Passive homes GUIDELINES FOR THE DESIGN AND CONSTRUCTION OF DWELLINGS IN IRELAND

https://www.mosart.ie/ https://www.mosart.ie/ Sustainable Energy Ireland (SEI)

Sustainable Energy Ireland was established as Ireland’s national energy agency under the Sustainable Energy Act 2002. SEI’s mission is to promote and assist the development of sustainable energy. This encompasses environmentally and economi- cally sustainable production, supply and use of energy, in support of Government policy, across all sectors of the economy including public bodies, the business sector, local communities and individual consumers. Its remit relates mainly to improv- ing energy efficiency, advancing the development and competitive deployment of renewable sources of energy and combined heat and power, and reducing the environmental impact of energy production and use, particularly in respect of greenhouse gas emissions.

SEI is charged with implementing significant aspects of government policy on sustainable energy and the climate change abatement, including: • Assisting deployment of superior energy technologies in each sector as required; • Raising awareness and providing information, advice and publicity on best practice; • Stimulating research, development and demonstration; • Stimulating preparation of necessary standards and codes; • Publishing statistics and projections on sustainable energy and achievement of targets.

It is funded by the Government through the National Development Plan with programmes part financed by the European Union.

© Sustainable Energy Ireland, 2008. All rights reserved.

No part of this material may be reproduced, in whole or in part, in any form or by any means, without permission. The material contained in this publica- tion is presented in good faith, but its application must be considered in the light of individual projects. Sustainable Energy Ireland can not be held responsible for any effect, loss or expense resulting from the use of material presented in this publication.

Prepared by MosArt Architecture, UCD Energy Research Group and SEI Renewable Energy Information Office

https://www.mosart.ie/ https://www.mosart.ie/ Table of Contents

Preface ...... ii

Foreword ...... iii

SECTION ONE

The ‘Passive House’ ...... 1 1.1 Passive House and the Passivhaus Standard ...... 1 1.1.1 Definition of the Passivhaus Standard ...... 1 1.1.2 Technical Definition of the Passivhaus Standard for Ireland ...... 3 1.2 Applications of the Passivhaus Standard in the EU and Ireland ...... 3 1.2.1 Evolution of the Passivhaus Standard in Europe ...... 3 1.2.2 Application of the Passivhaus Standard in Ireland ...... 4 1.3 Dwelling Energy Assessment Procedure ...... 5 1.3.1 Dwelling Energy Assessment Procedure ...... 5 1.3.2 Compliance with the Building Regulations ...... 5 1.3.3 Building Energy Rating ...... 6 1.3.4 PHPP and DEAP ...... 6

SECTION TWO

How to Design and Specify a Passive House in Ireland ...... 9 2.1 Building Design Process for a Passive House ...... 9 2.2 General Principles: Heat Energy Losses and Heat Energy Gains ...... 10 2.2.1 Passive House ...... 10 2.2.2 Passive House Building Systems ...... 17 2.3 Energy Balance Calculations and Passive House Specification ...... 24 2.3.1 PHPP Software and Applications ...... 24 2.3.2 Passive House Certifications ...... 25

SECTION THREE

Passive House Prototype for Application in Ireland ...... 31 3.1 Design and Specification ...... 31 3.1.1 Combining Aesthetic and Energy Performance in House Design ...... 31 3.1.2 Decision Support using Passive House Planning Package (PHPP) Software ...... 31 3.1.3 Prototype Passive House External Wall Sections ...... 38 3.1.4 Prototype Passive House Design including Mechanical and Electrical Services ...... 38 3.2 Cost Considerations ...... 39

https://www.mosart.ie/ i Preface By Dr Wolfgang Feist, Founder of the Passive House Institute, Germany

Energy Efficient Passive Houses – Reducing the Impact of Global Warming

The February 2007 report of the Inter-Governmental Panel on Climate Change (IPCC) has shown that climate change is already a very serious global issue. The negative effects it will have on the ecosystem, the world economy and on living conditions are anticipated to be on a massive scale.

Climate change is caused largely by human behaviour due mainly to the use of fossil fuels as our main source of energy generation. The magnitude of future climate changes is closely linked to worldwide CO2 emissions into the earth’s atmosphere. The worst effects of global warming, such as a thawing of the entire land-borne ice in Greenland and Antarctica, can still be prevented. However, this requires a substantial reduction in worldwide CO2 emissions far below the current level.

There is hardly any doubt that an energy system ready for the future will have to be sustainable. Sustainable development is economic development that can be continued in the future without causing significant problems for other people, the environment and future generations.

Passive Housing can play a major role in reducing the impact of global warming. The energy requirement of a passive house is so low that a family will never again need to worry about energy price hikes. Passive Houses are virtually independent of fossil sources of energy and can be fully supplied with renewable energy if a compact unit is used in combination with an ecological electricity supplier. Due to the low energy requirement of passive houses the regionally available renewable energy sources are sufficient to provide a constant supply of energy for everyone.

Ireland’s mild climate puts it in a favourable position to introduce Passive Houses to mainstream construction compared to the more severe climates prevalent in central Europe.

ii https://www.mosart.ie/ Foreword

Sustainable Energy Ireland is Ireland’s national energy authority, set up to support Irish government energy policy objectives. Following the introduction of new legislation, most notably the European Community Directive on the Energy Performance of Buildings and the recent announcement of the intent to regulate and require the use of renewable energy systems in new buildings, we are seeing the emergence of extraordinary standards of energy performance for building construction in Ireland, as well as a rapid increase in the uptake of renewable energy technologies for building services.

Ireland is facing a number of serious challenges including houses and facilitate the further development of this rising energy costs and meeting our emissions obligations standard here in Ireland SEI commissioned ‘Guidelines for under the Kyoto protocol. These and other factors have the Design and Construction of Passive House Dwellings in given rise to a fundamental rethink in the way we design, Ireland‘. These detailed guidelines for self-builders and construct and operate buildings. it is becoming clear that architects focus on new build houses and cover both building ‘green’ has evolved and is fast becoming the conventional block construction and timber frame preferred choice, providing high quality, high efficiency, construction methods. They will ultimately become part of dynamic and cost effective solutions for consumers and a suite of guidelines to cover, for example, multiple businesses. The passive house is the ultimate in low energy dwellings, non-residential buildings, extensions, renova- building and is recognised in Europe as the most advanced tions etc. in terms of energy performance of buildings. Interestingly, the European Commission is set on implementing more The guidelines cover the rationale and definition of the stringent requirements for the refurbishment of existing passive house standard, how to design and specify a passive buildings and moving towards the passive house standard. house along with, construction options, associated services, cost considerations and lifestyle issues. SEI hopes they will Today, the passive house offers one of the most desirable be useful in increasing awareness and understanding of the technological and economical solutions for comfortable key principles and techniques in designing, constructing living and working. It can be applied to new and existing and operating the ultimate low energy building – the buildings in the commercial, industrial, public and residen- passive house. tial sectors. With over 6,000 passive houses built in Europe, this well proven and tested innovative standard is now attracting significant interest in Ireland with pioneers like MosArt and Scandinavian Homes leading an emerging movement in the construction industry.

In response to the need to educate professionals and their Brendan Halligan clients on how to design, specify and construct passive Chairman, Sustainable Energy Ireland

https://www.mosart.ie/ iii https://www.mosart.ie/ SECTION ONE

The ‘Passive House’

https://www.mosart.ie/ https://www.mosart.ie/ The ‘Passive House’

1.1 Passive House and the 1.1.1 Definition of the Passivhaus Passivhaus Standard Standard

A passive house1 is an energy-efficient The Passivhaus Standard is a specific building with year-round comfort and construction standard for buildings with good indoor environmental conditions good comfort conditions during winter without the use of significant active and summer, without traditional space space heating or cooling systems. The heating systems and without active space heat requirement is reduced by cooling. Typically this includes means of passive measures to the point optimised insulation levels with minimal at which there is no longer any need for a thermal bridges, very low air-leakage conventional ; the air through the building, utilisation of supply system essentially suffices to passive solar and internal gains and distribute the remaining heat require- good maintained by a ment. A passive house provides a very mechanical ventilation system with high level of and provi- highly efficient heat recovery. Passive house in Ghent, Belgium (2004). Source: Passiefhuis Platform vzw. sion of whole-house even temperature. Renewable energy sources are used as The concept is based on minimising heat much as possible to meet the resulting losses and maximising heat gains, thus energy demand (Promotion of European enabling the use of simple building Passive Houses (PEP) 2006), including services. The appearance of a passive that required for the provision of domes- house does not need to differ from a tic hot water (DHW). conventional house and living in it does It should be noted that the primary not require any lifestyle changes. Passive focus in building to the Passivhaus houses are naturally well lit due to large Standard is directed towards creating a glazed areas designed to optimise solar thermally efficient envelope which Passive house in Oberosterreich, Austria (2000). gains, as well as healthy buildings in makes optimum use of free heat gains in Source: IG Passivhaus Osterreich Innovative Passivhaus which to live and work due to fresh air projekte. order to minimise space heating require- supply through the controlled ventila- ment. While there are also limitations on tion system. the amount of primary energy that can The Passivhaus Standard is a construc- be used by a dwelling for such demands tion standard developed by the as DHW, lighting and household appli- Passivhaus Institut in Germany ances, this will not be the primary focus (http://www.passiv.de). The standard can of these guidelines. That is not intended be met using a variety of design strate- to imply that such energy uses are gies, construction methods and insignificant, however. In fact, a passive technologies and is applicable to any house may have similar DHW require- building type. ments as would apply to any typical house in Ireland and given the low This publication outlines the require- energy required for space heating the ments in applying that standard in energy demand for DHW will thus repre- Ireland, and in all cases when referring to sent a relatively high proportion of the a passive house is describing a house overall consumption. In order to address built to the requirements of the Interior of passive house in Oberosterreich, Austria this, some guidance is provided on (2000). Source: IG Passivhaus Osterreich Innovative Passivhaus Standard. Passivhaus projekte.

https://www.mosart.ie/ page 1 Measure/Solution Passivhaus Standard for the Prototype House in the Irish Climate 1. Super Insulation Insulation Walls U < 0.175 W/(m2K) Insulation Roof U < 0.15 W/(m2K) Insulation Floor U < 0.15 W/(m2K) Window Frames, Doors U < 0.8 W/(m2K) Window Glazing U < 0.8 W/(m2K) Thermal Bridges Linear heat Coefficient Ψ < 0.01 W/(m2K) Structural Air Tightness n50 < 0.6/ air changes per hour

2. Heat Recovery/ Air Quality Ventilation counter flow Heat Recovery Efficiency > 75% air to air Minimal Space Heating Post heating ventilation air/ Low temperature Passive house in Hannover, Germany (2004). heating Source: IG Passivhaus Deutschland Innovative Efficient small capacity heating system Biomass, compact unit, gas etc. Passivhaus projekte. Air quality through ventilation rate Min 0.4 ac/hr or 30m3/pers/hr Ventilation Supply Ducts Insulated Applicable DHW Pipes Insulated Applicable Air-leakage (or ) is the uncontrolled penetration of outside 3. Passive Solar Gain air into a building. It takes place Window Glazing Solar energy transmittance g > 50% through openings, primarily through Solar Orientation Minimal glazing to north inadequate and imperfect sealing within Envelope Recommended between window frames and walls, between the opening sections of the 4. Electric Efficiency Energy Labelled Household Appliances A rated appliances windows and along the joints of the Hot water connection to washing Recommended building. machines/ dishwashers Compact Fluorescent or LED Lighting Recommended Regular maintenance ventilation filters Recommended Energy Efficient Fans/Motors Recommended Thermal bridging refers to a material, or assembly of materials, in a build- 5. On-site Renewables ing envelope through which heat is DHW Solar Heating Area to be dictated by house size and occupancy transferred at a substantially higher Biomass system Recommended rate (due to higher thermal conduc- Photovoltaics Application in a case by case basis tivity) than through the surrounding Wind Turbine Application in a case by case basis materials. Junctions between Other including geothermal Application in a case by case basis window or door and wall, wall and Table 1. Technical Definition of the Passivhaus Standard for Ireland. floor, and wall and roof should be designed carefully to avoid or strategies to ensure that renewable The upper limit for total primary minimise thermal bridging. A thermal energies are employed as much as possi- energy demand for space and water bridge increases heat loss through ble for production of DHW. heating, ventilation, electricity for the structure, and in some extreme fans and pumps, household appli- cases may cause surface condensa- Structural air-tightness (reduction of air ances, and lighting not exceeding tion or interstitial condensation into infiltration) and minimal thermal bridg- 120 kWh/(m2a), regardless of energy the construction. Surface mould ing are essential. A whole-house source. growth or wood rot may be the conse- mechanical heat recovery ventilation quences of a thermal bridge. system (MHRV) is used to supply Additionally, the air-leakage test results controlled amounts of fresh air to the must not exceed 0.6 air changes per house. The incoming fresh air is pre- hour using 50 Pascal over-pressurisation heated, via a heat exchanger, by the and under-pressurisation testing. outgoing warm stale air. If additional In order to maintain high comfort levels heat is required, a small efficient backup in any building, heat losses must be system (using a renewable energy replaced by heat gains. Heat losses occur source, for example a wood pellet stove) through the building fabric due to trans- can be used to boost the temperature of mission through poorly insulated walls, the fresh air supplied to the house. floor, ceiling and glazing as well as from The energy requirement of a house built uncontrolled cold air infiltration through to the Passivhaus Standard is: leaky construction and poorly fitted windows and doors. In a typical older Annual space heating requirement dwelling, such heat losses have to be of 15 kWh/(m2a) treated floor area balanced by heat gains mostly (TFA), and

page 2 https://www.mosart.ie/ 1.1.2 Technical Definition of the Passivhaus Standard for Ireland

