin façade considered in the Dynamic building case study.

The successful exploration on of the Passivhaus case study hinged, then, on the ability of the software to offer an accurate representation of the performance of the MVHR units required to meet the ventilation requirement. It has been accepted throughout the research program that the use of detailed HVAC system models may be required to represent fully the benefits of a particular system and this practice was now carried out on the Passivhaus case study.

The only current Passivhaus certified office building in the UK is the Interserve Office [4], which is significantly smaller in volume and usable floor area than the case that was

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used in this program of research. Even in this smaller, exemplar case, it was found that some form of thermal mass strategy was required to mitigate overheating. The use of increased air volume had already been taken as a design constant but it alone did not result in a satisfactory internal condition. The Passivhaus method was originally developed for houses, which, depending on the construction method, may not have the option of exposed thermal mass. In this case the case study building was assumed to share the concrete slab construction method of the previous case studies. As such the concrete floor slabs could be exposed to reduce heat up time during the day and facilitate a more successful night purge outside occupied hours. The designers of the Interserve Office offered up an alternative [190], however, namely the connection of earth tubes to the inlet of the MVHR system. This design solution was explored further in the detail design stage of the design process.

5.5.6.1 Earth coupling

The use of earth tubes as a means of preconditioning the air supplied to the office space offered several benefits which were in keeping with both the Passivhaus ethos in particular as well as the more general directive of the research project to identify rational means of reducing demand within a building. Earth tubes are a longstanding technology which controls the supply air temperature used in natural and mechanical ventilation strategies through first passing the air through a subterranean network which will expose the air to the more consistent temperatures found below ground.

Figure 56: Wireframe of Passivhaus case study including 'earth tube' geometry

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The earth tubes themselves were modelled using the recommendations of the IES Knowledge Base [144] as a starting point. Its recommendation was that earth tubes should be modelled as a series of connected zones with adjacent conditions set to ground temperature on all sides and the Macroflo bulk airflow model activated.

Figure 57: Detail view of earth tube in operation, showing Macroflow air flow direction 5.5.6.1.1. MVHR model

The limitation of the IES proposed model was that the earth tubes would be connected directly to the building air volume and this was not appropriate for the Passivhaus ventilation system. An alternative model was proposed which represented the MVHR unit in Apache HVAC and exploited the ability of this system model to draw from air spaces and in turn drive a supply through a natural inlet represented by Macroflo. The schematic pictured in Figure 58 below represents a single MVHR unit model attributed to one floor of the building. The supply air is piped to each ‘zone’ of the office space.

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Figure 58: MVHR and distribution schematic in Apache HVAC module of the IESVE The ‘zone’ on the left of the image above represents the outlet of the earth tube. By setting the system inlet to zero and then creating a flow demand after the outlet room Macroflo detects a pressure deficit and a flow is created through the earth tube from the inlet. The ground temperature was set to 11°C and the earth tube length to 70m [115]. Finally, the supply profile was changed from 0800-1800 and Night Purge to CONSTANT.

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5.5.7 Results – Detail design option

5.5.7.1 Energy

140.0

120.0

floor area area floor

100.0

) 2 80.0

60.0 (kWh/m

40.0

20.0

0.0 Primary Energy consumption per m per consumption Energy Primary BASE FINAL Heating 0 0 Cooling 0 0 Ventilation 23.4 66.9 Domestic Hot Water 4.38 4.38 Lighting 51.5 51.5

Figure 59: Distribution of primary energy demand per m2 floor area for 'final' concept of Passivhaus case study

Building Concept Energy Consumption ‘Base’ ‘Final’ Total (MWh) 98.9 148.0 Total per unit floor area (kWh/m2) 30.0 44.9 Primary energy per unit floor area (kWh/m2) 79.4 122.8

Table 28: Total energy consumption for 'base' and ‘final’ building concept of Passivhaus case study 5.5.7.2 Analysis

The overheating test using the Design Summer Year demonstrated no hours over 28°C when supplying air pre-conditioned by the earth tubes when in combination with the solar control blinds and the option for window opening on peak days. Due to this model representing a significant increase in detail over the previous case it was determined that the data could be taken as valid and that the earth tubes had successfully mitigated the overheating issue within the building concept.

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The successful implementation of a Passivhaus office design facilitated a closer examination of the energy consumption associated with the concept. The lack of heating or cooling requirement on the building was offset by the need to supply air constantly and at volumetric rates of up to 24000m3/h (2ac/h for this building geometry).

5.5.8 Case Summary

The end result of this case study was that while the Passivhaus concept was ultimately functional as a ‘comfortable’ office space it was also the only one of the concepts which reached final design stage to exceed the 120kWh/m2year primary energy maximum, albeit by a relatively small, 2%, excess.

5.6 Summary of Results

Three of the four case studies examined in this program of research yielded an acceptable design solution, in line with the targets set out by the review of literature and the subsequent research methodology.

The incremental improvement case demonstrated the significant improvements that could be made to the energy efficiency of a traditional commercial office space through the application of energy efficiency measures and sustainable technologies while retaining the stable, comfortable environment of an air conditioned office space.

The natural ventilation case was demonstrated to be a more inherently energy efficient solution than the incremental improvement case, with lower primary energy per square metre of floor area at both the ‘base’ and ‘final’ design stages as displayed in Table 29.

Primary Energy Consumption (kWh/m2.year) CASE STUDY BASE FINAL Incremental Improvement 155.7 68.3 Natural Ventilation 76.8 41.4 Passivhaus N/A 122.8 Table 29: Comparison of Primary Energy Consumption per metre squared of floor area across case study buildings. The ‘base’ case for the Passivhaus case study was not included in this comparison as it failed to meet the thermal comfort criteria laid out in the research methodology; however the ‘final’ case for the Passivhaus was found to offer sufficient thermal comfort, but also to demonstrate the highest primary energy consumption of the three

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solutions, due to its reliance on large volumes of mechanically delivered air to condition the internal space of the office.

At this stage of the program of research there is evidence to suggest that there is validity in the construction of a naturally ventilated commercial office with thermal mass and change-over mixed mode winter ventilation in order to reduce energy consumption and carbon emissions. There is also evidence to suggest that when a controlled internal condition is of high priority that the application of the correct energy efficiency measures can yield significant improvements over a traditionally designed commercial office space.

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5.7 Post-design Analysis

This subchapter describes the results of the post-design analysis proposed in the research methodology. The chapter re-introduces the method used in the parameter sweeps before presenting the overheating tests and percentage increase or decrease in primary energy demand for each case. Simulation output data for the post-design analysis can be found in Appendix C.

5.7.1 Introduction

The target of the post-design analysis was to test the robustness of the successful building concepts derived from the design case studies. The implementation of the design methodologies had yielded three functional building models which represented a saving in energy consumption over the typical and a comfortable environment for the occupants. These three models were denoted in their case studies as follows:

1. Incremental Improvement – ‘Final’ with VRF model; 2. Natural Ventilation – ‘Final’ with Under-floor Heating model; 3. Passivhaus – ‘Final’ with MVHR and Earth Tubes model.

The parameter sweeps were then performed as specified in Section 4.1.3.4 for the following variations in external and internal condition:

1. Future weather data; 2. Location; 3. Occupancy; 4. Change of Use; 5. Orientation.

The research identified two KPIs that would demonstrate the impact of these changes on the building performance and how they would react to replication or climate change. Firstly, the overheating criteria were re-visited to confirm that the building would remain a comfortable environment for the user. Secondly, the percentage change in energy consumption was determined, as the replication of design in differing conditions is not only a matter of retaining internal condition but ensuring that the building retains its low energy credentials. Similarly, a building cannot be considered truly ‘future-

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proof’ simply because it can maintain internal condition but it must also retain its standard of energy efficiency where possible.

5.7.2 Overheating

Percentage of occupied hours over Parameter Input Data 28°C internal temperature Type Natural Vent. Passivhaus Future Manchester 2030 Moderate 1 1 Weather Manchester 2030 Harsh 1.8 1.3 Manchester 2050 Moderate 2.2 1.6 Manchester 2050 Harsh 3.8 3.6 Manchester 2080 Moderate 5.1 4.5 Manchester 2080 Harsh 11.8 10.6 Location Southampton 0.2 0.3 London 0.4 0.5 Birmingham 0 0.3 Leeds 0 0 Newcastle 0 0.1 Occupancy 8m2/Person 0 0 16m2/Person 0 0 Change of Mixed use 0 0 Use Extended hours 0.1 0 Public office 0 0 Shift office 0.2 0.2 24hr call centre 3.7 0.2 Orientation 90° 0.3 0 60° 0.2 0 30° 0 0 -90° 0.2 0 -60° 0.1 0 -30° 0 0 Table 30: Overheating checks for parameter sweeps of the Natural ventilation and Passivhaus case studies The overheating checks were performed for all cases but the Incremental improvement was unaffected; with the VRF model controlling the internal conditions regardless. The results for the Natural ventilation case and the Passsivhaus case are displayed in Table 30 above. The Natural ventilation case was found to be unsuitable for a 24 hour call centre office space, which was expected as this interrupts the effectiveness of the night purge in cooling the building thermal mass. This was the only case where change of use impacted on the comfort of either case. Similarly changes in location and orientation, while not without effect in some cases (London in particular demonstrated values which might require further analysis in an actual design situation in order to be confident of 189

successful transition) were not found to have a detrimental impact on the comfort of the occupants.

The impact of the future weather data, however, drew attention to a major issue with the Natural ventilation case study. While overheating was present in both the Passivhaus and Natural ventilation case, the Passivhaus HVAC system is designed for easy retrofit of heating and cooling components if necessary [189] and this response is accepted as a viable part of Passivhaus if energy consumption conditions are met [156]. The Natural ventilation case, however, uses under-floor heating and exposed ceilings, meaning that any cooling retrofit would be costly and intrusive and furthermore would compromise the design strategy which had achieved the near zero energy performance standard.

5.7.3 Energy Consumption

The percentage change in energy consumption offered the opportunity to directly compare the three case study buildings under the defining Key Performance Indicator of the program of research. The internal conditions explored in the overheating test reflected the impact of the varied level of adaptability required of the occupants by the designers with regards to what could be considered a comfortable and consistent working environment. The examination of energy consumption gives a more definitive commercial value to the testing of the case studies as it reflects both the ability to meet performance criteria under changing conditions and the in occupation value given to the client.

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-10 Percentage variationin

Energy Energy Consumption(%) -20

-30 Incremental Natural ventilation Passivhaus improvement 2030 Moderate 5.1 -4.99 10.59 2030 Harsh 5.1 -6.38 11.07 2050 Moderate 9.1 -7.87 15.7 2050 Harsh 8.6 -11.9 17.77 2080 Moderate 14 -15.9 24.97 2080 Harsh 18.1 -21.9 31.17

Figure 60: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a changing climate (Manchester) The application of the future weather data sets demonstrated that the problems caused to a commercial building by a changing climate would not be limited to overheating in cases without comfort cooling. The energy consumption of the Natural ventilation case drops as the heating demand for the year is decreased but it has already been observed that the overheating issues in this concept are severe and difficult to remedy so any benefit seen here is misleading. The Incremental improvement and Passivhaus cases see a significant increase in energy consumption (with the Passivhaus case also failing the overheating checks as seen in Table 30). This increase took both buildings over the maximum primary energy per unit floor area of 120kWh/m2year and demonstrated a major issue with the longevity of the building concepts and hence the design methodologies as applied in the case studies.

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-2

Percentage variationin Energy Energy Consumption(%) -4

-6 Incremental Natural ventilation Passivhaus improvement Southhampton -2.45 -5.27 3.593 London 0.51 -3.23 5.697 Birmingham -0.52 4.93 0.355 Leeds 0.065 5.29 0.725 Newcastle -2.29 6.4 -1.931

Figure 61: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of location within the UK The impact of relocation on the energy consumption of the building cases demonstrated that while some variation between locations is to be expected the impact of local climate could affect the energy consumption of a building to sufficient degree to warrant the attention of the design team. In particular the warmer climate in southern England can be seen to improve the performance of the Natural ventilation case (without triggering the overheating issue seen in the application of climate change scenarios). Conversely Passivhaus appeared to suit a cooler climate, making it a more viable solution for northern regions of the UK. The air conditioned incremental improvement case adapts to both conditions with minimal variation in performance.

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-1

Percentage variationin Energy Energy Consumption(%) -2

-3 Incremental Natural ventilation Passivhaus improvement 90° -1.703 3.4 0.17 60° -1.717 3.45 0.28 30° -1.873 3.5 0.29 -90° -1.703 3.53 0.26 -60° -1.35 3.72 0.05 -30° -1.484 3.59 -0.14

Figure 62: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of building orientation The variation of orientation has some noticeable effect on the performance of both the Incremental improvement concept and the Natural ventilation concept, though the responses themselves differ in both change in demand and level of impact. The Natural ventilation case exploits the winter solar gains to reduce heating demand and the loss of this through a less than optimal orientation results in an increase in heating demand. The loss of daylight for the Incremental improvement concept was actually found to benefit performance, with any additional energy required by the reduced effectiveness of daylight dimming being offset by a reduction in summer cooling load.

The Passivhaus concept remained largely unaffected by the change in orientation, largely due to its lack of a mechanical heating or cooling system.

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140

120

100

-20

Percentage variationin Energy Consumption(%) Incremental Natural ventilation Passivhaus improvement Mixed use -4.32 3.2 -2.62 Extended hours 13.13 22.6 13.75 Public office -3.6 0.19 -1.76 Shift office 62.32 51.1 40.97 24hr call centre 127.63 111.95 95.95

Figure 63: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of building usage The change in usage for the buildings demonstrated the most significant changes to the energy consumption of all three buildings. The increase in occupied hours found in the ‘extended hours’, ‘shift’ and particularly the ’24 hour call centre’ scenarios caused a large spikes in consumption as would be expected. That the Passivhaus office (which requires 24 hour ventilation regardless of occupation) would result in the least percentage increase in energy demand suggested that this is a use to which that particular design strategy might be well suited. Conversely, the Incremental improvement concept, which coped best with the other changes in condition, experienced a severe spike in demand over and above the what would be expected from the increase in hours occupied.

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-2

-4 Percentage variationin Energy Consumption(%)

-6 Incremental Natural ventilation Passivhaus improvement 8m2/Person 0.56 6.5 4.23 16m2/Person -4.98 2.96 -2.15

Figure 64: Percentage variation in energy consumption for Incremental improvement, Natural ventilation and Passivhaus case studies under a change of building occupancy The change in occupancy density had some impact on all the buildings in terms of energy demand, as would be expected but it did not instigate any extreme changes in the energy consumption or overheating conditions. It was accepted that there was sufficient flexibility in all the cases for the building occupiers to make decisions with regard to office population without any caveats from the design team.

5.7.4 Conclusions

Three case study buildings were tested to measure their response to changes in usage and external conditions. It was determined that increases in working hours and the changing UK climate were the biggest risks to the continued good performance of the building cases, with the caveat that the Passivhaus case appeared suited to use as an office with increased usage hours. The impact of orientation and location suggested that certain building types would respond better than others to replication in non-optimal conditions but that it should not impact performance to the point of making the designs non-viable.

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6. Discussion

6.1 Findings

The goal of this program was the investigation of rational strategies for the design of near zero energy commercial buildings. This was to be achieved through the identification of appropriate design strategies for achieving the level of demand reduction necessary to approach nZEB standard, with the selection of on or near-site generation technologies falling outside the remit of the research.

The impact of UK Government Building Regulations and accreditation schemes such as BREEAM was found to be significant and the methods used to assess building designs against their performance standards inappropriate for use within a robust design process.

The review of literature identified four clear approaches to the design of speculative commercial offices which could improve the performance beyond what is typical. These four strategies were then developed into design methodologies which could be applied to design case studies. The testing of these design strategies was conducted through their application to case study buildings in an attempt to replicate a simulation-led commercial design process that could be replicated within industry. The Incremental improvement strategy was identified as the approach which most closely reflects industrial practice when not working on exemplar buildings with an increased interest in energy consumption, emissions or sustainability.

The application of these methodologies yielded three commercial building concepts which improved upon the primary energy demand per unit floor area of the ‘base’ case in the Incremental improvement strategy, which was considered to be a typical commercial building of indifferent performance with respect to energy consumption. The application of the Dynamic building methodology failed to produce a successful case, due to both the limitations of the software and simulation approach used in the design process. As this software had been used as a representation of the practices common in commercial building design it was concluded that these technologies were only viable in cases where the appropriate specific expertise, and potentially proprietary

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software, was available. This was reinforced by a further review of literature and as such the design methodology was rejected as viable for use in a typical design process for speculative commercial offices.

The successful case studies were optimised to provide the maximum simulation fidelity possible within the constraints of the research problem and this demonstrated that the most successful means of achieving significant reduction in energy consumption per floor area for a commercial office was the implementation of change-over mixed mode ventilation system, in conjunction with exposed thermal mass and thermal mass activation in the form of under-floor heating.

In contrast to substantial reductions possible through this change in approach to how office space is conditioned, the two mechanical solutions both demonstrated limitations in the amount of demand reduction that was feasible, despite the use of extremely efficient systems in the case of the Incremental improvement case study and extreme fabric measures and a complete absence of mechanical heating or cooling in the Passivhaus case study. These limitations are a fundamental issue with the design of nZEB office space as the exclusion of external condition leads to an inability to exploit it when favourable.

These findings initially suggested that the use of a naturally ventilated office building with thermal mass activation would be the clear recommendation for a rational design strategy going forward. However, the application of the post-design analysis to the case studies yielded findings which ran contrary to this and required a reassessment of each of the building cases.

It was established that the requirement for rationale within the building design strategies encompassed a consideration of the effect of the replication of the building concept, a change in its use and a change in the local climate. The investigation into the robustness of the building concepts and their associated design methodologies demonstrated that the Natural ventilation concept, while superior under ideal conditions, was limited in this regard. Whereas the Passivhaus building, which achieved the highest primary energy demand per unit floor area, proved to be the most adaptable to change of use and potentially to changes in climate, though it would require the addition of cooling to achieve comfort. The Incremental improvement strategy demonstrated the middle

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ground between a building which is responsive to its environment and a building which excludes it to the maximum degree possible. The results of the post-design analysis reflected this as it maintained a comfortable internal condition throughout all changes of condition but demonstrated a propensity towards spikes of demand when those conditions overloaded the measures put in place to manage them.

6.2 Assessment of design methodologies and building concepts

This section contains a summary of the perceived effectiveness of the design methodology as applied to the case studies and the performance of the final building concepts.

6.2.1 Incremental improvement

This methodology represented the most straightforward approach to the performance improvement of a commercial building as well as reflecting the industry standard approach to managing energy demand and associated carbon emissions. The design delivered by this methodology is characterised by its similarity to a traditional commercial building, albeit with a greatly improved energy consumption. It was primary energy intensive as it featured both mechanical ventilation and electric heating and cooling. It demonstrated a strong adaptability to changes of condition in its provision of thermal comfort but was at risk of developing demand spikes during peak conditions under heavy occupation or climate change.

6.2.2 Natural ventilation

This methodology reflected the opportunity to place some responsibility for the reduction of energy consumption on the occupant by offering a building concept that did not employ comfort cooling. As such occupants would face a greater range of internal temperatures than those found in an air conditioned office space. The design delivered by the methodology was characterised by its exploitation of thermal mass to control the internal condition of the building with the minimum use of heating and no use of comfort cooling. It delivered a design which was highly successful in terms of energy efficiency and thermal comfort within the design conditions attributed to the

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main design case studies. It was ultimately demonstrated as extremely vulnerable to changes in both usage and climate, which called into question its long-term effectiveness as a design methodology for nZEB buildings going forward.

6.2.3 Dynamic building

This methodology presented the possibility of further exploiting the conditions used in the natural ventilation methodology through the use of responsive building elements which feature improved mixed-mode ventilation and thermal mass capabilities over the more traditional methods considered in that case. Ultimately this methodology failed to produce a case study building due to the limitations of the simulation approach used in the research methodology. A further review of literature demonstrated that the design of these building elements requires specialist knowledge and software tools which make them inaccessible to the commercial design process as a solution to be considered rather than a definitive feature of a pre-agreed design concept.

6.2.4 Passivhaus

This methodology was developed from the available information on the domestic Passivhaus design methodology and on the understanding that a successful exemplar Passivhaus office had been certified in the UK. The building concept developed by this methodology exhibited the design features associated with a Passivhaus construction; extreme U-values and air tightness, mechanical ventilation with heat recovery and minimal heating and cooling of supply air. Both the design of the building itself and the use of Earth Tubes to pre-treat the supply air in place of mechanical heating and cooling were demonstrated to upscale successfully from the exemplar case to a larger size of commercial building. The design concept did not demonstrate the same level of energy efficiency as either the Incremental improvement concept or the Natural ventilation concept; however it displayed a greater robustness in the face of changes of use than either case and in changes in climate over the Natural ventilation case. While this methodology cannot be recommended as a definitive solution to the problem of replicable nZEB commercial offices, it offers a promising opportunity for further research.

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6.3 Limitations of commercial design and simulation process

The major limitation on the commercial design process at the present time is the influence of the NCM and Part L of the building regulations on the assessment of building energy performance. The parallel testing of the building case studies using the dynamic compliance software available in the IESVE demonstrated that this simplified, comparative approach does not always reflect the true nature of the building which it is testing even in the area of energy consumption and carbon emissions, which is its specific area of focus. This is compounded by its lack of consideration of the internal condition of the building, which is highly relevant to the design team and must be investigated through alternate means, causing a disassociation between the modelling of building system performance and the analysis of the conditions that these systems are providing. This issue can be addressed through a change in good practice, which would see commercial design embrace building simulation software as a general investigative tool to be used on ever project, rather than as a means of ratifying the building performance after the design process has been completed or investigating a single issue such as overheating if and when the issue arises.

