ENERGY ANALYSIS AND AUDIT OF AEROSPACE MUSEUM
IN SACRAMENTO
A Thesis
Presented to the faculty of the Department of Mechanical Engineering
California State University, Sacramento
Submitted in partial satisfaction of the requirements for the degree of
MASTER OF SCIENCE
in
Mechanical Engineering
by
Priyanka Bhujbal
FALL 2020
© 2020
Priyanka Bhujbal
ALL RIGHTS RESERVED
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ENERGY ANALYSIS AND AUDIT OF AEROSPACE MUSEUM
IN SACRAMENTO
A Thesis
by
Priyanka Bhujbal
Approved by:
______, Committee Chair Farshid Zabihian, Ph.D.
______, Second Reader Michael Sahm, Ph.D.
______Date
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Student: Priyanka Bhujbal
I certify that this student has met the requirements for format contained in the University format manual, and this thesis is suitable for electronic submission to the library and credit is to be awarded for the thesis.
______, Graduate Coordinator ______Kenneth Sprott, Ph.D. Date
Department of Mechanical Engineering
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Abstract
of
ENERGY ANALYSIS AND AUDIT OF AEROSPACE MUSEUM
IN SACRAMENTO
by
Priyanka Bhujbal
These days sustainability in the construction sector is imperative especially in building systems to achieve environmental and economic benefits. Out of the total energy consumption in the United
States, the construction sector alone consumes 35% energy Therefore, it is the need of the hour that this sector must switch towards sustainability. An energy audit helps to establish baseline measures related to energy usage. This project aims to perform an energy audit to achieve the right balance among social, economic, and environmental factors which is the triple bottom line of the sustainability process. In this regard, the first step towards sustainability is the reduction in current energy usage. Energy audit targets areas for energy efficiency improvement. Thus, the data deduced from the energy audit will guide further in designing an action plan for the sustainable operation of the building. To achieve sustainability goals, emphasis will be on five design categories as Sustainable sites, Water efficiency, Energy and Atmosphere, Material and resources, indoor air quality. Once an energy audit is accomplished, the owner can apply for
LEED (Leadership in energy and environmental design) certification of the building. LEED certification is a globally recognized symbol of sustainability achievement. This facilitates the owner to take advantage of a growing number of state and local government incentives. Once the
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analysis of current energy usage is done to achieve maximum energy efficiency, we can use renewable energy sources (on-site or off-sites) to make building ‘Zero Energy building’.
______, Committee Chair Farshid Zabihian, Ph.D.
______Date
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ACKNOWLEDGEMENTS
I would like to express my appreciation and gratitude towards my professor Dr. Farshid Zabihian for his professional guidance, support, and assistance. He motivated me to work on energy analysis and gave me the possibility to complete this research. I would like to thank Prof. Michael
Sahm for his advice and guidance in REVIT software. I would like to thank Prof. Akihiko
Kumagai and Prof. Troy Topping for all guidance during my master’s program. Many thanks to
Tom Jones executive director of Aerospace museum for his support and patience in my research journey and for providing me with all the required data for museum building that was needed to
complete this work. I am extremely grateful to my husband for his support, sacrifices, and hard
work throughout my master’s program journey. I am also grateful to Sacramento State University
for giving me this great opportunity.
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TABLE OF CONTENTS Page
Acknowledgements ...... vii
List of Tables ...... xi
List of Figures ...... xii
Chapter
1. INTRODUCTION ...... 1
1.1. Thesis objective ...... 2
1.2. Thesis Outline ...... 2
2. BACKGROUND OF THE STUDY ...... 4
2.1 Energy Use in Museums ...... 4
2.2 Principles of energy efficient museum buildings ...... 4
2.3 Life cycle energy analysis of buildings ...... 10
2.4 Zero Energy Buildings ...... 12
3. LITERATURE REVIEW ...... 18
3.1 Building Information Modeling (BIM) ...... 18
3.2 Building Energy Modeling (BEM) ...... 19
3.3 Energy Modeling System ...... 20
3.4 Literature Review on Building Energy Simulation ...... 21
3.5 Energy Simulation Software Tools ...... 24
3.5.1 Autodesk Revit ...... 25
3.5.2 Autodesk Insight 360 ...... 26
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3.5.3 eQUEST ...... 27
3.6 Building Energy Modeling (BEM) in BIM Environment ...... 28
3.7 Performance Gap of Buildings ...... 28
4. SOLAR PHOTOVOLTAIC SYSTEMS ...... 30
4.1 Introduction ...... 30
4.2 Solar Photovoltaic Technologies ...... 30
4.2.1 Off-Grid System ...... 31
4.2.2 On-Grid System ...... 32
4.2.3 Hybrid System ...... 33
4.3 Solar PV Power Components ...... 34
5. METHODOLOGY ...... 35
5.1 Case Study ...... 35
5.2 Building Characterization ...... 36
5.3 Three Phase Methodology ...... 38
5.3.1 Phase 1: Data Collection ...... 38
5.3.2 Phase 2: Developed Building Energy Model ...... 39
5.3.3 Phase 3: Details of Building Energy Analysis in eQUEST ...... 46
5.4 Solar PV Array ...... 49
5.4.1 Existing Solar PV Array Specifications ...... 49
5.4.2 Location (Weather & Solar Radiation) ...... 51
6. RESULT & ANALYSIS ...... 54
6.1 Energy Simulation ...... 54
6.2 Solar PV System ...... 61
7. CONCLUSION ...... 65 ix
Appendix ...... 73
References ...... 75
x
LIST OF TABLES Tables Page
2.1. External Disturbances to Internal Museum Conditions and Control Actions ...... 10
2.2. Hierarchy of ZEB Renewable Energy Supply Option ...... 15
5.1. Building Energy Analysis Workflow ...... 37
5.2. Specification of the Existing and Proposed Grid-connected Solar PV Array ...... 50
5.3. The site information ...... 52
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LIST OF FIGURES Figures Page
2.1. Annual distribution of illumination.………………………………….…………………...7
2.2. Skylight with movable shading devices (Emil-Schumacher-Museum) …………………..8
4.1. The classification of PV solar cell according to the technologies ...... 31
4.2. Off-Grid system ...... 32
4.3. On-Grid system ...... 33
4.4. Hybrid system ...... 34
5.1 The Aerospace Museum of California- front facade oriented to the North ...... 36
5.2. Building Energy analysis workflow ...... 38
5.3. BIM modeling workflow chart using Revit and Insight 360 ...... 39
5.4. Virtual 3D model in Autodesk Revit 2019 ...... 40
5.5. Thermal zones layout in the Ground floor ...... 41
5.6. Thermal zones layout on the First floor ...... 42
5.7. Aerospace Museum Location ...... 43
5.8. Aerospace Museum Location weather ...... 43
5.9. Building energy analytical model ...... 44
5.10. 3D building energy view and export options in Autodesk Insight 360 ...... 45
5.11. Virtual 3D building energy model in eQUEST ...... 46
5.12. Utility grid rate ...... 47
5.13. Water-Side HVAC system loop in eQuest ...... 48
5.14 . The existing location of solar PV array on the building’s rooftop ...... 49
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5.15. Monthly average temperature in Sacramento ...... 52
5.16. Monthly average of wind speed in Sacramento ...... 53
6.1. Annual Actual electrical consumption in 2018 …………………………………………54
6.2. Actual versus simulated electrical consumption in eQuest ...... 55
6.3. Insight 360 estimated monthly energy cost...... 55
6.4. Insight 360 estimated monthly electricity use in kWh ...... 56
6.5. Insight 360 estimated monthly fuel cost ...... 57
6.6. Insight 360 estimated monthly energy use ...... 58
6.7. Insight 360 estimated monthly energy cost ...... 58
6.8. Insight 360 estimated monthly fuel use ...... 59
6.9. Autodesk Green Building Studio energy simulation ...... 59
6.10. HVAC System Types options ...... 60
6.11. Existing PV system simulated in HelioScope ...... 61
6.12. Simulated annual electrical energy production of the current PV system ...... 62
6.13. Figure East-West Racking PV modules arrangement ...... 63
6.14. East-west Racking arrangement Annual electrical energy production ...... 64
6.15. Existing PV Inverter type ...... 68
6.16. Existing PV module type ...... 69
6.17. Existing PV HelioScope Single Line Diagram ...... 69
6.18. Existing PV System Module specification ...... 70
6.19. Existing PV system Inverter Specification...... 70
6.20. Simulated current PV system monthly Electrical Energy Production...... 71 xiii
6.21. Current system Energy Losses ...... 71
6.22. Pie Chart for Energy Use in Museum …...……………………………………...72
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Chapter 1
INTRODUCTION
The building sector currently contributes significantly to the total energy consumption. This makes it critical to enforce energy efficiency measures in buildings. Globally, energy efficiency has become a critical factor in buildings with the focus of optimizing their performance by reducing energy consumption per the International Energy Agency (IEA)[1]. New technologies have revolutionized the process of building designs and the way energy analysis is being carried.