In Table 1 a range of U-values is specified in order to meet the Passivhaus Standard of annual space heating requirement of 15 kWh/(m2a) for the Irish climate. Specifying U-values is dependent upon many variables and can only be verified through testing the performance of the dwelling design in the Passive House Planning Package (PHPP) software. The U-values included in Table 1 have been tested for the prototype passive house OLDER DWELLINGS PASSIVHAUS STANDARD presented later in Section 3. This proto- Illustration of comparative heat losses and heat gains in older dwellings and in dwellings built to Passivhaus type house is a semi-detached two Standard. Source: Passivhaus Institut. http://www.passiv.de. storey house of compact form. A detached bungalow house of sprawling 80 form would require much lower U-values 70 to meet the Passivhaus Standard. Due to

60 the mild Irish climate, it is possible to meet the standard using U-values for

/y 50 2 walls in the prototype house that are 40 higher than those typically recom- kWh/m 30 1 mended by the Passivhaus Institut for 20 colder central European climates. 10 A sensitivity analysis was undertaken 0 Part L 2005 Part L 2007 Passivhaus Standard using different U-values for the proto- Space heating energy comparison, Building Regulations (TGD) Part L 2005 and 2007 and the Passivhaus Standard . type house in order to see whether it Source: Sustainable Energy Ireland would be possible to relax the building fabric requirements e.g. in relation to contributed by a space heating system. now contribute a relatively high propor- glazing, in Ireland and still achieve the The internal heat gains from occupants tion of the total need. As a result of this, Passivhaus Standard. The results of this and other sources such as household a smaller space heating system is analysis are included in Section 2. appliances as well as passive solar gains required compared to that needed in a contribute a relatively small proportion conventional older dwelling. of the total overall need in a conven- 1.2 Applications of the A new built semi-detached, two storey tional older dwelling. In a passive house, Passivhaus Standard in Irish house built to comply with the the heat losses are reduced so dramati- the EU and Ireland requirements of Building Regulations cally (through better insulation and Technical Guidance Document (TGD) airtight detailing) such that the same 1.2.1 Evolution of the Passivhaus Part L 2005, Conservation of Fuel and internal gains and passive solar gain Standard in Europe Energy), uses approximately 75 kWh/(m2a) energy requirement for space The Passivhaus Standard originated in Primary energy, in kWh/year: This heating and 156 kWh/(m2a) primary 1988 by Professor Bo Adamson of the includes delivered energy, plus an energy. The equivalent house built to the University of Lund, Sweden and Dr. allowance for the energy “overhead” requirements of TGD Part L 2007 would Wolfgang Feist of the Institute for incurred in extracting, processing and be liable to use 40-50 kWh/(m2a) deliv- Housing and the Environment. The transporting a fuel or other energy concept was developed through a carrier to the dwelling. For example, ered / useful energy for space heating 2 number of research projects and first in the case of electricity it takes and 90-95 kWh/(m a) primary energy. tested on a row of terraced houses by Dr. account of generation efficiency at The Passivhaus Standard requirement for 2 Wolfgang Feist in 1991 in Darmstadt, power stations. SEI, Dwelling Energy space heating is 15kWh/(m a). When Assessment Procedure (DEAP), 2006 compared, and having regard to Germany. The Passivhaus Institut version 2, pp. 28. constraints imposed by other require- (http://www.passiv.de) was founded in ments in the Building Regulations Part L, Darmstadt, Germany in 1996 by Dr. Delivered energy, in kWh/year: This a passive house thus represents a saving Wolfgang Feist as an independent corresponds to the energy consump- of around 70% on space heating demand research institution. Since then, it has tion that would normally appear on relative to a typical house built to the been at the forefront of the Passive the energy bills of the dwelling for Building Regulations 2005, and around House movement in Germany and has the assumed standardised occupancy been instrumental in disseminating the and end-uses considered. 60% relative to a typical house built to the Building Regulations 2007. standard throughout Europe and

https://www.mosart.ie/ page 3 overseas. The Institut provides a number likely that the limit will be overshot by of services including: "Passivhaus up to 37% (74Mt CO2) by 2010 (O’Leary Projektierungs Paket" (PHPP - Passive et al, 2005). The EC Green Paper on House Planning Package), a worksheet Energy Efficiency (EU, 2005), states that it used to determine the energy supply / is possible for the EU-25 Member States demand balance for passive buildings to achieve energy savings of 20% by (available in Ireland from SEI Renewable 2010, and sees the greatest proportion Energy Information Office of these savings (32%) coming from the email:[email protected]); consultancy built environment. design of passive buildings and building In Ireland the residential sector accounts components; and certification of quality Passive house in Guenzburg, Germany (2006) for 25% of primary energy consumption Source: UCD Energy Research Group approved passive houses (more details and energy related CO emissions in Section 2). 2 (11,896 kt CO2), the second largest Over 6,000 dwellings built to the sector after transport at 35%. The Passivhaus Standard have been average dwelling is responsible for constructed all over Europe in recent approximately 8.1 tonnes of CO2 years. This includes 4,000 in Germany emissions, 4.8 tonnes from direct fuel and Austria,2 where the Passivhaus use and 3.3 tonnes from electricity use. Standard was first applied as well as Irish dwellings have a higher average Norway, Sweden, Denmark and Belgium level of fuel, electricity and energy and numbers are continuing to grow. related CO2 emissions per dwelling CEPHEUS3 (Cost Efficient Passive Houses compared to the average of the EU-15 Passive house Eusenstadt, Austria as European Standards) was a research (SEI, 2008). Source: Construct Ireland Issue 2, Vol 3 project (1998-2001) that assessed and Following the Government White Paper validated the Passivhaus Standard on a ‘Delivering a Sustainable Energy Future wider European scale. The project was for Ireland’ (DCMNR, 2007), and the sponsored by the European Union as subsequent Programme for Govern- part of the THERMIE Programme of the ment, the Building Regulations Part L in European Commission, Directorate- respect of new dwellings have been General of Transport and Energy. Under strengthened to bring a 40% reduction CEPHEUS, 14 housing developments relative to previous standards in respect were built, resulting in a total of 221 of primary energy consumption and homes constructed to the Passivhaus associated CO emissions arising from Standard in five European countries. 2 space heating, , ventila- Another project supported by the tion, associated pumps and fans, and Multi-family dwelling ‘ Hohe Strasse’ Hannover, European Commission Directorate Germany Source: UCD Energy Research Group lighting energy usage. These provisions General for Energy and Transport is PEP, apply from July 2008. This policy has which stands for ‘Promotion of European committed to a further review in 2010 Passive Houses’ (http://www.european with the aim of extending that improve- passivehouses.org). PEP is a consortium ment to 60%. of European partners aiming to spread the knowledge and experience on the It is clear that the performance of both passive house concept throughout the new build and existing housing stock professional building community, must be addressed if we are to achieve beyond the select group of specialists. the objectives set out both at European and national level. The energy require- 1.2.2 Application of Passivhaus ment of a house built to Passivhaus Standard in Ireland Standard goes beyond the 40% improvement that applies from July The Kyoto Protocol was ratified in 2005 2008. and the proposed targets of reducing greenhouse gas (principally CO2) The Passivhaus Standard was first intro- emissions by 8% compared to 1990 duced in Ireland by the Swedish archi- levels by the period 2008-2012 became tect Hans Eek at the ‘See the Light’ legally binding for EU Member States conference organised by Sustainable Kronsberg Passivhaus Complex Hannover, (UNFCCC, 1997). Within the EU burden Energy Ireland (SEI) in June 2002. Tomás Source: UCD Energy Reseach Group sharing agreement in this regard, O’Leary of MosArt Architects, a delegate Ireland's target limit of 13% above 1990 at the conference, was so enthused by levels had been reached in 1997, and it is Mr Eek’s presentation that he decided on

page 4 https://www.mosart.ie/ the spot to sell his townhouse, buy a site in the countryside in Co. Wicklow and The EU Energy Performance of Buildings Directive (EPBD) was transposed into Irish law on 4th January 2006. This states that when a building is constructed, rented or build a passive house. The O’Leary family sold a Building Energy Rating (BER) certificate and label must be made available to has been living in the “Out of the Blue” prospective buyers or tenants. The BER is expressed in terms of KWh of primary house since Spring 2005. This house is energy/m2/year. A passive house has the potential to achieve an A2 or even an A1 the first Irish passive house to be certi- rating as shall be demonstrated in Section 3(MosArt). fied by the Passivhaus Institut in Germany, and has been the focus of a research, demonstration and energy monitoring project funded by SEI. MosArt Architects, the Passivhaus Institute of Dr Wolfgang Feist and the UCD Energy Research Group are partners in the project. The project has been instrumental in establishing the basis for the deployment of the Passivhaus Standard in Ireland in differ- ent ways:

it has provided a learning experience for professionals involved in the design, specification, construction and servicing stages

it will provide a scientific basis for performance assessment through monitoring and evaluation

it is an excellent demonstration tool and has been the focus of many visits, presentations and journal articles.

1.3 Dwelling Energy Assessment Procedure

1.3.1 Dwelling Energy Assessment Procedure

The Dwelling Energy Assessment Procedure (DEAP) is the Irish official procedure for calculating and assessing the energy performance of dwellings. The procedure takes account of the energy required for space heating, ventilation, water heating, associated Building Energy Rating Label. Source: Sustainable Energy Ireland. pumps and fans, and lighting, less savings from energy generation to demonstrate compliance with certain ular, it is used to calculate the primary technologies. The DEAP calculations are provisions in the Building Regulations energy consumption associated with based on standardised occupancy and and the second is to produce a Building the space heating and ventilation, water the procedure determines annual Energy Rating for a dwelling. heating, associated pumps and fans, and values for delivered energy consump- lighting requirements of a dwelling and to determine the amount of CO tion, primary energy consumption, CO2 1.3.2 Compliance with the Building 2 emissions and costs. These values are Regulations emissions associated with this energy expressed both in terms of annual totals use. The DEAP methodology is used to and per square metre of total floor area demonstrate compliance with certain If both the energy consumption and the of the dwelling. aspects of Part L of the Irish Building CO2 emissions are below the limits set by As the national methodology, DEAP Regulations (The Conservation of Fuel the regulations (determined relative to serves two primary functions. The first is and Energy - Dwellings: 2007). In partic- what would arise for a “reference

https://www.mosart.ie/ page 5 dwelling” of the same dimensions) then 1.3.4 PHPP and DEAP References the dwelling is deemed to be compliant. Whereas DEAP is the mandatory method European Commission (EC), 2005. for both producing a Building Energy 1.3.3 Building Energy Rating “Green Paper on Energy Efficiency”. Rating and for demonstrating compli- [Internet] EC. Available at: A Building Energy Rating (BER) is an ance with certain aspects of the Irish http://ec.europa.eu/energy/efficiency/i objective scale of comparison for the Building Regulations, the Passivhaus ndex_en.html energy performance of a building Standard and the associated PHPP is a ranging from A1 to G (see graphic on voluntary design standard for achieving European Commission (EC), 2006. “ previous page). Essentially a BER is an low levels of total energy consumption Promotion of European Passive Houses (PEP)”. [Internet] PEP. Available at: asset rating, based on a standardised within a dwelling. occupancy and usage pattern, and is http://www.europeanpassivehouses.or While it is to be expected that a dwelling calculated for a dwelling using DEAP. g/html conforming to the Passivhaus Standard The rating is the annual primary energy will comply with Irish Building consumption of the dwelling expressed Government of Ireland, Department of Regulations Part L, a separate calculation in terms of kWh per m2 of floor area. The Communications, Energy and Natural using DEAP will be required to demon- Resources (DCMNR), 2007. Government CO emissions associated with this 2 strate both this and to determine its BER. “White Paper Delivering a Sustainable energy consumption are also reported Energy Future for Ireland”. [Internet] on the BER certificate and expressed in The Passivhaus Standard can be met DCERN. Available at: 2 terms of kg of CO2 per m of floor area. using a variety of design strategies, http://www.dcmnr.gov.ie/Energy/Energ construction methods and technologies. y+Planning+Division/Energy+White+P In general, the low energy consumption aper.html required to meet the standard will result in a dwelling achieving a favorable BER, O’Leary, F., Howley, M., and provided that attention is paid to the O’Gallachóir, B., 2006. “Energy in advice outlined in later sections of these Ireland 1990-2004, Trends, issues, guidelines. forecast and indicators”. Dublin. Sustainable Energy Ireland.