The delivery of high performance exemplar buildings has employed research tools and simulation to optimise building performance and to create design strategies such as the Passivhaus method, which was subsequently adapted for a functioning office building and subsequently investigated in this program of research. The exemplar buildings do not represent the norm, however, and this thesis demonstrates that there are performance improvements to be made in commercial buildings, through the application of a more detailed approach to building simulation, that have the potential to deliver the simple, replicable concepts which will facilitate the proliferation of nZEB building designs within the UK commercial new build.

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6.4 Limitations of research methodology

The research methodology was ultimately a replication of a simulation-led commercial design process with the goal of demonstrating that rational strategies for nZEB buildings could be developed and replicated in order to encourage design beyond the current regulatory and accreditation scheme requirements. The limitations of this approach were found in the determination not to pursue technologies and solutions which could not be accurately tested using a simulation approach that was viable in the commercial environment. This was necessary in that it ensured that the context and focus of the program of research remained constant, however it exposed limitations in the commercial process and its ability to represent novel solutions and test their viability for replication. This constraint precludes the assertion of any firm conclusions as to the ideal approach for reducing the energy consumption of buildings towards an nZEB standard as the maturation of a technology such as thermal mass activation or phase change materials could result in a sudden widening of the design options available. As a result the thesis was limited to drawing conclusions with regards to the current best practice within the commercial building industry and how it might be best exploited and optimized to produce a higher standard of building performance.

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7. Conclusions

The development of rational strategies for the design of near zero energy commercial office buildings was motivated by a need to move the typical commercial design practices for office space beyond the meeting of current regulatory demands and towards the level of performance required to meet the target of energy neutral buildings as standard by the end of the decade. This program of research has demonstrated that there are opportunities within the sphere of commercial design, particularly through the use of dynamic thermal modelling packages, to explore design solutions that perform to a higher standard of energy efficiency than is currently typical.

Objective 1: To identify the most appropriate performance metrics for the assessment of building performance when designing for a sustainable future.

The review established that the most appropriate measurements for the energy consumption of a building were Energy Consumption (MWh) per annum and Energy Consumption per unit floor area (kWh/m2) per annum. Energy Consumption (MWh) per annum is a fundamental design value that defines the total energy consumption of the core services of the system: Heating, Cooling, Ventilation, Domestic Hot Water and Lighting. Energy Consumption per unit floor area (kWh/m2) per annum is a common interpretation of energy consumption that was considered beneficial as a means of comparison between case studies of differing floor areas. These values do not take into account the providence of the energy consumed and as they tend towards zero the building would tend towards “zero energy” performance.

In order to establish the sustainability criteria, two alternative metrics were considered; the UK Building Regulations interpretation of carbon dioxide emissions based upon fuel 2 consumption per unit floor area (kgCO2/m /year) and the Energy Performance of Buildings Directiveapproach of primary energy consumption per unit floor area 2 2 (kWh/m ). The comparison of Building Emissions Rate (BER) (kgCO2/m /year) versus 2 Target Emissions Rate (TER) (kgCO2/m /year) is the chosen sustainability criteria of the UK Building Regulations and is limited in accuracy due to its reliance on both the sourcing of its carbon emissions factors and the conversion between efficiency and carbon footprint. Primary Energy Consumption per unit floor area (kWh/m2) per annum is the chosen sustainability criteria of the Energy Performance of Buildings 202

Directiveand of this research project. It shares the issue of accuracy due to sourcing of its data on energy provision but offers a value that can be directly compared to the outputs of any on-site generation (biomass, CHP etc). It also had the benefit of distinguishing the simulation outputs generated by the full thermal simulations used in this process from those provided by the Part L Dynamic Simulation Method.

The literature review yielded four distinct design strategies for a near Zero Energy Building commercial office building.

Incremental improvement strategy

This strategy generates a commercial office building of the traditional type, where the design team seeks to institute performance improvement by reducing the demand on otherwise traditional systems through a series of mitigation measures. The internal conditions are typical of a traditional air-conditioned office building.

Natural ventilation strategy

A definitive change of internal condition priorities, this design strategy places a requirement for flexibility on the occupants by attempting to provide natural or mixed mode ventilation through conventional methods. This design offers a contrast to the ‘incremental improvement strategy’ as it is also a series of performance improvement measures but one which demands a much greater level of control over form and façade.

Dynamic building strategy

This design strategy uses dynamic control of the physical properties of the building materials to control heating, cooling and ventilation demand. This approach attempts to bridge the gap between the controlled internal conditions of the ‘incremental improvement’ strategy and the low baseline energy demands of the ‘natural ventilation strategy’ through the application of control measures.

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Passivhaus strategy

This strategy offers a definitive method for demand reduction. This strategy is distinct to the other strategies identified, as it is an extrapolation of an existing design and accreditation scheme. This strategy represents an attempt to follow the Passivhaus design ethos rather than a rigid attempt at creating a Passivhaus office building.

Objective 3: To identify those design strategies for building performance improvement, which have been publicized within the industry and formulate methodologies for their testing on appropriate case studies in a simulation led design environment.

The thesis contains four design methodologies formulated from the strategies identified during the completion of Objective 2 of the program of research. These four design methodologies were applied to case study buildings and the resultant designs assessed.

The assessment of the case studies established that the use of Natural Ventilation strategy with simple thermal mass activation could yield a successful nZEB building under current best practice without compromising internal thermal comfort or air quality.

The Incremental Improvement strategy offered a reduction in energy consumption up to a point, but it was ultimately limited by its reliance on the highest efficiency components in each of the traditional design elements.

The Passivhaus strategy did not yield the same level of reduction as either the Natural Ventilation or the Incremental Improvement strategy and as such was determined to be the least successful design solution under current climate conditions.

The approach was limited by the available design data that can be incorporated at a speculative stage in the process but also by the use of typical simulation practice. The need for expertise in the application of certain complex components, in particular dynamic building elements, meant that they must still be selected as a solution, rather than compared as a design option. The potential maturation of these technologies limits the definite conclusions that can be drawn on the best practice for developing an nZEB commercial building stock.

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The fact that these limitations ultimately prevented the dynamic building case study from returning satisfactory results reflects the need to reject the National Calculation Method as a means of design.

The comfort criteria identified in the literature review were number of occupied hours over 28°C and carbon dioxide concentration in the occupied space (ppm).

The use of these criteria allowed the designs to be assessed during the design process for suitability for occupation. This was of particular value during the design of the Natural Ventilation case study as it demonstrated that the design of a commercial office without comfort cooling is possible but that the risk of overheating is present if the solution is not appropriately specified. These two criteria also assisted in the meeting of Objective 5 and Objective 6 of the program of research.

While the Natural Ventilation concept was the most successful design under current ideal internal and external conditions it was found constrained by a poor response to changes in thermal condition due to any major deviation from typical office occupancy periods and densities, making it a poor choice for office spaces that would see a greater than typical level of activity. Conversely the Incremental Improvement concept was the only strategy to retain thermal comfort completely through all changes of external and internal condition due to its use of traditional comfort cooling systems. It should be noted, however, that it also experienced the highest spike in energy consumption as a result of the high load on those same systems. The Passivhaus was the most adaptable strategy to changes in location and usage in that it experienced neither the high spikes in overheating of the Natural Ventilation case nor the high spikes in energy of the Incremental Improvement case.

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Objective 6: Identify climate change scenarios that can be integrated into the testing process and investigate the impact of these scenarios on the markers of building performance.

The future weather data sourced for this case study reflected the best available representation of the UKCIP09 predictions as produced by the PROMETHEUS project [128]. The application of this data demonstrated that all concepts were vulnerable to a changing climate. The overheating in the Natural Ventilation case was extreme and only marginally less so in the Passivhaus case, where its response to increased internal gains was superior. As in the tests conducted to meet Objective 5 above, the Incremental Improvement case suffered from a large spike in energy consumption due to increased cooling loads. These simulations demonstrated that a changing climate is a major risk to the performance of UK buildings, even those specified to a high standard of performance under current climate conditions.

Summary

The findings of the case study approach to testing the design methodology offered insight into the potential energy conservation benefits of a naturally ventilated office space as well as the vulnerability of that solution to changes in climate and use. It also demonstrated the potential value of a Passivhaus office while also identifying the need for commercial ventilation solutions that match the performance requirements of both the nZEB standard and indeed the Passivhaus standard.

Finally, the research demonstrated that the status quo of improving the fabric quality and mechanical efficiencies of commercial buildings will result in a reduction in energy consumption but it will not drive innovation and its continued proliferation within the design process removes the opportunity to test the methodologies explored in this thesis before the levels of performance sought herein cease to be aspirational and become obligatory.

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7.1 Recommendations for further work

The investigation of this research question offered up several areas for further research;

1. The up-scaling of exemplar buildings to commercially viable floor areas. The Passivhaus case study reflected an attempt to develop a solution used on a small, exemplar office building and apply it to a larger commercial office space. The formalization of this process of identifying successful sustainable building projects and rationalizing them for large scale commercial ventures is the logical progression of this line of enquiry. 2. The investigation of the complete design, construction and commissioning process of a practical near zero energy commercial office space. The research methodology employed in this thesis permitted a focus on the simulation of several design alternatives and the investigation of their theoretical robustness. The investigation of a building which was motivated by commercial interests but possessed of performance credentials would offer a grounded perspective on the implementation of rational design strategies for near zero energy buildings and is the logical step forward from the test case buildings such as the Interserve Passivhaus office [4]. 3. The production and dissemination of easy to use simulation tools for advanced building features. In particular the design and application of responsive building elements such as hollow core slabs and double skin facades could benefit from such bespoke tools and would encourage their consideration as design alternatives in a wider range of commercial projects. 4. An investigation of the application of the Building Regulations to larger and more complex buildings and whether the implementation of a multi-criterion simulation approach to their evaluation would provide a more valid assessment and better integrate with the design process.

It should be noted that proposals 1 and 2 in particular would require commercial transparency and participation in order to further the theoretical work conducted in the thesis. It is believed that this collaboration on conventional building projects with real constraints, rather than highly funded ‘green buildings’ will provide the true opportunity to move towards an nZEB standard.

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Selected bibliography

CIBSE (2007) Guide A - Environmental Design; Page Bros. (Norwich) Ltd; ISBN-10: 1-903287-66-9

Clarke JA (2001) Energy simulation in building design; Butterworth-Heinemann, Oxford; ISBN:0-7506-5082-6; 2nd Ed.

Hensen LM, Lamberts R (Edited by) (2011) Building performance simulation for design and operation; Spon Press, Oxford; IBSN13: 978-0-415-47414-6;

Incropera, DeWitt, Bergman, Lavine (2007) Fundamentals of Heat and Mass Transfer; IBSN-13 978-0-471-45728-2; 6th Ed.Oughton D, Hodkinson S, Brailsford R: (2008) Heating and Air-Conditioning of Buildings Tenth Edition Butterworth Heinemann ISBN: 978-0-7506-8365-4

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APPENDIX A – IESVE Simulation Inputs

This appendix contains the simulation inputs for the three successful building case studies. The arrangement of each sub-appendix is such that the complete input parameters are detailed for the “BASE CASE”. This is followed by the changes of input used in the interim design stages (where applicable). Each sub-appendix is completed by the listing of the inputs for the “FINAL CASE”, with the parameters used in the ApacheHVAC system models also detailed.

The following general assumptions were made in the simulation process and are included here:

1. The building materials used in the simulation processes were sourced from the IESVE databases, in line with standard usage of the software and validated against CIBSE TM33 [21] [22], unless explicitly stated within the relevant sub- appendix; 2. U-values and thermal mass were calculated automatically by the materials management tool within the IESVE; 3. Daylight dimming controls, where applied, were simulated using the inputs obtained from the RadianceIES model produced for that design iteration; 4. The hot water supplies were set to 60°C in accordance with UK Health and Safety regulation [191]. 5. Internal partitions were given some insulation where they bounded areas with differing heating and cooling set points. In the case of the Passivhaus case study this insulation was increased in line with the focus on preservation of internal conditions and the lack of heating or cooling plant.

The use of further assumptions, specific to the case study or iteration of design are detailed within the appropriate table or appended afterward.

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APPENDIX A.1 - “Incremental Improvement” Case

A.1.1 “Incremental Improvement” BASE CASE

A.1.1.1 Building Materials

Case Study “Incremental Improvement” Iteration “BASE CASE” Construction “External Wall” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) External rendering 0.0100 0.500 1300.0 1000.0 EPS slab 0.0650 0.035 25.0 1400.0 Cast concrete 0.1000 1.400 2100.0 840.0 Plaster 0.1250 0.160 600.0 1000.0 U-value (W/m2K) 0.35 Thermal mass (KJ/m2K) 60 Construction “Internal Partition” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Plasterboard 0.0125 0.160 600.0 1000.0 EPS Slab 0.0750 0.035 25.0 1400.0 Plasterboard 0.0125 0.160 600.0 1000.0 U-value (W/m2K) 0.4 Thermal mass (KJ/m2K) 7.5 Construction “Internal Floor/Ceiling” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Wilton carpet 0.005 0.06 186.3 1360.0 Screed 0.10 0.41 1200.0 840.0 Cast concrete 0.15 1.40 2100.0 840.0 EPS slab 0.1 0.035 25.0 1400.0 Ceiling void (0.3m) Ceiling tile 0.03 0.05 290.0 800.0 U-value (W/m2K) 0.28 Thermal mass (KJ/m2K) 0.00 Construction “Roof” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Felt/Bitumen Layers 0.05 0.5 1700.0 1000.0 EPS slab 0.13 0.035 25.0 1400.0 Ceiling void (0.3m) Ceiling tile 0.03 0.05 290.0 800.0 U-value (W/m2K) 0.25 Thermal mass (KJ/m2K) 0.0 Construction “Ground Floor” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Ground layer 1.6 1.41 1900.0 1000.0 Cast concrete 0.15 1.40 2100.0 840.0 EPS slab 0.075 0.035 25.0 1400.0 Screed 0.10 0.41 1200.0 840.0 Wilton carpet 0.01 0.06 186.3 1360.0 U-value (W/m2K) 0.25 Thermal mass (KJ/m2K) 0.0 Construction “Cladding” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Anti-sun glass cladding 0.042 1.05 2500.0 750.0 EPS slab 0.01 0.035 25.0 1400.0 Plaster 0.012 0.16 600.0 1000.0 U-value (W/m2K) 1.8 Thermal mass (KJ/m2K) 0.0

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Case Study “Incremental Improvement” Iteration “BASE CASE” Infiltration 0.25 air changes per hour

Case Study “Incremental Improvement” Iteration “BASE CASE” Construction “South Facing Façade” Conductivity Material Thickness (m) Transmittance Outside Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 2.2 G-value 0.63 Construction “North Facing Façade” Conductivity Material Thickness (m) Transmittance Outside Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 2.2 G-value 0.63

A.1.1.2 Lighting and Internal Gains

Case Study “Incremental Improvement” Iteration “BASE CASE” Internal Gains People (W/person) Lighting Equipment Room Sensible Latent (W/m2 p.100lux) (W/m2) Office Space 90 60 2.5 @ 400lux 10 WC 70 45 5.2 @ 200lux 5.48 Circulation 70 65 5.2 @ 100lux 1.85

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A.1.1.3 HVAC Systems

Case Study “Incremental Improvement” Iteration “BASE CASE” Heating Room System Type Fuel COP (kW/kW) Del. Eff. (%) Office Space Multi-split system Electricity 2.2 97% WC Multi-split system Electricity 2.2 97% Circulation Multi-split system Electricity 2.2 97% Cooling Room System Type Fuel SEER (kW/kW) Del. Eff. (%) Office Space Multi-split system Electricity 2.5 97% WC Multi-split system Electricity 2.5 97% Circulation Multi-split system Electricity 2.5 97% Mechanical Ventilation Room System Type Fuel SFP (W/l/s) AEV (W/m2) HR (%) Office Space Supply and Ext. Electricity 1.8 0.39 65% WC Local Extract Electricity 0.6 0.39 65% Circulation Supply and Ext. Electricity 1.8 0.39 65% Domestic Hot Water Room System Type Fuel Sys. Eff. (%) Del. Eff. (%) Office space* Direct supply hot water (60°C) Natural Gas 73% 91% Key: Sys. Eff. – System efficiency (%) Del. Eff. – Delivery efficiency (%) SEER – Seasonal Energy Efficiency Ratio (kW/kW) SFP – Specific Fan Power (W/l/s) AEV – Auxiliary Energy Value (W/m2) HR – Heat Recovery (%) *DHW consumption linked to occupancy

Case Study “Incremental Improvement” Iteration “BASE CASE” Heating Room System Type Days ON Hours ON Set Point Office Space Multi-split system MON-FRI 0800-1800 19 WC Multi-split system MON-FRI 0800-1800 19 Circulation Multi-split system MON-FRI 0800-1800 19 Cooling Room System Type Days ON Hours ON Set Point Office Space Multi-split system MON-FRI 0800-1800 23 WC Multi-split system MON-FRI 0800-1800 23 Circulation Multi-split system MON-FRI 0800-1800 23 Mechanical Ventilation Room System Type Control Days ON Hours ON Flow rate Office Space Supply and Ext. Timed ON/OFF MON-FRI 0800-1800 10l/s/person WC Local Extract Timed ON/OFF MON-FRI 0800-1800 5 ac/h Circulation Supply and Ext. Timed ON/OFF MON-FRI 0800-1800 9.6l/s Domestic Hot Water Room System Type Days ON Hours ON Demand (l/p.hr) Office space* Direct supply hot water (60°C) MON-FRI 0800-1800 0.2 *DHW consumption linked to occupancy

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A.1.2 “Incremental Improvement” Design Variations

Case Study “Incremental Improvement” Area of Percentage Improved Improvement Type Improvement Improvement Characteristic Value Air tightness -40% 3.0 (0.08ac/h) Wall U-value -20% 0.28 W/m2K Wall U-value -40% 0.21 W/m2K Floor U-value -20% 0.2 W/m2K Floor U-value -40% 0.15 W/m2K Fabric Roof U-value -20% 0.2 W/m2K Roof U-value -40% 0.15 W/m2K Glazing U-value -30% 1.8 W/m2K Glazing U-value -40% 1.6 W/m2K Glazing U-value -50% 1.4 W/m2K External Shading N/A 1m(horizontal, south) Internal Shading N/A Blinds* Glazing G-value -20% 0.56 Light Glazing G-value -40% 0.43 Lighting Efficiency +20% 2.0W/m2 per 100lux Lighting Efficiency +40% 1.5W/m2 per 100lux Daylight dimming N/A Light sensor Specific Fan Power -20% 1.44 W/l/s Air Specific Fan Power -30% 1.26 W/l/s Distribution Specific Fan Power -40% 1.08 W/l/s Co-efficient of Performance +40% 3.1 (kW/kW) Heating Co-efficient of Performance +60% 3.5 (kW/kW) Seasonal Energy Efficiency Ratio +40% 3.5 (kW/kW) Cooling Seasonal Energy Efficiency Ratio +60% 4.0 (kW/kW) Seasonal Energy Efficiency Ratio +80% 4.5 (kW/kW) Efficiency +20% 78% Heat Recovery Efficiency +40% 91% Boiler Efficiency +20% 86% DHW Solar Hot Water N/A 300m2 *Blinds set to lower at incident radiation greater than 300 W/m2 and to be raised again at incident radiation of less than 100W/m2. Percentage reductions were applied to U-values and G-values in order to reduce heating and cooling loads respectively. Percentage reductions in specific fan power and lighting demand were applied to represent the sourcing of more efficient components. Likewise percentage increases in system efficiencies represented the sourcing of more efficient systems.

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A.1.3 “Incremental Improvement” FINAL CASE

A.1.3.1 Building Materials

Case Study “Incremental Improvement” Iteration “FINAL” + VRF Construction “South Facing Façade” Conductivity Material Thickness (m) Transmittance Outside Reflectance (W/(m.K)) Glazing 0.006 1.06 0.44 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 2.2 G-value 0.43 Construction “North Facing Façade” Conductivity Material Thickness (m) Transmittance Outside Reflectance (W/(m.K)) Glazing 0.006 1.06 0.44 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 2.2 G-value 0.43

A.1.3.2 Lighting and Internal Gains

The internal gains for occupancy and equipment remained constant but the internal gains for lighting reflected the improved lighting efficacy and the implementation of daylight dimming controls using RadianceIES simulation output data.