It has become an important aspect of buildings to come up with strategies to reduce carbon dioxide emissions, optimize building profitability, and to make it more environmentally friendly.
Engineers have been working around the clock to come up with new and more accurate building energy modeling strategies that would give an insight on how to minimize building energy consumptions and to make it sustainable [2].
Building Energy Modeling (BEM) is the process of creating intelligent 3D architectural and energy models using computer software and predicting energy consumption as well as analyzing ways to optimize energy consumption. By comparing the predicted energy consumption from the models with the actual energy consumption, the building owner can get useful information such as malfunctioning or can locate low efficient equipment [3]. The current study is to establish and analyze the annual energy consumption of the Aerospace Museum of California as well as identifying possible ways for energy consumption reduction. The model of the museum was developed using Autodesk Revit 2019 and for energy analysis, the energy model was sent to cloud-based Autodesk Insight 360 to produce an analytical model. Then exporting the 3D model
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and detailing it in eQUEST 3.65 software, enabled the prediction base model as well as getting a simulated energy consumption which was compared to actual energy utility bills.
1.1. Thesis Objective The main objectives of this report are:
• To create a 3D model of aerospace museum building in Autodesk Revit 2019 and generate
its energy analytical model, simulate the model in the cloud-based insight 360, and carry out
a parametric analysis.
• To import the generated energy model to eQuest and carry out energy analysis.
• Compare the predicted simulated energy consumption versus the actual consumption of the
building.
• To identify potential energy saving in the building by analyzing how specific control variable
inputs impact energy consumption.
1.2. Thesis Outline
Below is the outline of the study
Chapter 1: Precise introduction to building energy consumption and objectives of the thesis
Chapter 2: Brief background on energy consumption in museums
Chapter 3: Literature overview of building energy, simulation tools, building performance gap and building energy performance,
Chapter 4: A literature review for solar photovoltaic systems
Chapter 5:
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• Study case description
• The workflow steps of building an energy model for the case study building.
• Detailing of the museum energy model in eQUEST for energy analysis.
• Existing solar PV system
Chapter 6: Validation of the results carried out along the case study obtained from:
• The building energy simulations within eQUEST software.
• Validation of the PV system on HelioScope
Chapter 7: Study conclusion based on the results
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Chapter 2
BACKGROUND
2.1. Energy use in Museums
Museums are usually a special kind of buildings with well-defined sound conditions of exhibits and comfortable to visitors. The temperature and relative humidity also have to keep to a certain value with minimum allowable tolerance despite fluctuations in the external environment. Energy consumption also needs to be kept to extremely low levels for sustainability. It is possible to achieve high-quality museums with low energy consumption through the utilization of energy- efficient measures as well as incorporating renewable energy technologies [4]. Examples of an outstanding piece of architecture in the museum industry include Emil- Schumacher-Museum,
Hagen (architect M. Lindemann), Cologne (architect P. Zumthor). These buildings are integrated with advanced technologies like low air changes ventilation, geothermal heating and cooling, thermal active room surfaces, and controlled daylighting [4].
2.2 Principles of energy efficient museum buildings
Light control
Lighting in museums is aimed at achieving three objectives i.e. illuminations for the rooms, conservation of objects, and visibility of objects. This can be achieved by either artificial lighting or daylight or a combination of both [5]
For good visibility, the objects need to have the right illumination and contrast without shadows and glare. The type of objects on display in a museum has a significant effect on the choice of lighting as different objects have a different light requirement for accurate color rendering.
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However, the right balance has to be struck between good visibility and conservation of objects.
This is because as brightness is increased for better illumination, objects tend to absorb light energy which can damage them. Short-wavelength light radiation is more destructive compared to long-wavelength radiation. This means that the blue light or UV light has a higher damage factor than red or green. This means that dark surfaces are more negatively impacted by light than light ones. Also, the nature of material plays a role when it comes to the impact of light for example metal is more resistant to light damage compared to a piece of paper. Finally, the duration of exposure to light affects the aging of materials. More light exposure quickens aging. Due to the discussed factors, maximum values of energic exposure to light have been defined. 50 lux is the maximum value for sensitive objects such as fabric [5]. It’s also defined as the lowest value for good visibility. 150 lux is the defined values for paintings on canvas. The shortcoming of this specification is that it does not factor the spectral component of the light as well as the time of illumination. This has forced museums to come up with their specification to conserve objects
• Definition of varying maximum illumination depending on the light source
• Limitation of the maximum duration of the exhibition
• Absolute protection against UV and blacking-out before/after
visiting hours
• Individual classification of artwork in light sensitivity
categories
The above regulations point out the need for light control in the museum, in regard to both artificial light and daylight.
Daylight is preferred in many museums as it has a high color rendering index, continuous spectral distribution, natural lighting conditions, and energy efficiency. However, to realize the benefits of daylighting energy efficiency, glazing through which the radiation passes need to have selective
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wavelength control to cover for both winter and summer. this is because during winter thermal gain is desirable while during the summer it increases cooling loads This is usually a part of architectural design although it is very recommended to consult a lighting expert. Skylights are more effective than vertical windows for daylighting, however glazing need to as described above to cater for both summer and winter However, care must be taken as direct sunlight can cause glare and heating of the rooms. Solar heat gains need to be minimized during the summer period when cooling of the spaces is required. This is done by having movable or fixed shading devices.
To avoid glare when using solar control glass needs to have a light diffuser or additional shading.
Movable shading devices such as lamellas give the flexibility of accurate daylight control. This helps to some extent to thermal control as well. The figure below shows the annual illumination of an exhibition room with a skylight and fixed shading device, this is designed to ensure the illumination does not exceed 400 lux under the most extreme maximum external illumination.
When the daylighting condition is very poor especially during winter or cloudy weather, artificial light is used to boost the light levels.
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Figure 2. 1: Annual distribution of illumination
Legend Dark green – Inside Illumination Light Blue – Outside Illumination
Annual distribution of horizontal outside (light blue) and inside illumination
(dark green calculated for a room with skylight and fixed shading device for all solar positions.
A movable shading device with variable light transmission, as shown in Fig. 2.2 can offer
controlled daylighting for a significant longer time of the year. The figure shows external lighting
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control with movable solar glass with lamellas to control glare, light-diffusing ceiling, conditioned air gap, and well-insulated glazing.