Ireland’s 1st Passivhaus, Wicklow O’Leary, F., Howley, M., and Source: Tomás O’Leary, MosArt Architecture O’Gallachóir, B., 2008, “Energy in the Residential Sector: 2008 Report”. Dublin. Sustainable Energy Ireland. 1 A passive house is a building, for which thermal comfort (ISO 7730) can be achieved solely by United Nations Framework Convention post-heating or post-cooling of the fresh air mass, which is required to fulfill sufficient indoor on Climate Change (UNFCCC), 1997. air quality conditions (DIN 1946) - without a need for recirculated air. Source: The Kyoto Protocol. [Internet]. UNFCCC. http://www.passivhaustagung.de/Passive_House_E/passivehouse_definition.html Available at: http://unfccc.int/resource/ 2 See http://www.passiv-on.org/ docs/convkp/kpeng.html 3 See http://www.passiv.de/07_eng/ news/ CEPHEUS_final_short.pdf

page 6 https://www.mosart.ie/ SECTION TWO

How to Design and Specify a Passive House in Ireland

https://www.mosart.ie/ https://www.mosart.ie/ How to Design and Specify a Passive House in Ireland

This section introduces the passive the site are to the north suggesting the whether the Passivhaus Standard is house building design process as well as placement of large glazing areas on the being achieved. explaining the balance between energy northern façade in order to exploit that If the space heat requirement is signifi- losses and gains. It also provides an view. All orientation options must be cantly above the threshold of 15 overview of the various building systems considered by the designer at this stage kWh/(m2a) then the building will have to and technologies typically employed in – the house must not only function well be modified whether in terms of a passive house and presents the PHPP in terms of energy efficiency but also in improved U-values, reorganisation of software used for energy balance calcu- terms of optimising the potential of the glazing or adjustment of form. The lations. The design and specification of site and its surroundings. designer should intuitively know how the example prototype passive house in Sketch Design improvements can best be achieved the Irish climate developed as part of The next phase of the design process is while broadly remaining true to the these guidelines will be covered in to develop a sketch design for the house. agreed sketch design. If the space heat greater detail in Section 3. The basic principles of passive house requirement is significantly less than the design will greatly inform the develop- threshold level, then it might be possible 2.1 Building Design Process ment of the initial design. An ideal to increase the U-values and therefore for a Passive House approach would be to have the longest save on insulation costs. Client’s Brief façade of the house facing south, a bias Care should also be taken to note other The design of a passive house will of glazing towards the southern eleva- performance indicators calculated by typically commence with developing a tion with reduced glazing area on the the software, such as frequency of brief with the client, whether this is a northern elevation and a compact form overheating, for example. family wishing to build a single rural in order to minimise surface to volume dwelling, a Local Authority progressing a ratio. Shading devices may be required Detailed Design and Specification housing scheme or a commercial devel- in order to protect against the risk of The design of the house is next devel- oper proposing a mixed residential overheating in summer and the oped to the level of detail required to project. The brief would typically outline aesthetic integration of this is essential. apply for planning permission. Typically the client’s practical requirements in In terms of internal layout, it is preferable this would not require all construction terms of space functions and density to organise, where possible, family details but it is wise to consider the and also their preferred image or rooms and bedrooms on the southern various technologies at this stage in concept for the building(s). Clients inter- elevation with utility room and circula- order to avoid difficulties later on. ested in building a passive house will tion spaces on the northern elevation The type of construction will need to be often have carried out some research on where availability of sunlight is not so considered, whether timber frame, the subject and so may already be critical. masonry, externally insulated masonry, relatively well informed regarding the Initial Evaluation of Energy Performance insulated concrete formwork, steel benefits of living in a passive house. Once the sketch design has been frame or straw bale as well as the space Site Visit approved by the client, it is important to required for services such as solar A site visit is important to identify the test the energy balance of the house panels, large domestic hot water tank, presence of structures, landform or design using the Passive House Planning mechanical ventilation equipment with evergreen trees which might cast Package (PHPP). The essential elements supply and exhaust ducting. The specifi- shadows on the house during the short of the design are entered into the cation of such services might be outside winter days when the sun is low in the spreadsheet, including U-values of walls, the expertise of the house designer and sky (thus reducing the potential for floors, roof and glazing as well as orien- it may be required to commission the achieving a glazed south facing façade). tation, volume, and size of the house. services of a Mechanical and Electrical It may happen that the best views from This will provide an early indication of Engineer.

https://www.mosart.ie/ page 9 It is also critically important to plan It will usually be necessary to engage Areas of Heat Loss in Homes ahead in terms of airtightness and cold specialist sub-contractors to supply and Loss Roof Loss 30%-35% bridging detailing as these often repre- install such elements as the ventilation Loss through sent the most challenging aspects of equipment, solar system, back up Walls Ventilation 25%-30% Loss 25% passive house design. heating systems and controls.

The detailed design should be re-tested Post Construction Testing in the PHPP software to ensure that the This is the final stage to determine Passivhaus Standard is achieved. At this whether the constructed dwelling stage all the required data fields have to actually meets the airtightness require- be completed as accurately as possible ments of the Passivhaus Standard. The Window Loss 15% (details of the PHPP tool datasheets are air-leakage must not exceed 0.6 air Floor Loss 7%-10% outlined in section 2.2.1). The result of this changes per hour using 50 Pa (0.6ac/h @ Comparison typical building fabric heat loss patterns detailed test might suggest that minor 50 Pa) overpressurisation and under- in a detached dwelling, excluding ventilation and infil- alterations are required to the initial pressurisation testing. An independent tration (Source: UCD Energy Research Group) house design in order to meet the inspection and testing body should passivhaus standard. The client should be conduct the testing activities. It is impor- kept informed at all times of the decisions tant to undertake this test as soon as the being made by the design team and have airtight layer is complete so that any the opportunity to suggest alterations leaks can be rectified. Where the should the need arise. dwelling does not meet the require- ments further testing may be required. Tender Documents and Drawings Once planning permission has been 2.2 General Principles: Heat granted, a more detailed set of technical Energy Losses and Heat drawings will be required in order to Energy Gains enable the construction of the house. As highlighted above, the emphasis will be on detailing of junctions between differ- ent elements of the building, practical requirements for minimising heat loss through cold bridging, planning for airtightness and the location and routing of services. The sizing of the ventilation equipment, backup space heating, solar domestic hot water system, as well as details of controls for space and water heating and ventilation, Comparison of energy rating between different will have to be specified at this stage. German construction standards and the passive The detailed drawings and specification house. (Source: Passivhaus Institut, Germany http://www.passiv.de can then be issued for tender to compe- tent contractors. 2.2.1 Passive House Building Site Operations Envelope The detailed design of the passive house The building envelope consists of all must now be realised on-site and quality elements of the construction which control is paramount to achieving the separate the indoor climate from the standard envisaged in the PHPP outdoor climate. The aim of the passive software. The most challenging aspect house is to construct a building will typically be achieving the required envelope that will minimise heat loss level of airtightness, as this is greatly and optimise solar and internal heat affected by the quality of craftsmanship gain to reduce the space heating on site. The challenge becomes all the requirement to 15 kWh/(m2a). more difficult if the building contractor has no prior experience of building to the Passivhaus Standard. More challeng- Comparison between PHPP and DEAP ing again is the common practice of the house built by ‘direct labour’ and The dimensions used in PHPP are without an experienced supervisor with always external dimensions (Figure 2.2.1.1). DEAP calculates with internal overall responsibility to achieve the high dimensions. standards set.

page 10 https://www.mosart.ie/ heat is lost through windows but heat lost through external walls is very low. In Irish Building Regulations, Elemental the conventional building, on the other Heat Loss Method (Building Regulations Technical Guidance hand, there can be significant heat loss Document L, Conservation of Fuel and from the entire building envelope, Energy TGD Part L 2007). especially through windows. Maximum average elemental U-value Insulation of the building envelope can W/(m2K) be divided into four distinct areas: exter- • Pitched roof, insulation horizontal nal wall, floor, roof and windows. at ceiling level 0.16 Existing passive houses in Central and • Pitched roof, insulation on slope 0.20 Northern European countries have been Calculation of building element areas using external • Flat roof 0.22 achieved with U-values for walls, floors dimensions. Source PHPP 2007 Handbook, pg 37 • Walls 0.27 and roofs ranging from 0.09 to 0.15 • Ground Floors 0.25 The following building envelope param- W/(m2K) and average U-value for • Floors with eters are fundamental in this process: windows (including glazing and 0.15 window frames) in the region of 0.60 to 1. Well insulated building envelope • Other exposed floors 0.25 0.80 W/(m2K). These U-values are far • Windows and roof lights 2.00 2. High energy performing windows below (i.e. better than) the limits and doors currently set under the Irish Building Regulations, with the most marked 3. Minimised heat loss through thermal difference pertaining to windows, wall bridging and floor. 4. Significantly reduced structural air A sensitivity analysis using the Passive infiltration House Planning Package (PHPP), v. 5. Optimal use of passive solar and 2007, was undertaken using a range of internal heat gains U-values for the timber frame and masonry constructions of the prototype Building Envelope Insulation house using climatic data for Dublin. In Many building methods can be used in all options tested, the same data input the construction of a passive house, was used for airtightness 0.6ac/h@50Pa, including masonry, lightweight frames ventilation and minimised thermal (timber and steel), prefabricated bridging. Various parameters were elements, insulated concrete formwork, tested in order to determine, for straw bale and combinations of the example, the required level of U-values above. The prototype passive house for the building envelope in the Irish presented in this publication (details in climate, and to ascertain whether it Section 3) illustrates both masonry and would be possible to use double glazing timber frame construction as represen- and still achieve the Passivhaus tative of the most typically used building Standard in Ireland. The results as methods for dwellings in Ireland. outlined below are: Option 1 being the Continuous insulation of the entire most energy efficient house and Option thermal envelope of a building is the 8 being the least energy efficient. An most effective measure to reduce heat losses in order to meet the Passivhaus Thermal transmittance (U-value) Standard. relates to a building component or structure, and is a measure of the rate A thermographic image can be used to at which heat passes through that illustrate the difference between good component or structure when unit and poor levels of insulation in a house. temperature difference is maintained Heat loss through the building envelope between the ambient air tempera- is highlighted by the green, yellow and tures on each side. It is expressed in red colouring. The green areas represent units of Watts per square metre per the best insulation whereas the red degree of air temperature difference represents the warmest outer surface (W/m2K). (hence the worst insulated). The amount Source: Building Regulations Thermographic image illustrating difference in heat of thermal radiation emitted increases Technical Guidance Document, loss through building envelope in a conventional and with temperature, therefore warm Conservation of Fuel and Energy (TGD passive house building. Source:http://upload.wikimedia.org/wikipedia/en/f/f2 Part L) 2007. objects stand out well against cooler /Passivhaus_thermogram_gedaemmt_ungedaemmt. backgrounds. In the passive house some png

https://www.mosart.ie/ page 11 Average Option U-values of U-values of Space heating U-values of roof U-value of ext. wall floor windows and requirement

doors

1 0.10 W/(m2K) 0.10 W/(m2K) 0.10 W/(m2K) 0.80 W/(m2K) 7 kWh/(m2a)

2 0.15 W/(m2K) 0.15 W/(m2K) 0.15 W/(m2K) 0.80 W/(m2K) 12 kWh/(m2a)

3 0.175 W/(m2K) 0.15 W/(m2K) 0.15 W/(m2K) 0.80 W/(m2K) 13 kWh/(m2a)

4 0.10 W/(m2K) 0.10 W/(m2K) 0.10 W/(m2K) 1.50 W/(m2K) 20 kWh/(m2a)

5 0.27 W/(m2K) 0.16 W/(m2K) 0.25 W/(m2K) 0.80 W/(m2K) 20 kWh/(m2a)

6 0.10 W/(m2K) 0.10 W/(m2K) 0.10 W/(m2K) 2.00 W/(m2K) 31 kWh/(m2a)

7 0.15 W/(m2K) 0.15 W/(m2K) 0.15 W/(m2K) 2.00 W/(m2K) 37 kWh/(m2a)

8 0.27 W/(m2K) 0.16 W/(m2K) 0.25 W/(m2K) 2.00 W/(m2K) 48 kWh/(m2a)

Sensitivity analysis of the prototype passive house in Ireland outline test results for eight options. Source: MosArt Architecture outline description of each of the eight Note: Advantages and disadvantages of dwelling in Ireland. Meeting the options analysed is provided. Only the using triple glazed windows are discussed Passivhaus Standard must be tested and first three achieve the Passivhaus in detail in section ‘Windows & Doors’) verified with the PHPP software for the Standard set for annual space heating of specific dwelling design. Option 5 – U-values for walls, roof 15 kWh/(m2a) treated floor area: and floor employed at the limits of Thermal Conductivity Option 1 – U-value 0.10 W/(m2K) for the individual elemental heat loss Thermal conductivity (λ-value) relates to all building elements combined with requirements in the Irish Building a material or substance, and is a measure triple glazed windows with average Regulations, (Building Regulations of the rate at which heat passes through U-value (including glazing and TGD Part L, Conservation of Fuel and a uniform slab of unit thickness of that window frames) of 0.80 W/(m2K) Energy 2005 and 2007) combined material or substance, when unit results in space heating requirement with triple glazed windows, failing to temperature difference is maintained significantly below the standard achieve the required standard. between its faces. It is expressed in units limit required of 15 kWh/(m2a). of Watts per metre per degree (W/mK), Option 6 – also a failure is the combi- (Building Regulations Technical Option 2 – U-value 0.15 W/(m2K) for nation of U-value 0.10 W/(m2K) for Guidance Document Part L, all building envelope elements building fabric in combination with Conservation of Fuel and Energy 2007). combined with triple glazing. The standard double glazed units. Insulation materials for walls, roofs and results show space heating require- Option 7 – U-values 0.15 W/(m2K) for floors vary in terms of thermal conduc- ment below the Passivhaus Standard walls, roof and floor as the prototype tivity. Typical conductivities for different limit. house but with standard double insulation materials are included below Option 3 – this is the option that has glazing U-value 2.0 W/(m2K) which as well as the approximate thicknesses been used in the design of the comes way above the limits set for required in order to achieve a wall (or prototype passive house in Ireland the Passivhaus Standard. roof) U-value of 0.15 W/(m2K) and 0.10 as part of these Guidelines, with U- W/(m2K) Option 8 – U-values for walls, roof value of 0.175 W/(m2K) for external and floor employed at the limits of Typical insulation materials used in walls and U-value 0.15 W/(m2K) for the individual elemental heat loss Ireland include mineral/rockwool, all other building envelope requirements in the Irish Building polystyrene, polyurethane, polyisocya- elements, coupled with triple glazed Regulations, (Building Regulations nurate, sheep wool and hemp. Different windows. TDG Part L, Conservation of Fuel and insulation materials may suit different Option 4 - U-value for all building Energy 2005 and 2007) and standard types of construction application and it is envelope elements of 0.10 W/(m2K) double glazed units, failing to important to consider the material best combined with an efficient double achieve the Passivhaus Standard. suited for the situation and pay attention glazed unit with low U-value of 1.5 to detail in its proper installation. For Note: Results presented here are indicative W/(m2K ) which does not achieve the example, quilted or loose fill insulation is only and should be used as starting point Passivhaus Standard. generally suitable for use on the floor of for specification of a passive house

page 12 https://www.mosart.ie/ an open attic space where it will fill taking into account building orientation, completely between ceiling joists, but areas of glazing and specific types of care needs to be taken in ensuring venti- glazing so the optimum balance of lation in the attic whilst avoiding risk of glazing for each passive house design wind displacement of insulation near can be reached. Also, as highlighted eaves. In contrast, rigid insulation may further below, there is a need for the be at lower risk of displacement by wind, design to ensure that the risk of solar but would need to be cut perfectly to fit overheating is minimised. snugly between the joists, to avoid a risk It has been illustrated above that the use of thermal looping or leakage. As a of windows and doors with average U- further example, a high density rigid values of 0.8 W/(m2K) can be combined insulation tends to be better suited with U-values for opaque elements of Light filled room in a passive house. under a floor slab compared with insula- 0.15 W/(m2K) to comfortably achieve the Source: MosArt Architecture. tion that easily compress or are affected Passivhaus Standard in Ireland. There are by moisture.