Case Study “Incremental Improvement” Iteration “FINAL” + VRF Internal Gains People (W/person) Lighting Equipment Room Sensible Latent (W/m2 p.100lux) (W/m2) Office Space* 90 60 1.5 @ 400lux 10 WC 70 45 1.5 @ 200lux 5.48 Circulation 70 65 1.5 @ 100lux 1.85 *daylight dimming

A.1.3.3 Control of Solar and Lighting Gain

Case Study “Incremental Improvement” Iteration “FINAL” + VRF External Shading Location Horizontal shading at ceiling height (all levels) Orientation South façade Depth (m) 1m Dimming Control type Photoelectric dimming of office space lighting Reduction of lighting by up to 75% at 300 lux natural light Control parameters (modelled using Radiance data and a control formula in IES)

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A.1.3.4 HVAC Systems

Case Study “Incremental Improvement” Iteration “FINAL” + VRF Heating Room System Type Fuel COP (kW/kW) Del. Eff. (%) Office Space Variable Refrigerant Flow Electricity 3.5 97% WC Variable Refrigerant Flow Electricity 3.5 97% Circulation Variable Refrigerant Flow Electricity 3.5 97% Cooling Room System Type Fuel SEER (kW/kW) Del. Eff. (%) Office Space Variable Refrigerant Flow Electricity 4.5 97% WC Variable Refrigerant Flow Electricity 4.5 97% Circulation Variable Refrigerant Flow Electricity 4.5 97% Mechanical Ventilation Room System Type Fuel SFP (W/l/s) AEV (W/m2) HR (%) Office Space Supply and Ext. Electricity 1.08 0.39 91% WC Local Extract Electricity 0.6 0.39 91% Circulation Supply and Ext. Electricity 1.8 0.39 91% Domestic Hot Water Room System Type Fuel Sys. Eff. (%) Del. Eff. (%) Direct supply hot water (60°C) with Office space* Natural Gas 86% 91% solar hot water panels (300m2) Key: Sys. Eff. – System efficiency (%) Del. Eff. – Delivery efficiency (%) SEER – Seasonal Energy Efficiency Ratio (kW/kW) SFP – Specific Fan Power (W/l/s) AEV – Auxiliary Energy Value (W/m2) HR – Heat Recovery (%) *DHW consumption linked to occupancy

Case Study “Incremental Improvement” Iteration “FINAL” + VRF Heating Room System Type Days ON Hours ON Set Point Office Space Variable Refrigerant Flow MON-FRI 0800-1800 19 WC Variable Refrigerant Flow MON-FRI 0800-1800 19 Circulation Variable Refrigerant Flow MON-FRI 0800-1800 19 Cooling Room System Type Days ON Hours ON Set Point Office Space Variable Refrigerant Flow MON-FRI 0800-1800 23 WC Variable Refrigerant Flow MON-FRI 0800-1800 23 Circulation Variable Refrigerant Flow MON-FRI 0800-1800 23 Mechanical Ventilation Room System Type Control Days ON Hours ON Flow rate Office Space Supply and Ext. Timed ON/OFF MON-FRI 0800-1800 10l/s/person WC Local Extract Timed ON/OFF MON-FRI 0800-1800 5 ac/h Circulation Supply and Ext. Timed ON/OFF MON-FRI 0800-1800 9.6l/s Domestic Hot Water Room System Type Days ON Hours ON Demand (l/p.hr) Office space* Direct supply hot water (60°C) MON-FRI 0800-1800 0.2 *DHW consumption linked to occupancy

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Appendix A.2 - “Natural Ventilation” Case

A.2.1 “Natural Ventilation” BASE CASE

A.2.1.1 Building Materials

Case Study “Natural Ventilation” Iteration “BASE CASE” Construction “External Wall” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) External Render 0.01 0.5 1300 1000 EPS Slab 0.12 0.035 25 1400 Cast Concrete 0.1 1.4 2100 840 U-value (W/m2K) 0.26 Thermal mass (KJ/m2K) 176.4 Construction “Internal Partition” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Plasterboard 0.0125 0.16 600 1000 EPS Slab 0.075 0.035 25 1400 Plasterboard 0.0125 0.16 600 1000 U-value (W/m2K) 0.40 Thermal mass (KJ/m2K) 70.0 Construction “Internal Floor/Ceiling” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Flooring 0.005 0.160 1379.0 1004.0 Screed 0.1890 0.410 1200.0 840.0 EPS Slab 0.100 0.035 25.0 1400.0 Concrete Slab (ceiling) 0.300 1.400 2100.0 840.0 U-value (W/m2K) 0.30 Thermal mass (KJ/m2K) 176.4 Construction “Roof” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Felt/Bitumen 0.01 0.500 1700.0 1000.0 EPS Slab 0.15 0.035 25.0 1400.0 Concrete Slab (ceiling) 0.1 1.400 2100.0 840.0 U-value (W/m2K) 0.22 Thermal mass (KJ/m2K) 176.4 Construction “Ground Floor” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Foundations 1.595 1.410 1900.0 1000.0 Concrete 0.150 1.400 2100.0 840.0 EPS Slab 0.140 0.035 25.0 1400.0 Screed 0.189 0.410 1200.0 840.0 Flooring 0.005 0.160 1379.0 1004.0 U-value (W/m2K) 0.184 Thermal mass (KJ/m2K) 40.0

Case Study “Natural Ventilation” Iteration “BASE CASE” Infiltration 0.25 air changes per hour

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Case Study “Natural Ventilation” Iteration “BASE CASE” Construction “South Facing Façade” Conductivity Material Thickness (m) Transmittance Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 1.8 G-value 0.63 Construction “North Facing Façade” Conductivity Material Thickness (m) Transmittance Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 1.8 G-value 0.63

A.2.1.2 Lighting and Internal Gains

Case Study “Natural Ventilation” Iteration “BASE CASE” Internal Gains People (W/person) Lighting Equipment Room Sensible Latent (W/m2 p.100lux) (W/m2) Office Space 90 60 1.5 @ 400lux 10 WC 70 45 1.5 @ 200lux 5.48 Circulation 70 65 1.5 @ 100lux 1.85

A.2.1.3 Natural Ventilation

Case Study “Natural Ventilation” Iteration “BASE CASE” Window Opening Room Office Space Opening Type Window - Top hung Number of Openings 260 Size of Openings (m2) 0.96 Equivalent orifice area (m2) 0.32 08:00-18:00 – OPEN IF INTERNAL TEMP > 23 AND graded on Control strategy wind speed between 0 - 10m/s (closed at wind speeds > 10m/s) Trickle Vents Room Office Space Number of Openings 260 Flow rate (l/s) 12

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A.2.1.3 HVAC Systems

Case Study “Natural Ventilation” Iteration “BASE CASE” Heating Room System Type Fuel Sys. Eff. (%) Del. Eff. (%) Office Space Radiators Natural Gas 89% 97% WC Radiators Natural Gas 89% 97% Circulation Radiators Natural Gas 89% 97% Cooling Room System Type Fuel SEER (kW/kW) Del. Eff. (%) Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Mechanical Ventilation Room System Type Fuel SFP (W/l/s) AEV (W/m2) HR (%) Office Space N/A N/A N/A N/A N/A WC Local Extract Electricity 0.6 0.39 91% Circulation N/A N/A N/A N/A N/A Domestic Hot Water Room System Type Fuel Sys. Eff. (%) Del. Eff. (%) Office space* Direct supply hot water (60°C) Natural Gas 89% 97% Key: Sys. Eff. – System efficiency (%) Del. Eff. – Delivery efficiency (%) SEER – Seasonal Energy Efficiency Ratio (kW/kW) SFP – Specific Fan Power (W/l/s) AEV – Auxiliary Energy Value (W/m2) HR – Heat Recovery (%) *DHW consumption linked to occupancy

Case Study “Natural Ventilation” Iteration “BASE CASE” Heating Room System Type Days ON Hours ON Set Point Office Space Radiators MON-FRI 0800-1800 19 WC Radiators MON-FRI 0800-1800 19 Circulation Radiators MON-FRI 0800-1800 19 Cooling Room System Type Days ON Hours ON Set Point Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Mechanical Ventilation Room System Type Control Days ON Hours ON Flow rate Office Space N/A N/A N/A N/A N/A WC Local Extract Timed ON/OFF MON-FRI 0800-1800 5 ac/h Circulation N/A N/A N/A N/A N/A Domestic Hot Water Room System Type Days ON Hours ON Demand (l/p.hr) Office space* Direct supply hot water (60°C) MON-FRI 0800-1800 0.2 *DHW consumption linked to occupancy

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A.2.2 “Natural Ventilation” Design Variations

Case Study “Natural Ventilation” Iteration Basic Night purge External shading Mixed mode Reduction in glazing g-value Reduction in glazing g-value and night purge External shading and night purge Mixed mode and night purge Atrium Mixed mode, night purge and external shading Basic Windcatcher External shading Reduction in glazing g-value

Case Study “Natural Ventilation” Mixed mode Room Office Space Ventilation Rate (l/s/person) 10 l/s/person Ventilation control strategy 08:00 – 18:00 Controlled on CO2 (800 parts per million) Specific Fan Power (W/l/s) 1.2 (centralised system) Fuel Electricity

Case Study “Natural Ventilation” Atrium Room Atrium roof, controls in office space Opening Type Louvre Number of Openings 4 Size of Openings (m2) 6.4 Co-efficient of discharge 0.55 08:00-18:00 – OPEN IF INTERNAL TEMP > 23 AND graded on Control strategy wind speed between 0 - 10m/s (closed at wind speeds > 10m/s) 00:00-06:00 – OPEN IF INTERNAL TEMP > 20

Case Study “Natural Ventilation” Windcatcher Type of windcatcher Monodraught XVent – IESVE stock model Number of units 10 Monodraught pre-calibrated daytime vent Control strategy 00:00-06:00 – OPEN IF INTERNAL TEMP > 20

Case Study “Natural Ventilation” Night purge Type Window opening Opening Type Window - Top hung Number of Openings 260 Size of Openings (m2) 0.96 Equivalent orifice area (m2) 0.32 Control strategy 00:00-06:00 – OPEN IF INTERNAL TEMP > 20

Case Study “Natural Ventilation” External shading Location Horizontal shading at ceiling height (all levels) Orientation South façade Depth (m) 1m

Case Study “Natural Ventilation” Reduction in glazing G-value Façade modified North and South Façade Glazing g-value 0.43

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A.2.3 “Natural Ventilation” FINAL CASE

A.2.3.1 Building Materials

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Construction “External Wall” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) External Render 0.01 0.5 1300 1000 EPS Slab 0.12 0.035 25 1400 Cast Concrete 0.1 1.4 2100 840 U-value (W/m2K) 0.26 Thermal mass (KJ/m2K) 176.4 Construction “Internal Partition” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Plasterboard 0.0125 0.16 600 1000 EPS Slab 0.075 0.035 25 1400 Plasterboard 0.0125 0.16 600 1000 U-value (W/m2K) 0.40 Thermal mass (KJ/m2K) 70.0 Construction “Internal Floor/Ceiling” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Flooring 0.005 0.160 1379.0 1004.0 Screed 0.1890 0.410 1200.0 840.0 EPS Slab 0.100 0.035 25.0 1400.0 Concrete Slab (ceiling) 0.300 1.400 2100.0 840.0 U-value (W/m2K) 0.30 Thermal mass (KJ/m2K) 176.4 Construction “Roof” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Felt/Bitumen 0.01 0.500 1700.0 1000.0 EPS Slab 0.15 0.035 25.0 1400.0 Concrete Slab (ceiling) 0.1 1.400 2100.0 840.0 U-value (W/m2K) 0.22 Thermal mass (KJ/m2K) 176.4 Construction “Ground Floor” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Foundations 1.595 1.410 1900.0 1000.0 Concrete 0.150 1.400 2100.0 840.0 EPS Slab 0.140 0.035 25.0 1400.0 Screed 0.189 0.410 1200.0 840.0 Flooring 0.005 0.160 1379.0 1004.0 U-value (W/m2K) 0.184 Thermal mass (KJ/m2K) 40.0

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Infiltration 0.25 air changes per hour

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Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Construction “South Facing Façade” Conductivity Material Thickness (m) Transmittance Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 1.8 G-value 0.63 Construction “North Facing Façade” Conductivity Material Thickness (m) Transmittance Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.42 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 1.8 G-value 0.63

A.2.3.2 Lighting and Internal Gains

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Internal Gains People (W/person) Lighting Equipment Room Sensible Latent (W/m2 p.100lux) (W/m2) Office Space 90 60 1.5 @ 400lux 10 WC 70 45 1.5 @ 200lux 5.48 Circulation 70 65 1.5 @ 100lux 1.85 A.2.3.3 Natural Ventilation

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Window Opening Room Office Space Opening Type Window - Top hung Number of Openings 260 Size of Openings (m2) 0.96 Equivalent orifice area (m2) 0.32 08:00-18:00 – OPEN IF INTERNAL TEMP > 23 AND graded on Control strategy wind speed between 0 - 10m/s (closed at wind speeds > 10m/s)

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Night purge Type Window opening Opening Type Window - Top hung Number of Openings 260 Size of Openings (m2) 0.96 Equivalent orifice area (m2) 0.32 Control strategy 00:00-06:00 – OPEN IF INTERNAL TEMP > 20

A.2.3.4 Control of Solar Gain

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating External shading Location Horizontal shading at ceiling height (all levels) Orientation South façade Depth (m) 1m

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A.2.3.5 HVAC Systems

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Heating Room System Type Fuel Sys. Eff. (kW/kW) Del. Eff. (%) Office Space Under-floor heating Electricity (heat pump) 4.3 100% WC Under-floor heating Electricity (heat pump) 4.3 100% Circulation Under-floor heating Electricity (heat pump) 4.3 100% Cooling Room System Type Fuel SEER (kW/kW) Del. Eff. (%) Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Mechanical Ventilation Room System Type Fuel SFP (W/l/s) AEV (W/m2) HR (%) Office Space Supply Electricity 1.2 0.39 91% WC Local Extract Electricity 0.6 0.39 91% Circulation N/A N/A N/A N/A N/A Domestic Hot Water Room System Type Fuel Sys. Eff. (%) Del. Eff. (%) Office space* Direct supply hot water (60°C) Natural Gas 89% 97% Key: Sys. Eff. – System efficiency (%) Del. Eff. – Delivery efficiency (%) SEER – Seasonal Energy Efficiency Ratio (kW/kW) SFP – Specific Fan Power (W/l/s) AEV – Auxiliary Energy Value (W/m2) HR – Heat Recovery (%) *DHW consumption linked to occupancy

Case Study “Natural Ventilation” Iteration “FINAL CASE” + Under floor heating Heating Room System Type Days ON Hours ON Set Point Office Space Under-floor heating MON-FRI 24hrs (01/09 – 30/04) 19 WC Under-floor heating MON-FRI 24hrs (01/09 – 30/04) 19 Circulation Under-floor heating MON-FRI 24hrs (01/09 – 30/04) 19 Cooling Room System Type Days ON Hours ON Set Point Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Mechanical Ventilation Room System Type Control Days ON Hours ON Flow rate

Office Space Supply CO2 (PPM) MON-FRI 0800-1800 10 l/s.person WC Local Extract Timed ON/OFF MON-FRI 0800-1800 5 ac/h Circulation N/A N/A N/A N/A N/A Domestic Hot Water Room System Type Days ON Hours ON Demand (l/p.hr) Office space* Direct supply hot water (60°C) MON-FRI 0800-1800 0.2 *DHW consumption linked to occupancy

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Appendix A.3 - “Passivhaus” Case

A.3.1 “Passivhaus” BASE CASE

A.3.1.1 Building Materials

Case Study “Passivhaus” Iteration “BASE CASE” Construction “External Wall” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Wooden cladding 0.01 0.165 650.0 1600.0 EPS Slab 0.05 0.035 25.0 1400.0 Natural fibre insulation 0.219 0.038 50.0 1700.0 EPS Slab 0.05 0.035 25.0 1400.0 Plasterboard 0.0125 0.16 800.0 837.0 U-value (W/m2K) 0.12 Construction “Internal Partition” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Plasterboard 0.0125 0.16 800.0 837.0 EPS Slab 0.075 0.035 25 1400 Plasterboard 0.0125 0.16 800.0 837.0 U-value (W/m2K) 0.15 Construction “Internal Floor/Ceiling” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Wilton carpet 0.005 0.06 186.3 1360.0 EPS slab 0.10 0.035 25.0 1400.0 Natural fibre insulation 0.219 0.038 50.0 1700.0 Concrete Slab 0.300 1.400 2100.0 840.0 Plaster 0.0125 0.16 800.0 837.0 U-value (W/m2K) 0.15 Construction “Roof” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Wooden cladding 0.01 0.165 650.0 1600.0 EPS Slab 0.05 0.035 25.0 1400.0 Natural fibre insulation 0.30 0.038 50.0 1700.0 EPS Slab 0.05 0.035 25.0 1400.0 Plasterboard 0.0125 0.16 800.0 837.0 U-value (W/m2K) 0.1 Construction “Ground Floor” Conductivity Density Capacity Material Thickness (m) (W/(m.K)) (kg/m3) (J/(kg.K)) Foundations 1.595 1.410 1900.0 1000.0 Concrete 0.150 1.400 2100.0 840.0 Natural fibre insulation 0.219 0.038 50.0 1700.0 EPS slab 0.10 0.035 25.0 1400.0 Wilton carpet 0.005 0.06 186.3 1360.0 U-value (W/m2K) 0.1

Case Study “Passivhaus” Iteration “BASE CASE” Infiltration 0.25 air changes per hour

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Case Study “Passivhaus” Iteration “BASE CASE” Construction “South Facing Façade” Conductivity Material Thickness (m) Transmittance Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.72 Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.65 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 0.85 G-value 0.56 Construction “North Facing Façade” Conductivity Material Thickness (m) Transmittance Reflectance (W/(m.K)) Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.72 Glazing 0.006 1.06 0.68 0.07 Cavity Resistance (m2K/W) = 0.65 Glazing 0.006 1.06 0.68 0.07 U-value (W/m2K) 0.85 G-value 0.56 A.3.1.2 Lighting and Internal Gains

Case Study “Passivhaus” Iteration “BASE CASE” Internal Gains People (W/person) Lighting Equipment Room Sensible Latent (W/m2 p.100lux) (W/m2) Office Space 90 60 1.5 @ 400lux 10 WC 70 45 1.5 @ 200lux 5.48 Circulation 70 65 1.5 @ 100lux 1.85

A.3.1.3 Natural Ventilation

Case Study “Passivhaus” Iteration “BASE CASE” Window Opening Room Office Space Opening Type Window - Sash Number of Openings 260 Size of Openings (m2) 2.24 Equivalent orifice area (m2) 0.9 08:00-18:00 – OPEN IF INTERNAL TEMP > 25 AND WIND SPEED 0 - 10m/s (closed Control strategy at wind speeds > 10m/s)

A.3.1.4 Control of Solar Gain

Case Study “Passivhaus” Iteration “BASE CASE” External Shading Location Office space Type Automated shutter blinds Incident radiance to lower shading (W/m2) 300 Incident radiance to raise shading (W/m2) 100 Shading co-efficient 0.5

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A.3.1.5 HVAC Systems

Case Study “Passivhaus” Iteration “BASE CASE” Heating Room System Type Fuel Sys. Eff. (kW/kW) Del. Eff. (%) Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Cooling Room System Type Fuel SEER (kW/kW) Del. Eff. (%) Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Mechanical Ventilation Room System Type Fuel SFP (W/l/s) AEV (W/m2) HR (%) Office Space Supply and Extract Electricity 1.9 0.39 91% WC Local Extract Timed ON/OFF MON-FRI 0800-1800 5 ac/h Circulation N/A Electricity 0.6 0.39 91% Domestic Hot Water Room System Type Fuel Sys. Eff. (%) Del. Eff. (%) Office space* Direct supply hot water (60°C) Natural Gas 89% 97% Key: Sys. Eff. – System efficiency (%) Del. Eff. – Delivery efficiency (%) SEER – Seasonal Energy Efficiency Ratio (kW/kW) SFP – Specific Fan Power (W/l/s) AEV – Auxiliary Energy Value (W/m2) HR – Heat Recovery (%) *DHW consumption linked to occupancy

Case Study “Passivhaus” Iteration “BASE CASE” Heating Room System Type Days ON Hours ON Set Point Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Cooling Room System Type Days ON Hours ON Set Point Office Space N/A N/A N/A N/A WC N/A N/A N/A N/A Circulation N/A N/A N/A N/A Mechanical Ventilation Room System Type Control Days ON Hours ON Flow rate Office Space Supply and Extract FLOW RATE on TEMP MON-SUN 24hrs 2 l/s.m2 (MAX) WC Local Extract Timed ON/OFF MON-FRI 0800-1800 5 ac/h Circulation N/A N/A N/A N/A N/A Domestic Hot Water Room System Type Days ON Hours ON Demand (l/p.hr) Office space* Direct supply hot water (60°C) MON-FRI 0800-1800 0.2 *DHW consumption linked to occupancy

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A.3.2 “Passivhaus” FINAL CASE

A.3.2.1 HVAC Systems

Case Study “Passivhaus” Iteration “BASE CASE” System type Mechanical Ventilation Heat Recovery Units Model Paul ‘Maxi’ 6001DC Max. supply rate 6000m3/h Power consumption (per fan) 3219W Heat Recovery (Plate exchanger) 91.1% Number of units installed 4 Actual supply rate 10l/s/person fixed 40l/s/person dependant on internal temperature Supply profile 0800-1800 + NIGHT PURGE

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APPENDIX B –Case Study Simulation Outputs

Appendix B.1 - “Incremental Improvement” Design Options

Case Study “Incremental Improvement” Iteration “BASE CASE” Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.04 3.53 15.96 Feb 01-28 5.39 2.33 0.15 3.11 13.87 Mar 01-31 4.67 2.56 0.47 3.53 15.26 Apr 01-30 3.32 2.45 2.18 3.98 14.57 May 01-31 1.41 2.68 6.52 5.80 15.96 Jun 01-30 0.39 2.45 10.31 6.82 14.57 Jul 01-31 0.05 2.56 14.37 8.39 15.26 Aug 01-31 0.03 2.68 14.93 8.74 15.96 Sep 01-30 0.34 2.33 8.19 5.92 13.87 Oct 01-31 2.36 2.68 3.96 4.90 15.96 Nov 01-30 5.71 2.56 0.14 3.41 15.26 Dec 01-31 6.65 2.45 0.02 3.22 14.57 TOTAL 37.32 30.42 61.27 61.37 181.07