Figure 2. 2: Skylight with movable shading devices (Emil-Schumacher-Museum in Hagen)
Skylight with movable shading devices (Emil-Schumacher-Museum in Hagen)
Thermal control - Museums need to have a narrow band of relative humidity and room temperature. This is maintained by air conditioning, dehumidification, cooling, varying air
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changes rates, and humidification of air in the museums. These ideal conditions are very difficult to achieve especially with the varying number of people coming and going out of the museums and due to changes in the external climate factors. People and occupancy also introduce thermal sensible and latent loads and moisture that may need to be accounted for, depending on the level of occupancy] The large volumes of air that need to be heated or cooled during peak loads and transferred make it almost impossible to prevent negative effects of the draft. A backup system needs to be installed for redundancy.
The energy of air conditioning systems in museums can be improved by passive methods of thermal insulation, the orientation of windows, geometry, and thermal capacity of room surfaces.
The table below illustrates some of the external factors which have an impact on the internal conditions of a building and measures taken to mitigate their effects
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Disturbances and means of climate control for museum buildings.
Disturbances of Effect Means of control Means of control
climate factor passive Active
Ambient temperature Heat transmittance Thermal Capacity Surface Temperature
Control
Solar radiation Heat Gain Solar Control Surface Temperature
Control
Wind Infiltration Airtight Joints Air Locks
Lighting Heat Gain Ventilation + Surface
Temperature Control
Visitors Humidity and Heat Sorption Ventilation
Gain
Table 2. 1: External Disturbances to internal museum conditions and control actions [5]
The basic principles for stable climate control are the combination of heated/chilled floors, ceiling, and walls.
2.3 Life cycle energy analysis of buildings
Energy use is a tool that is widely used to assess the impact of buildings on the environment.
Recent researches have revealed the need for both the operational and energy attribute to building throughout their lifetime. The process of assessing lifetime building energy is referred to as lifecycle energy analysis. This is a very crucial process as it guides designers and building operators to comply with codes, improve energy efficiency, and minimize emissions to the environment.
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It is a fact that while buildings are in operation, they contribute to environmental degradation especially in situations where fossils fuels are the primary sources of energy (England and Casler,
1995) [6]. Coal-fired plants emit carbon dioxide which contributes to global warming. Other emissions such as nitrous oxide and Sulphur dioxide cause degradation to air, water, and soil.
The process of assessing the environmental impacts of products or buildings throughout their lifetime is referred to as Life-Cycle Assessment (LCA). Life-Cycle Energy Analysis (LCEA) however focuses only on the impact of energy use on the environment. Subsequently, it is possible to have a broader analysis of energy-related attributes to buildings. The main objective of LCEA is however not to override the need for LCA but to come up with a more detailed specific assessment that will facilitate decision-making on energy efficiency. Comparing the operational energy of a building to its embodied energy, it’s possible to point out the life cycle energy efficiency and savings strategies. LCEA concepts are also used to illustrate the life cycle benefits of the strategies taken to optimize the embodied energy or operational energy of a building. A good example is the thermal insulation of buildings. This will have an embodied energy cost to execute but results in overall saving in operational energy over the lifetime of the building. LCEA is a key tool in estimating net energy savings in buildings as well as the payback
time for embodied energy costs.
To summarize, the life cycle energy of a building consists of the initial embodied energy, the
recurrent embodied energy. Recurrent embodied energy results from embodied energy added to buildings during maintenance through goods and services. To model recurrent embodied energy,
typical replacement rates are assumed e.g. paint and the operational energy. The best time to use
LCEA for decision making is during the design development stage for new construction [This
ensures that there is net reduced energy use over the projected life of the building
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2.4 Zero Energy Buildings
A net-zero building (ZEB) is a commercial or residential building that has very low energy needs achieved by efficiency gains to the extent that all the energy needed can be supplied using renewable technologies. There is a lot of excitement associated with the term “zero energy” yet it’s still one of the most misunderstood concepts with a lack of common definition.
The definition of zero energy goal affects design decisions to achieve this goal. It also defines whether the goal can be fully achieved. The zero-energy building definition can either be focused on the energy demand side or energy supply strategies. Four key terms need to be completely understood to grasp the concept of ZEB i.e. net-zero energy costs, net-zero site energy, net-zero source, and net-zero energy emissions.
The building has a huge impact on the environment and energy use. Commercial and residential buildings account for almost 40% of primary energy use and 70% of electricity in the United
States (EIA 2005) [7]. There is an increasing trend in energy consumption as new buildings being constructed at a faster rate than the ones being superannuated. Between 1980 and 2000, the electricity consumption in the commercial buildings had doubled and it’s expected to increase by another 50% by 2025(EIA 2005. The energy consumption is not expected to drop anytime soon unless building designs incorporate energy-efficient designs to match the growing energy demands in new buildings. The US Department of Energy (DOE) is making significant investments and supports energy efficiency and alternative energy technologies to create technology and pass out a knowledge base for creating cost-effective zero-energy commercial buildings (ZEB) by 2025.
Zero-energy building: boundary definitions and energy flows
The key idea of a ZEB building is a building is having a high energy efficient building whose energy needs can be met by locally available, low-cost renewable energy sources. When the
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highest standards of strictness are applied to the concept of ZEB, all energy requirements of a building need to be realized by renewable energy or even out the energy requirements
The below assumptions and concepts are used in understanding ZEB concepts
• Allow grid connection to make up for necessary energy balances
In ZEB buildings when the energy requirements cannot be met by on-site energy generation, the
traditional source of energy such as electric and natural gas are used to make up for the energy
difference. However, when the on-site energy generation is more than the building’s load
requirements, excess energy is then exported to the utility grid. By allowing connection to the
grid, excess energy produced is disposed of and can be later compensated from the same. This is because it is very difficult to store excess energy generated Off-grid buildings usually rely on
other sources of energy like propane for space heating, water heating, cooking, and backup
generators. When buildings are off-grid, they cannot feed their excess energy to the grid.
Conversely, they cannot make up for energy shortages by supply from the grid hence energy production by renewable energy need to be oversized to cover the worst conditions.
The only assumption in this concept of grid connection is that it is assumed that the grid will
require the excess energy from the on-site generation which might not always be the case. When
this happens on-site energy, storage needs to be considered. The other technologies like parking
lot-based PV or wind systems are also available but with limited applications
• Prioritizing supply-side technologies.
there are several renewable technologies on the supply-side for ZEBs. These include solar water
heater, PV, hydroelectric, wind, and biofuels. When compared to conventional energy sources, all
these renewable energy technologies are more preferred. However, this is not to say that they are
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all equally good in performance. This creates the need to have a priority ranking preference based on the below principles:
- Reduce overall environmental impact by having energy-efficient designs and minimizing
conversion losses
- Looking at which renewable energy technology will last through the life of the building
- Which technologies are widely available and can be easily replicated in the future?
The hierarchy below is based on the ease of availability of the technologies within the building
footprint and the site conditions. Solar water heaters and Rooftop PV are the most applied
technologies applied in ZEBs. Renewable energy sources not within the boundary of the building
site can also be used to achieve a ZEB building. Although this approach may result in net-zero
energy consumption, it is very different from the one in which all the energy is generated on-site
and hence should be classified as such. An “off-site ZEB” is used to describe such buildings with
renewable energy sources outside building boundaries.
The table below shows the Hierarchy of ZEB Renewable Energy Supply Option [8]
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Table 2. 2: Hierarchy of ZEB Renewable Energy Supply Option
Ideal ZEB definition encourages energy usage efficiency and the use of available renewable energy sources on site. There are no incentives to reduce buildings load for off-site ZEB that buys energy from the renewable source located outside the site
Building boundaries is a very important concept in ZEB when defining an on-site generation. The boundary sometimes can be larger than the footprint of the building itself. This raises the need to
answer the question about which area can be considered to be an onsite generation. However, the
only area that a building can be guaranteed will be available for use through the lifetime of the building is the one within its footprint. Many states in the US have given solar access ordinances.