The U-value of the construction is deter- mined by the conductivity of materials and components used from the internal surface to the external surface of the thermal envelope. Examples of typical construction methods and materials used for the prototype passive house in Ireland are illustrated later in Section 3.

Windows & Doors The recommended approach to the design of a passive house is to have Comparison of the interior surface temperature depending of the type of glazing. Source: Internorm, fenster – Licht avoid an excessive area of north facing und Leben catalogue 2007/2008, pp.91. glazing and place relatively large a number of advantages in using natural which is driven by windows facing south or due south. This windows with average U-values of 0.8 temperature difference between the is in order to minimise heat losses W/(m2K) as well as highly insulated inside face of the glass and the room through the north facing elevation, doors, principally the assurance of a interior is much reduced, thereby avoid- which receives no direct sunlight during comfortable indoor climate due to the ing this source of cold air flows and most of the heating season, while lower cold radiation at the thermal discomfort. maximising ‘free’ solar heat gains on the surface of the glass. One will not sense a south. An advantage of large windows is The sensitivity analysis for a passive drop in temperature standing immedi- an increase in interior daylight levels house dwelling in Ireland showed that in ately adjacent to this standard of which in turn reduces the need for use of the case of Option 4 above the window, unlike the experience of stand- electricity for artificial lighting and also Passivhaus Standard yearly space ing next to a conventional double ensures a more pleasant natural light- heating requirement could not be glazed unit with U-value, for example of filled living environment. achieved with efficient double glazed 2.0 W/(m2K). An added benefit of using windows with a U-value of 1.5 W/(m2K). There is, however, a balance to be highly energy efficient windows and achieved between heat losses through doors includes significant draught Typically triple glazed window units are the glazing and solar heat gains through reduction due to the fact that they have used in passive houses in Central and the south/east/west facing windows. typically two seals or gaskets (compared Northern Europe. The Passivhaus Institut When designing a passive house, the with conventional double glazed units has certified a range of glazing and door PHPP software should be used to calcu- which often have only one) as well as units suitable for use in passive house late the heat losses and heat gains excellent sound insulation. Finally, buildings. Although it is not a prerequi- site to use certified passive house Insulation Material Thermal Thickness for Thickness for products (http://www.passiv.de) in a Type U-value of 0.15 U-value of 0.10 conductivity W/mK passive house, choosing approved W/(m2K) W/(m2K) products means the validity of technical Polyisocyuranate or 0.023 145mm 220mm polyurethane data has been tested and verified by an Polystyrene, sheep wool 0.035 220mm 340mm independent certifier. The principal Cellulose, Hemp and characteristics and advantages of using 0.04 250mm 400mm Rockwool triple glazed windows in a passive house Wood 0.15 825mm 1,250mm are listed below, for both glazing and the Conductivity of insulation materials and approximate thickness to achieve specific U-value for external walls (k frames: values will vary according to density). Source: MosArt Architecture

https://www.mosart.ie/ page 13 With triple glazing the solar energy typically transmit 65% of visible light transmittance (gs), i.e. the amount of (these are indicative values only - actual solar energy entering through that values depend on the manufacturer’s glazing is somewhat reduced specification). compared to double glazing due to In a conventionally constructed older the effect of the additional layer of house in Ireland radiators are typically glass. A requirement of the positioned under windows in order to Passivhaus Standard is to use glazing heat the cold air entering through the with minimum solar transmittance single or double glazing. In a passive of 50% or higher. house, locating a heat source beneath Frame: windows is simply not required as the The frame must be well insulated heat load is transferred throughout the and also have a thermal barrier (be house via the mechanical ventilation “thermally broken”). Even wood system. This has the added benefit of conducts heat and a thermally enabling unobstructed use for placing broken timber window frame will furniture against all external walls. result in much lower heat losses than Thermal Bridging Cross section though a triple glazed insulated window a solid one. and frame. Source: MosArt Architecture. Thermal bridging (i.e. un-insulated joints There will typically be two weather between walls, floors/ walls, ceilings/ Glazing: gaskets on triple glazed windows adjacent walls, windows/walls etc) are Three panes of glass separated by used in a passive house dwelling, the weak points of thermal resistance in the special low-conductivity spacers primary function of the outer one building envelope and cause unwanted eliminates the risk of condensation being for weathering with the inner losses of energy which should be elimi- at the bottom of the glass in cold one serving to improve airtightness. nated or significantly reduced to a weather (which could lead to rotting The majority of these types of degree that the associated heat losses of timber frames over time); window open outwards which is become negligible. commonplace in Continental High solar energy transmittance (g ≥ A thermal bridge increases heat loss Europe; however, there are models 50), referring to the amount of solar through the structure, and in some of inward opening windows being radiation which can penetrate the extreme cases this may cause surface developed which will be available glass and thereby contribute condensation or interstitial condensa- soon in the Irish market. One advan- towards heating of the dwelling; tion in the structure. Surface mould tage of outward opening windows is growth or wood rot may be the conse- A low emissivity (low-e) coating on that they don’t intrude in the room quences of a thermal bridge. Typical the inside of the outer two panes space which might be important in effects of thermal bridges are: which reduces thermal re-radiation more compact dwellings. back out through the glass. It should Significantly increased heat losses; Triple glazed window frames are be noted that a ‘soft coat’ has slightly typically much wider and stronger Decreased interior surface tempera- better U-value but a ‘hard coat’ construction than their conventional ture (cold spots) which may also glazing has higher solar transmit- double glazing counterparts. result in high in parts of the tances. construction; and The use of larger areas of glazing on the Insulating gases between the glass south elevation is helpful in maximising Mould growth cause by warm inter- panes, typically argon or krypton, the amount of sunlight available in the nal air condensing on cold surfaces. which help to reduce heat escaping short days of winter. It must be remem- through the glass. All of the above situations can be bered, however, that highly energy avoided in houses built to the efficient windows allow less daylight Passivhaus Standard. The Passivhaus (visible light transmittance) into a build- The quantity which describes the heat Standard for linear thermal transmit- ing than normal double glazed windows loss associated with a thermal bridge is tance (Ψ) should not exceed 0.01 W/(mK). ψ without e-coating. Light transmittance is its linear thermal transmittance ( ). This requires the building designer to This is a property of a thermal bridge an optical property that indicates the identify and locate all potential thermal and is the rate of heat flow per degree amount of visible light being transmit- per unit length of bridge that is not ted through the glazing. It varies Comparison between PHPP and DEAP accounted for in the U-values of the between 0 and 1 (0 to 100% light trans- plane building elements containing mitted), representing the proportion of Thermal bridges are calculated in PHPP the thermal bridge. light transmitted. A double glazed on the external face of the thermal Source: SEI, Dwelling Energy Assess- window with low-e coating will typically envelope whereas in DEAP the thermal ment Procedure (DEAP) 2005 edition, transmit 72% of visible light. A triple bridges are calculated on the internal version 2, pp.55 glazed energy efficient window will surface of the envelope.

page 14 https://www.mosart.ie/ bridging in the construction, applying house. By sucking air out of the house, careful specification and detailing of for example, a negative pressure is those elements providing where possi- created with the result that external air ble a continuous layer of insulation, as will be sucked in through any gaps or well as taking care to execute those cracks in the building envelope. The elements on site as per design details. pressure used for such tests is 50 Pascal which can be accurately set by the Designing and building a passive house equipment. in Ireland requires the development of Infrared image of the interior of a passive house construction details that go far beyond When undertaking the test it is usually window. All surfaces (wall structure, window frame, guidance provided (to avoid excessive quite easy to identify any major leaks and the glazing) are pleasantly warm (over 17 °C). Even at the glass edge, the temperature does not fall below heat losses and local condensation) in due to the presence of a strong draught 15 °C (light-green area) Building Regulations Technical Guidance which can be felt by the hand or, for (Source: Passivhaus Institut, http://www.passiv.de from the passive house Kranichstein) Document Part L, Conservation of Fuel smaller leaks, can be detected by a and Energy. Building practitioners could thermographic camera. The cause of refer to the accredited construction these draughts can then be sealed with details specifically developed for passive appropriate materials as the test is on house building published in Germany going. It may also happen that the leaks “Thermal Bridge-Free Construction” in the envelope are very minor and (PHPP 2007, pp.96). Thermal bridging therefore difficult to locate. In these can be tested and verified in the PHPP situations it is typical to reverse the software as the design of the passive direction of the and blow air into the house building is being developed. house putting it under positive pressure. For comparison, a typical older double glazed window Odorless smoke can then be released is shown. The centre of glass surface temperature is Structural Airtightness and Draught- below 14 °C. In addition, there are large thermal into the building and leaks can be bridges, particularly where the window meets the Proofing observed from the outside where the external wall. The consequences are significant radiant Building an airtight or leak-free structure temperature asymmetry, drafts, and pooling of cold air smoke appears through the envelope. It is imperative to achieving the Passivhaus in the room. is important to notify the fire service if (IR-photography: Passivhaus Institut offices, Standard. If there are gaps in the build- you are carrying out such a test in case it http://www.passiv.de ) ing structure then uncontrolled is mistakenly reported as a house fire by amounts of cold external air can infil- passers by. trate the building. Achieving a high level of airtightness eliminates cold draughts The Passivhaus Standard is reached and associated comfort losses. It also when there are less than or equal to 0.6 prevents condensation of indoor moist, @50 Pa pressure. warm air penetrating the structure, and The most critical issue regarding testing possible structural damages due to for airtightness is timing during the decay, corrosion and frost. building process. It is important that Air tightness is achieved in masonry remedial measures can be carried out in construction by careful application of order to remedy any leaks or cracks. The appropriate membranes and tapes or test should be carried out before second wet plastering within the building fix carpentry, for example, where there envelope. A great deal of attention must are no skirting boards or window boards be paid to detailing and workmanship in fitted and where the junctions covered order to ensure that the airtight layer is by such materials are still accessible and continuous all round the building, can be sealed. The test should also be especially around junctions between carried out after all mechanical and walls and floors, roof, windows, doors, etc. Penetrations of the airtight layer by Comparison between PHPP and DEAP mechanical and electrical services must In the ventilation sheet of PHPP the air be properly sealed. changes @ 50 Pa have to be entered. The DEAP calculation uses air changes The air tightness of a building can be Timber Frame I-Beam construction reducing thermal accurately measured by carrying out a @ normal pressure for its inputs. bridging. Source: Passivhaus Institut, Germany. blower-door test. The test involves The results of the blower door test @ 50 placing a powerful fan suspended in a Pa have to be divided by 20 to enter sealed canvas sheet within a door the correct value in DEAP opening and operating the fan at very Example: 0.6 ac/hr / 20 = 0.03 ac/hr high speeds thereby creating either negative or positive pressure within the Input PHPP: 0.6, Input DEAP: 0.03

https://www.mosart.ie/ page 15 electrical services that need to penetrate Passive Heat Gains the building envelope have been Passive heat gains in a passive house are installed. Otherwise, installing such a result of the combination of solar gains services after the test could severely and internal gains. compromise the airtightness of the building. Solar Heat Gains Passive solar gain is optimised by provid- In a typical Irish house built in accor- ing an east-west alignment to the build- dance with TGD Part F 2002 the method ing, if possible with the site, resulting in in which habitable rooms are ventilated the longest façade facing south, and by has usually been via a hole in the wall or placing the majority of the glazing ventilator in the windows of 6,500mm2 towards the south. Very high quality Correctly insulated house avoiding thermal bridge. fitted with a controllable . Such windows (average U-value ≤ 0.8 Source: Passivhaus Institut, Germany means of ventilation can result in large W/(m2K)) facing south will have a amounts of cool external air infiltrating positive thermal balance – they will have the building depending on wind speed more heat gain than heat loss through- and pressure. The same is true for open out the year. Results of a recent paramet- chimneys or in conventional ric study by J. Schnieders of the houses. Passivhaus Institut “Climate Data for In a passive house, on the other hand, Determination of Passive House Heat the supply of fresh air is provided by a Loads in Northwest Europe” illustrates whole house mechanical ventilation the relationship between the area of system with heat recovery which south facing glazing and the space heat negates the necessity for openings in demand for a passive house dwelling the wall or windows. Thereby draughts located in Ireland (measured climate are eliminated and structural air tight- data for Birr used). The parametric study Continuous Airtight Membrane. ness is not compromised. uses the first passive house built by Dr. Source: Passivhaus Institut, Germany Wolfgang Feist of the Passivhaus Institut In developing the building design it is as a case study building, shown below. It very important to anticipate differential can be seen that the space heating movement and decay of adhesives and demand initially decreases quite steeply chemical bonds by detailing junctions with increasing south facing glazing. which will assist in maintaining an There are diminishing returns from airtight layer for the life of the building. increasing the area of south facing glass, Many excellent details, for example, can however, and there eventually comes a be found at the website of the Scottish point where there is little or no benefit in Ecological Design Association providing more south facing glass as the (www.seda2.org/dfa/index.htm). It can net heat loss is greater than the heat also be important to use membranes gains over the year. and plasters that are both airtight but also vapour diffuse which allow the There is no optimal ratio of glazing to structure to “breathe” to its cold side. floor area that can be used as a rule of This means allowing moisture within the thumb in deciding what proportion of a structure to escape to the outside given façade should be glazed. The area thereby reducing the risk of interstitial of glass has to be determined as part of moisture and the threat of rot and decay the design verification procedure using