Case Study “Incremental Improvement” Iteration 20% reduction to wall U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.81 2.68 0.04 3.53 15.96 Feb 01-28 5.25 2.33 0.15 3.11 13.87 Mar 01-31 4.54 2.56 0.50 3.54 15.26 Apr 01-30 3.22 2.45 2.23 3.99 14.57 May 01-31 1.36 2.68 6.60 5.83 15.96 Jun 01-30 0.36 2.45 10.39 6.85 14.57 Jul 01-31 0.05 2.56 14.45 8.42 15.26 Aug 01-31 0.03 2.68 15.01 8.77 15.96 Sep 01-30 0.32 2.33 8.27 5.95 13.87 Oct 01-31 2.28 2.68 4.02 4.92 15.96 Nov 01-30 5.56 2.56 0.14 3.42 15.26 Dec 01-31 6.48 2.45 0.02 3.22 14.57 TOTAL 36.26 30.42 61.83 61.57 181.07

Case Study “Incremental Improvement” Iteration 40% reduction to wall U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.58 2.68 0.04 3.53 15.96 Feb 01-28 5.08 2.33 0.16 3.12 13.87 Mar 01-31 4.37 2.56 0.53 3.55 15.26 Apr 01-30 3.10 2.45 2.30 4.02 14.57 May 01-31 1.30 2.68 6.72 5.87 15.96 Jun 01-30 0.33 2.45 10.50 6.89 14.57 Jul 01-31 0.04 2.56 14.55 8.46 15.26 Aug 01-31 0.02 2.68 15.12 8.81 15.96 Sep 01-30 0.28 2.33 8.39 5.99 13.87 Oct 01-31 2.17 2.68 4.10 4.95 15.96 Nov 01-30 5.37 2.56 0.15 3.42 15.26 Dec 01-31 6.26 2.45 0.02 3.22 14.57 TOTAL 34.89 30.42 62.58 61.83 181.07

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Case Study “Incremental Improvement” Iteration 20% reduction to floor U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.93 2.68 0.04 3.53 15.96 Feb 01-28 5.31 2.33 0.15 3.11 13.87 Mar 01-31 4.58 2.56 0.50 3.54 15.26 Apr 01-30 3.25 2.45 2.25 4.00 14.57 May 01-31 1.37 2.68 6.64 5.84 15.96 Jun 01-30 0.37 2.45 10.45 6.87 14.57 Jul 01-31 0.05 2.56 14.49 8.44 15.26 Aug 01-31 0.03 2.68 15.03 8.78 15.96 Sep 01-30 0.33 2.33 8.26 5.95 13.87 Oct 01-31 2.33 2.68 4.01 4.92 15.96 Nov 01-30 5.65 2.56 0.14 3.41 15.26 Dec 01-31 6.55 2.45 0.02 3.22 14.57 TOTAL 36.74 30.42 61.99 61.62 181.07

Case Study “Incremental Improvement” Iteration 40% reduction to floor U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.89 2.68 0.04 3.53 15.96 Feb 01-28 5.23 2.33 0.16 3.12 13.87 Mar 01-31 4.50 2.56 0.54 3.55 15.26 Apr 01-30 3.18 2.45 2.32 4.02 14.57 May 01-31 1.33 2.68 6.75 5.88 15.96 Jun 01-30 0.35 2.45 10.58 6.91 14.57 Jul 01-31 0.04 2.56 14.60 8.48 15.26 Aug 01-31 0.03 2.68 15.13 8.81 15.96 Sep 01-30 0.32 2.33 8.33 5.98 13.87 Oct 01-31 2.30 2.68 4.05 4.94 15.96 Nov 01-30 5.59 2.56 0.14 3.42 15.26 Dec 01-31 6.47 2.45 0.02 3.22 14.57 TOTAL 36.23 30.42 62.67 61.86 181.07

Case Study “Incremental Improvement” Iteration 20% reduction to roof U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.87 2.68 0.04 3.53 15.96 Feb 01-28 5.31 2.33 0.15 3.11 13.87 Mar 01-31 4.59 2.56 0.48 3.54 15.26 Apr 01-30 3.27 2.45 2.22 3.99 14.57 May 01-31 1.39 2.68 6.58 5.82 15.96 Jun 01-30 0.38 2.45 10.37 6.84 14.57 Jul 01-31 0.05 2.56 14.42 8.41 15.26 Aug 01-31 0.03 2.68 14.99 8.76 15.96 Sep 01-30 0.33 2.33 8.26 5.95 13.87 Oct 01-31 2.32 2.68 4.01 4.92 15.96 Nov 01-30 5.62 2.56 0.14 3.41 15.26 Dec 01-31 6.54 2.45 0.02 3.22 14.57 TOTAL 36.72 30.42 61.68 61.51 181.07

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Case Study “Incremental Improvement” Iteration 40% reduction to roof U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.79 2.68 0.04 3.53 15.96 Feb 01-28 5.25 2.33 0.15 3.11 13.87 Mar 01-31 4.53 2.56 0.50 3.54 15.26 Apr 01-30 3.23 2.45 2.25 4.00 14.57 May 01-31 1.37 2.68 6.64 5.84 15.96 Jun 01-30 0.37 2.45 10.42 6.86 14.57 Jul 01-31 0.05 2.56 14.46 8.43 15.26 Aug 01-31 0.03 2.68 15.04 8.78 15.96 Sep 01-30 0.32 2.33 8.32 5.97 13.87 Oct 01-31 2.28 2.68 4.05 4.94 15.96 Nov 01-30 5.55 2.56 0.14 3.42 15.26 Dec 01-31 6.46 2.45 0.02 3.22 14.57 TOTAL 36.24 30.42 62.03 61.64 181.07

Case Study “Incremental Improvement” Iteration 40% increase in air tightness Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.71 2.68 0.14 3.57 15.96 Feb 01-28 4.38 2.33 0.38 3.19 13.87 Mar 01-31 3.71 2.56 1.27 3.81 15.26 Apr 01-30 2.62 2.45 3.51 4.44 14.57 May 01-31 1.13 2.68 8.69 6.56 15.96 Jun 01-30 0.27 2.45 12.20 7.48 14.57 Jul 01-31 0.03 2.56 16.15 9.02 15.26 Aug 01-31 0.02 2.68 16.65 9.35 15.96 Sep 01-30 0.23 2.33 9.94 6.54 13.87 Oct 01-31 1.88 2.68 5.40 5.41 15.96 Nov 01-30 4.68 2.56 0.34 3.49 15.26 Dec 01-31 5.43 2.45 0.06 3.23 14.57 TOTAL 30.10 30.42 74.74 66.08 181.07

Case Study “Incremental Improvement” Iteration 20% reduction in glazing G-value Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.14 2.68 0.01 3.53 15.96 Feb 01-28 5.55 2.33 0.02 3.13 13.87 Mar 01-31 4.89 2.56 0.10 3.64 15.26 Apr 01-30 3.51 2.45 0.58 4.87 14.57 May 01-31 1.51 2.68 1.93 9.03 15.96 Jun 01-30 0.43 2.45 3.24 12.47 14.57 Jul 01-31 0.07 2.56 4.61 16.53 15.26 Aug 01-31 0.04 2.68 4.81 17.26 15.96 Sep 01-30 0.38 2.33 2.55 10.35 13.87 Oct 01-31 2.45 2.68 1.17 6.87 15.96 Nov 01-30 5.84 2.56 0.03 3.45 15.26 Dec 01-31 6.80 2.45 0.00 3.22 14.57 TOTAL 38.61 30.42 19.05 94.35 181.07

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Case Study “Incremental Improvement” Iteration 40% reduction in glazing G-value Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.40 2.68 0.00 3.52 15.96 Feb 01-28 5.84 2.33 0.01 3.06 13.87 Mar 01-31 5.29 2.56 0.09 3.40 15.26 Apr 01-30 3.85 2.45 0.94 3.54 14.57 May 01-31 1.69 2.68 4.02 4.92 15.96 Jun 01-30 0.52 2.45 7.57 5.86 14.57 Jul 01-31 0.11 2.56 11.22 7.29 15.26 Aug 01-31 0.05 2.68 11.83 7.66 15.96 Sep 01-30 0.45 2.33 5.86 5.11 13.87 Oct 01-31 2.61 2.68 2.46 4.38 15.96 Nov 01-30 6.07 2.56 0.03 3.37 15.26 Dec 01-31 7.06 2.45 0.00 3.21 14.57 TOTAL 40.94 30.42 44.02 55.33 181.07

Case Study “Incremental Improvement” Iteration 30% reduction to glazing U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.58 2.68 0.06 3.54 15.96 Feb 01-28 5.08 2.33 0.21 3.13 13.87 Mar 01-31 4.38 2.56 0.66 3.60 15.26 Apr 01-30 3.11 2.45 2.52 4.10 14.57 May 01-31 1.33 2.68 7.11 6.01 15.96 Jun 01-30 0.35 2.45 10.87 7.02 14.57 Jul 01-31 0.04 2.56 14.91 8.58 15.26 Aug 01-31 0.03 2.68 15.47 8.93 15.96 Sep 01-30 0.31 2.33 8.72 6.11 13.87 Oct 01-31 2.21 2.68 4.36 5.04 15.96 Nov 01-30 5.40 2.56 0.18 3.43 15.26 Dec 01-31 6.26 2.45 0.03 3.22 14.57 TOTAL 35.06 30.42 65.10 62.71 181.07

Case Study “Incremental Improvement” Iteration 40% reduction to glazing U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.39 2.68 0.07 3.54 15.96 Feb 01-28 4.94 2.33 0.24 3.15 13.87 Mar 01-31 4.24 2.56 0.77 3.63 15.26 Apr 01-30 3.01 2.45 2.71 4.16 14.57 May 01-31 1.28 2.68 7.42 6.12 15.96 Jun 01-30 0.33 2.45 11.15 7.11 14.57 Jul 01-31 0.04 2.56 15.18 8.68 15.26 Aug 01-31 0.02 2.68 15.74 9.03 15.96 Sep 01-30 0.29 2.33 8.99 6.20 13.87 Oct 01-31 2.14 2.68 4.57 5.12 15.96 Nov 01-30 5.25 2.56 0.21 3.44 15.26 Dec 01-31 6.07 2.45 0.04 3.23 14.57 TOTAL 34.00 30.42 67.08 63.41 181.07

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Case Study “Incremental Improvement” Iteration 50% reduction to glazing U-values Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.27 2.68 0.08 3.55 15.96 Feb 01-28 4.85 2.33 0.27 3.15 13.87 Mar 01-31 4.16 2.56 0.84 3.66 15.26 Apr 01-30 2.94 2.45 2.83 4.20 14.57 May 01-31 1.26 2.68 7.62 6.19 15.96 Jun 01-30 0.32 2.45 11.33 7.18 14.57 Jul 01-31 0.04 2.56 15.35 8.74 15.26 Aug 01-31 0.02 2.68 15.91 9.09 15.96 Sep 01-30 0.28 2.33 9.16 6.26 13.87 Oct 01-31 2.09 2.68 4.71 5.17 15.96 Nov 01-30 5.16 2.56 0.23 3.45 15.26 Dec 01-31 5.96 2.45 0.04 3.23 14.57 TOTAL 33.35 30.42 68.36 63.85 181.07

Case Study “Incremental Improvement” Iteration 20% improvement in lighting efficiency Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.30 2.68 0.02 3.53 13.00 Feb 01-28 5.61 2.33 0.10 3.09 11.30 Mar 01-31 4.86 2.56 0.29 3.47 12.43 Apr 01-30 3.43 2.45 1.75 3.83 11.87 May 01-31 1.45 2.68 5.68 5.51 13.00 Jun 01-30 0.39 2.45 9.39 6.50 11.87 Jul 01-31 0.06 2.56 13.38 8.05 12.43 Aug 01-31 0.03 2.68 13.90 8.38 13.00 Sep 01-30 0.35 2.33 7.33 5.62 11.30 Oct 01-31 2.44 2.68 3.37 4.70 13.00 Nov 01-30 5.95 2.56 0.09 3.40 12.43 Dec 01-31 6.98 2.45 0.01 3.22 11.87 TOTAL 38.86 30.42 55.33 59.29 147.49

Case Study “Incremental Improvement” Iteration 40% improvement in lighting efficiency Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.68 2.68 0.01 3.52 10.04 Feb 01-28 5.86 2.33 0.07 3.08 8.73 Mar 01-31 5.08 2.56 0.17 3.43 9.60 Apr 01-30 3.55 2.45 1.37 3.69 9.17 May 01-31 1.49 2.68 4.90 5.23 10.04 Jun 01-30 0.40 2.45 8.48 6.18 9.17 Jul 01-31 0.06 2.56 12.40 7.71 9.60 Aug 01-31 0.03 2.68 12.88 8.03 10.04 Sep 01-30 0.36 2.33 6.49 5.33 8.73 Oct 01-31 2.53 2.68 2.83 4.51 10.04 Nov 01-30 6.23 2.56 0.07 3.39 9.60 Dec 01-31 7.36 2.45 0.01 3.22 9.17 TOTAL 40.63 30.42 49.68 57.31 113.92

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Case Study “Incremental Improvement” Iteration Daylight dimming in office space Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.43 2.68 0.01 3.52 11.89 Feb 01-28 5.79 2.33 0.04 3.08 9.38 Mar 01-31 5.10 2.56 0.12 3.41 9.01 Apr 01-30 3.57 2.45 1.20 3.63 8.62 May 01-31 1.49 2.68 4.61 5.13 9.09 Jun 01-30 0.40 2.45 8.18 6.07 8.25 Jul 01-31 0.06 2.56 12.06 7.58 8.58 Aug 01-31 0.03 2.68 12.53 7.90 9.01 Sep 01-30 0.36 2.33 6.24 5.24 7.99 Oct 01-31 2.52 2.68 2.56 4.42 9.43 Nov 01-30 6.11 2.56 0.05 3.38 11.08 Dec 01-31 7.08 2.45 0.01 3.21 11.16 TOTAL 39.95 30.42 47.60 56.59 113.50

Case Study “Incremental Improvement” Iteration External shading on south facade Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.09 2.68 0.02 3.52 15.96 Feb 01-28 5.55 2.33 0.06 3.08 13.87 Mar 01-31 4.92 2.56 0.22 3.44 15.26 Apr 01-30 3.57 2.45 1.34 3.68 14.57 May 01-31 1.53 2.68 4.79 5.19 15.96 Jun 01-30 0.45 2.45 8.75 6.28 14.57 Jul 01-31 0.07 2.56 12.45 7.72 15.26 Aug 01-31 0.04 2.68 13.05 8.08 15.96 Sep 01-30 0.40 2.33 6.90 5.47 13.87 Oct 01-31 2.46 2.68 3.22 4.65 15.96 Nov 01-30 5.82 2.56 0.08 3.39 15.26 Dec 01-31 6.74 2.45 0.01 3.22 14.57 TOTAL 38.64 30.42 50.88 57.74 181.07

Case Study “Incremental Improvement” Iteration Internal shading on south facade Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 7.31 2.68 0.00 3.52 15.96 Feb 01-28 5.65 2.33 0.02 3.07 13.87 Mar 01-31 4.98 2.56 0.24 3.45 15.26 Apr 01-30 3.62 2.45 1.41 3.71 14.57 May 01-31 1.53 2.68 5.11 5.31 15.96 Jun 01-30 0.45 2.45 9.18 6.43 14.57 Jul 01-31 0.07 2.56 12.87 7.87 15.26 Aug 01-31 0.04 2.68 13.27 8.16 15.96 Sep 01-30 0.43 2.33 6.79 5.44 13.87 Oct 01-31 2.54 2.68 2.90 4.53 15.96 Nov 01-30 5.91 2.56 0.05 3.38 15.26 Dec 01-31 6.95 2.45 0.00 3.21 14.57 TOTAL 39.49 30.42 51.84 58.07 181.07

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Case Study “Incremental Improvement” Iteration Solar hot water system Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 1.44 0.04 3.53 15.96 Feb 01-28 5.39 1.09 0.15 3.11 13.87 Mar 01-31 4.67 0.81 0.47 3.53 15.26 Apr 01-30 3.32 0.66 2.18 3.98 14.57 May 01-31 1.41 0.51 6.52 5.80 15.96 Jun 01-30 0.39 0.36 10.31 6.83 14.57 Jul 01-31 0.05 0.33 14.37 8.40 15.26 Aug 01-31 0.03 0.39 14.93 8.75 15.96 Sep 01-30 0.34 0.51 8.19 5.93 13.87 Oct 01-31 2.36 0.84 3.96 4.91 15.96 Nov 01-30 5.71 1.37 0.14 3.41 15.26 Dec 01-31 6.65 1.51 0.02 3.22 14.57 TOTAL 37.32 9.84 61.27 61.41 181.07

Case Study “Incremental Improvement” Iteration 20% improvement to DHW boiler efficiency Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.03 0.04 3.53 15.96 Feb 01-28 5.39 1.77 0.15 3.11 13.87 Mar 01-31 4.67 1.94 0.47 3.53 15.26 Apr 01-30 3.32 1.85 2.18 3.98 14.57 May 01-31 1.41 2.03 6.52 5.80 15.96 Jun 01-30 0.39 1.85 10.31 6.82 14.57 Jul 01-31 0.05 1.94 14.37 8.39 15.26 Aug 01-31 0.03 2.03 14.93 8.74 15.96 Sep 01-30 0.34 1.77 8.19 5.92 13.87 Oct 01-31 2.36 2.03 3.96 4.90 15.96 Nov 01-30 5.71 1.94 0.14 3.41 15.26 Dec 01-31 6.65 1.85 0.02 3.22 14.57 TOTAL 37.32 23.05 61.27 61.37 181.07

Case Study “Incremental Improvement” Iteration 40% improvement to cooling SEER Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.03 3.53 15.96 Feb 01-28 5.39 2.33 0.11 3.11 13.87 Mar 01-31 4.67 2.56 0.35 3.52 15.26 Apr 01-30 3.32 2.45 1.62 3.94 14.57 May 01-31 1.41 2.68 4.85 5.70 15.96 Jun 01-30 0.39 2.45 7.68 6.67 14.57 Jul 01-31 0.05 2.56 10.70 8.18 15.26 Aug 01-31 0.03 2.68 11.12 8.52 15.96 Sep 01-30 0.34 2.33 6.10 5.80 13.87 Oct 01-31 2.36 2.68 2.95 4.84 15.96 Nov 01-30 5.71 2.56 0.10 3.41 15.26 Dec 01-31 6.65 2.45 0.02 3.22 14.57 TOTAL 37.32 30.42 45.63 60.46 181.07

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Case Study “Incremental Improvement” Iteration 60% improvement to cooling SEER Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.03 3.53 15.96 Feb 01-28 5.39 2.33 0.09 3.11 13.87 Mar 01-31 4.67 2.56 0.30 3.52 15.26 Apr 01-30 3.32 2.45 1.40 3.91 14.57 May 01-31 1.41 2.68 4.19 5.61 15.96 Jun 01-30 0.39 2.45 6.63 6.53 14.57 Jul 01-31 0.05 2.56 9.24 7.98 15.26 Aug 01-31 0.03 2.68 9.60 8.32 15.96 Sep 01-30 0.34 2.33 5.26 5.69 13.87 Oct 01-31 2.36 2.68 2.54 4.79 15.96 Nov 01-30 5.71 2.56 0.09 3.41 15.26 Dec 01-31 6.65 2.45 0.01 3.22 14.57 TOTAL 37.32 30.42 39.39 59.62 181.07

Case Study “Incremental Improvement” Iteration 80% improvement to cooling SEER Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.02 3.53 15.96 Feb 01-28 5.39 2.33 0.09 3.11 13.87 Mar 01-31 4.67 2.56 0.27 3.52 15.26 Apr 01-30 3.32 2.45 1.27 3.91 14.57 May 01-31 1.41 2.68 3.78 5.60 15.96 Jun 01-30 0.39 2.45 5.99 6.51 14.57 Jul 01-31 0.05 2.56 8.34 7.95 15.26 Aug 01-31 0.03 2.68 8.67 8.29 15.96 Sep 01-30 0.34 2.33 4.75 5.67 13.87 Oct 01-31 2.36 2.68 2.30 4.78 15.96 Nov 01-30 5.71 2.56 0.08 3.41 15.26 Dec 01-31 6.65 2.45 0.01 3.22 14.57 TOTAL 37.32 30.42 35.57 59.49 181.07

Case Study “Incremental Improvement” Iteration 20% improvement to heating COP Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.42 2.68 0.04 3.53 15.96 Feb 01-28 4.99 2.33 0.15 3.11 13.87 Mar 01-31 4.40 2.56 0.47 3.53 15.26 Apr 01-30 3.19 2.45 2.18 3.98 14.57 May 01-31 1.40 2.68 6.52 5.80 15.96 Jun 01-30 0.39 2.45 10.31 6.82 14.57 Jul 01-31 0.05 2.56 14.37 8.39 15.26 Aug 01-31 0.03 2.68 14.93 8.74 15.96 Sep 01-30 0.34 2.33 8.19 5.92 13.87 Oct 01-31 2.28 2.68 3.96 4.90 15.96 Nov 01-30 5.31 2.56 0.14 3.41 15.26 Dec 01-31 6.04 2.45 0.02 3.22 14.57 TOTAL 34.86 30.42 61.27 61.37 181.07

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Case Study “Incremental Improvement” Iteration 60% improvement to heating COP Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.27 2.68 0.04 3.53 15.96 Feb 01-28 4.87 2.33 0.15 3.11 13.87 Mar 01-31 4.33 2.56 0.47 3.53 15.26 Apr 01-30 3.15 2.45 2.18 3.98 14.57 May 01-31 1.40 2.68 6.52 5.80 15.96 Jun 01-30 0.39 2.45 10.31 6.82 14.57 Jul 01-31 0.05 2.56 14.37 8.39 15.26 Aug 01-31 0.03 2.68 14.93 8.74 15.96 Sep 01-30 0.34 2.33 8.19 5.92 13.87 Oct 01-31 2.26 2.68 3.96 4.90 15.96 Nov 01-30 5.20 2.56 0.14 3.41 15.26 Dec 01-31 0.37 2.45 0.00 0.15 14.57 TOTAL 28.67 30.42 61.25 58.30 181.07

