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S E I Passive House

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  • 1. Passive homes GUIDELINES FOR THE DESIGN AND CONSTRUCTION OF PASSIVE HOUSE DWELLINGS IN IRELAND
  • 2. 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 economically 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 improving 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, 2007. 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 publication 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 and UCD Energy Research Group with contribution from Sharon McManus as part of MEngSc thesis.
  • 3. Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii S ECTION O NE 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 Application 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 S ECTION T WO How to Design and Specify a Passive House in Ireland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 Building Design Process for a Passive House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 General Principles: Heat Energy Losses & Heat Energy Gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.1 Passive House Building Envelope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 S ECTION T HREE Passive House Prototype for Application in Ireland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.1.4 Prototype Passive House Design including Mechanical and Electrical Services . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.2 Cost Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 i
  • 4. 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 heat pump 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
  • 5. Foreword Sustainable Energy Ireland is Ireland’s national energy agency, 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. As we move forward, it is architects focus on new build houses and cover both becoming clear that building ‘green’ has evolved and is fast conventional block construction and timber frame becoming the preferred choice, providing high quality, high construction methods. They will ultimately become part of efficiency, dynamic and cost effective solutions for a suite of guidelines to cover, for example, multiple consumers and businesses. The passive house is the dwellings, non-residential buildings, extensions, ultimate low energy building. The passive house standard is renovations etc. recognised in Europe as the most advanced in terms of energy performance of buildings and going forward the The guidelines cover the rationale and definition of the European Commission is set on implementing the passive passive house standard, how to design and specify a passive house standard and also on setting more stringent house along with, construction options, associated services, requirements for the refurbishment of existing buildings. cost considerations and lifestyle issues. SEI hopes they will be useful in increasing awareness and understanding of the Today, the passive house offers one of the most desirable key principles and techniques in designing, constructing technological and economical solutions for comfortable and operating the ultimate low energy building – the living and working. It can be applied to new and existing passive house. buildings in the commercial, industrial, public and residential sectors. With close to 10,000 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 David Taylor clients on how to design, specify and construct passive CEO Sustainable Energy Ireland iii
  • 6. S ECTION O NE The ‘Passive House’
  • 7. 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 active space heating and summer, without traditional space or cooling systems. The space heat heating systems and without active requirement is reduced by means of cooling. Typically this includes passive measures to the point at which optimised insulation levels with minimal there is no longer any need for a thermal bridges, very low air-leakage conventional heating system; the air through the building, utilisation of supply system essentially suffices to passive solar and internal gains and distribute the remaining heat good indoor air quality maintained by a requirement. A passive house provides mechanical ventilation system with very high level of thermal comfort and highly efficient heat recovery. Passive house in Ghent, Belgium (2004). Source: Passiefhuis Platform vzw. provision of whole-house even Renewable energy sources are used as temperature. The concept is based on much as possible to meet the resulting minimising heat losses and maximising energy demand (PEP, 2006), including heat gains, thus enabling the use of that required for the provision of simple building services. The domestic hot water (DHW). It should be appearance of a passive house does not noted that the primary focus in building need to differ from a conventional house to the Passivhaus Standard is directed and living in it does not require any towards creating a thermally efficient lifestyle changes. Passive houses are envelope which makes the optimum use light and bright due to large glazed of free heat gains in order to minimise Passive house in Oberosterreich, Austria (2000). areas designed to optimise solar gains, space heating requirement. While there Source: IG Passivhaus Osterreich Innovative Passivhaus as well as healthy buildings in which to are also limitations on the amount of projekte. live and work due to fresh air supply primary energy that can be used by a through the ventilation system. dwelling for such uses as DHW, lighting and household appliances, this will not The Passivhaus Standard is a be the primary focus of these guidelines. construction standard developed by the That is not intended to imply that such Passivhaus Institut in Germany energy uses are insignificant, however. (http://www.passiv.de). The Standard can In fact, a passive house will have the be met using a variety of design same DHW requirements as any typical strategies, construction methods and house in Ireland and given the low technologies and is applicable to any energy required for space heating the building type. energy demand for DHW will represent a This publication outlines the relatively high proportion of the overall requirements in applying that standard consumption. In order to address this, in Ireland and in all cases when referring some guidance is provided on strategies to a passive house is describing a house to ensure that renewable energies are built to the requirements of the employed as much as possible for Interior of passive house in Oberosterreich, Austria (2000). Source: IG Passivhaus Osterreich Innovative Passivhaus Standard. production of DHW. Passivhaus projekte. 1
  • 8. 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/mK 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 heat exchanger 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 Air-leakage (or infiltration) is the 3. Domestic Hot Water Biomass, compact unit, gas, heat pump, etc. uncontrolled penetration of outside DHW cylinder and pipes well insulated Applicable air into a building. It takes place Solar thermal system Recommended through openings, primarily through inadequate and imperfect sealing 4. Passive Solar Gain between window frames and walls, Window Glazing Solar energy transmittance g > 50% between the opening sections of the DHW solar heating Area to be dictated by house size and window and along the joints of the occupancy building envelope. Solar Orientation Minimal glazing to north Thermal Mass within Envelope Recommended 5. Electric Efficiency Energy labelled Household appliances A rated appliances Thermal bridging refers to a material, Hot water connection to washing Recommended or assembly of materials, in a machines/ dishwashers building envelope through which Compact Fluorescent Lighting Recommended heat is transferred at a substantially Regular maintenance ventilation filters Recommended higher rate (due to higher thermal Energy Efficient fans Recommended conductivity) than through the surrounding materials. Junctions 6. On-site Renewables between window or door and wall, Solar thermal system Recommended wall and floor, and wall and roof Biomass system Recommended should be designed carefully to avoid Photovoltaics Application in a case by case basis Wind Turbine Application in a case by case basis thermal bridging. A thermal bridge Other including geothermal Application in a case by case basis increases heat loss through the Table 1. Technical Definition of the Passivhaus Standard for Ireland. structure, and in some extreme cases may cause surface condensation or interstitial condensation into the Structural air-tightness (reduction of air treated floor area (TFA), and construction. Surface mould growth infiltration) and minimal thermal • The upper limit for total primary or wood rot may be the consequences bridging are essential. A whole-house energy demand for space and water of a thermal bridge. mechanical heat recovery ventilation heating, ventilation, electricity for system (MHRV) is used to supply fans and pumps, household controlled amounts of fresh air to the appliances, and lighting not house. The incoming fresh air is pre- exceeding 120kWh/(m2year), regard- heated via a heat exchanger, by the less of energy source. outgoing warm stale air. If additional heat is required, a small efficient back-up Additionally, the air-leakage test results system (using a renewable energy must not exceed 0.6 air changes per source, for example) can be used to hour using 50Pa overpressurisation and boost the temperature of the fresh air under-pressurisation testing. supplied to the house. In order to maintain high comfort levels The energy requirement of a house built in any building, heat losses must be to the Passivhaus Standard is: replaced by heat gains. Heat losses occur through the building fabric due to • Space heating requirement (deliver- transmission through poorly insulated ed energy) of 15kWh/(m2year) walls, floor, ceiling and glazing as well as 2
  • 9. Standard of space heating requirement (delivered energy) of 15kWh/(m2year) 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 PHPP software. The U-values included in Table 1 have been tested for the prototype passive house presented later in Section 3. This prototype house is a semi-detached two storey house of very compact form. A detached bungalow house of sprawling form would require much lower U-values to meet the Passivhaus Standard. Due to the mild Irish climate, it is possible to use U-values for walls in the prototype house that are higher than those typically recommended by the Comparison of delivered energy in conventional house and in house built to Passivhaus Standard. Source: Passivhaus Institut. http://www.passiv.de. Passivhaus Institute for colder central European climates. A sensitivity analysis was undertaken 80 using different U-values for the Building Regulations 2005 (TGD) Part L prototype house in order to see, for 70 example, whether it would be possible 60 to relax the building fabric requirements e.g. double glazing, in Ireland and still 50 achieve the Passivhaus Standard. The kWh/m2 y 80% Reduction 40 results of this analysis are included in Section 2. 30 20 1.2 Applications of the Passive House Passivhaus Standard in 10 the EU and Ireland 0 1.2.1 Evolution of the Passivhaus 1 2 Standard in Europe Delivered space heating energy comparison, Building Regulations (TGD) Part L and Passivhaus Standard. The Passivhaus Standard originated in Source: UCD Energy Research Group. 1988 by Professor Bo Adamson of the University of Lund, Sweden and Dr. from uncontrolled cold air infiltration needed in a conventional dwelling. Wolfgang Feist of the Institute for through leaky construction and poorly A new built semi-detached, two-storey Housing and the Environment. The fitted windows and doors. In a typical Irish house built to comply with the concept was developed through a dwelling, such heat losses have to be requirements of Building Regulations number of research projects and first balanced by heat gains mostly Technical Guidance Document (TGD) tested on a row of terraced houses by Dr. contributed by a space heating system. Part L 2005, Conservation of Fuel and Wolfgang Feist in 1991 in Darmstadt, The internal heat gains from occupants Energy), uses approx. 75kWh/m2 Germany. The Passivhaus Institut and other sources such as household delivered energy for space heating and (http://www.passiv.de) was founded in appliances as well as passive solar gains 159kWh/m2 primary energy. The Darmstadt, Germany in 1996 by Dr. contribute a relatively small proportion Passivhaus Standard requirement for Wolfgang Feist as an independent of the total overall need in a space heating is 15kWh/(m2year) research institution. Since then, it has conventional dwelling. In a passive delivered energy. When compared, the been at the forefront of the Passive house, the heat losses are reduced so reduction in space heating demand House movement in Germany and has dramatically (through better insulation represents 80%. been instrumental in disseminating the and airtight detailing) such that the standard throughout Europe and same internal gains and passive solar 1.1.2 Technical Definition of the overseas (more details in Section 2). gain now contribute a relatively high Passivhaus Standard for Ireland proportion of the total need. As a result of this, a smaller space heating system is In Table 1, a range of U-values are therefore required compared to that specified in order to meet the Passivhaus 3