Timber frame house pre-cladding fitted airtight over time. the PHPP software. membrane. Source: Passivhaus Institut, Germany. Internal Heat Gains A passive house is very efficient at utilis- There are two measurements used to define airtightness, namely cubic metres of air ing ‘free’ internal heat gains from domes- per square metre of exposed fabric per hour (m3/m2/hr) or air changes per hour (ACH). tic household appliances, kitchen and While the measured result for the former is generally 20% greater than that of the utility equipment, electronic equipment, latter, the difference is practice greatly depends on the building form. artificial lighting, and occupants. Heat Example to convert: losses from stoves or also contribute towards the overall space 3 The prototype house in section 3 has a volume of 503.40 m and a total envelope area heating requirement as long as they are of 324.21 m2. positioned within the building envelope. The blower door test result is assumed, with 0.6 ac/h @ 50 Pa Occupants of the building also contribute to meeting the heat load; a 503.40 m3 x 0.6 ac/hr / 324.21 m2 = 0.47 m3/m2/hr

page 16 https://www.mosart.ie/ 24 22 Ireland - Birr 20 18 16 14 12 10 8 6 U-Value Wall = 0.175 W/(m2K) 4 U-Value Window = 0.85 W/(m2K) Space Heat Demand [kWh/(m2a)] Heat Load [W/m2]

Space Heat Demand / Heat Load Heat Demand / Space Heat 2 0 0 102030405060 Area South Facing Windows [m2]

Source: Climate Data for the Determination of Passive House Heat Loads in Northwest Europe, J. Schnieders, Passivhaus Institut, pp.17. typical adult human continuously emits long the sun only enters the building in 100W of heat when stationary. A family the middle period of the day while of five persons, therefore, can emit up to during winter when the daylight hours 0.5 kW of heat. This may seem like a are short the low sun completely illumi- small amount but it equates to approxi- nates the entire interior of the building. mately one third of the total space heat In the temperate climate in Ireland load for the prototype passive house where external temperature rarely No more than 0.6 air changes/hour at 50 Pascal presented in Section 3. exceeds 25˚C, the risk of overheating can pressure should be observed in accordance with the Passivhaus Standard. This should be checked for Risk of Overheating be easily avoided by careful considera- compliance with a blower-door test which will Placing extensive areas of glass on the tion of shading devices and provision of immediately highlight leaky areas. Airtightness can be achieved through the use of membranes, roofing felts south facing façade in a well insulated openings for natural ventilation in and plasters combined with sealants and vapour diffu- and airtight dwelling might lead to combination with thermal mass inside sion resistant materials. Source: UCD Energy Research Group overheating in warm sunny days. The the dwelling (exposed concrete floor; PHPP software will alert the designer to masonry wall, etc.). In some cases the any risk of overheating by calculating mechanical ventilation system could be the frequency of overheating and used to distribute fresh air throughout expressing this as a percentage of the the building by switching to a ‘summer Deep roof overhang shades upstairs windows year in which the internal temperature in bypass’ setting. This however should be the house rises above 25˚C. If the avoided where possible as the ventila- frequency of temperatures over this tion system will consume electricity comfort limit of 25˚C exceeds 10% of the resulting in increased primary energy. It year (measurement referring to hours is preferable that the dwelling designer rather than days), additional measures should employ ‘passive’ cooling strate- Balcony shades downstairs windows for reducing overheating should be gies to minimise overheating. included in the dwelling. To prevent uncomfortable indoor temperatures in a 2.2.2 Passive House Building Systems Location of overhang and balcony. passive house dwelling it is recom- Source: MosArt Architecture. As indicated earlier a passive house mended to specify shading devices does not need a conventional space (blinds, overhangs or awnings, etc.) heating system of radiators or under- which will let the low sun enter the floor heating to maintain a comfortable home in winter but prevent the high sun indoor climate. Instead, typically, the entering in summer. following building services are required In the first Irish passive house in Wicklow in a passive house: shading was not in place on south facing Mechanical ventilation system with glazing during the first summer and the heat recovery which provides most house did overheat. A balcony was of the space heat requirement installed ahead of the second summer, which significantly reduced the Backup system capable of heating frequency of overheating. In mid- the air passing through the dwelling Lighting contributes towards internal heat gains. summer when the daylight hours are via mechanical ventilation to meet Source: MosArt Architecture.

https://www.mosart.ie/ page 17 any auxiliary space heating needs, fresh air do not mix in the heat expected to be small. Typical fuel exchanger and therefore there is no risk sources for the back up system whatsoever of what might be referred to include biomass, gas, and in some as ‘’. Rather, the instances electricity (for example stale air and clean air is channelled ‘green electricity’ from renewable through closely spaced but separate sources). The back up system is also narrow sleeves in the core of the heat used to provide hot water, either exchanger. throughout the year or during Ventilation systems use electric power Photo depicting how the low winter sun enters the winter if a solar water heating room below the overhang/awning/balcony. and therefore have a slightly negative system is used during summer. Source: MosArt Architecture. impact on the primary energy consump- Each of these items is dealt with tion. This will have affect the Building separately in greater detail below. Energy Rating. In our example in Section 3, the energy used by the MHRV is about Given the lengths to which the designer 10% of the annual primary energy and builder must go to in terms of ensur- demand. ing a highly insulated building envelope, excellent airtightness and minimal The benefits of having a whole-house thermal bridging, it is important that the mechanical heat recovery ventilation building services in a passive house are system (MHRV) are many, including: as energy efficient as possible. This is Constant supply of the correct especially critical in the case of the amount of fresh air to all habitable mechanical ventilation heat recovery rooms thereby reducing indoor CO system. Therefore, the required 2 levels and removing the cause of efficiency of the mechanical ventilation stuffiness and tiredness; system with heat recovery for a passive house dwelling is at least 75%. It is also Simultaneous extraction of very important to consider comfort, moisture-laden air from bathrooms, Photo depicting how the house is shaded from the high health and safety issues in the design of utility rooms and kitchens as well as summer sun by the overhang/awning/balcony. the building services for a passive house, ventilating noxious gases and Source: MosArt Architecture. ensuring for example that the backup unwanted smells if present; and heating system is adequately sized to A lowering in humidity levels reduc- deal with extreme weather conditions, ing mould and fungus that may that filters in the ventilation equipment appear over time and decreasing are replaced regularly and that there is dust mite levels. an independent fresh air supply for any combustion devices such as a . There are databases (SAP Appendix Q or These and other issues are dealt with in www.passiv.de) in which various MHRV greater detail below. products are listed in terms of efficiency and performance. Mechanical Heat Recovery Ventilation (MHRV) MHRV System Efficiency An airtight house requires a well- The efficiency of the heat exchanger in designed mechanical ventilation system the MHRV determines the amount of to provide good indoor air quality. A heat that can be recovered from the Schematic of the supply air ducts, the extract air ducts passive house is ventilated using a exhaust air and, therefore, has a very and the heat exchanger within mechanically venti- mechanical system which incorporates significant influence on the additional lated house. Source: Passivhaus Institut. air to air heat recovery (mechanical heat space heating that may be required in a recovery ventilation, or MHRV). Exhaust passive house. The aim is to use the air is extracted from rooms that typically warm exhaust air to raise the tempera- produce heat, moisture and unwanted ture of the cool fresh air to provide for odours such as kitchens and bathrooms. thermal comfort all around the house. Before this air is expelled to the outside On a night where outside temperatures it passes through a heat exchanger are below freezing, the fresh air might be where the heat is transferred to the raised to, for example, 18˚C having separate stream of incoming fresh air, passed through the MHRV. The thereby eliminating the need to efficiency of recovery completely heat the fresh air as it enters should exceed 75% for the nominal

The sommer-bypass can be used for cooling in the the building. It is important to appreci- range of flow rates specified for the unit summer if needed. Source: MosArt Architecture. ate that the stale exhaust air and clean when measured in terms of the supply-

page 18 https://www.mosart.ie/ air side temperature ratio as described in for different dwelling designs. Taking the 0.45Wh for every m3 transported air in EN 13141-7:20041. Specifiers and design- prototype house presented later in the calculation of electricity (due to ers should be wary of products claiming Section 3 as an example, an occupancy MHRV). When designing a passive house extraordinary efficiency rates of 95% or of five persons would require 150 m3 of in Ireland the specific fan power should higher. The safest route is to install fresh air delivered to the house per hour. be carefully considered as the electricity equipment that has been independently In terms of extract, the PHPP software consumed for fans has direct impact in tested and verified by such bodies as the uses the following rates for different terms of primary energy performance Passivhaus Institut. room types as default values, kitchen = and hence the Building Energy Rating 60m3/h, bathroom = 40m3/h , shower = (BER). Therefore, specific fan power for The graph below is based on actual 20m3/h and WC = 20m3/h. In the proto- fans should be less than 1 W/l/s . testing of the first Irish passive house in type house these total 140 m3/h which is Wicklow. It illustrates, for example, how Winter and Summer Mode close to the supply volume which will mechanical ventilation ensures good There are generally two ventilation ensure that the whole house system will indoor air quality by removing the high modes in a passive house: Summer be balanced. The supply and extract concentrations of a tracer gas that was Mode and Winter Mode. In winter, the volumes can be accurately set by using a deliberately released into the house as MHRV uses the heat in the exhaust air to digital anemometer and adjusting the part of the test procedure. In less than warm the incoming fresh air. In summer, valves on the vents in each room as 1.5 hours the air quality in the house had a bypass in the equipment can be set to required. A photograph of this process is returned to normal. open automatically (controlled by shown below. ) such that the incoming Recommended Ventilation Rate Adjustment of Fan Speed and Exchange fresh air is not heated. Alternatively in According to the Passivhaus Institut, the Rate summer natural cross ventilation may be appropriate air change rate for dwellings Most MHRV machines have different used and the MHRV system can be is between 0.3 and 0.4 times the volume settings for different circumstances. switched off. of the building per hour, with a general These are often referred to as a ‘party’ recommendation of leaning toward the Insulation and Positioning of Work setting, where there are a lot of people lower rate. This maintains high indoor air and Vents in the house and where additional fresh quality while ensuring a comfortable It is very important to adequately air is required, and ‘holiday’ setting, level of humidity and maximizing insulate the supply air ducting so that where the house is being left vacant and energy savings. there is minimal loss of temperature in the flow of air is reduced. Under normal delivering warm air around the house. Compliance with the Irish Building occupancy, the former of these settings The thickness of insulation generally Regulations Part F might require more air will use more energy and also decrease used in passive houses is between 6 cm changes per hour than the Passivhaus the level of humidity whereas the latter and 10 cm for ductwork. It is also prefer- Institut recommends. It is possible to will use less energy and perhaps lead to able to locate the ducting within the enter a higher air changing rate into the an increase in humidity. thermal envelope and to keep pipe runs PHPP which consequently leads to a slight It is not advisable to constantly run the increase of the energy consumption. equipment on the lower setting just to The PHPP software suggests that 30m3 save energy when the house is occupied. per person per hour should be provided MHRV machines uses surprisingly little to dwellings to ensure good air quality. energy given the important role that These two measurements can be used to they play in the passive house. The PHPP choose an appropriately sized machine software uses a standard value of

Using a digital anemometer. Source: MosArt Architecture IR Concentration

Hours Graph depicting how mechanical ventilation ensures a good indoor air quality by removing the high concentrations Ceiling air supply vent. of tracer gas that were inserted into the house under test conditions. Source: UCD Energy Research Group. Source: MosArt Architecture.

https://www.mosart.ie/ page 19 noticeable. MHRV machines are gener- out the house is through the mechanical ally housed in a well insulated casing ventilation system. This section of the and noise should not be a critical issue. guidelines will provide an overview of the typical backup heating systems used Maintaining Good Air Quality in passive houses to provide thermal It is important that attention is paid to comfort1. regular replacement of air-filters for both incoming and exhaust air. Filters are It is recommended to use high efficiency used not only to provide clean air for the heat generation systems for this auxiliary Dust laden used . Source: MosArt Architecture. occupants but also to ensure that the purpose. The HARP database (viewable heat exchanger is not clogged with dust on www.sei.ie) provides output and and other matter. If the filters are not efficiency data on a wide range of boilers regularly replaced (for example every six and other heating appliances, and is to twelve months) and they themselves updated on a monthly basis. become clogged with dirt the MHRV will Insulated distribution pipes and hot have to work harder to provide the same water cylinders are mandatory to reduce volume of air to the house, thereby the heat losses, achieve a quicker increasing the speeds of the fans and, response and increase the efficiency of ultimately, using more energy. In the heating and hot water system. The countries where this system is relatively details (length of pipes, size of hot water new, occupants may not be aware of this storage, thickness and thermal conduc- maintenance need and indoor air quality tivity of the insulation) can be entered may suffer as a consequence. Equipment into PHPP. differs with respect to the types of filters