Case Study “Incremental Improvement” Iteration 20% improvement to heat recovery Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.69 2.68 0.04 3.53 15.96 Feb 01-28 5.22 2.33 0.15 3.11 13.87 Mar 01-31 4.58 2.56 0.47 3.53 15.26 Apr 01-30 3.28 2.45 2.18 3.98 14.57 May 01-31 1.41 2.68 6.52 5.80 15.96 Jun 01-30 0.39 2.45 10.31 6.82 14.57 Jul 01-31 0.05 2.56 14.37 8.39 15.26 Aug 01-31 0.03 2.68 14.93 8.74 15.96 Sep 01-30 0.34 2.33 8.19 5.92 13.87 Oct 01-31 2.34 2.68 3.96 4.90 15.96 Nov 01-30 5.54 2.56 0.14 3.41 15.26 Dec 01-31 6.33 2.45 0.02 3.22 14.57 TOTAL 36.19 30.42 61.26 61.37 181.07

Case Study “Incremental Improvement” Iteration 40% improvement to heat recovery Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.48 2.68 0.04 3.53 15.96 Feb 01-28 5.09 2.33 0.15 3.11 13.87 Mar 01-31 4.50 2.56 0.47 3.53 15.26 Apr 01-30 3.24 2.45 2.18 3.98 14.57 May 01-31 1.41 2.68 6.52 5.80 15.96 Jun 01-30 0.39 2.45 10.31 6.82 14.57 Jul 01-31 0.05 2.56 14.37 8.39 15.26 Aug 01-31 0.03 2.68 14.93 8.74 15.96 Sep 01-30 0.34 2.33 8.19 5.92 13.87 Oct 01-31 2.31 2.68 3.95 4.90 15.96 Nov 01-30 5.41 2.56 0.14 3.41 15.26 Dec 01-31 6.09 2.45 0.02 3.22 14.57 TOTAL 35.33 30.42 61.26 61.37 181.07

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Case Study “Incremental Improvement” Iteration 20% improvement to specific fan power Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.04 2.97 15.96 Feb 01-28 5.39 2.33 0.15 2.62 13.87 Mar 01-31 4.67 2.56 0.47 2.99 15.26 Apr 01-30 3.32 2.45 2.18 3.46 14.57 May 01-31 1.41 2.68 6.52 5.23 15.96 Jun 01-30 0.39 2.45 10.31 6.30 14.57 Jul 01-31 0.05 2.56 14.37 7.85 15.26 Aug 01-31 0.03 2.68 14.93 8.18 15.96 Sep 01-30 0.34 2.33 8.19 5.43 13.87 Oct 01-31 2.36 2.68 3.96 4.34 15.96 Nov 01-30 5.71 2.56 0.14 2.87 15.26 Dec 01-31 6.65 2.45 0.02 2.70 14.57 TOTAL 37.32 30.42 61.27 54.94 181.07

Case Study “Incremental Improvement” Iteration 30% improvement to specific fan power Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.04 2.68 15.96 Feb 01-28 5.39 2.33 0.15 2.37 13.87 Mar 01-31 4.67 2.56 0.47 2.72 15.26 Apr 01-30 3.32 2.45 2.18 3.20 14.57 May 01-31 1.41 2.68 6.52 4.95 15.96 Jun 01-30 0.39 2.45 10.31 6.05 14.57 Jul 01-31 0.05 2.56 14.37 7.58 15.26 Aug 01-31 0.03 2.68 14.93 7.89 15.96 Sep 01-30 0.34 2.33 8.19 5.19 13.87 Oct 01-31 2.36 2.68 3.96 4.05 15.96 Nov 01-30 5.71 2.56 0.14 2.60 15.26 Dec 01-31 6.65 2.45 0.02 2.44 14.57 TOTAL 37.32 30.42 61.27 51.72 181.07

Case Study “Incremental Improvement” Iteration 40% improvement to specific fan power Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.98 2.68 0.04 2.40 15.96 Feb 01-28 5.39 2.33 0.15 2.13 13.87 Mar 01-31 4.67 2.56 0.47 2.45 15.26 Apr 01-30 3.32 2.45 2.18 2.94 14.57 May 01-31 1.41 2.68 6.52 4.67 15.96 Jun 01-30 0.39 2.45 10.31 5.79 14.57 Jul 01-31 0.05 2.56 14.37 7.31 15.26 Aug 01-31 0.03 2.68 14.93 7.61 15.96 Sep 01-30 0.34 2.33 8.19 4.94 13.87 Oct 01-31 2.36 2.68 3.96 3.77 15.96 Nov 01-30 5.71 2.56 0.14 2.33 15.26 Dec 01-31 6.65 2.45 0.02 2.18 14.57 TOTAL 37.32 30.42 61.27 48.51 181.07

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Case Study “Incremental Improvement” Iteration FINAL Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.60 1.40 0.00 2.39 7.60 Feb 01-28 5.31 1.06 0.00 2.08 6.03 Mar 01-31 5.06 0.78 0.00 2.28 5.85 Apr 01-30 3.78 0.63 0.18 2.18 5.60 May 01-31 1.84 0.49 1.78 2.39 5.92 Jun 01-30 0.56 0.35 4.28 2.18 5.37 Jul 01-31 0.12 0.31 7.25 2.29 5.59 Aug 01-31 0.06 0.37 7.66 2.39 5.87 Sep 01-30 0.49 0.49 2.93 2.08 5.20 Oct 01-31 2.67 0.81 0.98 2.39 6.12 Nov 01-30 5.61 1.34 0.00 2.28 7.09 Dec 01-31 6.17 1.48 0.00 2.18 7.12 TOTAL 38.27 9.51 25.06 27.10 73.37

Case Study “Incremental Improvement” Iteration FINAL + VRF Model Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.49 1.40 0.03 2.39 7.60 Feb 01-28 4.31 1.06 0.05 2.08 6.03 Mar 01-31 3.99 0.78 0.08 2.28 5.85 Apr 01-30 3.01 0.63 0.39 2.18 5.60 May 01-31 1.43 0.49 1.71 2.39 5.92 Jun 01-30 0.43 0.35 3.39 2.18 5.37 Jul 01-31 0.09 0.31 5.20 2.29 5.59 Aug 01-31 0.05 0.37 5.44 2.39 5.87 Sep 01-30 0.36 0.49 2.31 2.08 5.20 Oct 01-31 2.08 0.81 1.08 2.39 6.12 Nov 01-30 4.65 1.34 0.05 2.28 7.09 Dec 01-31 5.03 1.48 0.01 2.18 7.12 TOTAL 30.92 9.51 19.72 27.10 73.37

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Appendix B.2 - “Natural Ventilation” Design Options

Case Study “Natural Ventilation” Iteration “BASE CASE” Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 33.89 1.25 N/A 0.00 3.46 Feb 01-28 27.40 1.09 N/A 0.00 2.35 Mar 01-31 20.51 1.19 N/A 0.00 2.28 Apr 01-30 10.55 1.14 N/A 0.00 1.69 May 01-31 1.45 1.25 N/A 0.00 1.76 Jun 01-30 0.88 1.14 N/A 0.00 1.56 Jul 01-31 0.06 1.19 N/A 0.00 1.63 Aug 01-31 0.38 1.25 N/A 0.00 1.86 Sep 01-30 0.49 1.09 N/A 0.00 1.74 Oct 01-31 6.86 1.25 N/A 0.00 2.39 Nov 01-30 19.84 1.19 N/A 0.00 3.09 Dec 01-31 35.02 1.14 N/A 0.00 3.13 TOTAL 157.33 14.17 N/A 0.00 26.94

Case Study “Natural Ventilation” Iteration Mixed mode ventilation Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 8.24 1.25 N/A 0.17 3.46 Feb 01-28 6.13 1.09 N/A 0.14 2.35 Mar 01-31 3.90 1.19 N/A 0.16 2.28 Apr 01-30 1.24 1.14 N/A 0.15 1.69 May 01-31 0.03 1.25 N/A 0.17 1.76 Jun 01-30 0.02 1.14 N/A 0.15 1.56 Jul 01-31 0.00 1.19 N/A 0.16 1.63 Aug 01-31 0.00 1.25 N/A 0.17 1.86 Sep 01-30 0.60 1.09 N/A 0.14 1.74 Oct 01-31 1.02 1.25 N/A 0.17 2.39 Nov 01-30 3.78 1.19 N/A 0.16 3.09 Dec 01-31 8.91 1.14 N/A 0.15 3.13 TOTAL 33.88 14.17 N/A 1.87 26.94

Case Study “Natural Ventilation” Iteration Mixed mode ventilation with night purge Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 8.22 1.25 N/A 0.17 3.46 Feb 01-28 6.12 1.09 N/A 0.14 2.35 Mar 01-31 3.88 1.19 N/A 0.16 2.28 Apr 01-30 0.78 1.14 N/A 0.15 1.69 May 01-31 0.51 1.25 N/A 0.17 1.76 Jun 01-30 0.30 1.14 N/A 0.15 1.56 Jul 01-31 0.00 1.19 N/A 0.16 1.63 Aug 01-31 0.00 1.25 N/A 0.17 1.86 Sep 01-30 0.40 1.09 N/A 0.14 1.74 Oct 01-31 0.93 1.25 N/A 0.17 2.39 Nov 01-30 3.79 1.19 N/A 0.16 3.09 Dec 01-31 8.88 1.14 N/A 0.15 3.13 TOTAL 33.84 14.17 N/A 1.87 26.94

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Case Study “Natural Ventilation” Iteration Mixed mode ventilation with external shading Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 8.61 1.25 N/A 0.17 3.55 Feb 01-28 6.63 1.09 N/A 0.14 2.47 Mar 01-31 4.61 1.19 N/A 0.16 2.44 Apr 01-30 1.54 1.14 N/A 0.15 1.81 May 01-31 0.01 1.25 N/A 0.17 1.85 Jun 01-30 0.01 1.14 N/A 0.15 1.61 Jul 01-31 0.00 1.19 N/A 0.16 1.67 Aug 01-31 0.00 1.25 N/A 0.17 2.02 Sep 01-30 0.48 1.09 N/A 0.14 1.87 Oct 01-31 0.68 1.25 N/A 0.17 2.55 Nov 01-30 4.12 1.19 N/A 0.16 3.18 Dec 01-31 9.23 1.14 N/A 0.15 3.22 TOTAL 35.92 14.17 N/A 1.87 28.24

Case Study “Natural Ventilation” Iteration Mixed mode ventilation with reduction in glazing g-value Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 9.61 1.25 N/A 0.17 3.46 Feb 01-28 7.65 1.09 N/A 0.14 2.35 Mar 01-31 5.55 1.19 N/A 0.16 2.28 Apr 01-30 2.08 1.14 N/A 0.15 1.69 May 01-31 0.01 1.25 N/A 0.17 1.76 Jun 01-30 0.00 1.14 N/A 0.15 1.56 Jul 01-31 0.00 1.19 N/A 0.16 1.63 Aug 01-31 0.00 1.25 N/A 0.17 1.86 Sep 01-30 0.35 1.09 N/A 0.14 1.74 Oct 01-31 1.11 1.25 N/A 0.17 2.39 Nov 01-30 4.96 1.19 N/A 0.16 3.09 Dec 01-31 10.30 1.14 N/A 0.15 3.13 TOTAL 41.62 14.17 N/A 1.87 26.94

Case Study “Natural Ventilation” Mixed mode ventilation with reduction in glazing g-value and night Iteration purge Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 9.59 1.25 N/A 0.17 3.46 Feb 01-28 7.64 1.09 N/A 0.14 2.35 Mar 01-31 5.55 1.19 N/A 0.16 2.28 Apr 01-30 2.06 1.14 N/A 0.15 1.69 May 01-31 0.48 1.25 N/A 0.17 1.76 Jun 01-30 0.32 1.14 N/A 0.15 1.56 Jul 01-31 0.00 1.19 N/A 0.16 1.63 Aug 01-31 0.00 1.25 N/A 0.17 1.86 Sep 01-30 0.28 1.09 N/A 0.14 1.74 Oct 01-31 1.29 1.25 N/A 0.17 2.39 Nov 01-30 4.96 1.19 N/A 0.16 3.09 Dec 01-31 10.27 1.14 N/A 0.15 3.13 TOTAL 42.44 14.17 N/A 1.87 26.94

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Case Study “Natural Ventilation” Iteration Mixed mode ventilation with external shading and night purge Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 8.61 1.25 N/A 0.17 3.55 Feb 01-28 6.63 1.09 N/A 0.14 2.47 Mar 01-31 4.61 1.19 N/A 0.16 2.44 Apr 01-30 1.43 1.14 N/A 0.15 1.81 May 01-31 0.48 1.25 N/A 0.17 1.85 Jun 01-30 0.32 1.14 N/A 0.15 1.61 Jul 01-31 0.00 1.19 N/A 0.16 1.67 Aug 01-31 0.01 1.25 N/A 0.17 2.02 Sep 01-30 0.33 1.09 N/A 0.14 1.87 Oct 01-31 0.92 1.25 N/A 0.17 2.55 Nov 01-30 4.15 1.19 N/A 0.16 3.18 Dec 01-31 9.23 1.14 N/A 0.15 3.22 TOTAL 36.72 14.17 N/A 1.87 28.24

Case Study “Natural Ventilation” Iteration Atrium with mixed mode and night purge Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 9.34 1.25 N/A 0.17 3.47 Feb 01-28 6.87 1.09 N/A 0.14 2.35 Mar 01-31 4.35 1.19 N/A 0.16 2.27 Apr 01-30 0.94 1.14 N/A 0.15 1.68 May 01-31 0.84 1.25 N/A 0.17 1.76 Jun 01-30 0.60 1.14 N/A 0.15 1.56 Jul 01-31 0.00 1.19 N/A 0.16 1.63 Aug 01-31 0.00 1.25 N/A 0.17 1.86 Sep 01-30 0.16 1.09 N/A 0.14 1.74 Oct 01-31 1.51 1.25 N/A 0.17 2.39 Nov 01-30 4.47 1.19 N/A 0.16 3.09 Dec 01-31 10.06 1.14 N/A 0.15 3.15 TOTAL 39.14 14.17 N/A 1.87 26.95

Case Study “Natural Ventilation” Iteration Atrium with mixed mode, night purge and external shading Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 9.73 1.25 N/A 0.17 3.54 Feb 01-28 7.37 1.09 N/A 0.14 2.45 Mar 01-31 5.08 1.19 N/A 0.16 2.41 Apr 01-30 1.57 1.14 N/A 0.15 1.80 May 01-31 2.55 1.25 N/A 0.17 1.84 Jun 01-30 1.71 1.14 N/A 0.15 1.60 Jul 01-31 0.00 1.19 N/A 0.16 1.67 Aug 01-31 0.02 1.25 N/A 0.17 2.01 Sep 01-30 0.92 1.09 N/A 0.14 1.85 Oct 01-31 4.39 1.25 N/A 0.17 2.52 Nov 01-30 5.05 1.19 N/A 0.16 3.16 Dec 01-31 10.41 1.14 N/A 0.15 3.20 TOTAL 48.81 14.17 N/A 1.87 28.05

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Case Study “Natural Ventilation” Iteration Windcatcher Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 15.96 1.25 N/A 0.00 3.62 Feb 01-28 12.07 1.09 N/A 0.00 2.64 Mar 01-31 9.43 1.19 N/A 0.00 2.72 Apr 01-30 3.72 1.14 N/A 0.00 2.10 May 01-31 2.76 1.25 N/A 0.00 2.13 Jun 01-30 1.99 1.14 N/A 0.00 1.82 Jul 01-31 0.00 1.19 N/A 0.00 1.90 Aug 01-31 0.02 1.25 N/A 0.00 2.34 Sep 01-30 0.94 1.09 N/A 0.00 2.11 Oct 01-31 2.27 1.25 N/A 0.00 2.77 Nov 01-30 9.02 1.19 N/A 0.00 3.29 Dec 01-31 17.55 1.14 N/A 0.00 3.28 TOTAL 75.72 14.17 N/A 0.00 30.74

Case Study “Natural Ventilation” Iteration Windcatcher with external shading Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 16.61 1.25 N/A 0.00 3.74 Feb 01-28 13.14 1.09 N/A 0.00 2.83 Mar 01-31 10.69 1.19 N/A 0.00 2.94 Apr 01-30 4.76 1.14 N/A 0.00 2.36 May 01-31 3.20 1.25 N/A 0.00 2.40 Jun 01-30 2.43 1.14 N/A 0.00 2.05 Jul 01-31 0.00 1.19 N/A 0.00 2.13 Aug 01-31 0.02 1.25 N/A 0.00 2.61 Sep 01-30 1.19 1.09 N/A 0.00 2.31 Oct 01-31 2.65 1.25 N/A 0.00 2.97 Nov 01-30 9.69 1.19 N/A 0.00 3.42 Dec 01-31 18.07 1.14 N/A 0.00 3.35 TOTAL 82.45 14.17 N/A 0.00 33.09

Case Study “Natural Ventilation” Iteration Windcatcher with reduction in glazing G-value Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 18.25 1.25 N/A 0.00 3.62 Feb 01-28 14.88 1.09 N/A 0.00 2.64 Mar 01-31 12.31 1.19 N/A 0.00 2.72 Apr 01-30 5.76 1.14 N/A 0.00 2.10 May 01-31 3.51 1.25 N/A 0.00 2.13 Jun 01-30 2.79 1.14 N/A 0.00 1.82 Jul 01-31 0.00 1.19 N/A 0.00 1.90 Aug 01-31 0.03 1.25 N/A 0.00 2.34 Sep 01-30 1.38 1.09 N/A 0.00 2.11 Oct 01-31 3.34 1.25 N/A 0.00 2.77 Nov 01-30 11.25 1.19 N/A 0.00 3.29 Dec 01-31 19.37 1.14 N/A 0.00 3.28 TOTAL 92.88 14.17 N/A 0.00 30.74

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Case Study “Natural Ventilation” Iteration “FINAL” Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 4.71 1.25 N/A 0.17 3.55 Feb 01-28 3.85 1.09 N/A 0.14 2.47 Mar 01-31 2.56 1.19 N/A 0.16 2.44 Apr 01-30 0.89 1.14 N/A 0.15 1.81 May 01-31 0.09 1.25 N/A 0.17 1.85 Jun 01-30 0.00 1.14 N/A 0.15 1.61 Jul 01-31 0.00 1.19 N/A 0.16 1.67 Aug 01-31 0.00 1.25 N/A 0.17 2.02 Sep 01-30 0.06 1.09 N/A 0.14 1.87 Oct 01-31 0.50 1.25 N/A 0.17 2.55 Nov 01-30 2.62 1.19 N/A 0.16 3.18 Dec 01-31 4.86 1.14 N/A 0.15 3.22 TOTAL 20.14 14.17 N/A 1.87 28.24

Case Study “Natural Ventilation” Iteration “FINAL with under floor heating” Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.63 1.25 N/A 0.17 3.55 Feb 01-28 2.35 1.09 N/A 0.14 2.47 Mar 01-31 1.64 1.19 N/A 0.16 2.44 Apr 01-30 0.64 1.14 N/A 0.15 1.81 May 01-31 0.09 1.25 N/A 0.17 1.85 Jun 01-30 0.00 1.14 N/A 0.15 1.61 Jul 01-31 0.00 1.19 N/A 0.16 1.67 Aug 01-31 0.00 1.25 N/A 0.17 2.02 Sep 01-30 0.06 1.09 N/A 0.14 1.87 Oct 01-31 0.17 1.25 N/A 0.17 2.55 Nov 01-30 1.49 1.19 N/A 0.16 3.18 Dec 01-31 2.71 1.14 N/A 0.15 3.22 TOTAL 11.79 14.17 N/A 1.87 28.24

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Appendix B.3 - “Passivhaus” Design Options

Case Study “Passivhaus” Iteration “BASE CASE” Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 2.09 5.13 Feb 01-28 N/A 1.09 N/A 1.82 4.46 Mar 01-31 N/A 1.19 N/A 2.00 4.91 Apr 01-30 N/A 1.14 N/A 1.91 4.69 May 01-31 N/A 1.25 N/A 2.09 5.13 Jun 01-30 N/A 1.14 N/A 1.91 4.69 Jul 01-31 N/A 1.19 N/A 2.00 4.91 Aug 01-31 N/A 1.25 N/A 2.09 5.13 Sep 01-30 N/A 1.09 N/A 1.82 4.46 Oct 01-31 N/A 1.25 N/A 2.09 5.13 Nov 01-30 N/A 1.19 N/A 2.00 4.91 Dec 01-31 N/A 1.14 N/A 1.91 4.69 TOTAL N/A 14.17 N/A 23.77 58.24

Case Study “Passivhaus” Iteration “FINAL” Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.34 5.13 Feb 01-28 N/A 1.09 N/A 4.31 4.46 Mar 01-31 N/A 1.19 N/A 5.72 4.91 Apr 01-30 N/A 1.14 N/A 6.28 4.69 May 01-31 N/A 1.25 N/A 7.02 5.13 Jun 01-30 N/A 1.14 N/A 8.01 4.69 Jul 01-31 N/A 1.19 N/A 9.47 4.91 Aug 01-31 N/A 1.25 N/A 9.57 5.13 Sep 01-30 N/A 1.09 N/A 6.81 4.46 Oct 01-31 N/A 1.25 N/A 6.79 5.13 Nov 01-30 N/A 1.19 N/A 4.68 4.91 Dec 01-31 N/A 1.14 N/A 3.92 4.69 TOTAL N/A 14.17 N/A 76.93 58.24