  • 10. Dwellings built to the Passivhaus and 27% of energy related CO2 Standard have been constructed all over emissions (11,376 kt CO2), the second Europe in recent years but most largest sector after transport at 32%. The especially in Germany and Austria where average dwelling emits approximately the Passivhaus Standard was first 8.2 tonnes of CO2 emissions, 5 tonnes applied.2 Over 10,000 dwellings have from direct fuel use and 3.2 tonnes from been built to the standard throughout electricity use (O’Leary et al, 2006) and Europe, including 4,000 in Germany and Irish dwellings have a higher Austria, Norway, Sweden, Denmark and consumption of energy, electricity and Belgium and this number is continuing energy related CO2 emissions per Passive house in Guenzburg, Germany (2006). to grow. CEPHEUS3 (Cost Efficient Passive dwelling compared to the average of the Source: UCD Energy Research Group. Houses as European Standards) was a EU-15 (EC, 2005). research project (1998–2001) that The Government White Paper ‘Delivering assessed and validated the Passivhaus a Sustainable Energy Future for Ireland’ Standard on a wider European scale. The (DCMNR, 2007) highlighted that project was sponsored by the European amendment to the Building Regulations Union as part of the THERMIE in 2008 would bring a further 40% Programme of the European energy reduction and related CO2 Commission, Directorate-General of emissions in new build construction. The Transport and Energy. Under CEPHEUS, recent Programme for Government has 14 housing developments were built, brought forward that amendment to resulting in a total of 221 homes 2007 and committed to a further Passivhaus Eusenstadt, Austria. constructed to the Passivhaus Standard amendment in 2010 to 60% below Source: Construct Ireland Issue 2, Vol 3. in five European countries. Another current standards. project supported by the European Commission, Dictorate General for It is clear that the performance of both Energy and Transport is PEP, which new build and existing housing stock stands for ‘Promotion of European must be addressed if we are to achieve Passive Houses’ (http://www.european the objectives set out both at European passivehouses.org). PEP is a consortium and national level. The energy of European partners aiming to spread requirement of a house built to the knowledge and experience on the Passivhaus Standard goes beyond the passive house concept throughout the proposed 40% energy reduction and professional building community, related CO2 emissions in new build beyond the select group of specialists. construction. Multy family dwelling, ‘Hohe Strasse’, Hannover, 1.2.2 Application of Passivhaus A study completed by UCD Energy Germany. Source: UCD Energy Research Group. Standard in Ireland Research Group quantified the potential reduction for space heating energy and The Kyoto Protocol came into force in CO2 emissions when the Passivhaus 2005 and the proposed targets of Standard for space heating of reducing CO2 emissions by 8% 15kWh/m2year is applied to the Irish new compared to 1990 levels by the period build residential construction market 2008–2012 became legally binding for (Brophy et al. 2006). Five scenarios of EU Member States (UNFCCC, 1997). varying levels of application were Ireland’s target under the Kyoto Protocol investigated. The tool used in this study to limit green house gas emissions to was a computer based model, 13% above 1990 levels by that period developed as part of the “Homes for the was reached in 1997, and it is likely that 21st Century” study (Brophy et al. 1999), the target will be overshot by up to 37% which profiled the existing national (74Mt CO2) by 2010 (O’Leary et al, 2006). dwelling stock by dwelling form, The EC Green Paper on Energy Efficiency insulation characteristics and heating (EC, 2005), states that it is possible for system types. The model was used to the EU-25 Member States to achieve predict the energy consumption and energy savings of 20% by 2010, and sees CO2 emissions of dwellings with a typical the greatest proportion of these savings floor area of 100m2, constructed to 2002 Kronsberg Passivhaus Complex Hannover, Germany. (32%) coming from the built environ- building regulation standard. This Source: UCD Energy Research Group. ment. provided national common practice In Ireland the residential sector accounts energy consumption and CO2 emissions for 26% of primary energy consumption figures. It was found that a typical Irish 4
  • 11. dwelling consumes 9,722 kWh/year of The EU Energy Performance of Buildings Directive (EPBD) was transposed into Irish delivered energy on space heating and law on 4th January 2006. This states that when a building is constructed, rented or as a result releases 2,855 kgCO2/year sold a Building Energy Rating (BER) certificate and label must be made available to into the atmosphere. The space heating prospective buyers or tenants. The BER is expressed in terms of kWh of primary requirements for the same size of energy/m2/year. A passive house would achieve an A2 rating (UCD Energy Research dwelling built to Passivhaus Standards Group). was found to be only 1,500 kWh/year of delivered energy which equates to 176 kgCO2/year. (It was assumed 50:50 split Percentage (and number) of new Potential energy and CO2 Potential energy and CO2 dwellings built to Passivhaus emissions savings per emissions savings in between the use of gas and wood Standard year 20 years pellets for space heating energy source as typically used in passive houses). The 3.29 GWh 0.691 TWh 1% (400) difference in delivered energy 1.07 ktCO2 5.02 MtCO2 consumption and carbon dioxide 16.44 GWh 3.453 TWh emissions between the two construction 5% (2,000) 5.36 ktCO2 25.10 MtCO2 types for a single building over one year 65.78 GWh 13.813 TWh was therefore 8,222 kWh/year and 2,680 20% (8,000) kgCO2/year. Applying potential energy 21.44 ktCO2 100.41 MtCO2 and CO2 emissions saving rates to the 20 164.44 GWh 34.533 TWh 50% (20,000) year average new build dwelling 53.59 ktCO2 251.03 MtCO2 construction rate of 40,000 homes per Table 2: Potential for space heating energy and carbon dioxide savings. year the following results were calculated. The results showed that substantial savings are achievable through the application of the Passivhaus Standard in Ireland (Table 2). The Passivhaus Standard was first introduced in Ireland by the Swedish architect Hans Eek at the ‘See the Light’ conference organised by Sustainable Energy Ireland (SEI) in June 2002. Tomás O’Leary of MosArt Architects, a delegate at the conference, was so enthused by Mr Eek’s presentation that he decided on the spot to sell his townhouse, buy a site in the countryside in Co. Wicklow and build a passive house. The O’Leary family has been living in the “Out of the Blue” house since Spring 2005. This house is the first Irish passive house to be certified by the Passivhaus Institute in Germany, and has been the focus of a research, demonstration and energy monitoring project funded by Sustainable Energy Ireland. MosArt Architects, the Passivhaus Institute of Dr Wolfgang Feist and the UCD Energy Research Group are partners in the project. The project is instrumental in establishing the basis for the deployment of the Passivhaus Standard in Ireland in different 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 Building Energy Rating Label. Source: Sustainable Energy Ireland. 5
  • 12. monitoring and evaluation References • it is an excellent demonstration tool Brophy, V., Clinch, J.P., Convery, F.J., and has been the focus of many Healy, J.D., King, C. and Lewis, J.O., 1999 visits, presentations and journal “Homes for the 21st Century - The Costs articles. & Benefits of Comfortable Housing for Ireland”. Dublin. Report prepared for Energy Action Ltd. Brophy, V., Kondratenko, I., Hernandez, P., Burke, K., 2006 “Potential for Energy and CO2 Emission Savings through application of the Passive house Standard in Ireland”. Published in the Passive House Conference 2006 pp. 119- 124. Hanover, Germany. Ireland’s first Passive House, Wicklow. Source: MosArt Architecture. European Commission (EC), 2005. “Green Paper on Energy Efficiency”. [Internet] EC. Available at: http://ec.europa.eu/energy/efficiency/ index_en.html European Commission (EC), 2006. “Promotion of European Passive Houses (PEP)". [Internet] PEP. Available at: http://www.europeanpassivehouses.or g/html Government of Ireland, Department of Communications, Energy and Natural Resources (DCMNR), 2007. Government The O’Leary’s embark on their passive house project. Source: MosArt Architecture. "White Paper Delivering a Sustainable Energy Future for Ireland". [Internet] 1 DCERN. Available at: A passive house is a building, for which http://www.dcmnr.gov.ie/Energy/ thermal comfort (ISO7730) can be Energy+Planning+Division/Energy+ achieved solely by post-heating or post- White+Paper.html cooling of the fresh airmass, which is required to fulfill sufficient indoor air O’Leary, F., Howley, M., and O’Gallagher, quality conditions (DIN 1946) - without a B., 2006. “Energy in Ireland 1990-2004, need for recirculated air. Source: Trends, issues, forecast and indicators”. http://www.passivhaustagung.de/ Dublin. Sustainable Energy Ireland. Pa s s i v e _ H o u s e _ E / p a s s i v e h o u s e _ United Nations Framework Convention definition.html on Climate Change (UNFCCC), 1997. 2 See http://www.passiv-on.org/ The Kyoto Protocal. [Internet]. UNFCCC. 3 Available at: http://unfccc.int/resource/ See http://www.passiv.de/07_eng/ news/ docs/convkp/kpeng.html CEPHEUS_final_short.pdf 6
  • 13. S ECTION T WO How to Design & Specify a Passive House in Ireland
  • 14. How to Design & Specify a Passive House in Ireland This section introduces the passive sky. It may happen that the best views volume, and size of the house. This will house building design process as well as from the site are to the north suggesting provide an early indication of whether explaining the balance between energy the placement of large glazing areas on the Passivhaus Standard is being losses and gains. It also provides an the northern façade in order to optimise achieved. If the space heat requirement overview of the various building systems the best view. All orientation options is significantly above the threshold of and technologies typically employed in must be considered by the designer at 15kWh/(m2year) then the building will a passive house and presents the PHPP this stage - the house must not only have to be modified whether in terms of software used for energy balance function well in terms of energy improved U-values, reorganisation of calculations. The design and efficiency but also in terms of optimising glazing or adjustment of form. The specification of the example prototype the potential of the site and its designer should intuitively know how passive house in the Irish climate surroundings. improvements can best be achieved developed as part of these guidelines while broadly remaining true to the will be covered in greater detail in Sketch Design agreed sketch design. If the space heat Section 3. The next phase of the design process is requirement is significantly less than the to develop a sketch design for the house. threshold level, then it might be possible 2.1 Building Design Process The basic principles of passive house to increase the U-values and therefore for a Passive House design will greatly inform the save on insulation costs. Care should be Client’s Brief development of the initial design. An taken to note other performance The design of a passive house will ideal approach would be to have the indicators calculated by the software, typically commence with developing a longest façade of the house facing such as frequency of overheating, for brief with the Client, whether this is a south, a bias of glazing towards the example. family wishing to build a single rural southern elevation with reduced glazing area on the northern elevation and a Detailed Design and Specification dwelling, a Local Authority progressing a compact form in order to minimise The design of the house is next housing scheme or a commercial surface to volume ratio. Shading devices developed to the level of detail required developer proposing a mixed residential may be required in order to protect to apply for planning permission. project. The brief would typically outline against the risk of overheating in Typically this would not require all the Client’s practical requirements in summer and the aesthetic integration of construction details but it is wise to terms of space functions and density these are essential. In terms of internal consider the various technologies at this and also their preferred image or layout, it is preferable to organise, where stage in order to avoid difficulties later concept for the building(s). Clients possible, family rooms and bedrooms on on. The type of construction will need to interested in building a passive house the southern elevation with utility room be considered, whether timber frame, will often have carried out a and circulation spaces on the northern concrete, externally insulated masonry, considerable amount of research on the elevation where availability of sunlight is insulated concrete formwork, straw bale, subject and so will already be relatively not so critical. etc as well as the space required for well informed regarding the benefits of services such as solar panels, large living in a passive house. Initial Evaluation of Energy Performance domestic hot water tank, mechanical Site Visit Once the sketch design has been ventilation equipment with supply and A site visit is important to (thus reducing approved by the client, it is important to exhaust ducting. The specification of the potential for achieving a glazed test the energy balance of the house such services might be outside the south facing façade) identify the design using the Passive House Planning expertise of the house designer and it presence of structures, landform or Package (PHPP). The essential elements may be required to commission the evergreen trees which might cast of the design are entered into the services of a Mechanical and Electrical shadows on the house during the short spreadsheet U-values of walls, floors, Engineer. It is also critically important to winter days when the sun is low in the roof and glazing as well as orientation, plan ahead in terms of airtightness and 9