Water to air heat exchanger unit. used; some have to be replaced while Furthermore the fuel has to be taken Source: MosArt Architecture. others can be washed and reused. into account. Electric energy has a primary energy factor of 2.7 whereby for In single family houses, the extractor gas or oil the factor is 1.1. Where practi- hood in the kitchen is sometimes cable therefore, the use of electrical as short as possible by ideally position- connected to the MHRV equipment to heating appliances should be avoided to ing the MHRV unit in the centre of the extract kitchen smells and to use the prevent incurring such a penalty in house. This requires careful planning at a waste heat from cooking to warm the primary energy use, which will have an very early stage of building design. incoming fresh air. In such instances, it is adverse effect on the Building Energy very important that the hood is fitted Vents are normally placed in the ceiling Rating (BER) using the official DEAP with a high quality filter that can easily but can also be placed in the wall if methodology. This penalty is greatly be cleaned or replaced in order to necessary. The air inlets are typically reduced if using a correctly sized and prevent the built up of grease in the designed to spread the air horizontally high efficiency heat pump for such an ducting system which could be a health across the ceiling, minimising downward auxiliary purpose. and fire hazard. draughts. There should be a gap either PHPP specifies for wood pellets, chips under or over the door of each room to What happens in the event of a power and logs a primary energy factor of 0.2. enable the easy movement of air from failure? Because DEAP calculates with a primary one room to the next. If doors are fitted If there is a loss of electricity (and the energy factor of 1.1 for wood based fuel tight without such a gap, rooms with dwelling has no backup generator) the the results for the primary energy exhaust vents would be under negative ventilation system will stop working and demand for space heating and DHW pressure and rooms with supply air the supply of fresh air will be cut off. If differ significantly between PHPP and would be under positive pressure. power is lost for a short while (for DEAP. example a few hours), then there is likely Noise to be no noticeable difference in indoor Space heating demand in a passive Fan and valve noises can be almost air quality. If the loss of power is house is typically met through passive completely eliminated by sound control prolonged, the simple solution is to open solar gains (40 – 60 %), internal heat measures (e.g., vibration isolation the windows and to create natural cross gains (20 - 30%) and the remainder (10 - mounts, low air speed and acoustic flow ventilation through the building. 40%) needs to be provided from auxil- lining in ducts). The on vents iary heating systems . generally guide incoming air along the Backup Heating System ceiling from where it uniformly diffuses As previously highlighted in these The PHPP software will accurately throughout the room at velocities that guidelines, space heating requirement predict the following two measure- are barely perceptible. If the ventilation in a passive house is so low that there is ments for each passive house design: equipment is operating on a high no need for a traditional space heating Annual Space Heat Requirement – setting (‘Party Setting’) the noise of the system. The optimal way to transfer the this measures the amount of energy equipment and the air flow may be more small amount of required heat through- that is needed to maintain a

page 20 https://www.mosart.ie/ comfortable indoor temperature, circulated through the device, hence the An independent combustion air specified in kilowatt hours per title of ‘water to air heat exchanger’. supply must be provided to any square metre of treated floor area Once the house has reached the stove or boiler in a passive house per year, or kWh/(m2a). programmed temperature, the hot bearing in mind the level of airtight- water stops circulating and the air is no ness that has to be achieved. The Heat Load – this measures the capac- longer heated. The water in the domes- provisions of an air supply and flue ity of the space heating system tic hot water (DHW) tank is heated, in for stoves or boilers will generally required to maintain comfortable turn, by using a number of energy not significantly impact on airtight- indoor temperatures at any one sources including a stove or boiler (for a ness or the balancing of ventilation time, specified in Watts per square larger house) in combination with solar flows due to the ‘closed’ nature of metre of treated floor area, or W/m2. hot water panels. The principal advan- their construction. Air required for For the prototype house the annual tage of this system over the compact combustion is drawn in through a space heat requirement (without losses unit system described below is that relatively small diameter duct and of the heating system) is 13 kWh/(m2a). when fueled by a combination of expelled through the flue. Including the losses the so called final firewood and sunshine it is carbon Most wood stoves are highly energy is 26 kWh/(m2a) equating to neutral. efficient (up to 80 – 90%) and when approximately 2,860 kWh over an entire Compact Unit with Electrical Heat Pump burning pellets there is very little ash year (the house measures 110m2 in This system is so-named as it incorpo- remaining following combustion. A treated floor area).This would equate to rates all of the technology required for a flue will be required to take exhaust 270 litres/year of oil, 280 m3/year of passive house in a relatively small unit, gas emissions safely away from the mains gas or 570 kg/year of wood pellets namely the MHRV, the DHW and the house, as with any typical stove. (in bags) heating power for the home, in this case A stove or boiler that directs most of The heat load, on the other hand, is powered by an electrically powered heat the heat output to the DHW tank is approximately 1,800 W, or just 1.8 kW. pump. It is therefore very suited to essential if the hot water is to be used This amount of energy could be smaller homes where space might be to heat the ventilation air. If there is a provided by a very small stove / heater / limited for large tanks, stoves and need to back up the MHRV the stored boiler compared to what might be storage for wood. It is important to use a hot water will be used to re-heat the typically required in a family home. heat pump with the highest possible fresh air. This system can be used in efficiency (coefficient of performance or The most common method of ‘heating’ combination with thermal solar CoP) based on test results for these in a passive house is by post-heating the panels or other heat sources. A circumstances of use. Compact units are fresh air after it has already been model that simply radiates all the becoming more widespread in use in warmed by the exhaust air in the MHRV. heat into the space in which it is passive houses built in Central and There are a number of ways in which the located cannot generally be used for Northern Europe. temperature of the air can be boosted, whole house heating. Besides, it including those listed below: A 3D model of a typical compact unit is should be appreciated that there is a illustrated right. Water to air heat exchanger; Wood pellet/wood log boiler Compact unit with electrical heat Wood pellets or wood logs can be used pump as a heat source for a simple stove, back Wood pellet/wood log boiler; and boiler or for a boiler in the plant room to serve as an auxiliary or backup source of Compact unit with natural gas heat. The following issues should be The first three of these are explored in remembered when considering outline below. The compact unit with installing a wood stove or boiler: natural gas, while used in Central Pellet boilers are available in types Europe, is virtually unheard of in Ireland loaded automatically or manually, and would have to be approved for use whereas wood log boilers for domestic by the appropriate authorities. use are only manually charged. Water to Air Heat Exchanger The equipment must be sized appro- This method involves using a heating priately to the heat load of the device placed immediately on the fresh house. This will be defined by the air supply outlet of the MHRV. There is a ‘Verification page’ in the PHPP small inside this device and it is software. Taking the prototype heated by hot water connected to the house presented in these guidelines, domestic hot water tank. If the house a stove of 3kW output would be needs additional heat (which is deter- sufficient for all space heating and Compact unit including ventilation heat recovery and mined by a ) then hot water is air to water heat pump. (Source: Passivhaus Institut, DHW needs. Germany http://www.passiv.de)

https://www.mosart.ie/ page 21 high risk of overheating when using Automatic control of space heating The preferred internal temperature can a room heater or back boiler in the on the basis of ; be set using an internal thermostat. If living area because passive houses the internal temperature goes below the Automatic control of heat input to have very low heat losses through thermostat setting, the system will stored hot water on the basis of the building envelope. automatically start to heat the fresh air stored water temperature; passing through the ventilation equip- As previously indicated, it will often Separate and independent auto- ment. The principal function of the be logical for such units to be used matic time control of space heating heating control system is to ensure that for not only auxiliary space heating and hot water; there is always sufficient heat in the but also for auxiliary water heating. buffer tank to deliver the heat load Shut down of boiler or other heat Although the demand for such wood required to maintain the comfort levels source when there is no demand for fuel will be low, a dry space for set by the occupants. In the case of the either space or water heating from storage has to be provided. Wood Out of the Blue demonstration house, if that source. (whether logs, chipped or in pellets) there is insufficient heat in the buffer is bulky and a considerable volume is Additional control features can be incor- tank, and the solar input can not cover required for storage especially if it is porated to a heating system so the the heat demand at that particular time, purchased in bulk to keep costs to a overall system performance improves. the pellet stove can be ignited automat- minimum.It is recommended that One example is the ‘weather compensa- ically to provide the backup required. the demand of at least 1.5 years is tion’ feature, which is the ability to The pellet stove will then cut out when stocked up. The consumption of adjust the output of the system based there is sufficient energy available. A pellets in the example in Section 3 is on the measured external temperature. similar control system is found in the about 0.5 tonnes per year. The main advantage of using weather compact units, except that a heat pump compensation is that the heating system is used instead of a pellet stove. Integrated controls for heating in a closely monitors external temperature Passive House The amount of heat delivered to the trends and adjusts the output accord- Heating systems in Ireland have tradi- fresh air by the heat exchanger is ingly. If, for example, the external tionally been simple, with among the regulated by the internal and external temperature starts to drop rapidly, the most common boiler based systems temperatures. The control system is system can ‘anticipate’ that the dwelling being a timer and a cylinder thermostat, usually set up to deliver a relatively high may come under pressure to maintain its and with sometimes even room thermo- heat load if the temperature outside is current internal temperature and can stats being absent. However, the very cold, or alternatively a low heat load verify whether there is sufficient power Building Regulations Part L require if it is not too cold. to generate the backup heat that might minimum levels of control, installing be required. It would also be possible to use an equipment to achieve the following: ‘instantaneous’ system eliminating the need for a large buffer tank. Such systems do not typically suit the use of a pellet boiler, however, as the boiler would have to switch on and off for short periods of time to maintain an even temperature in the house.

The PHPP software assumes that the heating system is controlled by programmable timer and thermostats. However, the use of DEAP needs more detailed input data from the designer, specifier or BER assessor on the auxiliary heat generation, distribution and control system here.

Individual Room Temperature Control Different rooms may have different temperatures due to solar gains, occupa- tion and internal heat loads. Room based temperature controls for temper- ature differentiation between different rooms may be necessary if individual comfort requirements are set for differ- ent rooms. In a centralised ventilation Schematic of mechanical system that can be used for back-up heating in a passive house. heating system, however, the supply air Source: Passivhaus Institut, Germany (http://www.passiv.de).

page 22 https://www.mosart.ie/ temperature is relatively constant for the litres of oil. Many people would be A comparison of the performance of whole house and this would be typical surprised to learn that Dublin receives a these types, based on 5m2 collector area, for most houses built to the Passivhaus similar amount of annual irradiation as along with consideration of orientation Standard. Paris. and angle of incidence, is provided in the table over the page. The calculation Domestic Hot Water Production The table over the page shows that the was developed as part of these guide- As in any type of dwelling, the passive solar input and gain are dependent on lines for the prototype passive house house requires a system that provides the efficiency, orientation and angle of using the calculation methodology for domestic hot water (DHW). As with the solar collectors. solar water heating in the Dwelling space heating, it is important that the Assuming an area of 7.5 m2 south orien- Energy Assessment Procedure (DEAP system is energy efficient, well tated flat plate solar collectors with a tilt 2005, version 2). controlled and has an adequate capacity of 45° the solar contribution in our to meet demand. Generally the DHW Three different inclinations of solar example is 60% of DHW demand. The system in a passive house is combined panels (30˚, 45˚, 60˚) and three different remaining energy for DHW has to be with a heat source such as a wood stove, orientations were calculated, with the provided by the backup heating system. , compact unit or following specification: standard heat pump for space heating. Most In terms of specifying a solar collector number of 3.6 occupants according to passive house examples encountered system, the following outline guidance DEAP assumption, water storage tank have utilised solar thermal collectors as should be considered: 300 litres, with 150 litres dedicated to they reduce the use of primary energy solar, and 50mm factory insulation, with The optimal orientation is directly and CO emissions. It is important to thermostat control. 2 due south and deviation from this note, however, that the Passivhaus will reduce the contribution of the As a general rule of thumb, the area Standard is indeed achievable without collectors to DHW production. In of solar panels is roughly 1 to 2 m2 of solar based water heating. The introduc- places where there is no south facing collector area per person. The tion of Building Energy Rating system as roof, correspondingly larger panel system should be capable of provid- an indication of the energy performance areas can be fitted to east or west ing up to 50 litres of DHW per person of dwellings in Ireland, together with the facing roofs. per day in season. mandatory requirement in the Building Regulations Part L 2007 in relation to The optimal tilt of the solar panels to In terms of sizing a solar tank, a renewable energy provision is likely to meet approximately 50% of the minimum of 80 and preferably 100 increase the installation of solar technol- annual heating demand for DHW is litres storage per m2 of collector ogy. approximately 45 degrees (in a pitch should be provided. In a typical Irish that is greater than 45 degrees the home this could mean installing a The required volume of DHW is depend- potential annual output is compro- tank of between 300 and 500 litres ent on occupancy. PHPP assumes 35 m2 mised somewhat). capacity. It is important to use a treated floor area per person. It is also proper solar water tank which is very possible to enter in the verification sheet There are two types of solar collec- well insulated. Insulation of hot the actual number of occupants. The tors typically used, namely flat plate water pipes is also important for default settings for DHW in PHPP are 25 l panels and evacuated tubes. energy conservation, the thickness per person per day with a flow tempera- ture of 60° C.

Approximately 530 kWh/yr of useful heat per person plus provision for storage losses and distribution losses must be supplied.

Domestic Water Heating – Solar Input It is reasonable to expect that an optimized solar based system (flat plate or evacuated tubes of 5-7m2 area) will produce up to 60% of total annual hot water demand in the Irish climate. They tend to have a relatively shorter pay back period in comparison to other renewable energy technologies such as wind turbines or photovoltaic panels. In Ireland the amount of solar irradiation received each year is approximately 900- 1150 kWh/ma. After conversion into heat, this is the equivalent of over 30 Yearly total of global horizontal irradiation (kWh/m2) UK and Ireland. Source: European Commission Directorate General, Joint Research Centre http://re.jrc.cec.eu.int/pvgis/countries/europe/g13y_uk_ie.png

https://www.mosart.ie/ page 23 the house including all household appli- 5 square meters of FLAT PLATE collectors (η =0.75 and a1=6) 0 ances and lighting. In order to achieve No obstructions: the above mentioned Passivhaus Solar Input kWh/year Tilt of collector Standard it is necessary to specify refrig- South SE/SW E/W erators, freezers, cookers, artificial light- 30O 1264.9 1246.3 1191.2 ing, washing machines, dryers, etc. with 45O 1264.2 1240.4 1167.9 the highest energy efficiency available on the market (i.e. category ‘A’ energy 60O 1248.5 1221.3 1137.0 rated household appliances). The Solar input to demand ratio Tilt of collector second step is calculating the auxiliary South SE/SW E/W electricity requirement, in which 30O 49% 48% 46% electricity consumption is specified for 45O 49% 48% 45% mechanical ventilation system fans and 60O 48% 47% 44% controls, DHW circulation pumps, and any other present in the dwelling. Calculation results are presented in 5 square meters of EVACUATED TUBE collectors (η0=0.6 and a1=3) primary energy kWh/(m2a) and included No obstructions: in the PHPP ‘Verification page’. Solar Input kWh/year Tilt of collector South SE/SW E/W Comparison between PHPP and DEAP 30O 1324.3 1300.7 1231.5 Primary energy factor (most important O 45 1323.4 1293.2 1202.5 values) 60O 1303.4 1269.1 1164.4 PHPP DEAP Solar input to demand ratio Tilt of collector South SE/SW E/W Oil 1.1 1.1 30O 51% 50% 48% Gas 1.1 1.1