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APPENDIX C – Parameter Sweep Simulation Outputs Appendix C.1 – “Incremental Improvement”

Case Study “Incremental Improvement” Iteration Orientation 90° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.81 1.40 0.00 2.39 7.60 Feb 01-28 4.58 1.06 0.00 2.08 6.03 Mar 01-31 4.12 0.78 0.04 2.28 5.85 Apr 01-30 3.05 0.63 0.26 2.18 5.60 May 01-31 1.34 0.49 1.34 2.39 5.92 Jun 01-30 0.38 0.35 3.11 2.18 5.37 Jul 01-31 0.06 0.31 4.69 2.29 5.59 Aug 01-31 0.04 0.37 4.71 2.39 5.87 Sep 01-30 0.36 0.49 1.56 2.08 5.20 Oct 01-31 2.18 0.81 0.48 2.39 6.12 Nov 01-30 4.89 1.34 0.01 2.28 7.09 Dec 01-31 5.23 1.48 0.00 2.18 7.12 TOTAL 32.05 9.51 16.21 27.10 73.37

Case Study “Incremental Improvement” Iteration Orientation 60° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.70 1.40 0.00 2.39 7.60 Feb 01-28 4.46 1.06 0.00 2.08 6.03 Mar 01-31 4.06 0.78 0.03 2.28 5.85 Apr 01-30 2.96 0.63 0.26 2.18 5.60 May 01-31 1.36 0.49 1.61 2.39 5.92 Jun 01-30 0.40 0.35 2.95 2.18 5.37 Jul 01-31 0.07 0.31 4.75 2.29 5.59 Aug 01-31 0.04 0.37 4.76 2.39 5.87 Sep 01-30 0.35 0.49 1.73 2.08 5.20 Oct 01-31 2.13 0.81 0.59 2.39 6.12 Nov 01-30 4.82 1.34 0.01 2.28 7.09 Dec 01-31 5.16 1.48 0.00 2.18 7.12 TOTAL 31.52 9.51 16.71 27.10 73.37

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Case Study “Incremental Improvement” Iteration Orientation 30° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.54 1.40 0.01 2.39 7.60 Feb 01-28 4.36 1.06 0.02 2.08 6.03 Mar 01-31 4.02 0.78 0.06 2.28 5.85 Apr 01-30 2.98 0.63 0.30 2.18 5.60 May 01-31 1.40 0.49 1.54 2.39 5.92 Jun 01-30 0.42 0.35 2.91 2.18 5.37 Jul 01-31 0.08 0.31 4.66 2.29 5.59 Aug 01-31 0.04 0.37 4.78 2.39 5.87 Sep 01-30 0.35 0.49 1.87 2.08 5.20 Oct 01-31 2.10 0.81 0.80 2.39 6.12 Nov 01-30 4.69 1.34 0.02 2.28 7.09 Dec 01-31 5.06 1.48 0.01 2.18 7.12 TOTAL 31.02 9.51 16.99 27.10 73.37

Case Study “Incremental Improvement” Iteration Orientation -90° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.81 1.40 0.00 2.39 7.60 Feb 01-28 4.58 1.06 0.00 2.08 6.03 Mar 01-31 4.12 0.78 0.04 2.28 5.85 Apr 01-30 3.05 0.63 0.26 2.18 5.60 May 01-31 1.34 0.49 1.34 2.39 5.92 Jun 01-30 0.38 0.35 3.11 2.18 5.37 Jul 01-31 0.06 0.31 4.69 2.29 5.59 Aug 01-31 0.04 0.37 4.71 2.39 5.87 Sep 01-30 0.36 0.49 1.56 2.08 5.20 Oct 01-31 2.18 0.81 0.48 2.39 6.12 Nov 01-30 4.89 1.34 0.01 2.28 7.09 Dec 01-31 5.23 1.48 0.00 2.18 7.12 TOTAL 32.05 9.51 16.21 27.10 73.37

Case Study “Incremental Improvement” Iteration Orientation -60° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.70 1.40 0.00 2.39 7.60 Feb 01-28 4.47 1.06 0.01 2.08 6.03 Mar 01-31 4.08 0.78 0.08 2.28 5.85 Apr 01-30 3.02 0.63 0.35 2.18 5.60 May 01-31 1.35 0.49 1.48 2.39 5.92 Jun 01-30 0.39 0.35 3.14 2.18 5.37 Jul 01-31 0.07 0.31 4.78 2.29 5.59 Aug 01-31 0.04 0.37 4.88 2.39 5.87 Sep 01-30 0.35 0.49 1.77 2.08 5.20 Oct 01-31 2.15 0.81 0.68 2.39 6.12 Nov 01-30 4.80 1.34 0.02 2.28 7.09 Dec 01-31 5.13 1.48 0.00 2.18 7.12 TOTAL 31.55 9.51 17.20 27.10 73.37

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Case Study “Incremental Improvement” Iteration Orientation -30° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.55 1.40 0.02 2.39 7.60 Feb 01-28 4.38 1.06 0.04 2.08 6.03 Mar 01-31 4.03 0.78 0.09 2.28 5.85 Apr 01-30 3.02 0.63 0.37 2.18 5.60 May 01-31 1.39 0.49 1.50 2.39 5.92 Jun 01-30 0.42 0.35 3.02 2.18 5.37 Jul 01-31 0.08 0.31 4.68 2.29 5.59 Aug 01-31 0.04 0.37 4.87 2.39 5.87 Sep 01-30 0.36 0.49 1.90 2.08 5.20 Oct 01-31 2.12 0.81 0.87 2.39 6.12 Nov 01-30 4.69 1.34 0.04 2.28 7.09 Dec 01-31 5.06 1.48 0.01 2.18 7.12 TOTAL 31.15 9.51 17.42 27.10 73.37

Case Study “Incremental Improvement” Iteration ‘Shift’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 4.34 2.83 0.09 3.19 14.53 Feb 01-28 3.29 2.31 0.15 2.77 12.04 Mar 01-31 3.05 2.03 0.38 3.04 12.11 Apr 01-30 2.26 1.76 1.03 2.91 11.22 May 01-31 1.01 1.67 2.94 3.19 11.34 Jun 01-30 0.27 1.37 5.13 2.89 10.10 Jul 01-31 0.03 1.37 7.17 3.03 10.60 Aug 01-31 0.01 1.51 7.51 3.16 11.71 Sep 01-30 0.17 1.56 3.58 2.77 10.83 Oct 01-31 1.47 2.13 1.86 3.19 13.04 Nov 01-30 3.47 2.75 0.15 3.04 13.70 Dec 01-31 3.94 2.81 0.06 2.91 13.40 TOTAL 23.31 24.11 30.06 36.10 144.61

Case Study “Incremental Improvement” Iteration ‘Public Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.64 1.07 0.02 2.39 7.60 Feb 01-28 4.45 0.81 0.03 2.08 6.03 Mar 01-31 4.13 0.57 0.05 2.28 5.85 Apr 01-30 3.13 0.46 0.22 2.18 5.60 May 01-31 1.48 0.35 1.15 2.39 5.92 Jun 01-30 0.44 0.24 2.45 2.18 5.37 Jul 01-31 0.09 0.23 4.04 2.29 5.59 Aug 01-31 0.05 0.26 4.22 2.39 5.87 Sep 01-30 0.37 0.36 1.57 2.08 5.20 Oct 01-31 2.16 0.60 0.77 2.39 6.12 Nov 01-30 4.81 1.02 0.03 2.28 7.09 Dec 01-31 5.11 1.14 0.00 2.18 7.12 TOTAL 31.87 7.11 14.55 27.10 73.37

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Case Study “Incremental Improvement” Iteration ‘Mixed Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.71 0.89 0.02 2.39 7.60 Feb 01-28 4.55 0.71 0.03 2.08 6.03 Mar 01-31 4.21 0.50 0.05 2.28 5.85 Apr 01-30 3.21 0.41 0.16 2.18 5.60 May 01-31 1.50 0.31 1.04 2.39 5.92 Jun 01-30 0.45 0.20 2.23 2.18 5.37 Jul 01-31 0.09 0.20 3.78 2.29 5.59 Aug 01-31 0.05 0.21 3.92 2.39 5.87 Sep 01-30 0.38 0.29 1.40 2.08 5.20 Oct 01-31 2.20 0.51 0.67 2.39 6.12 Nov 01-30 4.91 0.87 0.04 2.28 7.09 Dec 01-31 5.18 0.96 0.01 2.18 7.12 TOTAL 32.44 6.05 13.33 27.10 73.37

Case Study “Incremental Improvement” Iteration ‘Extended Hours Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.21 1.77 0.05 2.62 9.37 Feb 01-28 4.03 1.37 0.09 2.28 7.51 Mar 01-31 3.69 1.06 0.12 2.50 7.16 Apr 01-30 2.80 0.87 0.50 2.39 6.67 May 01-31 1.31 0.71 1.88 2.62 6.97 Jun 01-30 0.39 0.54 3.59 2.38 6.33 Jul 01-31 0.08 0.49 5.41 2.50 6.57 Aug 01-31 0.04 0.57 5.62 2.61 6.98 Sep 01-30 0.31 0.71 2.40 2.27 6.30 Oct 01-31 1.92 1.10 1.20 2.62 7.76 Nov 01-30 4.31 1.70 0.07 2.50 8.75 Dec 01-31 4.75 1.84 0.02 2.39 8.74 TOTAL 28.84 12.72 20.96 29.65 89.11

Case Study “Incremental Improvement” Iteration ’24 hour Call Centre’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 3.64 4.17 0.60 3.99 20.02 Feb 01-28 2.75 3.40 0.76 3.47 16.77 Mar 01-31 2.60 3.12 1.51 3.81 17.25 Apr 01-30 1.92 2.76 2.42 3.64 16.14 May 01-31 0.86 2.69 5.30 3.98 16.70 Jun 01-30 0.21 2.26 7.94 3.61 14.99 Jul 01-31 0.02 2.27 10.44 3.77 15.71 Aug 01-31 0.01 2.50 10.93 3.93 17.06 Sep 01-30 0.12 2.47 6.02 3.45 15.49 Oct 01-31 1.27 3.27 3.82 3.98 18.41 Nov 01-30 2.95 4.01 0.93 3.81 18.94 Dec 01-31 3.27 4.09 0.53 3.64 18.47 TOTAL 19.61 37.01 51.22 45.05 205.94

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Case Study “Incremental Improvement” Iteration Location - Southampton Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.50 1.48 0.07 2.39 7.26 Feb 01-28 3.80 0.89 0.09 2.08 5.70 Mar 01-31 3.64 0.90 0.13 2.28 6.07 Apr 01-30 2.17 0.47 0.71 2.18 5.39 May 01-31 0.82 0.43 2.10 2.39 5.90 Jun 01-30 0.15 0.25 4.34 2.18 5.26 Jul 01-31 0.01 0.37 4.96 2.29 5.68 Aug 01-31 0.01 0.29 6.38 2.39 5.84 Sep 01-30 0.11 0.54 3.03 2.08 5.28 Oct 01-31 1.40 0.81 1.30 2.39 6.09 Nov 01-30 3.45 1.17 0.18 2.28 6.71 Dec 01-31 4.65 1.18 0.04 2.18 6.70 TOTAL 25.71 8.76 23.33 27.10 71.87

Case Study “Incremental Improvement” Iteration Location - London Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.12 1.45 0.04 2.39 7.56 Feb 01-28 4.25 1.11 0.04 2.08 5.95 Mar 01-31 3.84 0.89 0.12 2.28 6.00 Apr 01-30 1.92 0.55 0.64 2.18 5.48 May 01-31 0.63 0.46 2.74 2.39 5.93 Jun 01-30 0.10 0.19 4.82 2.18 5.22 Jul 01-31 0.00 0.27 7.14 2.29 5.58 Aug 01-31 0.01 0.40 6.47 2.39 5.92 Sep 01-30 0.18 0.40 3.42 2.08 5.20 Oct 01-31 1.25 0.95 0.89 2.39 6.45 Nov 01-30 3.06 1.44 0.07 2.28 7.32 Dec 01-31 4.39 1.34 0.04 2.18 7.12 TOTAL 24.73 9.46 26.42 27.10 73.73

Case Study “Incremental Improvement” Iteration Location - Birmingham Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.90 1.29 0.03 2.39 7.08 Feb 01-28 4.63 0.99 0.03 2.08 5.74 Mar 01-31 4.31 0.87 0.09 2.28 6.00 Apr 01-30 3.35 0.71 0.23 2.18 5.62 May 01-31 1.15 0.47 1.90 2.39 5.90 Jun 01-30 0.22 0.26 3.25 2.18 5.28 Jul 01-31 0.04 0.26 5.98 2.29 5.56 Aug 01-31 0.05 0.41 4.97 2.39 5.91 Sep 01-30 0.43 0.49 1.83 2.08 5.24 Oct 01-31 2.16 1.03 0.38 2.39 6.47 Nov 01-30 4.38 1.29 0.05 2.28 6.91 Dec 01-31 5.09 1.45 0.01 2.18 7.16 TOTAL 31.72 9.51 18.74 27.10 72.85

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Case Study “Incremental Improvement” Iteration Location - Leeds Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.48 1.51 0.01 2.39 7.62 Feb 01-28 4.89 1.17 0.01 2.08 6.21 Mar 01-31 3.96 0.90 0.21 2.28 5.99 Apr 01-30 2.63 0.66 0.31 2.18 5.61 May 01-31 1.33 0.45 2.22 2.39 5.87 Jun 01-30 0.29 0.33 2.95 2.18 5.34 Jul 01-31 0.04 0.28 5.84 2.29 5.56 Aug 01-31 0.08 0.41 4.27 2.39 5.94 Sep 01-30 0.39 0.50 2.05 2.08 5.23 Oct 01-31 2.06 1.13 0.43 2.39 6.76 Nov 01-30 4.08 1.42 0.03 2.28 7.18 Dec 01-31 4.65 1.41 0.02 2.18 7.37 TOTAL 30.88 10.17 18.37 27.10 74.67

Case Study “Incremental Improvement” Iteration Location - Newcastle Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 6.10 1.45 0.02 2.39 7.81 Feb 01-28 4.72 0.84 0.07 2.08 5.67 Mar 01-31 3.95 0.90 0.11 2.28 6.02 Apr 01-30 3.54 0.62 0.17 2.18 5.59 May 01-31 1.84 0.54 1.33 2.39 5.94 Jun 01-30 0.58 0.39 2.43 2.18 5.37 Jul 01-31 0.17 0.26 3.92 2.29 5.54 Aug 01-31 0.18 0.51 3.18 2.39 6.02 Sep 01-30 0.56 0.67 1.15 2.08 5.43 Oct 01-31 1.52 0.97 0.96 2.39 6.37 Nov 01-30 4.19 1.36 0.05 2.28 7.30 Dec 01-31 5.43 1.40 0.01 2.18 7.42 TOTAL 32.77 9.89 13.39 27.10 74.47

Case Study “Incremental Improvement” Iteration Future Weather Scenario – 2080 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.63 1.19 0.11 2.39 6.92 Feb 01-28 2.41 1.10 0.29 2.08 6.42 Mar 01-31 1.86 0.83 0.57 2.28 6.49 Apr 01-30 0.81 0.44 2.70 2.18 5.79 May 01-31 0.07 0.15 6.74 2.39 5.28 Jun 01-30 0.00 0.10 10.90 2.18 5.53 Jul 01-31 0.00 0.12 14.05 2.29 5.54 Aug 01-31 0.00 0.20 14.05 2.39 5.64 Sep 01-30 0.00 0.34 9.62 2.08 5.77 Oct 01-31 0.05 0.59 5.23 2.39 5.88 Nov 01-30 0.96 1.14 0.56 2.28 7.13 Dec 01-31 2.22 1.55 0.14 2.18 8.05 TOTAL 11.00 7.74 64.95 27.10 74.42

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Case Study “Incremental Improvement” Iteration Future Weather Scenario – 2080 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 3.54 1.27 0.07 2.39 7.06 Feb 01-28 2.90 1.14 0.14 2.08 6.43 Mar 01-31 2.31 0.81 0.64 2.28 6.39 Apr 01-30 0.95 0.34 2.44 2.18 5.64 May 01-31 0.14 0.26 5.11 2.39 5.40 Jun 01-30 0.00 0.15 9.61 2.18 5.57 Jul 01-31 0.00 0.22 12.33 2.29 5.62 Aug 01-31 0.00 0.16 12.41 2.39 5.61 Sep 01-30 0.00 0.45 7.57 2.08 5.89 Oct 01-31 0.16 0.70 3.56 2.39 5.87 Nov 01-30 1.25 1.13 1.10 2.28 7.18 Dec 01-31 3.18 1.59 0.09 2.18 8.24 TOTAL 14.42 8.22 55.05 27.10 74.92

Case Study “Incremental Improvement” Iteration Future Weather Scenario – 2050 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 4.04 1.36 0.03 2.39 7.13 Feb 01-28 3.49 1.10 0.14 2.08 6.42 Mar 01-31 2.21 0.89 0.59 2.28 6.57 Apr 01-30 1.41 0.47 1.53 2.18 5.81 May 01-31 0.15 0.22 4.78 2.39 5.37 Jun 01-30 0.00 0.28 7.38 2.18 5.73 Jul 01-31 0.00 0.22 10.16 2.29 5.65 Aug 01-31 0.00 0.14 10.27 2.39 5.54 Sep 01-30 0.02 0.36 7.02 2.08 5.72 Oct 01-31 0.30 0.99 2.28 2.39 6.47 Nov 01-30 1.52 1.12 0.38 2.28 7.20 Dec 01-31 3.30 1.54 0.02 2.18 8.03 TOTAL 16.44 8.68 44.58 27.10 75.63

Case Study “Incremental Improvement” Iteration Future Weather Scenario – 2050 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 4.06 1.46 0.02 2.39 7.34 Feb 01-28 3.87 1.19 0.13 2.08 6.40 Mar 01-31 2.90 0.91 0.29 2.28 6.57 Apr 01-30 1.52 0.51 1.23 2.18 5.85 May 01-31 0.21 0.19 3.99 2.39 5.32 Jun 01-30 0.00 0.32 7.58 2.18 5.69 Jul 01-31 0.00 0.19 10.51 2.29 5.57 Aug 01-31 0.00 0.24 10.43 2.39 5.72 Sep 01-30 0.04 0.49 5.29 2.08 5.91 Oct 01-31 0.39 0.74 3.04 2.39 6.06 Nov 01-30 1.91 1.31 0.28 2.28 7.37 Dec 01-31 3.98 1.46 0.05 2.18 7.73 TOTAL 18.89 9.00 42.85 27.10 75.53

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Case Study “Incremental Improvement” Iteration Future Weather Scenario – 2030 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 4.73 1.47 0.03 2.39 7.19 Feb 01-28 3.69 0.95 0.18 2.08 6.08 Mar 01-31 3.13 0.89 0.22 2.28 6.48 Apr 01-30 2.05 0.61 0.65 2.18 5.93 May 01-31 0.35 0.30 3.45 2.39 5.40 Jun 01-30 0.02 0.20 6.23 2.18 5.59 Jul 01-31 0.00 0.37 8.09 2.29 5.79 Aug 01-31 0.00 0.22 8.76 2.39 5.60 Sep 01-30 0.09 0.37 5.26 2.08 5.75 Oct 01-31 0.57 0.59 2.35 2.39 5.67 Nov 01-30 2.48 1.24 0.47 2.28 7.23 Dec 01-31 4.06 1.55 0.04 2.18 8.00 TOTAL 21.17 8.74 35.72 27.10 74.72

Case Study “Incremental Improvement” Iteration Future Weather Scenario – 2030 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 4.59 1.46 0.03 2.39 7.28 Feb 01-28 3.92 1.06 0.03 2.08 6.20 Mar 01-31 3.40 0.81 0.29 2.28 6.30 Apr 01-30 1.89 0.46 1.03 2.18 5.82 May 01-31 0.47 0.15 3.29 2.39 5.30 Jun 01-30 0.01 0.17 6.68 2.18 5.59 Jul 01-31 0.00 0.27 7.75 2.29 5.70 Aug 01-31 0.00 0.25 8.21 2.39 5.69 Sep 01-30 0.10 0.48 4.96 2.08 5.90 Oct 01-31 0.58 0.79 2.26 2.39 6.07 Nov 01-30 2.28 1.10 0.46 2.28 7.06 Dec 01-31 4.23 1.71 0.02 2.18 8.25 TOTAL 21.48 8.70 35.01 27.10 75.16

Case Study “Incremental Improvement” Iteration Occupancy Density – 8m2/Person Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.27 1.85 0.05 2.39 7.60 Feb 01-28 4.13 1.40 0.08 2.08 6.03 Mar 01-31 3.79 1.06 0.13 2.28 5.85 Apr 01-30 2.88 0.85 0.53 2.18 5.60 May 01-31 1.39 0.66 1.89 2.39 5.92 Jun 01-30 0.43 0.49 3.50 2.18 5.37 Jul 01-31 0.08 0.44 5.26 2.29 5.59 Aug 01-31 0.05 0.52 5.49 2.39 5.87 Sep 01-30 0.35 0.67 2.46 2.08 5.20 Oct 01-31 2.01 1.08 1.26 2.39 6.12 Nov 01-30 4.39 1.75 0.06 2.28 7.09 Dec 01-31 4.84 1.91 0.02 2.18 7.12 TOTAL 29.61 12.67 20.72 27.10 73.37