  • 15. cold bridging detailing as these often level of airtightness, as this is greatly Areas of Heat Loss in Homes represent the most challenging aspects affected by the quality of craftsmanship Flue Loss Roof Loss 30%-35% of passive house design. The detailed on site. The challenge becomes all the Loss through Walls design should be re-tested in the PHPP more difficult if the building contractor Ventilation 25%-30% Loss 25% software to ensure that the Passivhaus has no prior experience of building to Standard is achieved. At this stage all the the Passivhaus Standard. More required data fields have to be challenging again is the common completed as accurately as possible practice of the house built by ‘direct (details of the PHPP tool datasheets is labour’ and without an experienced outlined in section 2.3.1). This might supervisor with overall responsibility to Window Loss 15% require some minor redesign of the achieve the high standards set. initial house design. The Client should Floor Loss 7%-10% It will usually be necessary to engage be kept informed at all times of the Comparison typical building fabric heat loss patterns specialist Sub-Contractors to supply and in a detached dwelling, excluding ventilation and decisions being made by the design install such elements as the ventilation infiltration. Source: SEI. team and have the opportunity to equipment, solar system, back-up suggest alterations should the need heating systems and controls. arise. Post Construction Testing Tender Documents and Drawings This is the final stage to determine Once planning permission has been whether the constructed dwelling granted, a more detailed set of technical actually meets the air-tightness drawings will be required in order to requirements of the Passivhaus enable the construction of the house. As Standard. The air-leakage must not highlighted above, the emphasis will be exceed 0.6 air changes per hour using on detailing of junctions between 50Pa overpressurisation and different elements of the building, underpressurisation testing. An practical requirements for minimising independent inspection and testing heat loss through cold bridging, body should conduct the testing planning for airtightness and the activities. It is important to undertake location and routing of services. The this test as soon as the airtight layer is sizing of the ventilation equipment, complete so that any leaks can be back-up space heating, solar domestic rectified. When the house does not meet hot water system, as well as details of the requirements further testing may be controls for space and water heating and required. ventilation, will have to be specified at this stage. The detailed drawings and 2.2 General Principles: Heat specification can then be issued for Energy Losses & Heat tender to competent contractors. Energy Gains Site Operations Thermographic image illustrating difference in heat 2.2.1 Passive House Building loss through building envelope in a conventional and The detailed design of the passive house Envelope passive house building. must now be realised on-site and quality Source: UCD Energy Research Group. The building envelope consists of all control is paramount to achieving the standard envisaged in the PHPP elements of the construction which software. The most challenging aspect separate the indoor climate from the Thermal transmittance (U-value) outdoor climate. The aim of the passive will typically be achieving the required relates to a building component or structure, and is a measure of the rate 0.3 TGD Part L at which heat passes through that component or structure when unit 0.25 temperature difference is maintained 0.2 between the ambient air temper- U-value W/m2 K atures on each side. It is expressed in Passive House 0.15 units of Watts per square metre per degree of air temperature difference 0.1 (W/m2K). Source: Building Regulations Technical 0.05 Guidance Document, Part L Conserv- ation of Fuel and Energy 2005. 0 Walls 1 Floor 2 3 Roof Figure depicting 2005 Building Regulation standard required for insulation and required insulation to meet the Passivhaus Standard in Ireland. Source: UCD Energy Research Group. 10
  • 16. house is to construct a building temperature, therefore warm objects envelope that will significantly minimise stand out well against cooler Irish Building Regulations, Elemental heat loss and optimise solar and internal backgrounds. In the passive house some Heat Loss Method (Building Regulations Technical Guidance heat gain to reduce the space heating heat is lost through windows but heat Document Part L, Conservation of requirement to 15KWh/(m2year). lost through the external wall is very low. Fuel and Energy 2005). In the conventional building, on the The following building envelope Maximum average elemental U-value other hand, there is heat loss from the parameters are fundamental in this W/(m2K) entire building envelope, especially process: • Pitched roof, insulation horizontal through windows. at ceiling level 0.16 1. Well insulated building envelope • Pitched roof, insulation on slope Insulation of the building envelope can 2. High energy performing windows 0.20 be divided into four distinct areas: and doors • Flat roof 0.22 external wall, floor, roof and windows. 3. Minimised heat loss through thermal • Walls 0.27 Existing passive houses in Central and bridging • Ground Floors 0.25 Northern European countries have been • Other Exposed Floors 0.25 4. Significantly reduced structural air achieved with U-values for walls, floors • Windows and roof lights 2.20 infiltration and roofs ranging from 0.09 to 0.15 *Regulations due to be updated in 2008 5. Optimal use of passive solar and W/(m2K) and average U-value for internal heat gains windows (including glazing and window frames) in the region of 0.60 to 0.80 Building Envelope Insulation W/(m2K). These U-values far exceed Many building methods can be used in those currently required under the Irish the construction of a passive house, Building Regulations, with the most including masonry, lightweight frames marked difference pertaining to (timber and steel), prefabricated windows, wall and floor. elements, insulated concrete formwork, straw bale and combinations of the A sensitivity analysis using the Passive above. The prototype house presented House Planning Package (PHPP), v2004, in this publication (details in Section 2 software was undertaken using a range and 3) illustrates both masonry and of U-values for the timber frame and timber frame construction as masonry constructions of the prototype representative of most typically used house using climate data for Dublin. In Light filled room in a passive house. building methods for dwellings in all options tested the same data was Source: MosArt Architecture. Ireland. input into PHPP for air-tightness 0.6ac/h@50Pa, ventilation and Continuous insulation of the entire minimised thermal bridging. Various thermal envelope of a building is the parameters were tested in order to most effective measure to reduce heat determine, for example, the required losses in order to meet the Passivhaus level of U-values for the building Standard. envelope in the Irish climate, and to A thermographic image is used to ascertain whether it would be possible illustrate the difference between the to use double glazing and still achieve well and poorly insulation levels in a the Passivhaus Standard in Ireland. The house. Heat loss through the building results are: Option 1 being the most envelope is highlighted by the green, energy efficient house and Option 8 Light, bright and airy. yellow and red colouring. The amount of being the least energy efficient. An Source: MosArt Architecture. radiation emitted increases with outline description of each of the eight Comparison of the interior surface temperature depending on the type of glazing. Windows on the northern elevation should ideally be Source: Internorm, fenster–Lichtund Leben catalogue 2007/2008, pp.91. small. Source: MosArt Architecture. 11
  • 17. Average Option U-Values of U-Values of U-Value of Space heating U-Values of roof ext. wall floor windows and requirement doors 1 0.10 W(m2K) 0.10 W(m2K) 0.10 W(m2K) 0.80 W(m2K) 8 kWh/( m2a) 2 0.15 W(m2K) 0.15 W(m2K) 0.15 W(m2K) 0.80 W(m2K) 13 kWh/( m2a) 3 0.10 W(m2K) 0.10 W(m2K) 0.10 W(m2K) 1.10 W(m2K) 13 kWh/( m2a) 4 0.175 W(m2K) 0.15 W(m2K) 0.15 W(m2K) 0.80 W(m2K) 15 kWh/( m2a) 5 0.27 W(m2K) 0.16 W(m2K) 0.25 W(m2K) 0.80 W(m2K) 22 kWh/( m2a) 6 0.10 W(m2K) 0.10 W(m2K) 0.10 W(m2K) 2.20 W(m2K) 28 kWh/( m2a) 7 0.15 W(m2K) 0.15 W(m2K) 0.15 W(m2K) 2.20 W(m2K) 34 kWh/( m2a) 8 0.27 W(m2K) 0.16 W(m2K) 0.25 W(m2K) 2.20 W(m2K) 45 kWh/( m2a) Table 3: Sensitivity analysis of the passive house prototype house in Ireland outline test results for eight options. Source: MosArt Architecture. options analysed is provided. Only the W(m2K) for all other building first four achieve the Passivhaus envelope elements, coupled with Note: Results presented here are Standard set for space heating triple glazed windows. The result is indicative only and should be used as (delivered energy) of 15 kWh/(m2year) exactly at the threshold of the starting point for specification of a treated floor area: Passivhaus Standard but was not passive house dwelling in Ireland. used for the prototype house as there Meeting the Passivhaus Standard must • Option 1 - U-value 0.10 W(m2K) for all be tested and verified with the PHPP is no margin in site operations. building elements combined with software for the specific dwelling triple gazed windows with average • Option 5 - U-values for walls, roof design. U-value (including glazing and and floor employed in the Irish window frames) of 0.80 W(m2K) Building Regulations, Elemental Heat results in space heating requirement Loss Method (Building Regulations Thermal Conductivity significantly below the standard TGD Part L, Conservation of Fuel and Thermal conductivity ( -value) relates to required of 15 kWh/(m2 year). Energy 2005) combined with triple a material or substance, and is a measure glazed windows, failing to achieve of the rate at which heat passes through Note: Advantages and disadvantages the required standard. a uniform slab of unit thickness of that of using triple glazed windows are material or substance, when unit discussed in detail in section ‘Windows • Option 6 - also a failure is the temperature difference is maintained & Doors’) combination of U-value 0.10W(m2K) between its faces. It is expressed in units for building fabric in combination of Watts per metre per degree (W/mK), • Option 2 - (This is the option that has with standard double glazed units. (Building Regulations Technical been used in the design of the Guidance Document Part L, • Option 7 - U-values 0.15 W(m2K) for prototype passive house in Ireland as Conservation of Fuel and Energy 2005). walls, roof and floor as the prototype part of these Guidelines), with U- Insulation materials for walls, roofs and house but with standard double value 0.15 W(m2K) for all building floors vary in terms of thermal glazing U-value 2.20 W(m2 K) which envelope elements combined with conductivity. Typical conductivities for comes way above the Passivhaus triple glazing. The results show space different insulation materials are Standard. heating requirement below the included below as well as the Passivhaus Standard. • Option 8 - U-values for walls, roof approximate thickness required in order and floor employed in the Irish to achieve a U-value of 0.15 W(m2K) and • Option 3 - All building envelope Building Regulations, Elemental Heat 0.10W(m2K). (Table 4) elements with U-value of 0.10 Loss Method (Building Regulations W(m2 K) combined with an efficient Typical insulation materials used in TDG Part L, Conservation of Fuel and double glazed unit with low U-value Ireland include mineral wool, Energy 2005) and standard double 1.1 W/(m2 K) achieves the Passivhaus polystyrene, polyurethane, polyiso- glazed units underachieving the Standard. cyanurate, sheep wool and hemp. Passivhaus Standard. Different insulation materials suit • Option 4 - U-value 0.175 W(m2K) for different types of construction external walls and U-value 0.15 12
  • 18. application and it is important to use the the optimum balance of glazing for each the thermal comfort level in the house. material best suited for the situation. For passive house design can be reached. Typically triple glazed window units are example, cellulose insulation is suitable It has been illustrated above that the use used in passive houses in Central and for use in an open attic space where it of windows and doors with average U- Northern Europe. The Passivhaus Institut will fill completely between ceiling joists values of 0.8 W/(m²K) can be combined has certified a range of glazing and door in comparison with rigid insulation with U-values for opaque elements of units suitable for use in passive house where there is a high risk of thermal 0.15 W/(m²K) to comfortably achieve the buildings. Although it is not a bridging unless cut perfectly to fit Passivhaus Standard in Ireland. There are prerequisite to use certified passive snuggly between the joists. Conversely, a number of advantages in using house products (http://www.passiv.de) in a high density rigid insulation is better windows with average U-values of 0.8 a passive house, choosing approved suited under a floor slab compared with W/(m²K) as well as highly insulated products means the validity of technical insulation that easily compress or are doors, principally the assurance of a data has been tested and verified by an affected by moisture. comfortable indoor climate due to the independent certifier. The principle The U-value of the construction is lower cold radiation heat transfer at the characteristics and advantages of using determined by the conductivity of surface of the glass. One will not sense a triple glazed windows in a passive house materials and components used from drop in temperature standing are listed below, for both window the internal surface to the external immediately adjacent to this standard of glazing and frames: surface of the thermal envelope. window, unlike the experience of Glazing Examples of typical construction standing next to a conventional double • Three panes of glass separated by methods and materials used for the glazed unit with U-value, for example of special low-conductivity spacers prototype passive house in Ireland are 2.2 W/(m2 K). An