This gives the building owners the right to use the area available for solar energy production as a property right. A good example is the city of Boulder, Colorado where the ordinances guarantee
homeowners access to sunlight. This means the owners are protected from the number of
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shadows that can be cast on their buildings by new buildings being developed. This thus implies the potential of the solar system is not compromised throughout the life of the building. Roof PV generation offers more long-time availability compared to using a neighboring field to generate electricity, as fields tend to get developed in the future.
Wind resources for ZEB are not commonly utilized due to their shortcomings such as noise, wind patterns, and the fact that they require a field for installation as they cannot be installed on roofs.
In some cases, adjacent areas and parking spaces are used to produce energy but this depends on site conditions and may not be applicable in some sites. Also, as it is in the case with PV systems, there is no guarantee that there will be no future developments in the selected areas.
Imported renewable energy sources such as ethanol, wood pellets, and biodiesel although invaluable do not count as on-site renewable energy sources.
Purchasing “green credits” or renewable energy sources such as PV utility or wind power from the grid is also an option for supply-side renewable energy sources. However, these require infrastructure to reach the building location which is not always available. Despite an “off-site
ZEB” having little relation to the building design, it is still an accepted ZEB concept
Definitions of Zero-Energy Buildings
There are several definitions of zero energy buildings depending on the metric and defined building boundaries. The definitions are acceptable depending on the project owner, the values of
the design team, and project goals. For example, the owners of buildings are usually more
concerned about energy costs. Engineers and architects will be more interested in site energy use
for compliance with energy codes. Organizations like DOE are usually worried about national
energy numbers, and their interest is in energy sources. Finally, those concerned with the impacts
of buildings on environments are focused on reducing emissions from the power plants and fossil
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fuels. [Based on the above factors these definitions are widely used: net-zero source energy, net- zero site energy, net-zero energy emissions, and net-zero energy cost
• Net Zero Site Energy: A site ZEB can meet all its energy needs by on-site energy production through a period of one year
• Net Zero Source Energy: A source ZEB produces at least as much energy as it uses in a year, when accounted for at the source.
• Net Zero Energy Costs: In a cost ZEB, the amount of money the building owner pays to the utility to offset demand is equal to the amount of money he receives from exporting excess energy to the utility for a given period usually one year
• Net Zero Energy Emissions: A net-zero emissions building produces at least as much emissions-free renewable energy as it uses from emissions-producing energy sources.
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Chapter 3
LITERATURE REVIEW
3.1. Building Information Modeling (BIM)
There is no standard definition of Building Information Modeling (BIM). To define BIM several aspects of BIM are considered hence resulting in various definitions that are all acceptable. The aspects include the type of information stored, who uses the information when the information is used and the function it serves. The BIM concept has been very beneficial in the engineering and architectural fields. BIM can be broadly defined as a set of related processes and technologies that are used to create a methodology for managing critical construction design and data flow from different project team members in digital format. This process involves detailing the building’s geographic information, geometry spatial relationships, and properties of the building.
This information can then be used to validate the whole life cycle of the building. From construction to operation [9]. Eastman Kymmel described BIM as a modeling technology that associates a set of processes to produce, communicate, and analyze building models. These models are characterized by building components, constant and non-redundant data, and coordinated data [10]. According to Azhar, [11] BIM is the process that focuses on the development and use of a virtual model to simulate the design, planning, construction, and operation of buildings. BIM allows a virtual and early version of the whole proposal. Through modeling software, it is possible to plan and verify each part step by step through a 3D model and other specific features that make BIM a fundamental choice for any professional [11].
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3.2. Building Energy Modeling (BEM)
Building energy modeling is a multipurpose tool that is used in new buildings, major renovations, existing buildings, green certification, code compliance, utility incentives, real-time building control, and qualification for tax credits. BEM is also used in the analysis to advise policy decisions and come up with energy efficiency codes. BEM is a software that is used to simulate building energy use. Typical inputs to BEM software include building descriptions regarding construction material, geometry, HVAC, water heating, renewable energy technologies in place, and geometry. Other information about the building such as operational schedules, lighting schedules, thermostat settings is also part of the input to BEM software [12]. The BEM software will combine all these inputs with information about the weather of the building locality and calculate thermal loads, how the system responds to these loads and the resultant energy usage.
BEM can answer questions that other means find it difficult to answer. Due to this factor is it is widely applied in the following cases
• Architectural Design. Architects are now adopting the use of BEM to come up with
energy-efficient designs. When applied at these early stages it becomes, even more, cost-
effective than having to implement it at later stages of building a life.
• HVAC design and operation. Due to the complexity of modern HVAC systems,
mechanical engineers can use BEM to come up u with efficient systems to meet
buildings' thermal loads. Testing and control strategies are also possible by using BEM.
• Building performance rating. BEM is an important tool in assessing the inherent building
performance. This rating is based on things like financial incentives, code compliance,
and green certification
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3.3. Energy Modeling System
The key objective of performing energy simulations is to ensure buildings operate at optimum performance, efficiency is increased, and the energy consumption is minimized. The manual process of assessing energy consumption options in the building is a very time consuming and
costly exercise. This has forced engineers and architects to adopt a software-based simulation. By
defining building location, building core material, building location, climate characteristics, and
operation schedule, through simulation the user of these tools can be able to see the energy performance of the alternative design and hence choose the most efficient design with the least
operating cost and environmental impact [13]
To design an energy-efficient building or analyze an existing building for retrofitting, the energy
demand should be evaluated to recommend measures to reduce energy consumption. Assessment
includes analyzing the business cycle (i.e. prebuilding phase, building phase, and post building phase.) Energy efficiency is affected by changes in building use and systems within the building
Energy simulation is based on transient thermodynamics, heat transfer, fluid mechanics equations/principles, and assumptions [14]. Energy exchange is dynamic and transient but most codes use a quasi-steady approach rather than a full transient simulation. The resolution in time steps will determine the specific approach. Hourly simulation steps have much less dynamic influence than finer time steps such as 15 minutes, 5 minutes, or 1-minute intervals. The tradeoff is the time the computation requires. A full up transient analysis would also require a 2D or 3D spatial model including conduction through building elements. This can be done in isolated special-purpose tools such as finite element modeling platforms but is generally more of a research tool than a design tool due to the complexity of the thermal processes in a building, energy simulation programs rely on specific input requirements to approximate their predictions
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using mathematical calculations and assumptions [15]. This may lead to inaccurate results if certain assumptions are not met or input requirements are not met in the simulation. To obtain accurate results, advanced simulation tools which require an increased scope, complexity, and detailed input requirement and hence demand expertise and experience. This difficulty and complexity of simulation tools make it difficult to apply simulation to the building design. Many professionals and architects find it difficult to use these energy simulation tools effectively since they are unfamiliar with their properties and limitations [16]. Another factor is the cost of the analysis during design stages and due to the time and labor costs of the professionals needed.
These practices are more common on high-end designs for owner-occupied facilities and where some type of certification is sought such as LEED than in lower-end commercial design. The portion of the building market that uses these methods may be the top 5% to 20%
3.4. Literature Review on Building Energy Simulation
Several scholars have upheld for years, that energy simulation is a powerful and important analytical method for the study and evaluation of the energy consumption of buildings. Mehta et al. [17] evaluated the energy performance of a LEED building in Toronto. In this study, eQUEST was used to relate the baseline model and actual utility bill data using actual weather data for two years. The result showed that the eQUEST prediction was within 0.72% of the actual annual consumption. Analyzing the natural gas consumption with accuracy was difficult due to the absence of gas metering data on an hourly basis versus electrical sub-metering intervals.