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Case Study “Incremental Improvement” Iteration Occupancy Density – 16m2/Person Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 5.79 0.78 0.02 2.39 7.60 Feb 01-28 4.61 0.59 0.02 2.08 6.03 Mar 01-31 4.30 0.41 0.03 2.28 5.85 Apr 01-30 3.25 0.33 0.14 2.18 5.60 May 01-31 1.52 0.25 0.89 2.39 5.92 Jun 01-30 0.45 0.16 2.06 2.18 5.37 Jul 01-31 0.09 0.15 3.55 2.29 5.59 Aug 01-31 0.05 0.18 3.71 2.39 5.87 Sep 01-30 0.38 0.26 1.24 2.08 5.20 Oct 01-31 2.23 0.43 0.61 2.39 6.12 Nov 01-30 4.98 0.75 0.02 2.28 7.09 Dec 01-31 5.22 0.84 0.00 2.18 7.12 TOTAL 32.86 5.14 12.30 27.10 73.37

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Appendix C.2 - “Natural Ventilation”

Case Study “Natural Ventilation” Iteration Orientation 90° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.67 1.25 N/A 0.17 3.55 Feb 01-28 2.28 1.09 N/A 0.14 2.63 Mar 01-31 1.74 1.19 N/A 0.16 2.21 Apr 01-30 0.71 1.14 N/A 0.15 2.01 May 01-31 0.10 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.07 1.09 N/A 0.14 1.83 Oct 01-31 0.74 1.25 N/A 0.17 2.52 Nov 01-30 2.31 1.19 N/A 0.16 3.23 Dec 01-31 2.63 1.14 N/A 0.15 3.37 TOTAL 13.23 14.17 N/A 1.87 28.61

Case Study “Natural Ventilation” Iteration Orientation 60° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.63 1.25 N/A 0.17 3.55 Feb 01-28 2.23 1.09 N/A 0.14 2.63 Mar 01-31 1.73 1.19 N/A 0.16 2.21 Apr 01-30 0.80 1.14 N/A 0.15 2.01 May 01-31 0.12 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.07 1.09 N/A 0.14 1.83 Oct 01-31 0.74 1.25 N/A 0.17 2.52 Nov 01-30 2.26 1.19 N/A 0.16 3.23 Dec 01-31 2.61 1.14 N/A 0.15 3.37 TOTAL 13.20 14.17 N/A 1.87 28.61

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Case Study “Natural Ventilation” Iteration Orientation 30° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.57 1.25 N/A 0.17 3.55 Feb 01-28 2.22 1.09 N/A 0.14 2.63 Mar 01-31 1.85 1.19 N/A 0.16 2.21 Apr 01-30 1.02 1.14 N/A 0.15 2.01 May 01-31 0.14 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.07 1.09 N/A 0.14 1.83 Oct 01-31 0.60 1.25 N/A 0.17 2.52 Nov 01-30 2.17 1.19 N/A 0.16 3.23 Dec 01-31 2.54 1.14 N/A 0.15 3.37 TOTAL 13.19 14.17 N/A 1.87 28.61

Case Study “Natural Ventilation” Iteration Orientation -90° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.66 1.25 N/A 0.17 3.55 Feb 01-28 2.32 1.09 N/A 0.14 2.63 Mar 01-31 1.77 1.19 N/A 0.16 2.21 Apr 01-30 0.72 1.14 N/A 0.15 2.01 May 01-31 0.11 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.07 1.09 N/A 0.14 1.83 Oct 01-31 0.74 1.25 N/A 0.17 2.52 Nov 01-30 2.31 1.19 N/A 0.16 3.23 Dec 01-31 2.63 1.14 N/A 0.15 3.37 TOTAL 13.32 14.17 N/A 1.87 28.61

Case Study “Natural Ventilation” Iteration Orientation -60° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.65 1.25 N/A 0.17 3.55 Feb 01-28 2.30 1.09 N/A 0.14 2.63 Mar 01-31 1.81 1.19 N/A 0.16 2.21 Apr 01-30 0.83 1.14 N/A 0.15 2.01 May 01-31 0.11 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.08 1.09 N/A 0.14 1.83 Oct 01-31 0.69 1.25 N/A 0.17 2.52 Nov 01-30 2.27 1.19 N/A 0.16 3.23 Dec 01-31 2.61 1.14 N/A 0.15 3.37 TOTAL 13.33 14.17 N/A 1.87 28.61

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Case Study “Natural Ventilation” Iteration Orientation -30° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.57 1.25 N/A 0.17 3.55 Feb 01-28 2.22 1.09 N/A 0.14 2.63 Mar 01-31 1.85 1.19 N/A 0.16 2.21 Apr 01-30 1.02 1.14 N/A 0.15 2.01 May 01-31 0.14 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.07 1.09 N/A 0.14 1.83 Oct 01-31 0.60 1.25 N/A 0.17 2.52 Nov 01-30 2.17 1.19 N/A 0.16 3.23 Dec 01-31 2.54 1.14 N/A 0.15 3.37 TOTAL 13.19 14.17 N/A 1.87 28.61

Case Study “Natural Ventilation” Iteration ‘Shift’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 1.06 2.00 N/A 0.17 6.83 Feb 01-28 0.65 1.74 N/A 0.14 5.49 Mar 01-31 0.37 1.91 N/A 0.16 5.30 Apr 01-30 0.08 1.82 N/A 0.15 4.71 May 01-31 0.02 2.00 N/A 0.17 4.36 Jun 01-30 0.00 1.82 N/A 0.15 3.73 Jul 01-31 0.00 1.91 N/A 0.16 3.94 Aug 01-31 0.00 2.00 N/A 0.17 4.64 Sep 01-30 0.02 1.74 N/A 0.14 4.59 Oct 01-31 0.13 2.00 N/A 0.17 5.86 Nov 01-30 0.59 1.91 N/A 0.16 6.38 Dec 01-31 1.26 1.82 N/A 0.15 6.33 TOTAL 4.18 22.66 N/A 1.87 62.16

Case Study “Natural Ventilation” Iteration ‘Public Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.46 1.00 N/A 0.17 3.55 Feb 01-28 1.99 0.87 N/A 0.14 2.63 Mar 01-31 1.67 0.96 N/A 0.16 2.21 Apr 01-30 1.04 0.91 N/A 0.15 2.01 May 01-31 0.18 1.00 N/A 0.17 1.92 Jun 01-30 0.00 0.91 N/A 0.15 1.70 Jul 01-31 0.00 0.96 N/A 0.16 1.76 Aug 01-31 0.00 1.00 N/A 0.17 1.87 Sep 01-30 0.04 0.87 N/A 0.14 1.83 Oct 01-31 0.50 1.00 N/A 0.17 2.52 Nov 01-30 2.03 0.96 N/A 0.16 3.23 Dec 01-31 2.49 0.91 N/A 0.15 3.37 TOTAL 12.41 11.33 N/A 1.87 28.61

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Case Study “Natural Ventilation” Iteration ‘Mixed Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.52 1.25 N/A 0.17 3.55 Feb 01-28 2.09 1.09 N/A 0.14 2.63 Mar 01-31 1.82 1.19 N/A 0.16 2.21 Apr 01-30 1.12 1.14 N/A 0.15 2.01 May 01-31 0.17 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.87 Sep 01-30 0.06 1.09 N/A 0.14 1.83 Oct 01-31 0.54 1.25 N/A 0.17 2.52 Nov 01-30 2.12 1.19 N/A 0.16 3.23 Dec 01-31 2.52 1.14 N/A 0.15 3.37 TOTAL 12.98 14.17 N/A 1.87 28.61

Case Study “Natural Ventilation” Iteration ‘Extended Hours Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.23 1.62 N/A 0.17 4.93 Feb 01-28 1.73 1.41 N/A 0.14 3.80 Mar 01-31 1.34 1.55 N/A 0.16 3.38 Apr 01-30 0.79 1.48 N/A 0.15 2.93 May 01-31 0.10 1.62 N/A 0.17 2.63 Jun 01-30 0.00 1.48 N/A 0.15 2.30 Jul 01-31 0.00 1.55 N/A 0.16 2.36 Aug 01-31 0.00 1.62 N/A 0.17 2.73 Sep 01-30 0.05 1.41 N/A 0.14 2.84 Oct 01-31 0.27 1.62 N/A 0.17 3.85 Nov 01-30 1.70 1.55 N/A 0.16 4.53 Dec 01-31 2.23 1.48 N/A 0.15 4.63 TOTAL 10.44 18.41 N/A 1.87 40.90

Case Study “Natural Ventilation” Iteration ’24 hour Call Centre’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 0.05 3.00 N/A 0.17 9.98 Feb 01-28 0.01 2.61 N/A 0.14 8.19 Mar 01-31 0.00 2.87 N/A 0.16 8.18 Apr 01-30 0.00 2.74 N/A 0.15 7.49 May 01-31 0.03 3.00 N/A 0.17 7.36 Jun 01-30 0.00 2.74 N/A 0.15 6.44 Jul 01-31 0.00 2.87 N/A 0.16 6.77 Aug 01-31 0.00 3.00 N/A 0.17 7.64 Sep 01-30 0.02 2.61 N/A 0.14 7.22 Oct 01-31 0.06 3.00 N/A 0.17 8.90 Nov 01-30 0.02 2.87 N/A 0.16 9.36 Dec 01-31 0.23 2.74 N/A 0.15 9.24 TOTAL 0.41 34.00 N/A 1.87 96.76

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Case Study “Natural Ventilation” Iteration Location - Southampton Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.42 1.25 N/A 0.17 3.43 Feb 01-28 1.70 1.09 N/A 0.14 2.44 Mar 01-31 1.57 1.19 N/A 0.16 2.52 Apr 01-30 0.43 1.14 N/A 0.15 1.88 May 01-31 0.09 1.25 N/A 0.17 1.93 Jun 01-30 0.00 1.14 N/A 0.15 1.63 Jul 01-31 0.00 1.19 N/A 0.16 1.84 Aug 01-31 0.00 1.25 N/A 0.17 1.89 Sep 01-30 0.05 1.09 N/A 0.14 1.94 Oct 01-31 0.19 1.25 N/A 0.17 2.51 Nov 01-30 1.33 1.19 N/A 0.16 3.06 Dec 01-31 2.39 1.14 N/A 0.15 3.23 TOTAL 10.17 14.17 N/A 1.87 28.30

Case Study “Natural Ventilation” Iteration Location - London Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.43 1.25 N/A 0.17 3.63 Feb 01-28 1.89 1.09 N/A 0.14 2.55 Mar 01-31 1.74 1.19 N/A 0.16 2.41 Apr 01-30 0.48 1.14 N/A 0.15 1.86 May 01-31 0.08 1.25 N/A 0.17 1.92 Jun 01-30 0.00 1.14 N/A 0.15 1.58 Jul 01-31 0.00 1.19 N/A 0.16 1.77 Aug 01-31 0.00 1.25 N/A 0.17 1.94 Sep 01-30 0.05 1.09 N/A 0.14 1.87 Oct 01-31 0.17 1.25 N/A 0.17 2.69 Nov 01-30 1.24 1.19 N/A 0.16 3.50 Dec 01-31 2.29 1.14 N/A 0.15 3.49 TOTAL 10.36 14.17 N/A 1.87 29.21

Case Study “Natural Ventilation” Iteration Location - Birmingham Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.72 1.25 N/A 0.17 3.27 Feb 01-28 2.08 1.09 N/A 0.14 2.45 Mar 01-31 2.03 1.19 N/A 0.16 2.43 Apr 01-30 1.35 1.14 N/A 0.15 2.02 May 01-31 0.29 1.25 N/A 0.17 1.87 Jun 01-30 0.00 1.14 N/A 0.15 1.66 Jul 01-31 0.00 1.19 N/A 0.16 1.76 Aug 01-31 0.00 1.25 N/A 0.17 1.91 Sep 01-30 0.10 1.09 N/A 0.14 1.84 Oct 01-31 0.54 1.25 N/A 0.17 2.70 Nov 01-30 2.05 1.19 N/A 0.16 3.12 Dec 01-31 2.31 1.14 N/A 0.15 3.46 TOTAL 13.45 14.17 N/A 1.87 28.48

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Case Study “Natural Ventilation” Iteration Location - Leeds Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.78 1.25 N/A 0.17 3.60 Feb 01-28 2.31 1.09 N/A 0.14 2.78 Mar 01-31 1.69 1.19 N/A 0.16 2.42 Apr 01-30 0.90 1.14 N/A 0.15 1.99 May 01-31 0.19 1.25 N/A 0.17 1.88 Jun 01-30 0.00 1.14 N/A 0.15 1.65 Jul 01-31 0.00 1.19 N/A 0.16 1.73 Aug 01-31 0.00 1.25 N/A 0.17 1.93 Sep 01-30 0.09 1.09 N/A 0.14 1.82 Oct 01-31 0.62 1.25 N/A 0.17 2.97 Nov 01-30 1.93 1.19 N/A 0.16 3.27 Dec 01-31 2.26 1.14 N/A 0.15 3.54 TOTAL 12.77 14.17 N/A 1.87 29.58

Case Study “Natural Ventilation” Iteration Location - Newcastle Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.78 1.25 N/A 0.17 3.67 Feb 01-28 2.23 1.09 N/A 0.14 2.33 Mar 01-31 1.73 1.19 N/A 0.16 2.34 Apr 01-30 1.46 1.14 N/A 0.15 1.99 May 01-31 0.42 1.25 N/A 0.17 1.96 Jun 01-30 0.00 1.14 N/A 0.15 1.68 Jul 01-31 0.00 1.19 N/A 0.16 1.71 Aug 01-31 0.00 1.25 N/A 0.17 2.01 Sep 01-30 0.07 1.09 N/A 0.14 1.98 Oct 01-31 0.42 1.25 N/A 0.17 2.58 Nov 01-30 1.95 1.19 N/A 0.16 3.34 Dec 01-31 2.64 1.14 N/A 0.15 3.52 TOTAL 13.71 14.17 N/A 1.87 29.10

Case Study “Natural Ventilation” Iteration Future Weather Scenario – 2080 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 1.27 1.14 N/A 0.15 3.25 Feb 01-28 0.89 1.09 N/A 0.14 3.02 Mar 01-31 0.16 1.25 N/A 0.17 2.77 Apr 01-30 0.13 1.19 N/A 0.16 2.05 May 01-31 0.07 1.14 N/A 0.15 1.64 Jun 01-30 0.00 1.19 N/A 0.16 1.70 Jul 01-31 0.00 1.19 N/A 0.16 1.73 Aug 01-31 0.00 1.19 N/A 0.16 1.89 Sep 01-30 0.01 1.19 N/A 0.16 2.15 Oct 01-31 0.04 1.14 N/A 0.15 2.51 Nov 01-30 0.02 1.19 N/A 0.16 3.29 Dec 01-31 0.76 1.25 N/A 0.17 3.85 TOTAL 3.35 14.17 N/A 1.87 29.83

279

Case Study “Natural Ventilation” Iteration Future Weather Scenario – 2080 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 1.67 1.14 N/A 0.15 3.37 Feb 01-28 1.23 1.09 N/A 0.14 3.01 Mar 01-31 0.48 1.25 N/A 0.17 2.68 Apr 01-30 0.07 1.19 N/A 0.16 1.93 May 01-31 0.11 1.14 N/A 0.15 1.76 Jun 01-30 0.00 1.19 N/A 0.16 1.75 Jul 01-31 0.00 1.19 N/A 0.16 1.82 Aug 01-31 0.00 1.19 N/A 0.16 1.83 Sep 01-30 0.01 1.19 N/A 0.16 2.24 Oct 01-31 0.08 1.14 N/A 0.15 2.58 Nov 01-30 0.15 1.19 N/A 0.16 3.36 Dec 01-31 1.44 1.25 N/A 0.17 4.04 TOTAL 5.24 14.17 N/A 1.87 30.36

Case Study “Natural Ventilation” Iteration Future Weather Scenario – 2050 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.18 1.14 N/A 0.15 3.41 Feb 01-28 1.40 1.09 N/A 0.14 2.97 Mar 01-31 0.43 1.25 N/A 0.17 2.80 Apr 01-30 0.29 1.19 N/A 0.16 2.07 May 01-31 0.10 1.14 N/A 0.15 1.72 Jun 01-30 0.00 1.19 N/A 0.16 1.85 Jul 01-31 0.00 1.19 N/A 0.16 1.83 Aug 01-31 0.00 1.19 N/A 0.16 1.78 Sep 01-30 0.04 1.19 N/A 0.16 2.12 Oct 01-31 0.10 1.14 N/A 0.15 2.94 Nov 01-30 0.28 1.19 N/A 0.16 3.41 Dec 01-31 1.53 1.25 N/A 0.17 3.86 TOTAL 6.34 14.17 N/A 1.87 30.74

Case Study “Natural Ventilation” Iteration Future Weather Scenario – 2050 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.14 1.14 N/A 0.15 3.52 Feb 01-28 1.68 1.09 N/A 0.14 3.00 Mar 01-31 1.03 1.25 N/A 0.17 2.84 Apr 01-30 0.16 1.19 N/A 0.16 2.11 May 01-31 0.10 1.14 N/A 0.15 1.68 Jun 01-30 0.00 1.19 N/A 0.16 1.87 Jul 01-31 0.00 1.19 N/A 0.16 1.79 Aug 01-31 0.00 1.19 N/A 0.16 1.94 Sep 01-30 0.05 1.19 N/A 0.16 2.27 Oct 01-31 0.18 1.14 N/A 0.15 2.66 Nov 01-30 0.63 1.19 N/A 0.16 3.47 Dec 01-31 1.84 1.25 N/A 0.17 3.63 TOTAL 7.81 14.17 N/A 1.87 30.78

280

Case Study “Natural Ventilation” Iteration Future Weather Scenario – 2030 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.46 1.14 N/A 0.15 3.41 Feb 01-28 1.69 1.09 N/A 0.14 2.73 Mar 01-31 0.98 1.25 N/A 0.17 2.71 Apr 01-30 0.52 1.19 N/A 0.16 2.15 May 01-31 0.11 1.14 N/A 0.15 1.76 Jun 01-30 0.00 1.19 N/A 0.16 1.75 Jul 01-31 0.00 1.19 N/A 0.16 1.94 Aug 01-31 0.00 1.19 N/A 0.16 1.86 Sep 01-30 0.08 1.19 N/A 0.16 2.11 Oct 01-31 0.09 1.14 N/A 0.15 2.39 Nov 01-30 0.90 1.19 N/A 0.16 3.39 Dec 01-31 1.98 1.25 N/A 0.17 3.83 TOTAL 8.83 14.17 N/A 1.87 30.04

Case Study “Natural Ventilation” Iteration Future Weather Scenario – 2030 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.39 1.14 N/A 0.15 3.48 Feb 01-28 1.90 1.09 N/A 0.14 2.76 Mar 01-31 1.18 1.25 N/A 0.17 2.60 Apr 01-30 0.55 1.19 N/A 0.16 2.04 May 01-31 0.12 1.14 N/A 0.15 1.66 Jun 01-30 0.00 1.19 N/A 0.16 1.74 Jul 01-31 0.00 1.19 N/A 0.16 1.86 Aug 01-31 0.00 1.19 N/A 0.16 1.92 Sep 01-30 0.08 1.19 N/A 0.16 2.27 Oct 01-31 0.16 1.14 N/A 0.15 2.67 Nov 01-30 0.73 1.19 N/A 0.16 3.26 Dec 01-31 2.10 1.25 N/A 0.17 3.98 TOTAL 9.21 14.17 N/A 1.87 30.25

Case Study “Natural Ventilation” Iteration Occupancy Density – 8m2/Person Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.56 1.56 N/A 0.17 3.55 Feb 01-28 2.19 1.36 N/A 0.14 2.63 Mar 01-31 1.90 1.49 N/A 0.16 2.21 Apr 01-30 1.18 1.42 N/A 0.15 2.01 May 01-31 0.20 1.56 N/A 0.17 1.92 Jun 01-30 0.00 1.42 N/A 0.15 1.70 Jul 01-31 0.00 1.49 N/A 0.16 1.76 Aug 01-31 0.00 1.56 N/A 0.17 1.87 Sep 01-30 0.05 1.36 N/A 0.14 1.83 Oct 01-31 0.58 1.56 N/A 0.17 2.52 Nov 01-30 2.18 1.49 N/A 0.16 3.23 Dec 01-31 2.55 1.42 N/A 0.15 3.37 TOTAL 13.41 17.71 N/A 1.87 28.61

281

Case Study “Natural Ventilation” Iteration Occupancy Density – 16m2/Person Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 2.38 0.78 N/A 0.17 3.55 Feb 01-28 1.88 0.68 N/A 0.14 2.63 Mar 01-31 1.55 0.75 N/A 0.16 2.21 Apr 01-30 0.96 0.71 N/A 0.15 2.01 May 01-31 0.14 0.78 N/A 0.17 1.92 Jun 01-30 0.00 0.71 N/A 0.15 1.70 Jul 01-31 0.00 0.75 N/A 0.16 1.76 Aug 01-31 0.00 0.78 N/A 0.17 1.87 Sep 01-30 0.06 0.68 N/A 0.14 1.83 Oct 01-31 0.45 0.78 N/A 0.17 2.52 Nov 01-30 1.93 0.75 N/A 0.16 3.23 Dec 01-31 2.41 0.71 N/A 0.15 3.37 TOTAL 11.77 8.85 N/A 1.87 28.61

282

Appendix C.3 - “Passivhaus”