added benefit of using eliminates the risk of condensation at illustrated later in Section 3. highly energy efficient windows and the bottom of the glass in cold Windows & Doors doors includes significant draught weather (which may lead to rotting The recommended approach to the reduction due to the fact that they have of timber frames over time). design of a passive house is to have typically two seals or gaskets (compared with conventional double glazed units • High solar energy transmittance (g avoid excessive area of north facing which often have only one) as well as 50) which allows solar radiation to glazing and place relatively large excellent sound insulation. Finally, penetrate the glass and contribute windows facing south or due south. This natural convection which is driven by towards heating of the dwelling. is in order to minimise heat losses through the north facing elevation, temperature difference between the • A low emissivity (low-e) coating on which receives no direct sunlight, while inside face of the glass and the room the inside of the outer two panes maximising ‘free’ solar heat gains on the interior is much reduced with which in which reduces solar re-radiation back south. An advantage of large windows is turn will reduce cold air flows and out through the glass. It should be an increase in interior day light levels thermal discomfort. noted that a ‘soft coat’ has slightly which in turn reduces the need for use of better U-value but a ‘hard coat’ The sensitivity analysis for a passive electricity for artificial lighting and also glazing has higher solar trans- house dwelling in Ireland (showed in ensures a more pleasant natural light- mittances. Option 3), achieves the Passivhaus filled living environment. Standard yearly space heating • Insulating gases between the glass There is, however, a balance to be requirement with extremely efficient panes, typically argon or krypton, achieved between heat losses through double glazed windows with a U-value which help to reduce heat escaping the glazing and solar heat gains through no greater than 1.1 W/(m²K). When used through the glass. the south/east/west facing windows. in a passive house, however, they must Frame When designing a passive house, PHPP be used in conjunction with very low U- • The frame must be well insulated and software should be used to calculate the values for all other elements of the also be thermally broken. Even wood heat losses and heat gains taking into building envelope. This may negate any conducts heat and a thermally account building orientation, areas of financial saving in not using more broken timber window frame will glazing and specific types of glazing so efficient glazing as well as compromise result in much lower heat losses than Insulation Material Thermal Thickness for Thickness for a solid one. Type conductivity W/mK U-Value of 0.15 U-Value of 0.10 W(m2K) W(m2K) • There will typically be two weather Polyisocyuranate or gaskets on triple glazed windows 0.023 145mm 220mm used in a passive house dwelling, the polyurethane Polystyrene, sheep wool 0.035 220mm 340mm primary function of the outer one Cellulose, Hemp and being for weathering with the inner 0.04 250mm 400mm Rockwool one serving to improve airtightness. Wood 0.13 825mm 1,250mm The majority of these types of Table 4: Conductivity of insulation materials and approximate thickness to achieve specific U-value for external windows open outwards which is walls. Source: MosArt Architecture. common place in Continental Europe 13
  • 19. however, there are models of inward transferred throughout the house via opening windows being developed the mechanical ventilation system. This which will soon be available in the has the added benefit of enabling Irish market. One advantage of unobstructed use for placing furniture outward opening windows is that against all external walls. they don’t intrude in the room space Thermal Bridging which may be important in more Thermal bridging (i.e. un-insulated joints compact dwellings. between walls, floors/walls, ceilings/ • Triple glazing window frames are adjacent walls, windows/walls etc) are typically much wider and stronger weak points of the building envelope construction than their conventional and cause unwanted losses of energy double glazing counterparts. which should be eliminated or significantly reduced to a degree that • Triple glazed windows with low- the associated heat losses become emissivity coating and insulated negligible. window frames will have improved A thermal bridge increases heat loss U-values compared to double glazed through the structure, and in some Cross section though a triple glazed insulated window windows, resulting in less heat loss. and frame. Source: MosArt Architecture. extreme cases this may cause surface However with triple glazing the solar condensation or interstitial conden- energy transmittance (gs), that is, the sation in the structure. Surface mould amount of solar energy entering growth or wood rot may be the through that glazing, is somewhat consequences of a thermal bridge. reduced compared to double glazing Typical effects of thermal bridges are: due to the effect of the additional layer of glass. The requirements of • Significantly increased heat losses. the Passivhaus Standard is to use • Decreased interior surface temper- glazing with minimum solar ature which may result in high transmittance of 50% or higher. humidity in parts of the construction. The use of larger areas of glazing on the • Mould growth cause by warm south elevation is helpful in maximising internal air condensing on cold the amount of sunlight available in the surfaces. short days of winter. It must be All of the above situations can be remembered, however, that highly avoided in houses built to the energy efficient windows allow less Passivhaus Standard. The Passivhaus daylight (visible light transmittance) into Standard for linear thermal trans- a building than a normal double glazed mittance (ψ) should not exceed 0.01 windows without e-coating. Light W/(mK). This requires the building transmittance is an optical property that designer to identify and locate all indicates the amount of visible light potential thermal bridging in the The risk of internal condensation is dramatically being transmitted through the glazing. construction, careful specification and reduced. Source: MosArt Architecture. It varies between 0 and 1 (0 to 100% detailing of those elements providing light transmitted) with the higher the where possible a continous layer of The quantity which describes the heat light transmittance value the more light insulation, as well as care being taken to loss associated with a thermal bridge is is transmitted. A double glazed window execute those elements on site as per its’ linear thermal transmittance (ψ). with low-e coating will transmit 72% of design details. This is a property of a thermal bridge visible light. A triple glazed energy and is the rate of heat flow per degree Designing and building a passive house efficient window will transmit 65% of per unit length of bridge that is not in Ireland requires the development of visible transmittance (these are accounted for in the U-values of the construction details that go far beyond indicative values only - actual values plane building elements containing guidance provided (to avoid excessive depend on the manufacturer’s specific- the thermal bridge. heat losses and local condensation) in ation). Building Regulations Technical Guidance Source: SEI, Dwelling Energy Assess- ment Procedure (DEAP) 2005 edition, In a conventionally constructed house in Document Part L, Conservation of Fuel version 2, pp.55 Ireland radiators are typically positioned and Energy 2005. Building practitioners under windows in order to heat the cold could refer to the accredited con- air entering through the single or struction details specifically developed double glazing. In a passive house for passive house building published in locating radiators beneath windows is Germany “Thermal Bridge-Free Con- simply not required as the heat load is struction” (PHPP 2007, pp.96). Thermal 14
  • 20. bridging can be tested and verified in leaks in the envelope are very minor and the PHPP software as the design of the therefore difficult to locate. In these passive house building is being situations it is typical to reverse the developed. direction of the fan and suck air into the house putting it under positive pressure. Structural Air-Tightness and Draught- Odorless smoke can then be released Proofing into the building and leaks can be Building an airtight or leak-free structure observed from the outside where the is imperative to achieving the Passivhaus Infrared image of the interior of a passive house smoke appears through the envelope. It Standard. If there are gaps in the window. All surfaces (wall structure, window frame, is important to notify the fire service if and the glazing) are pleasantly warm (over 17°C). Even building structure then uncontrolled you are carrying out such a test in case it at the glass edge, the temperature does not fall below amounts of cold external air can 15°C (light green area). is mistakenly reported as a house fire by Source: Passivhaus Institut, http://www.passiv.de from infiltrate the building. Achieving a high passers by. the passive house Kranichstein). level of air-tightness eliminates cold draughts and associated comfort losses. The Passivhaus Standard is reached It also prevents condensation of indoor when there are less than or equal to 0.6 moist, warm air penetrating the air changes per hour @50Pa pressure. structure, and possible structural The most critical issue regarding testing damages due to decay, corrosion and for airtightness is timing during the frost. building process. It is important that Air-tightness is achieved by careful remedial measures can be carried out in application of appropriate membranes order to remedy any leaks or cracks. The For comparison, a typical older double glazed window and tapes or wet plastering in concrete test should be carried out before second is shown. The centre of glass surface temperature is construction within the building fix carpentry, for example, when there below 14°C. In addition, there are large thermal bridges, particularly where the window meets the envelope. A great deal of attention must are no skirting boards or window boards external wall. The consequences are significant radiant be paid to detailing and workmanship in fitted and where the junctions covered temperature asymmetry, drafts, and pooling of cold air in the room. IR-photography: Passivhaus Institut. order to ensure that the airtight layer is by such materials are still accessible and Source: Passivhaus Institut, http://www.passiv.de from continuous all round the building, can be sealed. The test should also be the passive house Kranichstein). especially around junctions between carried out after all mechanical and walls and floors, roof, windows, doors, electrical services, that need to etc. Penetrations of the airtight layer by penetrate the building envelope, have mechanical and electrical services must been installed. Otherwise, installing be properly sealed. such services after the test could severely compromise the airtightness of The air-tightness of a building can be the building. accurately measured by carrying out a blower-door test. The test involves In a typical Irish house built in placing a powerful fan suspended in a accordance with building regulations canvas sheet within a door opening and TGD Part F 2002 the method in which operating the fan at very high speeds habitable rooms are ventilated is usually thereby creating either negative or via a hole in the wall or ventilator in the positive pressure within the house. By windows of 6,500mm2 fitted with a sucking air out of the house, for controllable grille. Such means of example, a negative pressure is created ventilation can result in large amounts of with the result that external air will be cool external air infiltrating the building sucked in through any gaps or cracks in depending on wind speed and pressure. the building envelope. The pressure In a passive house, on the other hand, used for such tests is 50 Pascal which can the supply of fresh air is provided by a be accurately set by the blower door whole house mechanical ventilation equipment. system with heat recovery which negates the necessity for openings in When undertaking the test it is usually the wall or windows. Thereby draughts quite easy to identify major leaks due to Timber Frame I-Beam construction reducing thermal are eliminated and structural air- bridging. Source: Passivhaus Institut, Germany. the presence of a strong draught which tightness is not compromised. can be felt by the hand or, for smaller leaks, can be detected by a In developing the building design it is thermographic camera. The cause of very important to anticipate differential these draughts can then be sealed with movement and decay of adhesives and appropriate materials as the test is being chemical bonds by detailing junctions undertaken. It may also happen that the which will assist in maintaining an 15