Fokaides et al. [18] researched 10 residences in Cyprus. This energy performance research was assessed in the summer climate. The study used the SBEM online software [19] for commercial energy assessment, which made a comparison between the measured energy data versus the predicted energy consumption. The results indicated that the predicted energy consumption was
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three times higher than the actual energy consumption. Chu [3] evaluated the performance gaps in the design stage for three high-performance LEED-certified buildings in British Columbia. He found that one of the buildings in the case study was performing better while the other two buildings were performing poorly in comparison to the predicted results. Shailza [20] used a baseline model in Design Builder software for storied apartments in India. A manual calibration method was used to calibrate the baseline models based on IPMVP, 2010 [21] and ASHRAE guideline 14, 2002 [22]. The operation schedules, including occupancy and lighting, were used to calibrate the baseline model. The result showed that the building energy consumption was within a tolerable error (±15%) in line with ASHRAE guidelines 14-2014 [22].
Song et. al [23] used eQUEST software to build a university library model in North China and evaluate the yearly electrical consumption for the building. The baseline model used actual utility data and weather parameters. They also used control variables such as occupancy, indoor design temperature, and lighting power density to determine the effect of these factors on building energy consumption. They found that 49% of total electrical consumption was consumed by the
HVAC system, 35% by energy (plug loads), and 15% by lighting. Baig and Fung [24] developed a library building model in Ontario, Canada. They calibrated utility bills data between 2012 and
2014 to predict an accurate simulation. They used eQUEST software to develop the baseline model of the building. The natural gas-fired absorption heat pump (GAHP) was a substitute type to conventional heating equipment for the fuel cost savings and potential energy conservation against electricity cost. The results showed that the baseline predicted annual consumption for electricity was 1.5% less than the actual range, and 7% of the average difference for the natural gas versus the actual range. The heat pump is an excellent alternative to conventional heating equipment. Khan and Ghadge [25] used a hotel building with a gross area of 150 m 2 in India for sustainability analysis. In this case, Revit was used to develop a 3D model. To retain the data
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interoperability between Insight 360 and Revit, the model was exported in a gbXML file to use for a wind and sun path analysis, and the heating and cooling load studies. From the sun path analysis, the user could easily optimize the design of the building with accurate locations of the windows and doors to avoid unnecessary heating in the summer and decide the optimum and efficient location of PV panels. Abanda [26] created a small-scale building model in BIM tools using green building studio (GBS) and Revit software to analyze the effects of building orientation on cost and annual energy consumption. The results concluded that the annual energy cost saving difference was £878 all through 30 years of the life cycle of the building between the best and the worst of the building orientation, +180°, and +45° respectively. Elzarka [27] presented a retrofit university building model in the U.S., which had been built originally in
1960, and he used eQuest software to develop the building energy model. The actual building schedule was used for lighting, equipment, and occupancy to analyze the building energy performance by comparing the total annual energy consumption against the actual energy consumption. He discovered that there was an inconsistency on a monthly base for annual electrical consumption between the predicted result (1,179,634 kWh) and the actual result
(1,128,021 kWh) because of the service operations, building construction characteristics, and occupants’ activities. Shoubi [28] developed a double story house in Malaysia using BIM tools.
He identified the model elements and created the zones and environments in Revit 2012, then exported the file in gbXML to Autodesk Ecotec software for solar energy analysis. He proposed the alternative sustainable design parameters and the alternative construction materials to use in the case study building and compared to the baseline model simulation results to analyze their effects on annual energy consumption. The study found that the predicted annual energy consumption of the baseline model was 17,600 kWh and it could be minimized to 12,580 kWh by using alternative sustainable design parameters. Fasiuddin and Budaiwi [29][ used a
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commercial building that was modeled for Saudi Arabia, Dhahran weather. Visual-DOE program was used to research the design and operational parameters of HVAC systems affecting energy used. They suggested using an enthalpy economizer with a Variable Air Volume (VAV) system which resulted in the highest energy saving. Research results indicate that energy savings of up to 30% could be gained while maintaining a tolerable level of thermal comfort when HVAC systems were properly chosen and operated. Ahmed [30] adopted an existing hospital in
Alexandria, Egypt as a case study. They used a building model based on an efficient energy- saving technique using HAP software. The new system showed a huge potential annual electricity savings of 41% over the existing HVAC system.
3.5. Energy Simulation Software Tools
In the last decades, building energy simulations have been used to provide a detailed and accurate evaluation of the building’s energy consumption [31]. Energy simulation tools are used to predict building energy consumption as well as the thermal comfort of the building occupants. Presently, there are over 200 building energy simulation tools listed in the Building Energy Software Tools website maintained by the US Department of Energy [23] [mks comment, most likely reference
32, verify]. These tools provide for the simulation of building energy behavior and allow the analysis of several of the following aspects: thermal gains and losses, renewable energy systems,
HVAC systems, internal temperatures, and emissions to the environment. Generally, these tools create consolidated reports and grant the export of data for in-depth analysis with other tools
[32]. These tools allow the analysis of different scenarios, which represent a proposed or existing building design. They can evaluate the energy impacts of different concepts of architectural projects and allow designers to better explore the viability of various projects and various design strategies. Additionally, these tools are helpful to sustainability consultants and energy auditors
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to identify energy cost-effective strategies to enhance the building’s efficiency [33]. Several factors can decrease the building’s energy consumption and potential energy savings. HVAC system, occupancy behavior, and lighting are the main factors in potential energy conservation measures (ECMs) with a great effect on energy consumption [2]. Other important factors are the components of the building envelope, such as windows, roofs, exterior walls, among others. They are significant factors in determining the internal energy that will be required [13]. It is important to have weather information ready in the hourly weather data, which are used to represent external conditions (conditions outside the building), such as air temperature, wind conditions, solar radiation, and relative humidity [11].
3.5.1. Autodesk Revit
Autodesk Revit is a building information modeling software for architects, landscape architects, structural engineers, mechanical, electrical, and plumbing (MEP) engineers, designers, and contractors.
Autodesk Revit was created by the Revit Technology Corporation in 1997 and was purchased by Autodesk in 2002. Revit is Autodesk's platform for building information models
(BIM). The Revit platform is a complete and specific building design software for the discipline and a documentation system for all phases of design and construction. From the basic conceptual studies to the development of more detailed building drawings and schedules, Revit-based applications help provide an immediate competitive advantage, deliver better coordination and quality in project phases and disciplines, and can contribute to greater profitability for architects and designers [34]. Autodesk Revit is the current market leader and best-known tool for BIM architectural design. Revit software has been increasingly used in architectural design due to the advantages brought about by the incorporation of BIM technology, which combines all the
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information representing a real building into a single virtual model. Revit mainly consists of three interface categories (Architecture, MEP, and Structure), enabling the development of integrated projects. Revit operating system is compatible with Windows and it features the gbXML interface, a conceptual design tool that can import models [20]. Within the last few years, there have been several developments in terms of energy analysis in the Autodesk Revit software.
Until 2015, Autodesk sold the specific Ecotec Energy Analysis Software, which is currently integrated as a tool in Revit and allows direct connection to web-based Green Building Studio
(GBS) [35]. The latest development for Revit has been the launch of Insight 360 (cloud-based), instead of the GBS interface. Insight 360 is a plug-in for Revit that allows studies of heating and cooling loads, solar light, and radiation studies to be detailed. This platform allows visualizing and interacting with the results obtained by visualizing the effects in diagrams and performance diagrams directly in the three-dimensional model. This plug-in, like the building energy analysis, is based on calculations in the cloud, so we must be logged in with an Autodesk account to carry out the analysis [36].