O 45 51% 50% 47% Electricity 2.7 2.7 60O 50% 49% 45% Wood Pellets/Log/Chip 0.2 1.1 Domestic solar water heating - solar input (flat plate collectors and evacuated tube) for the prototype passive house (described in Section 3), calculated with the Dwelling Energy Assessment Procedure DEAP 2005 version 2. Source: UCD Energy Research Group. 2.3 Energy Balance Calculations and Passive House Specification of insulation should be at least Electricity Consumption in a Passive equivalent to the pipe diameter and House 2.3.1 PHPP Software and preferably 1.3 times the pipe diame- The Passivhaus Standard primary Applications ter. energy requirement has a limit of 120 kWh/(m2 year), regardless of energy An introduction to the PHPP was The 40% or more of DHW needs that are source for all space and water heating, provided at the beginning of this not provided by solar energy can be met ventilation, electricity for fans and Section within a discussion of the build- by several means including biomass pumps, household appliances, and ing design process for passive houses. boilers or stoves, immersion heaters or lighting energy requirements of the PHPP is a software package based on a natural gas. An outline of the first of house. This limit means that in a passive series of extensive and interlinked Excel these is provided below. It must be house the efficiency of household data sheets which collectively allow remembered that space heating in a appliances and all electrical systems is building designs to be verified against passive house is often provided by using crucial to meet this challenging require- the Passivhaus Standard. The latest hot water to heat the air passing ment. This is emphasised with the fact version of the PHPP software can be through the ventilation system. In such that the primary energy factor for purchased for a nominal fee from SEI cases, hot water production is essential electricity taken in the PHPP software Renewable Energy Information Office. in the heating season when solar panels (as well as in the DEAP, Dwelling Energy The verification requires the input of on the roof will not be sufficient to meet Assessment Procedure) is 2.7. Therefore very specific and detailed data about the the demand for heating the hot water. 1kWh electricity used in a passive design, materials and components into Accordingly, many passive houses will house accounts for 2.7kWh of primary the PHPP spreadsheets and is then have a biomass stove burning either energy. related to the climate data for the region natural logs or wood chip or pellets. An in which the house would be built. The advantage of the last two of these is that When designing a passive house, the validity of the result from this process is they are more easily automated so that PHPP software is used to calculate the of course highly dependent upon the they fire up and switch off in the same electricity balance. The first step is to validity of the data entered. way as a conventional gas or oil burner. calculate the electricity requirement in

page 24 https://www.mosart.ie/ Some of the principal datasheets friendly and the Verification page included in the software are listed enables the user to check whether or not below, along with their main functions: such thresholds such as Space Heating Requirement are met. In the event that Climate data – it is possible to the key Passivhaus Standard criteria are choose the climate which the not met, for example, the assessor will passive house is being designed for. firstly have to check to see if there are This has a potentially significant any fundamental errors in terms of data impact on the U-values required to entry. If this is not the cause of the achieve the threshold annual heat problem, then the building will likely requirement. have to be modified in order to achieve Verification – this sheet collates the the required standards. This will typically results of the overall evaluation of involve improving the U values of the the building including the space building envelope, or altering the heating requirement, specific proportion and orientation of glazing. primary energy requirement, heat Extracts from the PHPP software are load and frequency of overheating. included later in Section 3 pertaining to The user can see at a glance on this the prototype passive houses. sheet whether or not the building can be certified as a Passive House. 2.3.2 Passive House Certification Passivhaus Institut Certificate example, Quality U-value – this sheet enables the Approved Passive House. At the time of writing these Guidelines, a Source: Passivhaus Institut, Germany. assessor to specify the construction passive house in Ireland can be certified of all the opaque (ie. does not by the Passivhaus Institut in Darmstad, include windows) elements of the certifying party. If the necessary verifica- Germany (http://www.passiv.de ) or building envelope for the purposes tions have been found to be correct and certifying body approved by the of calculating the U-values of those the above criteria have been met the Passivhaus Institut. For further informa- elements. The sheet requires the ‘Quality Approved Passive House Dr. tion on certification of passive houses in input of the lambda value of the Wolfgang Feist’ certificate is issued Ireland contact the SEI Renewable building materials proposed as well (PHPP 2007, pp.28). Energy Information Office or the as their thicknesses and the propor- Passivhaus Institut directly. The evalua- A wider European passive house certifi- tion of insulation occupied by struc- tion criteria for the certification (Source: cation scheme was developed within the tural elements. PHPP 2007, pp.23) are: Intelligent Energy Europe Windows – the orientation and size project (2005-2007) “Promotion of - Specific Space Heat Demand of all windows is entered into this European Passive Houses, PEP” max. 15 kWh/(m2a) sheet, along with the U-values of the (http://www.europeanpassivehouses.org). glass and frames as well as other - Pressurisation Test Result n50 This certification scheme is applicable to technical specifications which have max. 0.6ac/h ‘an emerging market scenario’ (i.e. discussed earlier in this Section. countries with small number of passive - Entire Specific Primary Energy house building), aims to ensure that the Annual Heat Requirement – this Demand max. 120kWh/(m2a) includ- design of a particular passive house can value is calculated by determining ing domestic electricity. deliver the specific energy requirements the heat losses through transmission in accordance with the PHPP and confirm The above criteria have to be verified and ventilation and subtracting the the airtightness of the completed build- with the PHPP 2007, and the required list total solar and internal heat gains. ing. This certification scheme involves of documentation for the passive house The annual heat requirement must the verification of the 'as built' design (i.e. quality approval certificate, construction be less than 15 kWh/(m2a). that reflects the actual construction, drawings and technical specification incorporating any modifications made Heat Load – the building’s heat load with product data sheets, must be during construction) in accordance with is based on energy balance calcula- submitted to the certifying party the PHPP and confirmation of the air tions estimated by subtracting the (including PHPP calculations). Also, tightness of the completed building by a minimum solar gains and internal verification of the airtight building fan pressurization test performed in heat sources from the maximum envelope according to IS EN 13829, a accordance with IS EN 13829. transmission and ventilation heat record of adjustment of the ventilation losses. system, declaration of the construction Since the above assessment criteria supervisor and photographs of the apply to the 'as built' design details and The PHPP software is comprehensive complete building must also be submit- the completed building, there is a signif- and detailed and therefore requires ted. Upon examination of received icant risk that any non compliances due some training prior to embarking on documentation the applicant receives to fundamental errors will be difficult to practical application to a real project. the results of the examination from the correct when the building is complete. It However, the software is also quite user

https://www.mosart.ie/ page 25 Januray 2006 - November 2007 OUT OF THE BLUE TEMPERATURES

30

25

20 Bathroom Down Kitchen Main bedroom Stairs 15 Garage Living room Degree Celsius Office 10 External Temperature

5

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

2006 2007 Month

Average daily temperatures, January 2006 – November 2007, monitoring results for the first passive house in Wicklow. Source: UCD Energy Research Group. is therefore recommended that the house. They can indeed be opened but night depending on how many friends design is checked against the PHPP they don’t have to be opened. In a and neighbours you manage to attract before construction is started to confirm passive house the ventilation system to join the celebrations! that the criteria for the specific heating ensures that a constant controlled As an illustration of the indoor tempera- and primary energy requirements are amount of fresh air is circulated around ture comfort, monitoring results of the met, that the construction on site is the house so a stuffy or uncomfortable room temperatures in the passive house checked to ensure that the dwelling atmosphere is avoided. If the occupants in Wicklow and site measured tempera- design has been realised and that air would prefer to have the windows open ture is shown below. The graph repre- permeability measurements are made at night or provide natural cross ventila- sents measured average indoor and during the construction process so that tion during a hot summer’s day then it is outdoor temperatures from January air leakage problems can be identified entirely possible to open whatever 2006 to November 2007. and remedied while access to the windows or doors one chooses. The membranes etc is still available. MHRV should be switched off if there are The above diagram illustrates tempera- a lot of windows or doors being left ture variation in different parts of the Since the actual performance of the open as it would be an unnecessary house and cooler average temperatures building will be very dependent on the waste of electrical energy. in the first heating season (early 2006) correct operation and maintenance by compared to the second and third the occupant, it is recommended that Living in a passive house encourages a heating seasons (late 2006 / early 2007 adequate written information and greater interest in and awareness of and late 2007 respectively). The reasons instructions are provided to the weather patterns and the impact they for these variations are interesting and occupants, at the time when the certifi- have (or don’t have) on indoor climate. warrant some elaboration, below: cate is issued. Also, an approach to certi- The passing of cloud cover brings with it fication of products and technologies instant brightness and rising tempera- The three coolest rooms (‘office’, used in passive house designs has been tures on the display panel for the solar ‘garage’ and ‘bathroom down’) are developed. (Source: PEP Promotion of collectors. A very hard frost will each on the north side of the build- European Passive Houses, passive sometimes leave a veil of ice crystals on ing, receive no direct sunlight during house building certification, the outside pane of the glazing which the winter months and are very http://www.europeanpassivehouses.org ). rapidly melts in the morning sunshine. infrequently used compared to the Extremely cold clear weather usually remainder of the house. The first two For further information on passive house means that the backup heating is not of these spaces have three external certification in Ireland contact required during the day due to the high walls and so are more prone to heat Sustainable Energy Ireland Renewable levels of solar irradiation available. Dull losses compared with the rest of the Energy Information Office, SEI REIO muggy days, on the other hand, while house. email: [email protected] not especially cold, may well require the The three warmest rooms (‘kitchen’, Lifestyle Issues use of the pellet stove due to the lack of ‘main bedroom’ and ‘stairs’) all open It is a common misconception that sunlight. Windows may have to be flung out to the south of the house and so windows cannot be opened in a passive open to cool the house on New Years Eve

page 26 https://www.mosart.ie/ receive the maximum amount of last the test of time. The heavy doors and solar gain in winter. Furthermore, windows close with a reassuringly solid References they are occupied for significant ‘clunk’ and keep out draughts and Passive House Planning Package 2007, parts of the day and / or night. reduce external noise. The walls are thick “Protokolband and substantial and are packed full of 16:Waermedrueckenfreis Konstruiren In the first few months of 2006, the insulation to keep out the cold and the (Thermal Bridge-Free Construction)”, only backup heat source in the heat in. There is no condensation on the pp.96. PHPP 2007 Technical house was a pellet boiler in the internal glazing early on a cold morning. Information PHI-2007/1(E), Passive sitting room. This alone was insuffi- House Institut, Dr. Wolfgang Feist. cient to heat the entire house as its The health aspects of living in a mechan- direct output into the room is just ically ventilated house are also readily Passive House Planning Package 2007, “Certification of Passive Houses”, pp.28. 2kW. As a result, those rooms on the apparent, with no lingering odours, little PHPP 2007 Technical Information PHI- northern side of the house were or no condensation in washrooms after 2007/1(E), Passive House Institut, Dr. below thermal comfort levels for the showering and an overall sense of high Wolfgang Feist. first few months of 2006. This went indoor air quality throughout. Changing largely unnoticed by the family due the filters on the ventilation system is European Commission (EC), 2006. “ to the fact that the rooms in always an eye opener – seeing what dust Promotion of European Passive Houses (PEP)”. [Internet] PEP. Available at: question are not used. Since then and dirt is taken out of the incoming air http://www.europeanpassivehouses.or the temperatures have continued to and what is extracted from the indoor g/html improve. air. Schnieders J. 2006, “Climate Data for In the autumn of 2006, a water-to-air Living in a house that has a low carbon Determination of Passive House Heat heat exchanger was fitted to the footprint can bring about other changes Loads in Northwest Europe”. MHRV equipment which enabled in lifestyle that are positive for the Darmstadt, Germany, Passivhaus heating the fresh air as it passes environment, including growing your Institut. throughout the house. This was own food and reducing the impact of actively used for the first time in travel whether by car or by plane. 1 December 2006 which resulted in Raising children in a passive house will IS EN 13141-7:2004, Ventilation for buildings/ performance testing of raising the temperatures in all rooms also bring about positive change for the components/products for residential (even those three on the north side) next generation who will expect to ventilation. Performance testing of a to well within the normal comfort improve even further on what their mechanical supply and exhaust ventila- level. In late 2007 the temperatures parents achieved. tion units (including heat recovery) for have improved yet again. mechanical ventilation systems Perhaps the overall lifestyle benefit of intended for single family dwellings. There is still in evidence a tempera- living in a passive house is that it 2 Thermal comfort is defined in British ture gradient (increasing in tempera- provides very high levels of overall Standard IS EN ISO 7730 as: ‘that condi- ture) from north to south and from comfort without compromising the tion of mind which expresses satisfac- first floor to ground floor. environment and at a fraction of the cost tion with the thermal environment.’ It is of living in a traditional so-called affected by the key environmental The specification of materials and very factors as air temperature, radiant ‘normal’ house . high quality build creates a strong sense temperature, air velocity and humidity. of living in a well-built house that will

https://www.mosart.ie/ page 27 https://www.mosart.ie/ SECTION THREE

Passive House Prototype for Application in Ireland

https://www.mosart.ie/ https://www.mosart.ie/ Passive House Prototype for Application in Ireland