  • 21. airtight layer for the life of the building. Internal Heat Gains Many excellent details, for example, can A passive house is very efficient at be found at the website of the Scottish utilising ‘free’ internal heat gains from Ecological Design Association domestic household appliances, kitchen (www.seda2.org/dfa/index.htm). It is also and utility equipment, electronic important to use membranes and equipment, artificial lighting, and plasters that are both airtight but also occupants. Heat losses from stoves or vapour diffusing which allow moisture boilers also contribute towards the within the structure to escape to the overall space heating requirement as outside thereby reducing the risk of long as they are positioned within the interstitial moisture and the threat of rot building envelope. Occupants of the and decay over time. building also contribute to the heat load Correctly insulated house avoiding thermal brid. Source: Passivhaus Institut, Germany. - a human continuously emits 100W of Passive Heat Gains heat when stationary. A family of five Passive heat gains in a passive house are persons, therefore, can emit 0.5KW of a result of the combination of solar gains heat. This may seem like a small amount and internal gains. but it equates to approximately one third of the total space heat load for the Solar Heat Gains prototype passive house presented in Passive solar gain is optimised by Section 3. providing an east-west alignment to the building, if possible on the site, resulting Risk of Overheating in the longest façade facing south, and Placing extensive areas of glass on the by placing the majority of the glazing south facing façade in a well insulated towards the south. Very high quality and air-tight dwelling may lead to windows (average U-value 0.8W/m2K) overheating in warm sunny days. The facing south will have a positive thermal PHPP software will alert the designer to Continuous Airtight Membrane. balance - it will have more heat gain any risk of overheating by calculating Source: IG Passivhaus Osterreich Innovative Passivhaus projekte. than heat loss throughout the year. the frequency of overheating expressing Results of a recent parametric study by J. this as a percentage of the year in which Schnieders of the Passivhaus Institut the internal temperature in the house “Climate Data for Determination of rises above 25oC. If frequency of Passive House Heat Loads in Northwest temperatures over the comfort limit of Europe” illustrates the relationship 25oC exceeds 10% of the year, additional between the area of south facing glazing measures for reducing overheating and the space heat demand for a passive should be included in the dwelling. To house dwelling located in Ireland prevent uncomfortable indoor (measured climate data for Birr used). temperature in a passive house dwelling The parametric study uses the first it is recommended to specify shading passive house built by Dr. Wolfgang Feist devices (blinds, overhangs or awnings, of the Passivhaus Institut as a case study etc.) which allow low sun to enter the building, shown below. It can be seen home in winter but prevent the high sun that the space heating demand initially entering in summer. decreases quite steeply with increasing In the first Irish passive house in Wicklow south facing glazing. There are shading was not in place on the south diminishing returns from increasing the facing glazing during the first summer Timber frame house pre-cladding fitted airtight area of south facing glass, however, and and the house did overheat. A balcony membrane. Source: Passivhaus Institut, Germany. there eventually comes a point where was installed ahead of the second there is little or no benefit in providing summer, which significantly reduced the more south facing glass as the net heat There are two measurements used to frequency of overheating. In mid- loss is greater than the heat gains over define airtightness, namely cubic summer when the daylight hours are metres of air per square metre of the year. long the sun only enters the building external envelope per hour (m3/m2h) or later in the day while during winter air changes per hour (ac/h). While the There is no optimal ratio of glazing to when the daylight hours are short the measured result for the former is floor area that can be used as a rule of low sun completely illuminates the generally 20% greater than that of the thumb in deciding what proportion of a entire interior of the building. latter, the difference is practice greatly given façade should be glazed. The area depends on the building form. of glass has to be determined as part of In the temperate climate in Ireland the design verification procedure using where external temperature rarely the PHPP software. exceeds 25oC, the risk of overheating 16
  • 22. 24 22 Ireland - Birr 20 Space Heat Demand / Heat Load 18 16 14 12 10 8 6 U-Value Wall = 0.175 W/(m2K) U-Value Window = 0.85 W/(m2K) Space Heat Demand [kWh/(m2a)] 4 2 Heat Load [W/m2] 0 0 10 20 30 40 50 60 Area South Facing Windows [m2] Climate Data for the Determination of Passive House Heat Loads in Northwest Europe. Source: J. Schnieders, Passivhaus Institut. should be avoided by careful throughout the year or during winter consideration of shading devices, if a solar water heating system is used provision of openings for natural during summer. ventilation in combination with thermal mass inside the dwelling (exposed Each of these items is dealt with concrete floor; masonry wall, etc.). In separately in greater detail below. some cases the mechanical ventilation Given the lengths to which the designer No more than 0.6 air changes/hour at 50 Pascal system could be used to distribute fresh pressure should be observed in accordance with the and builder go to in terms of ensuring a air throughout the building by switching Passivhaus Standard. This should be checked for highly insulated building envelope, compliance with a blowerdoor test which will to a ‘summer bypass’ setting. This immediately highlight leaky areas. Air-tightness can be excellent air-tightness and minimal however should be avoided where achieved through the use of membranes, roofing felts thermal bridging, it is important that the and plasters combined with sealants and vapour possible as the ventilation system will building services in a passive house are diffusing resistant materials. consume electricity resulting in Source: UCD Energy Research Group. as energy efficient as possible. This is increased primary energy. The dwelling especially critical in the case of the designer should employ ‘passive’ cooling mechanical ventilation heat recovery strategies to minimise overheating. system. Therefore, the required 2.2.2 Passive House Building efficiency of the mechanical ventilation Deep roof overhang shades upstairs windows Systems system with heat recovery for a passive house dwelling is 75%. It is also very As explained earlier a passive house important to consider comfort, health does not need a conventional space and safety issues in the design of the heating system of radiators or building services for a passive house, underfloor heating to maintain a ensuring for example that the back-up Balcony shades comfortable indoor climate. Instead, downstairs windows heating system is adequately sized to typically, the following building services deal with extreme weather conditions; are required in a passive house: that filters in the ventilation equipment Location of overhang and balcony. are replaced regularly and that there is a Source: MosArt Architecture. • Mechanical ventilation system with heat recovery which provides most of fresh air supply for any combustion the space heat requirement. devices such as a boiler. These and other issues are dealt with in greater detail • Back-up system capable of heating below. the air passing through the dwelling via mechanical ventilation. Typical Mechanical Heat Recovery Ventilation fuel sources for the back-up system (MHRV) include biomass, gas, and in some An airtight house requires a well- instances electricity (for example designed mechanical ventilation system ‘green electricity’ from renewable to provide good indoor air quality. A sources). Since the demand for space passive house is ventilated using a heating in a passive house dwelling is mechanical system which incorporates very low, the back-up system is used air to air heat recovery (mechanical Lighting contributes towards internal heat gains. to provide hot water, either ventilation heat recovery, or MVHR). Source: MosArt Architecture. 17
  • 23. IR Concentration Photo depicting how the low winter sun enters the room below the overhang/awning/balcony. Source: MosArt Architecture. Hours Graph depicting how mechanical ventilation ensures a good indoor air quality by removing the high concentrations of tracer gas that were inserted into the house under test conditions. Source: UCD Energy Research Group. Exhaust air is extracted from rooms that space heating that may be required in a typically produce heat, moisture and passive house. The aim is to use the unwanted smells such as kitchens and warm exhaust air to raise the temper- bathrooms. Before this air is expelled to ature of the cool fresh air to provide for the outside it passes through a heat thermal comfort all around the house. exchanger where the heat is transferred On a night where outside temperatures to the incoming fresh air, thereby are below freezing, the fresh air should eliminating the need to completely heat be raised to, for example, 18oC, having the fresh air as it enters the building. It is passed through the MVHR. The important to highlight that the stale efficiency of sensible heat recovery exhaust air and clean fresh air do not mix should exceed 75% for the nominal Photo depicting how the house is shaded from the high in the heat exchanger and therefore range of flow rates specified for the unit summer sun by the overhang/awning/balcony. there is no risk whatsoever of what when measured in terms of the supply- Source: MosArt Architecture. might be referred to as ‘sick building air side temperature ratio as described in syndrome’. Rather, the stale air and clean EN 13141-7:2004.1 Specifiers and air is channelled through closely spaced designers should be wary of products but separate narrow sleeves in the core claiming extraordinary efficiency rates of of the heat exchanger. 95% or higher. The safest route is to install equipment that has been The benefits of having a whole-house independently tested and verified by mechanical heat recovery ventilation such bodies as the Passivhaus Institute. system (MHRV) are many, including: • Constant supply of the correct The graph above is based on actual amount of fresh air to all habitable testing of the first Irish passive house in rooms thereby reducing CO2 levels Wicklow. It illustrates, for example, how and removing the cause of stuffiness mechanical ventilation ensures good and tiredness. indoor air quality by removing the high • Simultaneous extraction of moisture- concentrations of a tracer gas that was Schematic of the supply air ducts, the extract air ducts laden air from bathrooms, utility deliberately released into the house as and the heat exchanger within mechanically part of the test procedure. In less than rooms and kitchens as well as ventilated house. Source: Passivhaus Institut. ventilating noxious gases and 1.5 hours the air quality in the house had unwanted smells if present. returned to normal. • A lowering in humidity levels Recommended Ventilation Rate reducing mould and fungus that may According to the Passivhaus Institut, the appear over time and decreasing appropriate air change rate for dwellings dust mite levels. is between 0.3 and 0.4 times the volume System Efficiency of the building per hour, with a general The efficiency of the heat exchanger in recommendation of leaning toward the the MHRV determines the amount of lower rate. This maintains high indoor air heat that can be recovered from the quality while ensuring a comfortable exhaust air and, therefore, has a very level of humidity and maximizing The sommer-bypass can be used for cooling in the summer if needed. Source: MosArt Architecture. significant influence on the additional energy savings. 18
  • 24. The PHPP software suggests that 30m3 Winter and Summer Mode per person per hour should be provided There are generally two ventilation to dwellings to ensure good air quality. modes in a passive house: Summer These two measurements can be used to Mode and Winter Mode. In winter, the choose an appropriately sized machine MHRV uses the heat in the exhausted air for different dwelling designs. Taking the to warm the incoming fresh air. In prototype house presented later in summer, a bypass in the equipment can Section 3 as an example, an occupancy be set to open automatically (controlled of 5 persons would require 150m3 of by thermostats) such that the incoming fresh air delivered to the house per hour. fresh air is not heated. Alternatively in In terms of extract, the PHPP software summer natural cross ventilation may be uses the following rates for different used and the MHRV system can be room types as default values, kitchen = switched off. 60m3h, bathroom = 40m3h, shower = 20m3h and WC = 20m3h. In the prototype Insulation and Positioning of Duct Work house these total 140 m3h which is close and Vents to the supply volume which will ensure Iit is very important to adequately that the whole house system will be insulate the supply air ducting so that balanced. The supply and extract there is minimal loss of temperature in volumes can be accurately set by using a delivering warm air around the house. The thickness of insulation generally A pellet stove is at the hearth of an Irish passive house. digital anemometer and adjusting the Source: MosArt Architecture. valves on the vents in each room as used in passive houses is between 6cm required. and 10cm for ductwork. It is also preferable to locate the ducting within Adjustment of Fan Speed and Exchange the thermal envelope and to keep pipe Rate runs as short as possible by ideally Most MVHR machines have different positioning the MVHR unit in the centre settings for different circumstances. of the house. This requires careful These are often referred to as a ‘party’ planning at a very early stage of building setting, where there are a lot of people design. in the house and where additional fresh air is required, and ‘holiday’ setting, Vents are normally placed in the ceiling where the house is being left vacant and but can also be placed in the wall if the flow of air is reduced. The former of necessary. The air inlets are typically these settings will use more energy and designed to spread the air horizontally also decrease the level of humidity across the ceiling, minimizing down- ward drafts. There should be a gap either The ventilation system can be used in a sealed closet to whereas the latter will use less energy dry clothes. Source: MosArt Architecture. and perhaps lead to an increase in under or over the door of each room to humidity. enable the easy movement of air from one room to the next. If doors are fitted It is not advisable to constantly run the tight without such a gap, rooms with equipment on the lower setting just to exhaust vents would be under negative save energy when the house is pressure and rooms with supply air occupied. MHRV machines uses under positive pressure. surprisingly little energy given the important role that they play in the Noise passive house. The PHPP software uses Fan and valve noises can be almost standard value 0.45Wh for every m3 Ceiling air supply vent. completely eliminated by sound control Source: MosArt Architecture. transported air software in the measures (e.g. vibration isolation calculation of electricity due to MHRV. mounts, low air speed and acoustic When designing a passive house in lining in ducts). The grilles on vents Ireland the specific fan power should be generally guide incoming air along the carefully considered as the electricity ceiling from where it uniformly diffuses consumed for fans has direct impact in throughout the room at velocities that terms of primary energy performance are barely perceptible. If the ventilation and energy labelling, the Building equipment is operating on a high Energy Rating (BER), recently introduced setting (‘Party Mode’) the noise of the to Ireland. Therefore, specific fan power equipment and the air flow may be more for fans should be less than 1w/l/s. noticeable. MVHR machines are Supply air ducts should be well insulated. generally housed in a well insulated Source: MosArt Architecture. 19