3.5.2. Autodesk Insight 360
Autodesk Insight 360 is an energy model and simulation tool important in the conceptual design for thermal comfort, energy efficiency, photovoltaics, and lighting based on the Energy Plus calculation engine. Data interoperability between Insight 360 and Autodesk Revit is guaranteed by using IFC cloud-based program files. This tool is both visual and flexible and does not require the building to be strictly defined for energy analysis to be performed. For instance, one can perform energy analysis by just defining the building shape with mass, orientation, and number of floors in Revit
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Insight is driven by the EnergyPlus engine and can also export EnergyPlus .idf files as well as
DOE2 .inp files. This development was supported by DOE over the last few years and contributed to the shift from GBS to Insight By exporting the 3D building model through the
Revit into Insight 360 creates an energy model in Insight 360. Insight 360 notifies the user via email once the model is received from Revit and once the analysis has been completed [23]
3.5.3. eQUEST
eQUEST (Quick Energy Simulation Tool) is extensively used in building energy performance analysis developed by U.S. DOE and then licensed and maintained by James J. Hirsch. It is available as a free download at www.doe2.com/eQuest/ [37]. eQUEST being free software makes it a good choice for use in this study. It is also very easy to use and has been in use for a very long and has since undergone several refinements to make it the most preferred tool in the commercial modeling community. eQuest has a user-friendly interface that uses the DOE-2.2 engine for energy analysis
Through interactive graphs, files, dynamic patterns, parametric analysis, fast deployment, and parametric analysis, it can perform analysis at different stages of the project. The software provides three levels of inputs namely; Design Development Wizard, Detailed interface, and
Schematic Design Wizard at which the user can provide project input data. The software gives its output in the form of summary graphs for single run results, comparative results for multiple separate building simulations runs, and parametric tabular results. Hourly simulations also form part of output results. The software also uses weather data files to calculate the energy consumption of a building for a whole year period [38]
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3.6. Building Energy Modeling (BEM) in BIM Environment
Several studies have been done with BIM and with interconnection to the BEM environment, making it a critical tool to analyze the operation and reliability of energy simulations. Building
Energy Modeling is a design tool that enables us to predict, through thermodynamic simulations, the energy consumption of buildings. It uses strategies that help projects achieve the desired savings or even surpass the anticipated levels [13]. This tool enables us to explore different options and situations in terms of the climatic environment of buildings. It can assist in determining the components of the envelope, the design, the orientation, and the systems that operate the building that maximize the opportunities to maximize user comfort, save energy, and achieve a high-performance building [39]. According to Reeves [40], an energy model created in the BIM offers various benefits since the information already contained in it enables to automate the process. Thus, the energy model created in this environment makes the exercise of energy performance simulations easier during project development, operation, construction, and maintenance.
3.7. Performance Gap of Buildings
The performance of a building when it is completed is different from the anticipated performance when it was being designed. This shows that there exists a gap between the energy behavior of the actual and simulated buildings [41]. However, this difference between the simulated and the measured energy consumption of actual buildings can be adjusted by calibrating the model [42].
The ASHRAE Guideline 14-2002 for the Measurement of Energy Saving and Demand includes calibrated simulations as an evaluation method [22]. It is difficult to develop validated models in real conditions in the field of energy simulation of buildings [43]. Validation of the simulated baseline model against the ideal situation is considered. This illustrates the energy gap that exists
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between actual energy use in the building and simulated energy use [44]. Study findings such as from PROBE (Post Occupancy Review of Buildings and their Engineering) which evaluated
23 buildings previously featured as ‘exemplar designs’ in the Building Services Journal between
1995 and 2002, showed that actual energy consumption in buildings is often twice as much as anticipated. For this reason, the building model must be defined by adjusting the input values to match the current energy demand. This simulation is called the calibrated simulation [45]. The
Efficiency Valuation Organization (EVO) was developed and published by the International
Performance Measurement and Verification Protocol (IPMVP), the leading international standard in measurement and verification protocols (M&V). It creates a framework to analyze energy consumption savings and offers a guide to developing reliable measurement and verification plans. There are different options (A, B, C, and D) of carrying out measurement and verification.
The selected option is dependent on conditions of the project, available budget, how the M & V plan was designed, and existing studies. Option D presents the savings realized by simulating energy of the entire building modeling in the base period while taking into consideration energy conservation measures (ECMs) like HVAC system and lighting [3]
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Chapter 4
SOLAR PHOTOVOLTAIC SYSTEMS
4.1. Introduction
The existing solar photovoltaic (PV) in the Aerospace museum was also evaluated using PVsyst
software while carrying out the annual energy consumption of the building.
4.2. Solar Photovoltaic Technologies
Solar photovoltaic technology is used to generate inexhaustible electricity while having no
negative impact on the environment. It a sustainable source of energy. However, due to
unpredictable weather changes, storage facilities are required to offset demand when the production is low (46). PV cells are manufactured from a variety of different materials. The
commonly used material in solar panels construction is silicon. Silicon has semiconducting properties and is one of the most abundant chemical elements on the earth.
We have three types of cell technology which are market leaders in the world that are polycrystalline silicon, monocrystalline silicon, and thin film. However, we have more efficient
PV technologies such as multi-junction cells and gallium arsenide, but they are not very common
due to their high cost. They are however suitable for use in space applications and concentrated photovoltaic systems
The figure below illustrates different PV cell technologies [47], all the PV technology converts
solar radiation into electric power. The conversion is performed by photovoltaic cells which in
most cases are made from silicon [49]. The amount of electrical energy produced is directly
influenced by clouds. The fewer the clouds the higher the energy production.
Solar energy is the most promising source of energy and countries are offering incentives to
encourage its use due to its environmental friendliness
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Figure 4. 1: The classification of PV solar cell according to the technologies [47]
4.2.1. Off-Grid System
These systems are also referred to as standalone. They are independent of grid utility. They are used in areas without a grid connection. All the energy required is produced on-site. Excess energy is then stored in battery banks and is used to offset demand during a time when energy production is low. Figure 4.2 below shows an off-grid system configuration
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Figure 4. 2: Off-Grid system [48]
4.2.2. On-Grid System
These systems are also known as grid-tied. They are usually connected to the electricity grid.
Solar energy is given priority. When the energy produced from the PV cell cannot meet the demand, the excess is supplied from the grid. Conversely, when solar energy production exceeds demand, the excess is supplied to the grid. Figure 4.3 shows a Grid-Tied system configuration
.
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Figure 4. 3: On-Grid system [48]
4.2.3. Hybrid System
These are systems are the Grid-tied system with an additional battery backup bank. These systems operate similarly to the UPS system such that when the mains are unavailable the batteries will supply electricity through an inverter system. Figure 4-5 shows a Grid-Tied system configuration
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Figure 4. 4: Hybrid system [48]
4.3. Solar PV Power Components
As an initial step for solar electricity installation, these components are needed [49]:
• Solar panels,
• Inverter system
• Batteries.
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Chapter 5
METHODOLOGY
Three software tools have been used in this study
1. Autodesk Revit 2019
2. Cloud-based Insight 360
3. eQuest software
The 3D model from Revit is then exported to eQuest software for analysis.
5.1. Case Study
The building under study is the aerospace museum of California. It’s a private, non-profit
museum located in North Highlands, California. The museum has incorporated technologies such
as roof skylight for daylighting and thermal performance, efficient HVAC systems, and roof solar
PV systems. The outdoor units for the HVAC system are located on the roof.
Factors that made this building an ideal study case include its design complexity and its
sustainable features. The museum’s anterior façade is oriented to the north. The building is well- positioned for solar energy generation with no possible shading from the neighboring buildings.