This Section of the guidelines demon- 3.1.1 Combining Aesthetic and strates the practical application of Energy Performance in House The prototype house presented below Passivhaus Standard to a prototype Design would achieve a BER rating of A2. passive house designed with a view to Should an A1 BER rating be desired, The design of a passive house is strongly one method of achieving this would its suitability for the mass housing influenced by the need to minimise heat be to improve the U value of the market in Ireland. The house type loss through the building fabric, to opaque elements of the entire build- demonstrated is a semi-detached two ing envelope from 0.15 W/(m2K) to 1 maximise solar gains and to cater for the storey house measuring approximately 0.10 W/(m2K), increase the area of 2 various building services. Form and 110m . The house is depicted in plan 2 2 function played equal roles in the design solar panels from 7.5m to 10.0m , and elevation below. The house is increasing the efficiency of the of the passive house. The overriding typical in most aspects of its design, heating system from 80% to 85% and principle used in the design of the house comprising three bedrooms upstairs adding approximately 7m2 photo was that it should be broadly similar in (including one ensuite and family voltaic panels. There would be other character to a conventional house, thus bathroom) and a living room, dining methods of improving the BER rating maximising ease of acceptance to the room, kitchen / utility and wheelchair other than those specified above. current housing market in Ireland. Furthermore, it has to be highlighted accessible WC downstairs. There are also that not all buildings designed to the some non-conventional elements As has been described in some detail in Passivhaus Standard would achieve an including a double-height sun room, the preceding sections, much of the ‘free’ A2 or A1 rating. The example below solar panels, pellet boiler and shading energy required to heat a passive house has been especially designed to pergola. These are all described in comes directly from the winter sun achieve both a good BER rating as well greater detail below. through south facing windows. It is there- as meeting the Passivhaus Standard, fore typical (though not essential) to have using both DEAP and PHPP. The final part of this section examines a bias in terms of placement of glazing on the capital construction costs associ- the southern elevation. Combined with ated with the passive house. such glazing is the need to prevent 3.1.2 Decision Support using Passive overheating in summer and this is easily House Planning Package (PHPP) 3.1 Design and Specification ensured through the use of shading, in this Software The two most common construction case with a balcony and pergola. The walls The Passive House Planning Package methods in Ireland were used in the of a passive house are typically thicker (PHPP V2007) has been introduced design and specification of the proto- than those of conventional construction already in these guidelines. It is an Excel- type passive house, namely timber due to the need for additional insulation based software that can be used to ‘test’ frame and concrete block2. It is demon- and this must be borne in mind in the early the energy performance of a building as strated below that the Passivhaus stages of design development. Another it is being designed. It includes Irish Standard can be easily achieved in key issue to consider when developing the climatic data which is useful in ensuring Ireland using both of these construction design of a passive house is the need to that buildings are not over-specified in methods and that there are no major minimise thermal bridging including that terms of thermal performance. Key advantages of one method over created between the foundation and inter- aspects of the emerging prototype another in terms of thermal perform- nal walls, for example. Bearing in mind the passive house are entered into the ance. Both passive house construction above principles of glazing orientation, software with a view to ensuring that types can be built using mostly conven- wall thickness and minimised thermal the design achieves the minimum tional materials as can be seen from the bridging, the designers commenced the requirements of (a) space heating deliv- detailed wall sections provided in development of the prototype passive ered energy demand of 15 kWh/(m2a) section 3.1.3. house. treated floor area (TFA3), and (b) upper limit for total primary energy demand

https://www.mosart.ie/ page 31 for space and water heating, ventilation, performance materials (in terms of lower ing. In both cases, the maximum space electricity for fans and pumps, house- Lambda values) requiring thinner walls heat requirement of 15 kWh/(m2a) has hold appliances, and artificial lighting than other less efficient materials. been achieved. not exceeding 120 kWh/(m2a), regard- Two extracts from the PHPP software are The second extracts provide an insight less of energy source. included below for both the timber into how the U-values of major building The thickness of insulation required in frame and masonry construction proto- elements are calculated for both timber the walls, floor and roof is evaluated and types in order to give an insight into how frame and masonry construction types. guided by the PHPP software, as is the the software can be used to assist the The table provide details on how the specification and positioning of the designer. The first extracts comprise the required U-values have been achieved windows, the sizing of the back-up space so-called ‘Verification’ page which for walls, floors and ceiling. The partial heating system, the consideration of summarises the performance of both thermal bridge caused by the timber thermal bridges and many other aspects construction types in terms of such criti- studs in the timber frame option is of the design including ventilation provi- cal matters as space heat demand, accurately calculated in the software by sions. The design is thus an iterative confirmation of blower door test results, specifying the proportion of the process. Different insulation types can be specific primary energy demand, insulated wall occupied by timber (in tested in the software, with higher heating load and frequency of overheat- this case 10%).

Passive House Verification for the prototype passive house, concrete block construction. Source: MosArt Architecture.

page 32 https://www.mosart.ie/ IFC, Insulated Concrete Forms. Externally insulated concrete block wall. Source: UCD Energy Research Group. Source: MosArt Architecture.

Passive House Verification for the prototype passive house, timber frame construction. Source: MosArt Architecture.

https://www.mosart.ie/ page 33 U-value of building elements for the prototype passive house, concrete block construction. Source: MosArt Architecture.

page 34 https://www.mosart.ie/ U-value of building elements for the prototype passive house, timber frame construction. Source: MosArt Architecture.

https://www.mosart.ie/ page 35 Cross section, prototype passive house. Concrete block construction. Source: MosArt Architecture.

page 36 https://www.mosart.ie/ Cross section, prototype passive house. Timber frame construction. Source: MosArt Architecture.

https://www.mosart.ie/ page 37 3.1.3 Prototype Passive House mately 115 m3/h would be required, delivers most of the heat output to a External Wall Sections representing an approximate air hot water tank which can be used change rate of 0.4 per hour. A fresh not only for domestic hot water but The wall sections for both construction air outlet is provided to the living also as a ‘buffer’ to work in tandem types have been illustrated previously. It room, dining room, double height with a water to air heat exchanger should be noted that no dimensions are sun room (at ground floor level) and (see below). A stove that only emits included on the sections below as they bedrooms whereas an extract vent is radiant heat directly into the room in are intended to be schematic only. They provided in WC’s and bathrooms as which it is located would likely should not be used as a basis for well as the kitchen, the utility room overheat that same room due to the detailed construction drawings. and the upper part of the sun room. high levels of insulation required in a The following key issues can be noted The heat recovery ventilation unit is passive house. from the detailed wall sections: located in the utility room and will The pellet stove can be filled recover the majority of the heat from Thicker than normal wall sections manually as the need arises, or could the extracted air to warm the incom- are designed in order to accommo- be automatically fed using an under- ing fresh air. An airing cupboard is date the required depth of insula- ground pellet storage ‘bunker’ located on the first floor along with tion. There is also substantial insula- located underground to the public the washing machine. This space is tion used in both the roof and under road side of the house for ease of connected to the ventilation system the floor. delivery. While a house of this size and can function as drying cabinet could probably manage without an The insulation at the junction of roof for drying clothes in the winter. automatic feed from a bunker (given and wall, as well as wall and floor, Sound attenuators should be used in an average use of approximately 40 overlap in order to minimise thermal order to minimise noise travelling kg of pellets per week5), the advan- bridging at these critical locations. along ducts and air filters should be tage of such a system is in the space The window frame is also partly changed as required in order not to saved from having to store pellets in bedded in insulation in order to compromise indoor airflows and / or the house or garden shed. In reduce heat loss. air quality. positioning the pellet stove in the Membranes and specialist tapes are A pellet stove is proposed for the sitting room, there is a perceived used to create an airtight envelope. backup space and water heating aesthetic benefit to be gained from This is especially critical at junctions system4. For the prototype house the visibility of the flames coupled with between different elements, such as annual space heat requirement the delivery of some heat directly around windows, and also where the (without losses of the heating into the sitting room. first floor penetrates the external system) is 13 (kWh/m2a). Including It is also critically important that the wall. the losses the final energy is 26 pellet stove has its own independent (kWh/m2a) equating to approxi- A service cavity is proposed, internal fresh air supply, given the airtight mately 2,860 kWh over an entire year to the airtight layer in the timber nature of the construction, and that (the house measures 110m2 in frame wall, in order to accommodate there is an appropriate flue for treated floor area). This would mechanical and electrical fittings. A venting of exhaust gases. Such equate to 269 litres/year of oil, 277 similar cavity is proposed in the systems are commonplace in passive m3/year of mains gas or 572 kg/year underside of the ceiling at first floor houses and confer both an efficiency of wood pellets (in bags). level for both house types. and a safety benefit that will not The design or peak heat load, on the adversely affect the balanced venti- Special blockwork with low thermal other hand, is approximately 1,800 lation system. conductivity is used in the rising W, or just 1.8 kW. This amount of walls to reduce thermal bridging The large domestic hot water tank energy could be provided by a very between foundations and walls. (1,000 litre), which serves as a ‘buffer’ small stove / heater incorporating a heat store as indicated above, is back boiler, or by a small separate located adjacent to the mechanical 3.1.4 Prototype Passive House boiler compared to what might be ventilation unit, in the utility room. Design including Mechanical typically required in a family home; The backup heating system in this and Electrical Services there are several such ‘small’ heating case is provided by heating the fresh appliances on the market which The final design of the prototype passive air circulating around the house range in output from 2.4 to 8kW, house is presented below in plan, eleva- from the hot water in the ‘buffer’ with an efficiency of up to 80%. tion, section and, finally, a 3D model. A tank using a water to air heat number of mechanical and electrical The pellet stove in the prototype exchanger. In this regard, all supply features are highlighted which have house has been positioned in the air ducts should be insulated in been included specifically in the devel- sitting room, but space has also order to minimise heat losses, even if opment of the passive house prototype: been left in the utility room as this they are located within the thermal In terms of mechanical ventilation, might be preferable to users. Care envelope. an average air flow rate of approxi- must be taken to use a stove that

page 38 https://www.mosart.ie/ Solar panels (measuring 7.5m2) are design and construction implica- thermal bridging) with the remaining positioned on the south facing roof tions. 40% covering building systems includ- which is pitched at the optimal angle ing MHRV, solar thermal system, wood The timber frame option depicted in of 45 degrees. These have been sized pellet boiler and low energy lighting. these guidelines is ventilated with in accordance with the needs of such an external cavity. Gardiner and Theobald next sought to a house and could include either flat express the additional passive house plate collectors or evacuated tubes. Energy efficient light fittings should costs as a proportion of conventional be used which use less primary Other aspects of the design which are construction costs. The cost of a conven- energy (they will also reduce internal not related to the mechanical or electri- tional house varies considerably accord- heat gains). It is also recommended cal services are listed below: ing to the quality of finishes required. An to use energy efficient household average cost of €196,000 was proposed All windows in the prototype house appliances for cooking, wet appli- as representing a mid-grade finish, are triple glazed with low emissivity ances, cold appliances etc. to enable including VAT and design fees. The coating, thermally broken frames the primary energy performance additional €25,000 thus represents and gaskets especially designed to target of 120 kWh/(m2a) to be met. approximately 12.5% of conventional minimise air infiltration. A passive Various building methods can be used in build costs. house triple glazed window is the construction of a passive house, typically three to four times more including insulated concrete formwork energy efficient than a standard and externally insulated concrete block double glazed unit and, if approxi- wall, shown below. This is in addition to mately south facing, will take in the more common masonry and timber more energy in a year than it lets out. frame construction methods, as illus- The use of such glazing ensures high trated in the prototype house examples thermal comfort in cold weather shown above. through minimal temperature differ- ence between the internal glass 3.2 Cost Considerations pane surface and room temperature. An analysis of additional costs associ- A balcony is provided at first floor ated with construction of the prototype level, the primary function of which house to the Passivhaus Standard was is to shade the extensive area of carried out by Gardiner and Theobald, glass on the south elevation. This Quantity Surveyors. The additional cost balcony can be accessed via the 1 of the key items including enhanced Approximately 17% of the overall gallery which overlooks the double- insulation, glazing, airtightness and housing stock in Ireland are semi- height sun room. A wooden pergola detached dwellings. thermal bridging was estimated, along is provided overhead the balcony to 2 with the cost of such technologies as According to the Irish Timber Frame shade the upper storey windows. A Manufacturers’ Association (ITFMA) the MHRV, solar panels for DHW, a pellet possible alternative to this pergola number of timber frame house comple- stove as well as energy efficient light could be a deep roof overhang but tions has grown from a market share of bulbs and household appliances. the steepness of the pitch in the 15% in 1999 to a market share of 30% in Included in their analysis was an 2006. prototype house would mean that allowance for the foregone costs associ- 3 this latter solution would restrict The TFA is the living area within the ated with ‘conventional’ house features high level views from the upper thermal envelope. Any rooms or areas such as a and boiler with radia- beyond the boundaries of the thermal storey. tors. Gardiner and Theobald completed envelope are not considered. The internal party walls can be their analysis for both the timber frame 4 Other sources of heat such as gas or heat constructed as per a conventional and the concrete block construction pumps can also be used. house as long as it is within the types. 5 Estimated heating requirement for hot boundaries of the building water (net of 60% SWH) + space heating The additional ‘extra over’ cost associ- envelope. = 6,300 kWh = c.1,260 kg pellets/year = ated with building the prototype house 40 kg/week over a 30 weeks heating The hatch to the attic should be very to the Passivhaus Standard was season. well insulated and completely estimated at approximately €25,000 for airtight to minimise cold air infiltra- both construction types, including VAT tion. and design fees (referring to 2007 build- References ing costs). Approximately 60% of this Ceiling insulation is placed horizon- cost can be attributed towards improve- Passive House Planning Package, PHPP tally on the attic floor in the proto- ment of the building shell (enhanced 2004, Technical Information PHI- type passive house. It would also be insulation, higher grade windows, 2004/1(E). Darmstadt, Germany. possible to place this insulation Passive House Institut, Dr. Wolfgang improved airtightness and reduced between the rafters, albeit with Feist.

https://www.mosart.ie/ page 39 Prototype passive house, floor plans (not to scale). Source: MosArt Architecture

page 40 https://www.mosart.ie/ Prototype passive house, floor plans (not to scale). Source: MosArt Architecture

https://www.mosart.ie/ page 41 Prototype passive house, cross section (not to scale). Source: MosArt Architecture

page 42 https://www.mosart.ie/ Prototype passive house, front, back and side elevations (not to scale). Source: MosArt Architecture

https://www.mosart.ie/ page 43 Prototype passive house, 3D model (not to scale). Source: MosArt Architecture

page 44 https://www.mosart.ie/ https://www.mosart.ie/ Sustainable Energy Ireland Renewable Energy Information Office Unit A, West Cork Technology Park Clonakilty Co Cork Ireland T. +353 23 63393 [email protected] F.+353 23 63398 www.sei.ie

SEI is funded by the Irish Government under the National Development Plan 2007 - 2013 with programmes part financed by the European Union.

https://www.mosart.ie/