  • 25. casing and noise should not be a critical ventilation system. This section of the issue. guidelines will provide an overview of the typical back-up heating systems Maintaining Good Air Quality used in passive houses to provide It is important that attention is paid to thermal comfort . regular replacement of air-filters for both incoming and exhaust air. Filters are Space heating demand in a passive used not only to provide clean air for the house is typically met through passive occupants but also to ensure that the solar gains (40–60%), internal heat gains Used air filter. Source: MosArt Architecture. heat exchanger is not clogged with dust (20–30%) and the remainder (10–40%) and other matter. If the filters are not needs to be provided from building regularly replaced (for example every six systems. to twelve months) and they themselves The PHPP software will accurately become clogged with dirt the MHRV will predict the following two measure- have to work harder to provide the same ments for each passive house design: volume of air to the house, thereby increasing the speeds of the fans and, • Annual Space Heat Requirement - ultimately, using more energy. In this measures the amount of energy countries where this system is relatively that is needed to maintain a new, occupants may not be aware of this comfortable indoor temperature, What a clean filter looks like. maintenance need and indoor air quality specified in kilowatt hours per square Source: MosArt Architecture. may suffer as a consequence. Equipment metre of treated floor area per year, differs with respect to the types of filters or kWh/(m2year). used, some have to be replaced while • Heat Load - this measures the others can be washed and reused. capacity of the space heating system Sometimes the extractor hood in the required to maintain comfortable kitchen is connected to the MHRV indoor temperatures at any one time, equipment to extract kitchen smells and specified in Watts per square metre of to use the waste heat from cooking to treated floor area, or W/m2. warm the incoming fresh air. In such For the prototype house the annual instances, it is very important that the space heat requirement is hood is fitted with a high quality filter 15kWh/(m2year) equating to approx- that can easily be cleaned or replaced in imately 1,650 KWh over an entire year order to prevent the built up of grease in (the house measures 110m2 in treated the ducting system which could be a fire floor area). This would equate to 155 Water to air heat exchanger unit. hazard. litres/year of oil, 160m3/year of mains gas Source: MosArt Architecture. What happens in the event of a power or 350kg/year of wood pellets (in bags) failure? at a cost of approximately €92/year If there is a loss of electricity (and the when using oil, €55/year when using gas dwelling has no back-up generator) the (without standing charges for gas or ventilation system will stop working and €345/year with standing charges) or the supply of fresh air will be cut off. If €97/year when using wood pellets. Unit power is lost for a short while (for price: heating oil 5.62c/kWh; mains gas example a few hours), then there is likely 3.39c/kWh standing charges €256/year; to be no noticeable difference in indoor wood pellets - in bags 5.92c/kWh. air quality. If the loss of power is Source: SEI, Dwelling Energy Assessment prolonged, the simple solution is to Procedure (DEAP) 2005 edition, version open the windows and to create natural 2, Manual pp. 84. cross flow ventilation through the The heat load, on the other hand, is building. approximately 1,800 W, or just 1.8 kW. This amount of energy could be Back-up Heating System provided by a very small stove / heater / As previously highlighted in these boiler compared to what might be guidelines, space heating requirement typically required in a family home. in a passive house is so low that there is no need for a traditional space heating The most common method of 'heating' system. The optimal way to transfer the in a passive house is by post-heating the Compact unit including ventilation heat recovery and small amount of required heat through- fresh air after it has already been air to water heat pump. Source: Drexel und Weiss. out the house is through the mechanical warmed by the exhaust air in the MVHR. 20
  • 26. There are a number of ways in which the temperature of the air can be boosted, including those listed below: • Water to air heat exchanger. • Compact unit with electrical heat pump. • Compact unit with natural gas. The first two of these is explored in outline below. The compact unit with natural gas, while used in Central Europe is virtually unheard of in Ireland and would have to be approved for use by the appropriate authorities. Water to Air Heat Exchanger This method involves using a heating device placed immediately on the fresh air supply outlet of the MVHR. There is a small radiator inside this device and it is heated by hot water connected to the domestic hot water tank. If the house needs additional heat (which is determined by a thermostat) then hot water is circulated through the device, Schematic of mechanical system that can be used for back-up heating in a passive house. hence the appropriate title of ‘water to Source: Passivhaus Institut, Germany (http://www.passiv.de). air heat exchanger’. Once the house has reached the programmed temperature, the hot water stops circulating and the air is no longer heated. The water in the domestic hot water (DHW) tank is heated, in turn, by using a number of energy sources including a stove or boiler (for a larger house) in combination with solar hot water panels. The principle advantage of this system over the compact unit system described below is that when fueled by a combination of firewood and sunshine it is carbon neutral. Compact Unit with Electrical Heat Pump This system is so-named as it incorporates all of the technology required for a passive house in a Sunlight amounts for Ireland. relatively small unit, namely the MVHR, Source: Green Design, Sustainable Building for Ireland, pp. 28. the DHW and the heating power for the the most common boiler based systems • Separate and independent auto- home, in this case powered by an using a timer and a cylinder thermostat, matic time control of space heating electrically powered heat pump. It is sometimes even room thermostats been and hot water; therefore very suited to smaller homes absent. New building regulations Part L where space might be limited for large • Shut down of boiler or other heat (2005) recommend minimum levels of tanks, stoves and storage for wood. source when there is no demand for control, installing equipment to achieve Compact units are becoming more either space or water heating from the following: widespread in use in passive houses that source. built in Central and Northern Europe. • Automatic control of space heating Additional control features can be on the basis of room temperature; Integrated controls for heating in a incorporated to a heating system so the Passive House • Automatic control of heat input to overall system performance improves. Heating systems in Ireland have stored hot water on basis of stored One example is the ‘weather com- traditionally been very simple, perhaps water temperature; pensation’ feature, which is the ability to 21
  • 27. adjust the output of the system based Room based temperature controls for will reduce the contribution of the on the measured external temperature. temperature differentiation between collectors to DHW production. In The main advantage of using weather different rooms may be necessary if places where there is no south facing compensation is that the heating system individual comfort requirements are set roof, additional panels over the m2 closely monitors external temperature for different rooms. In a centralised area which might otherwise be trends and adjusts the output ventilation heating system, however, the needed can be fitted to east or west accordingly. If, for example, the external supply air temperature is constant for facing roofs. temperature starts to drop rapidly, the the whole house and this would be • The optimal tilt of the solar panels to system can ‘anticipate’ that the dwelling typical for most houses built to the meet approximately 50% of the may come under pressure to maintain its Passivhaus Standard. annual heating demand for DHW is current internal temperature and can Domestic Hot Water Production approximately 45 degrees (at a pitch verify whether there is sufficient power As in any type of dwelling, the passive greater than 45 degrees the potential to generate the back-up heat that might house requires a system that provides annual output is compromised be required. domestic hot water (DHW). As with somewhat). The preferred internal temperature can space heating, it is important that the • There are two types of solar be set using an internal thermostat. If system is energy efficient, well collectors typically used in Ireland, the internal temperature goes below the controlled and has an adequate capacity flat plate panels and evacuated thermostat setting, the system will to meet demand. Generally the DHW tubes. A comparison of the automatically start to heat the fresh air system in a passive house is combined performance of these types, based passing through the ventilation with a heat source such as a wood stove, on 5m2 collector area, along with equipment. The principle function of the solar thermal collector, compact unit or consideration of orientation and heating control system is to ensure that heat pump for space heating. Most angle of incidence is provided here. there is always sufficient heat in the passive house examples encountered The calculation was developed for buffer tank to deliver the heat load have utilised solar thermal collectors as the prototype passive house using required to maintain the comfort levels they reduce the use of primary energy the calculation methodology for set by the occupants. In the case of the and CO2 emissions. It is important to solar water heating in Dwelling Out of the Blue house, if there is note, however, that the Passivhaus Energy Assessment Procedure DEAP insufficient heat in the buffer tank, and Standard is achievable without solar 2005, version 2. the solar input can not provide the heat based water heating. The introduction of demand at that particular time, the Building Energy Rating system as an Three different inclinations of solar pellet stove can be ignited automatically indication of the energy performance of panels (30o, 45o, 60o) and three different to provide the back-up required. The dwellings in Ireland is likely to increase orientations were calculated, with the pellet stove will then cut out when there the installation of solar technology as it following specification: standard is sufficient energy available. A similar influences the energy rating of a home, number of 3.6 occupants according to control system is found in the Compact and in particular CO2 emissions. DEAP assumption; water storage tank Units, except that a heat pump is used Domestic Water Heating - Solar Input 300 lit., with 150 lit. dedicated to solar, instead of a pellet stove. It is reasonable to expect that an and 50mm factory insulation; with optimized solar based system (flat plate thermostat control. The amount of heat delivered to the of 5–7m2 area or evacuated tubes) will fresh air by the heat exchanger is • As a general rule of thumb, the area produce up to 60% of total annual hot regulated by the internal and external of solar panels is roughly 1 to 2m2 of water demand the Irish climate and they temperatures. The control system is collector area per person. The system have a relatively shorter pay back period usually set up to deliver a relatively high should be capable of providing up to when taking into account available heat load if the temperature outside is 50 litres of DHW per person per day grants, in comparison to other re- very cold, or alternatively a low heat load in season. newable energy technologies such as if it is not too cold. wind turbines or photo voltaic panels. In • In terms of sizing a solar tank, a It would also be possible to use an Ireland the amount of solar irradiation minimum of 80 and preferably 100 ‘instantaneous’ system eliminating the received each year is approximately litres storage per m2 of collector need for a large buffer tank. Such 900–1,150 KWh/m². This is the equival- should be provided. In a typical Irish systems do not typically suit the use of a ent of close to 100 litres of oil. Many home this could mean installing a pellet boiler, however, as the boiler people would be surprised to learn that tank of between 300 and 500 litres would have to switch on and off for Dublin receives the same amount of capacity. It is important to use a short periods of time to maintain an irradiation as Paris. proper solar water tank which is very even temperature in the house. well insulated. Insulation of hot water In terms of specifying a solar collector pipes is also important for energy Individual Room Temperature Control system, the following outline guidance conservation, using at least 1 time Different rooms may have different should be considered: and preferably 1.3 times the pipe temperatures due to solar gains, • The optimal orientation is directly diameter. occupation and internal heat loads. due south and deviation from this 22