All the features can be easily noticed from the figure 5.1 below
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Figure 5. 1: The Aerospace Museum of California- front facade oriented to the North
5.2. Building Characterization
Energy simulations can be done on existing or new buildings. The reliability of the results depends on the accuracy of the input of the building parameters. While developing the model on
Revit it important to ensure the material selection are close to the actual materials used as possible. It is also important to ensure you have the right operation schedule of the building in terms of hours of use
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Table 5-1: The Aerospace Museum building basic geometric characteristics
Building Features
Building name Aerospace Museum of California
Building type Aviation Museum
Location McClellan Park, CA 95652.
GPS Coordinator 38.675099°N 121.391029°W
Main facade North
orientation
Year of built 1986
Number of stories 2
Building https://en.wikipedia.org/wiki/Aerospace_Museum_of_California
information link
Table 5. 1: Building Energy Analysis Workflow
The combination of Building Energy Modeling (BEM) and Building Information Modeling
(BIM) is the most widely used process by the commercial and academic community for energy efficiency simulations. During this study, a combination of three software was used; Insight 360
Revit and eQuest. This is illustrated in Figure 5-2
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Figure 5. 2: Building Energy analysis workflow
5.3 Three phase methodology
To achieve the desired objective, a three-phase methodology was adopted as explained in the following section:
5.3.1. Phase I: Data Collection
The data for the Aerospace Museum was collected from the property facility manager through site visits and email requests. The data included the following
• Utility energy consumption for three years from 2016-2018
• 2D as-built drawings - hardcopy
• Details about existing electric appliances
• HVAC system type and thermal zones
• Lighting specification and the type of fixtures
• Existing solar panel details
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5.3.2. Phase IΙ: Developed Building Energy Model
In this stage, the 2D CAD drawings were imported into Revit 2019 and the 3D model of the museum was developed based on the actual building orientation. According to HVAC information obtained, thermal zones were created by assigning the partitions of space boundaries.
The geographical location of the building was specified in the energy settings. Figure 5-5 below illustrates the BIM process for the case study using Insight 360 and Revit
Figure 5. 3: BIM modeling workflow chart using Revit and Insight 360
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The Aerospace Museum building 3D model was keenly developed according to the original drawings with the same thermal zones and local weather information [50, 51]:
STEP 1 :
The as-built drawing was opened in AutoCAD 2018 and evaluated to purge out unnecessary details before exporting to Revit
STEP 2 :
After importing the 2D into Revit, a 3D model was developed by adding architectural elements such as floors, walls roofs, windows, curtain elements, and doors. All building construction elements were selected to match the actual building construction material as much as possible as shown in Figure 5-2.
Figure 5. 4: Virtual 3D model in Autodesk Revit 2019
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STEP 3 :
Different spaces were defined in the model so that the actual loads of each thermal zones could be considered. A zone is defined as a space in a building that has the same thermal characteristics and has similar heating and cooling zones. Zones for each floor were defined as shown below
Figure 5. 5: Thermal zones layout in the Ground floor
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Figure 5. 6: Thermal zones layout on the First floor
STEP 4 :
The 3D building model was then analyzed by defining the weather station and building location.
Choosing accurate orientation and location is very crucial as distant points in the same city may
have different weather characteristics affecting the accuracy of simulated results
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Figure 5. 7: Aerospace Museum Location
The weather was also selected as shown in the figure below
Figure 5. 8: Aerospace Museum Location weather
STEP 5 :
The analytical model was created in Revit by setting all building parameters to reflect the actual building. These parameters include HVAC system type, building use, building operation time, and analytical surface resolutions
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STEP 6 :
The analytical energy model was created, and the analytical spaces and surfaces were created according to the analytical parameter resolution in the energy settings. Figure 5-5 presented the analytical energy model. This feature allows inspection of the spaces and zones for validation before sending the model to Insight 360 for simulation.
Figure 5. 9: Building energy analytical model
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STEP 7 :
After the energy analytical model is developed in Revit, it is sent to cloud-based Insight 360 for analysis. Once the analysis is complete the results are shared with your Autodesk email where you can access a link to the online results. From the result you can see the different options you can optimize the energy use in the building
Figure 5. 10: 3D building energy view and export options in Autodesk Insight 360
In the Insight browser, the simulation results and exporting options were downloaded as an INP file, which was a suitable format to export to eQUEST. Figure 5-13 shows the Insight 3D building view and export options window.
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5.3.3. Phase ΙΙΙ – Details of Building Energy Analysis in eQUEST
STEP 1:
Export the file to eQuest from Revit. This involves also importing a weather file from the Revit project to be used in eQuest simulations. Figure 5-7 below shows the imported 3D model
Figure 5. 11: Virtual 3D building energy model in eQUEST
Step 2:
To reduce the variance between the predicted annual consumption and actual utility consumption, data inputs are broken into the Set monthly utility charges in eQuest to be similar to the actual utility grid. The figure below shows the utility grid rate [52]. The utility bills for the museum are
47
seasonal i.e. they only apply during winter. The Museum also gets energy credit from the Utility as it also exports energy to the utility during summer.
Figure 5. 12: Utility grid rate
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i Define HVAC system equipment in waterside HVAC parameters per the actual system
Figure 5. 13:Water-Side HVAC system loop in eQuest
ii Implement the building operation schedule according to the actual S management data.
STEP 3 :
The forecast annual energy use of the baseline model was compared to the actual utility consumption. The EUI for the building was calculated for the average of three years from 2016 to
2018. The EUI for the actual energy yearly consumption was then compared to the median EUI of the U.S Energy State database [53]
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STEP 4:
A sensitivity analysis was carried on two factors i.e. lighting power density (LPD), and energy conservation measures (ECM) all set to baseline model to quantify the benefits of energy conservation.
5.4. Solar PV Array
5.4.1. Existing solar PV array specification
The Aerospace Museum of California was connected to solar PV in 2011. The Museum 90% runs on solar energy and even exports energy to the grid. However, a utility connection is still needed as the museum does not have enough energy storage capability to cover the whole period when there is no energy production.
Figure 5. 14: The existing location of solar PV array on the building’s rooftop
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Specification Existing solar PV array
System Type On-connected
Installed power 177.66KW DCS
Modules Type MOTECH MTPVp-235-MSC
Modules No. 756
Module Tilt 16º
Inverter Type SOLECTRIA, SGI 225kW
Inverter-480
Number of inverters 1
Inverter Efficiency 97.50%
System mounting Fixed mounting, Rooftop
Azimuth/inclination 180°
DC/AC losses 5.0% / 1.5%
Table 5. 2: Specification of the existing and proposed grid-connected Solar PV array
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The PV system is the major source of electric power for the museum. It provides 100% of the energy required at all times except during winter. During this period the utility is used to supplement the PV production.
Helioscope was used to predict the annual electrical energy production for the existing solar PV system. Several simulations were also done to see how the existing system can be improved without the need for additional space as there was none.
5.4.2. Location (Weather and Solar Radiation)
The weather conditions in North Highlands California are, dry, hot, and sunny in the summer
(May-Sep) and cold, wet, and rainy in the winter (Dec–Feb). Figure 5-17 shows the monthly average temperature during the year in Sacramento. June to September is the hot season, with an average daily high temperature above, 86°F, with July being the hottest month of the year, with an average high of 94°F and low of 61°F. November to February is the cool season, with an average low of 39°F and high of 53°F [53]. The highest average wind speed of 7.2 mph occurs around July, and the lowest average wind speed of 5.2 mph occurs around October. Figure 5-18 shows the monthly average wind speed in Sacramento
[53]. The average monthly global horizontal irradiance (GHI) is 5.49 kWh/m 2/day according to the National Renewable Energy Laboratory (NREL) [54]. Figure 5-19 shows the GHI per month versus average GHI for one year. The table below shows the site information.