Case Study “Passivhaus” Iteration Orientation 90° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 3.94 5.13 Feb 01-28 N/A 1.09 N/A 3.95 4.46 Mar 01-31 N/A 1.19 N/A 5.59 4.91 Apr 01-30 N/A 1.14 N/A 6.53 4.69 May 01-31 N/A 1.25 N/A 7.39 5.13 Jun 01-30 N/A 1.14 N/A 8.38 4.69 Jul 01-31 N/A 1.19 N/A 9.91 4.91 Aug 01-31 N/A 1.25 N/A 10.04 5.13 Sep 01-30 N/A 1.09 N/A 6.94 4.46 Oct 01-31 N/A 1.25 N/A 6.57 5.13 Nov 01-30 N/A 1.19 N/A 4.31 4.91 Dec 01-31 N/A 1.14 N/A 3.63 4.69 TOTAL N/A 14.17 N/A 77.18 58.24

Case Study “Passivhaus” Iteration Orientation 60° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.02 5.13 Feb 01-28 N/A 1.09 N/A 4.01 4.46 Mar 01-31 N/A 1.19 N/A 5.66 4.91 Apr 01-30 N/A 1.14 N/A 6.50 4.69 May 01-31 N/A 1.25 N/A 7.32 5.13 Jun 01-30 N/A 1.14 N/A 8.36 4.69 Jul 01-31 N/A 1.19 N/A 9.90 4.91 Aug 01-31 N/A 1.25 N/A 9.97 5.13 Sep 01-30 N/A 1.09 N/A 6.95 4.46 Oct 01-31 N/A 1.25 N/A 6.63 5.13 Nov 01-30 N/A 1.19 N/A 4.34 4.91 Dec 01-31 N/A 1.14 N/A 3.67 4.69 TOTAL N/A 14.17 N/A 77.32 58.24

283

Case Study “Passivhaus” Iteration Orientation 30° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.24 5.13 Feb 01-28 N/A 1.09 N/A 4.17 4.46 Mar 01-31 N/A 1.19 N/A 5.69 4.91 Apr 01-30 N/A 1.14 N/A 6.44 4.69 May 01-31 N/A 1.25 N/A 7.15 5.13 Jun 01-30 N/A 1.14 N/A 8.16 4.69 Jul 01-31 N/A 1.19 N/A 9.68 4.91 Aug 01-31 N/A 1.25 N/A 9.78 5.13 Sep 01-30 N/A 1.09 N/A 6.91 4.46 Oct 01-31 N/A 1.25 N/A 6.72 5.13 Nov 01-30 N/A 1.19 N/A 4.56 4.91 Dec 01-31 N/A 1.14 N/A 3.84 4.69 TOTAL N/A 14.17 N/A 77.35 58.24

Case Study “Passivhaus” Iteration Orientation -90° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 3.94 5.13 Feb 01-28 N/A 1.09 N/A 3.95 4.46 Mar 01-31 N/A 1.19 N/A 5.61 4.91 Apr 01-30 N/A 1.14 N/A 6.55 4.69 May 01-31 N/A 1.25 N/A 7.40 5.13 Jun 01-30 N/A 1.14 N/A 8.40 4.69 Jul 01-31 N/A 1.19 N/A 9.92 4.91 Aug 01-31 N/A 1.25 N/A 10.07 5.13 Sep 01-30 N/A 1.09 N/A 6.95 4.46 Oct 01-31 N/A 1.25 N/A 6.57 5.13 Nov 01-30 N/A 1.19 N/A 4.31 4.91 Dec 01-31 N/A 1.14 N/A 3.63 4.69 TOTAL N/A 14.17 N/A 77.29 58.24

Case Study “Passivhaus” Iteration Orientation -60° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.04 5.13 Feb 01-28 N/A 1.09 N/A 4.04 4.46 Mar 01-31 N/A 1.19 N/A 5.66 4.91 Apr 01-30 N/A 1.14 N/A 6.37 4.69 May 01-31 N/A 1.25 N/A 7.34 5.13 Jun 01-30 N/A 1.14 N/A 8.26 4.69 Jul 01-31 N/A 1.19 N/A 9.80 4.91 Aug 01-31 N/A 1.25 N/A 9.97 5.13 Sep 01-30 N/A 1.09 N/A 6.88 4.46 Oct 01-31 N/A 1.25 N/A 6.56 5.13 Nov 01-30 N/A 1.19 N/A 4.37 4.91 Dec 01-31 N/A 1.14 N/A 3.70 4.69 TOTAL N/A 14.17 N/A 77.00 58.24

284

Case Study “Passivhaus” Iteration Orientation -30° Turn Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.23 5.13 Feb 01-28 N/A 1.09 N/A 4.16 4.46 Mar 01-31 N/A 1.19 N/A 5.64 4.91 Apr 01-30 N/A 1.14 N/A 6.32 4.69 May 01-31 N/A 1.25 N/A 7.11 5.13 Jun 01-30 N/A 1.14 N/A 7.98 4.69 Jul 01-31 N/A 1.19 N/A 9.62 4.91 Aug 01-31 N/A 1.25 N/A 9.77 5.13 Sep 01-30 N/A 1.09 N/A 6.81 4.46 Oct 01-31 N/A 1.25 N/A 6.65 5.13 Nov 01-30 N/A 1.19 N/A 4.57 4.91 Dec 01-31 N/A 1.14 N/A 3.87 4.69 TOTAL N/A 14.17 N/A 76.73 58.24

Case Study “Passivhaus” Iteration ‘Shift’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.87 N/A 5.87 7.89 Feb 01-28 N/A 1.63 N/A 5.78 6.86 Mar 01-31 N/A 1.78 N/A 7.52 7.54 Apr 01-30 N/A 1.70 N/A 8.12 7.20 May 01-31 N/A 1.87 N/A 9.10 7.89 Jun 01-30 N/A 1.70 N/A 10.32 7.20 Jul 01-31 N/A 1.78 N/A 12.11 7.54 Aug 01-31 N/A 1.87 N/A 12.52 7.89 Sep 01-30 N/A 1.63 N/A 8.99 6.86 Oct 01-31 N/A 1.87 N/A 9.00 7.89 Nov 01-30 N/A 1.78 N/A 6.28 7.54 Dec 01-31 N/A 1.70 N/A 5.40 7.20 TOTAL N/A 21.17 N/A 100.99 89.51

Case Study “Passivhaus” Iteration ‘Public Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.04 N/A 4.11 5.13 Feb 01-28 N/A 0.91 N/A 4.10 4.46 Mar 01-31 N/A 0.99 N/A 5.47 4.91 Apr 01-30 N/A 0.95 N/A 6.05 4.69 May 01-31 N/A 1.04 N/A 6.98 5.13 Jun 01-30 N/A 0.95 N/A 8.00 4.69 Jul 01-31 N/A 0.99 N/A 9.47 4.91 Aug 01-31 N/A 1.04 N/A 9.57 5.13 Sep 01-30 N/A 0.91 N/A 6.78 4.46 Oct 01-31 N/A 1.04 N/A 6.56 5.13 Nov 01-30 N/A 0.99 N/A 4.45 4.91 Dec 01-31 N/A 0.95 N/A 3.72 4.69 TOTAL N/A 11.84 N/A 75.27 58.24

285

Case Study “Passivhaus” Iteration ‘Mixed Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 0.94 N/A 3.99 5.13 Feb 01-28 N/A 0.82 N/A 3.98 4.46 Mar 01-31 N/A 0.90 N/A 5.34 4.91 Apr 01-30 N/A 0.85 N/A 5.93 4.69 May 01-31 N/A 0.96 N/A 6.98 5.13 Jun 01-30 N/A 0.85 N/A 8.03 4.69 Jul 01-31 N/A 0.90 N/A 9.48 4.91 Aug 01-31 N/A 0.94 N/A 9.60 5.13 Sep 01-30 N/A 0.82 N/A 6.77 4.46 Oct 01-31 N/A 0.94 N/A 6.43 5.13 Nov 01-30 N/A 0.90 N/A 4.33 4.91 Dec 01-31 N/A 0.85 N/A 3.61 4.69 TOTAL N/A 10.66 N/A 74.46 58.24

Case Study “Passivhaus” Iteration ‘Extended Hours Office’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.46 N/A 4.99 6.05 Feb 01-28 N/A 1.27 N/A 4.93 5.26 Mar 01-31 N/A 1.39 N/A 6.46 5.79 Apr 01-30 N/A 1.33 N/A 7.00 5.52 May 01-31 N/A 1.46 N/A 7.66 6.05 Jun 01-30 N/A 1.33 N/A 8.64 5.52 Jul 01-31 N/A 1.39 N/A 10.17 5.79 Aug 01-31 N/A 1.46 N/A 10.34 6.05 Sep 01-30 N/A 1.27 N/A 7.43 5.26 Oct 01-31 N/A 1.46 N/A 7.60 6.05 Nov 01-30 N/A 1.39 N/A 5.35 5.79 Dec 01-31 N/A 1.33 N/A 4.52 5.52 TOTAL N/A 16.50 N/A 85.09 68.66

Case Study “Passivhaus” Iteration ’24 hour Call Centre’ Occupancy Pattern Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 2.69 N/A 8.96 11.56 Feb 01-28 N/A 2.34 N/A 8.47 10.05 Mar 01-31 N/A 2.57 N/A 10.37 11.06 Apr 01-30 N/A 2.45 N/A 10.84 10.56 May 01-31 N/A 2.69 N/A 11.34 11.56 Jun 01-30 N/A 2.45 N/A 12.49 10.56 Jul 01-31 N/A 2.57 N/A 14.51 11.06 Aug 01-31 N/A 2.69 N/A 15.23 11.56 Sep 01-30 N/A 2.34 N/A 11.35 10.05 Oct 01-31 N/A 2.69 N/A 12.23 11.56 Nov 01-30 N/A 2.57 N/A 9.35 11.06 Dec 01-31 N/A 2.45 N/A 8.38 10.56 TOTAL N/A 30.50 N/A 133.53 131.20

286

Case Study “Passivhaus” Iteration Location - Southampton Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.32 5.13 Feb 01-28 N/A 1.09 N/A 4.68 4.46 Mar 01-31 N/A 1.19 N/A 5.69 4.91 Apr 01-30 N/A 1.14 N/A 6.63 4.69 May 01-31 N/A 1.25 N/A 7.34 5.13 Jun 01-30 N/A 1.14 N/A 8.98 4.69 Jul 01-31 N/A 1.19 N/A 10.24 4.91 Aug 01-31 N/A 1.25 N/A 10.04 5.13 Sep 01-30 N/A 1.09 N/A 7.58 4.46 Oct 01-31 N/A 1.25 N/A 7.21 5.13 Nov 01-30 N/A 1.19 N/A 5.22 4.91 Dec 01-31 N/A 1.14 N/A 4.29 4.69 TOTAL N/A 14.17 N/A 82.22 58.24

Case Study “Passivhaus” Iteration Location - London Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.34 5.13 Feb 01-28 N/A 1.09 N/A 4.51 4.46 Mar 01-31 N/A 1.19 N/A 5.62 4.91 Apr 01-30 N/A 1.14 N/A 6.84 4.69 May 01-31 N/A 1.25 N/A 8.01 5.13 Jun 01-30 N/A 1.14 N/A 9.27 4.69 Jul 01-31 N/A 1.19 N/A 11.74 4.91 Aug 01-31 N/A 1.25 N/A 10.88 5.13 Sep 01-30 N/A 1.09 N/A 7.53 4.46 Oct 01-31 N/A 1.25 N/A 7.19 5.13 Nov 01-30 N/A 1.19 N/A 5.08 4.91 Dec 01-31 N/A 1.14 N/A 4.24 4.69 TOTAL N/A 14.17 N/A 85.25 58.24

Case Study “Passivhaus” Iteration Location - Birmingham Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 4.10 5.13 Feb 01-28 N/A 1.09 N/A 4.38 4.46 Mar 01-31 N/A 1.19 N/A 5.32 4.91 Apr 01-30 N/A 1.14 N/A 6.02 4.69 May 01-31 N/A 1.25 N/A 7.60 5.13 Jun 01-30 N/A 1.14 N/A 7.89 4.69 Jul 01-31 N/A 1.19 N/A 10.38 4.91 Aug 01-31 N/A 1.25 N/A 9.74 5.13 Sep 01-30 N/A 1.09 N/A 6.76 4.46 Oct 01-31 N/A 1.25 N/A 6.44 5.13 Nov 01-30 N/A 1.19 N/A 4.65 4.91 Dec 01-31 N/A 1.14 N/A 4.11 4.69 TOTAL N/A 14.17 N/A 77.40 58.24

287

Case Study “Passivhaus” Iteration Location - Leeds Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 3.87 5.13 Feb 01-28 N/A 1.09 N/A 4.05 4.46 Mar 01-31 N/A 1.19 N/A 5.59 4.91 Apr 01-30 N/A 1.14 N/A 6.50 4.69 May 01-31 N/A 1.25 N/A 7.57 5.13 Jun 01-30 N/A 1.14 N/A 8.27 4.69 Jul 01-31 N/A 1.19 N/A 11.00 4.91 Aug 01-31 N/A 1.25 N/A 8.96 5.13 Sep 01-30 N/A 1.09 N/A 6.91 4.46 Oct 01-31 N/A 1.25 N/A 6.32 5.13 Nov 01-30 N/A 1.19 N/A 4.74 4.91 Dec 01-31 N/A 1.14 N/A 4.18 4.69 TOTAL N/A 14.17 N/A 77.97 58.24

Case Study “Passivhaus” Iteration Location - Newcastle Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.25 N/A 3.97 5.13 Feb 01-28 N/A 1.09 N/A 4.41 4.46 Mar 01-31 N/A 1.19 N/A 5.74 4.91 Apr 01-30 N/A 1.14 N/A 5.93 4.69 May 01-31 N/A 1.25 N/A 6.95 5.13 Jun 01-30 N/A 1.14 N/A 7.71 4.69 Jul 01-31 N/A 1.19 N/A 8.89 4.91 Aug 01-31 N/A 1.25 N/A 8.16 5.13 Sep 01-30 N/A 1.09 N/A 6.60 4.46 Oct 01-31 N/A 1.25 N/A 7.16 5.13 Nov 01-30 N/A 1.19 N/A 4.74 4.91 Dec 01-31 N/A 1.14 N/A 3.87 4.69 TOTAL N/A 14.17 N/A 74.13 58.24

Case Study “Passivhaus” Iteration Future Weather Scenario – 2080 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.16 N/A 5.14 4.69 Feb 01-28 N/A 1.09 N/A 5.20 4.46 Mar 01-31 N/A 1.23 N/A 6.92 5.13 Apr 01-30 N/A 1.18 N/A 8.52 4.91 May 01-31 N/A 1.16 N/A 10.85 4.69 Jun 01-30 N/A 1.18 N/A 14.19 4.91 Jul 01-31 N/A 1.19 N/A 17.41 4.91 Aug 01-31 N/A 1.21 N/A 17.15 4.91 Sep 01-30 N/A 1.18 N/A 13.14 4.91 Oct 01-31 N/A 1.16 N/A 11.08 4.69 Nov 01-30 N/A 1.19 N/A 6.55 4.91 Dec 01-31 N/A 1.23 N/A 5.61 5.13 TOTAL N/A 14.17 N/A 121.76 58.24

288

Case Study “Passivhaus” Iteration Future Weather Scenario – 2080 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.16 N/A 4.75 4.69 Feb 01-28 N/A 1.09 N/A 4.93 4.46 Mar 01-31 N/A 1.23 N/A 6.84 5.13 Apr 01-30 N/A 1.18 N/A 8.30 4.91 May 01-31 N/A 1.16 N/A 9.76 4.69 Jun 01-30 N/A 1.18 N/A 13.46 4.91 Jul 01-31 N/A 1.19 N/A 16.31 4.91 Aug 01-31 N/A 1.21 N/A 16.42 4.91 Sep 01-30 N/A 1.18 N/A 11.36 4.91 Oct 01-31 N/A 1.16 N/A 9.11 4.69 Nov 01-30 N/A 1.19 N/A 6.67 4.91 Dec 01-31 N/A 1.23 N/A 4.96 5.13 TOTAL N/A 14.17 N/A 112.88 58.24

Case Study “Passivhaus” Iteration Future Weather Scenario – 2050 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.16 N/A 4.52 4.69 Feb 01-28 N/A 1.09 N/A 4.67 4.46 Mar 01-31 N/A 1.23 N/A 6.66 5.13 Apr 01-30 N/A 1.18 N/A 7.65 4.91 May 01-31 N/A 1.16 N/A 9.33 4.69 Jun 01-30 N/A 1.18 N/A 11.88 4.91 Jul 01-31 N/A 1.19 N/A 14.58 4.91 Aug 01-31 N/A 1.21 N/A 13.95 4.91 Sep 01-30 N/A 1.18 N/A 9.94 4.91 Oct 01-31 N/A 1.16 N/A 8.35 4.69 Nov 01-30 N/A 1.19 N/A 6.05 4.91 Dec 01-31 N/A 1.23 N/A 5.06 5.13 TOTAL N/A 14.17 N/A 102.64 58.24

Case Study “Passivhaus” Iteration Future Weather Scenario – 2050 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.16 N/A 4.38 4.69 Feb 01-28 N/A 1.09 N/A 4.49 4.46 Mar 01-31 N/A 1.23 N/A 6.03 5.13 Apr 01-30 N/A 1.18 N/A 7.43 4.91 May 01-31 N/A 1.16 N/A 8.21 4.69 Jun 01-30 N/A 1.18 N/A 11.63 4.91 Jul 01-31 N/A 1.19 N/A 14.69 4.91 Aug 01-31 N/A 1.21 N/A 14.44 4.91 Sep 01-30 N/A 1.18 N/A 8.84 4.91 Oct 01-31 N/A 1.16 N/A 8.68 4.69 Nov 01-30 N/A 1.19 N/A 5.75 4.91 Dec 01-31 N/A 1.23 N/A 5.05 5.13 TOTAL N/A 14.17 N/A 99.62 58.24

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Case Study “Passivhaus” Iteration Future Weather Scenario – 2030 (High) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.16 N/A 4.18 4.69 Feb 01-28 N/A 1.09 N/A 4.70 4.46 Mar 01-31 N/A 1.23 N/A 6.21 5.13 Apr 01-30 N/A 1.18 N/A 7.00 4.91 May 01-31 N/A 1.16 N/A 7.96 4.69 Jun 01-30 N/A 1.18 N/A 10.42 4.91 Jul 01-31 N/A 1.19 N/A 12.88 4.91 Aug 01-31 N/A 1.21 N/A 12.48 4.91 Sep 01-30 N/A 1.18 N/A 8.91 4.91 Oct 01-31 N/A 1.16 N/A 7.86 4.69 Nov 01-30 N/A 1.19 N/A 5.69 4.91 Dec 01-31 N/A 1.23 N/A 4.70 5.13 TOTAL N/A 14.17 N/A 92.98 58.24

Case Study “Passivhaus” Iteration Future Weather Scenario – 2030 (Medium) Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.16 N/A 4.14 4.69 Feb 01-28 N/A 1.09 N/A 4.58 4.46 Mar 01-31 N/A 1.23 N/A 6.15 5.13 Apr 01-30 N/A 1.18 N/A 7.28 4.91 May 01-31 N/A 1.16 N/A 7.78 4.69 Jun 01-30 N/A 1.18 N/A 10.75 4.91 Jul 01-31 N/A 1.19 N/A 12.58 4.91 Aug 01-31 N/A 1.21 N/A 12.05 4.91 Sep 01-30 N/A 1.18 N/A 8.53 4.91 Oct 01-31 N/A 1.16 N/A 8.07 4.69 Nov 01-30 N/A 1.19 N/A 5.82 4.91 Dec 01-31 N/A 1.23 N/A 4.56 5.13 TOTAL N/A 14.17 N/A 92.29 58.24

Case Study “Passivhaus” Iteration Occupancy Density – 8m2/Person Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 1.76 N/A 4.97 5.13 Feb 01-28 N/A 1.54 N/A 4.86 4.46 Mar 01-31 N/A 1.68 N/A 6.32 4.91 Apr 01-30 N/A 1.61 N/A 6.78 4.69 May 01-31 N/A 1.76 N/A 7.00 5.13 Jun 01-30 N/A 1.61 N/A 7.97 4.69 Jul 01-31 N/A 1.68 N/A 9.48 4.91 Aug 01-31 N/A 1.76 N/A 9.59 5.13 Sep 01-30 N/A 1.54 N/A 6.79 4.46 Oct 01-31 N/A 1.76 N/A 7.30 5.13 Nov 01-30 N/A 1.68 N/A 5.31 4.91 Dec 01-31 N/A 1.61 N/A 4.49 4.69 TOTAL N/A 20.01 N/A 80.87 58.24

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Case Study “Passivhaus” Iteration Occupancy Density – 16m2/Person Units MWh Date HEATING DHW COOLING VENTILATION LIGHTING Jan 01-31 N/A 0.99 N/A 4.04 5.13 Feb 01-28 N/A 0.87 N/A 4.04 4.46 Mar 01-31 N/A 0.94 N/A 5.41 4.91 Apr 01-30 N/A 0.91 N/A 5.99 4.69 May 01-31 N/A 0.99 N/A 7.00 5.13 Jun 01-30 N/A 0.91 N/A 8.02 4.69 Jul 01-31 N/A 0.94 N/A 9.47 4.91 Aug 01-31 N/A 0.99 N/A 9.59 5.13 Sep 01-30 N/A 0.87 N/A 6.81 4.46 Oct 01-31 N/A 0.99 N/A 6.50 5.13 Nov 01-30 N/A 0.94 N/A 4.38 4.91 Dec 01-31 N/A 0.91 N/A 3.66 4.69 TOTAL N/A 11.26 N/A 74.92 58.24

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