  • 28. η 5 square meters of FLAT PLATE collectors (η0=0.75 and a1=6) No obstructions: Primary energy, in kWh/year: This includes delivered energy, plus an Solar Input kWh/year allowance for the energy “overhead” Tilt of collector South SE/SW E/W incurred in extracting, processing and 30 O 1264.9 1246.3 1191.2 transporting a fuel or other energy carrier to the dwelling. For example, in 45O 1264.2 1240.4 1167.9 the case of electricity it takes account 60O 1248.5 1221.3 1137.0 of generation efficiency at power Solar input to demand ratio stations. Tilt of collector South SE/SW E/W Source: SEI, Dwelling Energy Assess- 30O 49% 48% 46% ment Procedure (DEAP), 2005 version 45O 49% 48% 45% 2, pp. 28. O 60 48% 47% 44% 5 square meters of EVACUATED TUBE collectors (η0=0.6 and a1=3) Delivered energy, in kWh/year: This No obstructions: corresponds to the energy con- Solar Input kWh/year sumption that would normally appear Tilt of collector on the energy bills of the dwelling for South SE/SW E/W the assumed standardised occupancy 30O 1324.3 1300.7 1231.5 and end-uses considered. 45O 1323.4 1293.2 1202.5 Source: SEI, Dwelling Energy Assess- O 60 1303.4 1269.1 1164.4 ment Procedure (DEAP), 2005 version Solar input to demand ratio 2, pp. 28. Tilt of collector South SE/SW E/W O 30 51% 50% 48% 45O 51% 50% 47% 60O 50% 49% 45% 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. The 40% or more of DHW needs that are appropriately to the heat load of the cannot generally be used for whole not provided by solar energy can be met house. This will be defined by the house heating. by several means including biomass ‘Verification page’ in the PHPP boilers or stoves, immersion heaters or software. Taking the prototype house • Wood (whether logs, chipped or in natural gas. An outline of the first of presented in these guidelines, a stove pellets) is bulky and a considerable these is provided below. It must be of 3kW output would be sufficient for volume is required for storage remembered that space heating in a all space heating and DHW needs. especially if it is purchased in bulk to passive house is often provided by using keep costs to a minimum. hot water to heat the air passing • A combustion air supply must be provided to any stove or boiler in a • Most wood stoves are highly efficient through the ventilation system. In such passive house bearing in mind the (up to 90%) and when burning cases, hot water production is essential level of airtightness that has to be pellets there is very little ash in the heating season when solar panels achieved. The provisions of an air remaining following combustion. A on the roof will not be sufficient to meet supply and flue for stoves or boilers flue will be required to take exhaust the demand for heating the hot water. will generally not adversely impact gas emissions safely away from the Accordingly, many passive houses will on airtightness or the balancing of house, as with any typical stove. have a biomass stove burning either natural logs or wood chip or pellets. The ventilation flows due to the 'closed' Electricity Consumption in a Passive advantage of the latter two of these is nature of their construction. Air House that they are more easily automated so required for combustion is drawn in The Passivhaus Standard primary energy that they fire up and switch off in the through a relatively small diameter requirement has a limit of 120 kWh/(m2 same way as a conventional gas or oil duct and expelled through the flue. year), regardless of energy source for all burner. • A stove or boiler that directs most of space and water heating, ventilation, The following issues should be the heat output to the DHW tank is electricity for fans and pumps, remembered when considering essential if the hot water is to be used household appliances, and lighting installing a wood stove or boiler: to heat the ventilation air. A model energy requirements of the house. This that simply radiates all the heat into limit means that in a passive house the • The equipment must be sized the space in which it is located efficiency of household appliances and 23
  • 29. all electrical systems is crucial to meet of course highly dependent upon the requires some training prior to this challenging requirement. This is validity of the data entered. embarking on practical application to a emphasised with the fact that the real project. However, the software is Some of the principle datasheets primary energy factor for electricity also quite user friendly and the included in the software are listed taken in the PHPP software (as well as in Verification page enables the user to below, along with their main functions: the DEAP, Dwelling Energy Assessment check whether or not such thresholds Procedure) is 2.7. Therefore 1kWh • Climate data - it is possible to choose such as Space Heating Requirement are electricity used in a passive house the climate which the passive house met. In the event that the key Passivhaus accounts for 2.7kWh of the primary is being designed for which has a Standard criteria are not met, for energy. significant impact on the U-values example, the assessor will firstly have to required to achieve the threshold check to see if there are any funda- When designing a passive house, the annual heat requirement. mental errors in terms of data entry. If PHPP software is used to calculate the this is not the cause of the problem, then electricity balance. The first step is to • Verification - this sheet collates the the building will likely have to be calculate the electricity requirement in results of the overall evaluation of the modified in order to achieve the the house including all household building including the Space Heating required standards. This will typically appliances and lighting. In order to Requirement, Specific Primary involve improving the U-values of the achieve the Passivhaus Standard it is Energy Requirement, Heat Load and building envelope, or altering the necessary to specify refrigerators, Frequency of Overheating. The user proportion and orientation of glazing. freezers, cookers, artificial lighting, can see at a glance on this sheet washing machines, dryers, etc. with the whether or not the building can be Extracts from the PHPP software are highest energy efficiency available on certified as a Passive House. included later in Section 3 pertaining to the market (i.e. category ‘A’ energy rated the prototype passive houses. household appliances). The second step • U-value - this sheet enables the is calculating the auxiliary electricity assessor to specify the construction 2.3.2 Passive House Certification requirement, in which electricity of all the opaque (i.e. does not At the time of writing these Guidelines, a consumption is specified for mechanical include windows) elements of the passive house in Ireland can be certified ventilation system fans and controls, building envelope for the purposes by the Passivhaus Institut in Darmstad, DHW circulation pumps, and any other of calculating the U-value of those Germany (http://www.passiv.de) or present in the dwelling. Calculation elements. The sheet requires the certifying body approved by the results are presented in primary energy input of the lambda value of the Passivhaus Institut. For further infor- kWh/(m2year) and included in the PHPP building materials proposed as well mation on certification of passive ‘Verification page’. as their thicknesses and the houses in Ireland contact the SEI proportion of insulation occupied by 2.3 Energy Balance Renewable Energy Information Office or structural elements. Calculations and Passive the Passivhaus Institut directly. The House Specification • Windows - the orientation and size of evaluation criteria for the certification all windows is entered into this sheet, (Source: PHPP 2007, pp.23) is: 2.3.1 PHPP Software and along with the U-values of the glass - Specific Space Heat Demand Applications and frames as well as other technical max. 15kWh/(m2year) An introduction to the Passivhaus specifications which have discussed - Pressurisation Test Result n50 Planning Package (PHPP) was provided earlier in this chapter. max. 0.6ac/h at the beginning of this chapter within a • Annual Heat Requirement - this value - Entire Specific Primary Energy discussion of the building design is calculated by subtracting the heat Demand max. 120kWh/(m2year) process for passive houses. PHPP is a losses through transmission and including domestic electricity. software package based on a series of elaborate and interlinked Excel data ventilation from the total solar and The above criteria have to be verified sheets which collectively allow building internal heat gains. The Annual Heat with the Passive House Planning designs to be verified against the Requirement must be less than Package 2007 and the required list of Passivhaus Standard. The latest version 15kWh/(m2year). documentation for the passive house of the PHPP software can be purchased • Heat Load - the building's heat load is quality approval certificate, construction for a nominal fee from SEI Renewable based on energy balance calculations drawings and technical specification Energy Information Office. The estimated by subtracting the with product data sheets, must be verification requires the input of very minimum solar gains and internal submitted to the certifying party specific and detailed data about the heat sources from the maximum (including PHPP calculations). Also, design, materials and components into transmission and ventilation heat verification of the airtight building the PHPP spreadsheets and is then losses. envelope according to DIN EN 13829, a related to the climate data for the region record of adjustment of the ventilation in which the house would be built. The The PHPP software is very com- system, declaration of the construction validity of the result from this process is prehensive and detailed and therefore supervisor and photographs of the 24
  • 30. complete building must also be occupants. Also, an approach to submitted. Upon examination of certification of products and tech- received documentation the applicant nologies used in passive house designs receives the results of the examination has been developed. (Source: PEP from the certifying party. Promotion of European Passive Houses, passive house building certification, A wider European passive house http://www.europeanpassive houses.org). certification scheme has been developed within the Intelligent Energy Lifestyle Issues Europe project (2005–2007) “Promotion It is a very common misconception that of European Passive Houses, PEP” windows cannot be opened in a passive (http://www.europeanpassivehouses. house. They can indeed be opened but org). This certification scheme is they don’t have to be opened. In a applicable to ‘an emerging market passive house the ventilation system scenario’ (i.e. countries with a small ensures that a constant controlled number of passive house buildings), amount of fresh air is circulated around aims to ensure that the design of a the house so a stuffy or uncomfortable particular passive house can deliver the atmosphere is avoided. If the occupants specific energy requirements in would prefer to have the windows open accordance with the Passive House at night or provide natural cross Planning Package (PHPP) and confirm ventilation during a hot summer’s day Passivhaus Institut Certificate example, Quality the air-tightness of the completed then it is entirely possible to open Approved Passive House. Source: Passivhaus Institut, Germany. building. This certification scheme whatever windows or doors one involves the verification of the ‘as built’ chooses. The MVHR should be switched design (i.e. that reflects the actual off if there are a lot of windows or doors construction, incorporating any being left open as it would be an modifications made during con- unnecessary waste of electrical energy. struction) in accordance with the Passive Living in a passive house encourages a House Planning Package (PHPP) and greater interest in and awareness of confirmation of the air-tightness of the weather patterns and the impact they completed building by a fan have (or don’t have) on indoor climate. pressurization test performed in The passing of cloud cover brings with it accordance with EN 13829. instant brightness and rising tem- Since the above assessment criteria peratures on the display panel for the apply to the ‘as built’ design details and solar collectors. A very hard frost will the completed building, there is a sometimes leave a veil of ice crystals on significant risk that any non compliances the outside pane of the glazing which due to fundamental errors will be rapidly melts in the morning sunshine. difficult to correct when the building is Extremely cold clear weather usually complete. It is therefore recommended means that the back-up heating is not that the design is checked against the required during the day due to the high PHPP before construction is started to levels of solar irradiation available. Dull confirm that the criteria for the specific muggy days, on the other hand, while heating and primary energy require- not especially cold, may well require the ments are met; the construction on site use of the pellet stove due to the lack of should be checked to ensure that the sunlight. Windows may have to be flung dwelling design has been realised; air open to cool the house on New Years Eve permeability measurements are night depending on how many friends recorded during the construction and neighbours you manage to attract process so that air leakage problems can to join the celebrations! be identified and remedied while access As an illustration of the indoor to the air-tightness membranes etc is temperature comfort,2 monitoring still available. results of the room temperatures in the Since the actual performance of the passive house in Wicklow and site building is very dependent on the measured temperature is shown on correct operation and maintenance by page 26. The graph represents measured the occupant, it is recommended that average indoor and outdoor tem- adequate written information and peratures from January 2006 to instructions are provided to the November 2007. 25