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Building Details
Building name Aerospace Museum of California
Building type Aviation Museum
Location McClellan Park, CA 95652
GPS 38.675099°N 121.391029°W
Coordinator
Main facade North
orientation
Table 5. 3: The site information
Figure 5. 15: Monthly average temperature in Sacramento [53]
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Figure 5. 16: Monthly average of wind speed in Sacramento [53]
Figure 5. 17: Daily average of GHI per month vs. GHI per year
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Chapter 6
RESULTS AND ANALYSIS
6.1 Energy Simulation
This section tries to analyze all the results obtained throughout the study of the Aerospace
Museum to come up with conclusive results. The actual average annual electricity consumption for the museum is about 243,339 kWh. figure [6.1] below shows the actual monthly electrical energy consumption for 2018
Figure 6. 1:Annual Actual electrical consumption in 2018
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Figure 6. 2:Actual versus simulated electrical consumption in eQuest
Figure 6. 3: Insight 360 estimated monthly energy cost.
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The simulated monthly electrical consumption in eQuest is higher than both actual and eQuest simulated values. This shows the importance of using eQuest software as the final study software as after several adjustments to the model to match the actual building, results within the acceptable range were obtained.
The above figure illustrates energy use is highest during July and August(Summer). This is also the same period when a lot of people visit the museum. This translates to more energy being used for cooling the spaces.
Figure 6. 4: Insight 360 estimated monthly electricity use in kWh
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Figure 6. 5: Insight 360 estimated monthly fuel cost
From the graph for monthly natural gas consumption, it can be observed that the energy usage is high during the winter. During this period, buildings use more natural gas for space heating. The amount greatly reduces during summer when the weather is hot and sunny
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Monthly data for museum energy use
Figure 6. 6: Insight 360 estimated monthly energy use
Figure 6. 7: Insight 360 estimated monthly energy cost
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From figure 6.8 it can be seen that electricity usage is highest during summer. A lot of energy is also used for cooling during the same period. During winter both electricity usage and space cooling is low. The energy usage is however higher than the actual energy use
Figure 6. 8: Insight 360 estimated monthly fuel use
From Autodesk Green Building Studio energy simulations, the following results were obtained
Figure 6. 9: Autodesk Green Building Studio energy simulation
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The actual utility data for three years was collected from 2016-2018. The total average annual consumption for the period was 129,379.2 kWh/year. This is less than the simulated value of
670,537 kWh. This illustrates the difference is offset from the PV solar system and the resulting cost savings.
Figure 6. 10: HVAC System Types options
The figure above clearly illustrates different types of HVAC system and their projected incremental energy cost if adopted in the museum
From the graph, it is clearly illustrated that the most efficient HVAC system for the museum would be high efficient Heat Pump for heating and cooling of the spaces.
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6.2 Solar PV System
The existing PV system was validated using Helioscope software and the amount of electrical energy produced was simulated
Figure 6. 11:Existing PV system simulated in HelioScope
The effects of adjusting the tilt angle of the PV arrays were simulated. It was noted that neither increasing or decreasing the tilt angle had any increase in the amount of electrical energy produced. They all resulted in less electrical energy production
A second simulation was carried to establish whether changing rack arrangements within the same space would result in more energy production. This was done because there is no space of adding more modules on the roof hence to increase energy production has to be done within the existing space. The current arrangement is a fixed-tilt racking as shown in Figure 6.12 below
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Figure 6. 12:Simulated annual electrical energy production of the current PV system
With East-West racking the roof was able to accommodate more PV modules (768 modules versus 756 modules with fixed-tilt arrangement) on the roof. See figure 6.13
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Figure 6. 13: Figure East-West Racking PV modules arrangement
However, the total annual electricity production after simulation was found to be less compared to electrical energy produced fixed-tilt racking This is even though fewer modules are used in the latter system. Figure 6.14 shows the total annual electrical energy production
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Figure 6. 14: East-west Racking arrangement Annual electrical energy production
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Chapter 7
CONCLUSION
The model of the Aerospace Museum of California was developed in Revit 2019 software and exported to Insight 360. From insight 360, the model was exported as a .inp file that was imported in eQuest for energy analysis.
Comparing the results of actual energy use with the monthly use from the simulated energy model after several adjustments to the model according to the building operation and to match equipment of the museum. The baseline model in eQuest electrical consumption had a deviation of 3% in comparison to actual utility data. This falls within the acceptable range of ±5% of MBE under IPMVP [21]
The sensitivity analysis of the ECMs conducted using occupancy density and lighting power density did result in significant energy savings. This is because the museum already uses LED lighting which is already energy-efficient and occupancy density could not be reduced to impact energy saving without being impractical
For LEED certification, it dictates that the operation schedule should not be considered in ECM hence was not considered.
More than 80% of electrical energy use in the museum is provided From the PV system. The museum also exports electrical energy to the utility. This means the museum can achieve a ZEB
(Net Zero Site Energy) status by increasing energy storage facilities. From analyzing the utility bills for the year 2018, it was clear that the museum can operate off the grid if it invests in energy storage facilities.
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From Autodesk Green Building Studio simulation, the following conclusions about the Aerospace museum can be deduced
• LEED daylight. The museum does not achieve LEED credit as the glazing factor is 0.6%
of the building area versus the recommended percentage of 2%. LEED requires the
project to achieve a minimum glazing factor of 2% in a minimum of 75% of all regularly
occupied areas]
This implies that the museum needs to increase glazing, especially in the general exhibit area.
This will not only help to achieve LEED requirements but also improve daylighting.
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PV Solar System Conclusions
For the Solar PV system, it was found out that changing the tilt angle of the solar modules had no positive increase in total energy production. This means that the current system uses the optimum tilt angle of 16 for the most efficient energy production
From the second simulation of racking arrangement, it was noted that by changing the arrangement from Fixed-tilt racking to East-west racking, the space was able to accommodate more solar modules. (756 modules to 768 modules). However, when the system was simulated, the actual energy produced was found to be less than the current system. This led to the conclusion that the fixed-tilt arrangement is the best design rack arrangement. To be able to operate completely off the grid the museum should not target improving electrical energy production but rather invest in energy storage facilities.
68
HelioScope Simulation Results
Figure 6. 15: Existing PV Inverter type
69
Figure 6. 16: Existing PV module type
Figure 6. 17: Existing PV HelioScope Single Line Diagram
70
Figure 6. 18: Existing PV System Module specification
Figure 6. 19: Existing PV system Inverter Specification
71
Figure 6. 20: Simulated current PV system monthly Electrical Energy Production
Figure 6. 21: Current system Energy Losses
72
Figure 6. 22: Pie Chart for energy use in the Museum
73
APPENDIX
AECO Architecture, Engineering, Construction, and Operations
AHU Air handling units
ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning
Engineers
BEM Building Energy Modeling
BIM Building Information Modeling
CO 2 Carbon dioxide emissions
DOE United States Department of Energy
CBECS Commercial Buildings Energy Consumption Survey
ECMs Energy conservation measures
EUI Energy Use Intensity
EVO Efficiency Valuation Organization
GBS Green Building Studio gbXML Green Building eXtensible Markup Language
GAHP Natural gas -fired absorption heat pump
GHI Global horizontal irradiance
HVAC Heating, ventilation, and air conditioning
IEA International Energy Agency
IPMVP International Performance Measurement and Verification Protocol
74
LED Light-emitting diode
LEED Leadership in Energy and Environmental Design
LPD Lighting power density
M&V Measurement and Verification protocols
MEP Mechanical, Electrical and Plumbing
NREL National Renewable Energy Laboratory
SBEM Simplified Building Energy Model
SMUD Sacramento Municipal Utility District
USGBC United States Green Building Council
VAV Variable Air Volume
2D Two dimensional
3D Three dimensional
75
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