  • 31. Januray 2006 - November 2007 OUT OF THE BLUE TEMPERATURES 30 25 20 Bathroom Down Degree Celsius Kitchen Main bedroom Stairs 15 Garage Living room 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. The above diagram illustrates just 2kW. As a result, those rooms on temperature variation in different parts the northern side of the house were of the house and cooler average below thermal comfort levels for the temperatures in the first heating season first few months of 2006. This went (early 2006) compared to the second largely unnoticed by the family due and third heating seasons (late 2006/ to the fact that the rooms in question early 2007 and late 2007 respectively). are not used. The reasons for these variations are • In the autumn of 2006, a water-to-air interesting and warrant some heat exchanger was fitted to the elaboration, below: MVHR equipment which enabled • The three coolest rooms (‘office’, heating the fresh air as it passes ‘garage’ and ‘bathroom down’) are throughout the house. This was each on the north side of the actively used for the first time in building, receive no direct sunlight December 2006 which resulted in during the winter months and are raising the temperatures in all rooms You can open windows and doors in passive houses! very infrequently used compared to (even those three on the north side) Source: MosArt Architecture. the remainder of the house. The first to well within the normal comfort two of these spaces have three level. In late 2007 the temperatures external walls and so are more prone have improved yet again. to heat losses compared with the rest • There is still in evidence a of the house. temperature gradient (increasing in • The three warmest rooms (‘kitchen’, temperature) from north to south ‘main bedroom’ and ‘stairs’) all open and from first floor to ground floor. out to the south of the house and so The specification of materials and very receive the maximum amount of high quality build creates a strong sense solar gain in winter. Furthermore, of living in a well-built house that will they are occupied for significant last the test of time. The heavy doors and parts of the day and / or night. windows close with a reassuringly solid • In the first few months of 2006, the ‘clunk’ and keep out draughts and only back-up heat source in the reduce external noise. The walls are thick house was a pellet boiler in the and substantial and are packed full of sitting room. This alone was insulation to keep out the cold and the insufficient to heat the entire house heat in. There is no condensation on the Comfort levels all year round in a passive house. Source: MosArt Architecture. as its direct output into the room is internal glazing early on a cold morning. 26
  • 32. The health aspects of living in a mechanically ventilated house are also References readily apparent, with no lingering Passive House Planning Package 2007, odours, little or no condensation in “Protokolband 16: Waermedruecken- washrooms after showering and an freis Konstruiren (Thermal Bridge-Free overall sense of high indoor air quality Construction)”, pp.96. PHPP 2007 throughout. Changing the filters on the Technical Information PHI-2007/1(E), ventilation system is always an eye Passive House Institute, Dr. Wolfgang opener - seeing what dust and dirt is Feist. taken out of the incoming air and what is Passive House Planning Package 2007, extracted from the indoor air. “Certification of Passive Houses”, pp.28. Passive houses provide a stable environment for house PHPP 2007 Technical Information PHI- Living in a house that has a low carbon plants. Source: MosArt Architecture. 2007/1(E), Passive House Institute, Dr. footprint can bring about other changes Wolfgang Feist. in lifestyle that are positive for the 1 EN 13141-7:2004, Ventilation for European Commission (EC), 2006. environment, including growing your buildings/ performance testing of “Promotion of European Passive Houses own food and reducing the impact of components/products for residential ventilation. Performance testing of a (PEP)”. [Internet] PEP. Available at: travel whether by car or by plane. http://www.europeanpassivehouses.or mechanical supply and exhaust Raising children in a passive house will g/html ventilation units (including heat also bring about positive change for the recovery) for mechanical ventilation next generation who will expect to Schnieders J. 2006, “Climate Data for systems intended for single family dwellings. Determination of Passive House Heat improve even further on what their Loads in Northwest Europe”. Darmstadt, parents achieved. 2 Thermal comfort is defined in British Germany, Passivhaus Institut. Standard BS EN ISO 7730 as: ‘that Perhaps the overall lifestyle benefit of condition of mind which expresses living in a passive house is that it satisfaction with the thermal environ- provides very high levels of overall ment.’ It is affected by the key environ- comfort without compromising the mental factors as air temperature, radiant temperature, air velocity and environment and at a fraction of the cost humidity. of living in a so-called ‘normal’ house. 27
  • 33. S ECTION T HREE Passive House Prototype for Application in Ireland
  • 34. Passive House Prototype for Application in Ireland This section of the guidelines 3.1.1 Combining Aesthetic and of the prototype passive house. demonstrates the practical application Energy Performance in House 3.1.2 Decision Support using Passive of Passivhaus Standard to a prototype Design House Planning Package (PHPP) house designed especially for this The design of a passive house is strongly Software project and suitable for the mass influenced by the need to minimise heat housing in Ireland. The house type The Passive House Planning Package loss through the building fabric, to demonstrated is a semi-detached two (PHPP v2004) has been introduced maximise solar gains and to cater for the storey house with a floor area of already in these guidelines. It is an Excel- various building services. Form and approximately 110m2. The house is based software that can be used to ‘test’ function played equal roles in the design depicted in plan and elevation below. the energy performance of a building as of the prototype passive house. The The house is typical in most aspects of its it is being designed. It includes Irish overriding principle used in the design design, comprising three bedrooms climatic data which is very useful in of the prototype house was that it upstairs (including one ensuite and ensuring that buildings are not over- should be broadly similar in character to family bathroom) and a living room, specified in terms of thermal per- contemporary housing, thus maximising dining room, kitchen/utility and formance. Key aspects of the emerging ease of acceptance to the current wheelchair accessible WC down-stairs. prototype passive house were entered housing market in Ireland. There are also some non-conventional into the software with a view to ensuring elements included, including a double- As has been described in some detail in that the design achieved the minimum height sun room, solar panels, pellet the preceding sections, much of the requirements of (a) yearly space heating boiler and shading pergola. These are all ‘free’ energy required to heat a passive delivered energy demand of 15 kWh/m2 described in greater detail below. house comes directly from the winter treated floor area (TFA3), and (b) upper sun through south facing windows. It is limit for total primary energy demand The final part of this section examines therefore typical (though not essential) for space and water heating, ventilation, the capital construction costs associated to have a bias in terms of placement of electricity for fans and pumps, house- with the passive house. glazing on the southern elevation. hold appliances, and artificial lighting 3.1 Design and Specification Combined with such glazing is the need not exceeding 120kWh/(m2year), regard- to prevent overheating in summer and less of energy source. The two most common residential this is easily ensured through the use of construction methods in Ireland were The thickness of insulation required in shading, in this case with a balcony and used in the design and specification of the walls, floor and roof is strongly pergola. The walls of a passive house are the prototype passive house, namely guided by the PHPP software, as is the typically thicker than those of timber frame1,2 and masonry. It is specification and positioning of the conventional construction due to the demonstrated below that the Passivhaus windows, the sizing of the back-up need for additional insulation and this Standard can be easily achieved in space heating system, the consideration must be borne in mind in the early Ireland using both of these construction of thermal bridges and many other stages of design development. The other methods and that there are no major aspects of the design. The design is thus key issue to consider when developing advantages of one method over another an iterative process. Different insulation the design of a passive house is the need in terms of thermal performance. Both types can be tested in the software, with to minimise thermal bridges including passive house construction types can be higher performance materials (in terms that created between the foundation built using mostly conventional of lower Lambda values) requiring and internal walls, for example. Bearing elements as can be seen from the thinner walls than other less efficient in mind the above principles of glazing detailed wall sections provided in materials. orientation, wall thickness and Section 3.1.4. minimised thermal bridging, the Two extracts from the PHPP software are designers commenced the development included below in order to give an 31
  • 35. insight into how the software can be details a timber frame wall with an intended to be diagram only. They used to assist the designer. Passive insulated service cavity and the third should not be used as a basis for House Verification Sheet deals with table illustrates the depth of insulation detailed construction drawings. annual heat requirement based on a required in the roof. The partial thermal The following key issues can be noted balance of heat losses (transmission and bridge caused by the timber studs is from the detailed wall sections: ventilation) pitched against heat gains taken into account in the software by (solar and internal) in order to calculating the proportion of the • Thicker than normal wall sections are summarise the Annual Heat Require- insulated wall occupied by timber (in designed in order to accommodate ment. The annual space heat require- this case 10%). the required depth of insulation. ment of 15kWh/m2 is achieved. There is also substantial insulation in 3.1.3 Prototype Passive House both the roof and under the floor. The second illustration provides an External Wall Sections insight into how the U-values of major • The insulation at the junction of roof building elements are calculated. The The wall sections for both construction and wall, as well as wall and floor, first table provides details on how a U- types are illustrated also. It should be overlap in order to minimise therma value of 0.15W/(m2K) is achieved for a noted that no dimensions are included l bridging at these critical locations. concrete cavity wall, the second table on the sections below as they are The window frame is also partly Passive House Verification for the prototype passive house, concrete block construction. Source: MosArt Architecture. 32
  • 36. bedded in insulation in order to • Blockwork with a low thermal reduce heat loss. conductivity is used in the rising walls to reduce thermal bridging • Membranes and specialist tapes are between foundations and walls. used to create an airtight envelope. This is especially critical at junctions between different elements, such as around windows, and also where the first floor penetrates the external wall façade. • A service cavity is proposed, internal to the airtight layer in the timber frame wall, in order to accommodate mechanical and electrical fittings. A similar cavity is proposed in the underside of the ceiling at first floor IFC, Insulated Concrete Forms. Externally insulated concrete block wall. level for both house types. Source: UCD Energy Research Group. Source: MosArt Architecture. Passive House Verification for the prototype passive house, timber frame construction. Source: MosArt Architecture. 33
  • 37. U-value of building elements for the prototype passive house, concrete block construction. Source: MosArt Architecture. 34
  • 38. U-value of building elements for the prototype passive house, timber frame construction. Source: MosArt Architecture. 35
  • 39. Cross section, prototype passive house. Concrete block construction. Source: MosArt Architecture. 36
  • 40. Cross section, prototype passive house. Timber frame construction. Source: MosArt Architecture. 37
  • 41. 3.1.4 Prototype Passive House charges €256/year; wood pellets - in heat exchanger. In this regard, all Design including Mechanical bags 5.92c/kWh. Source: SEI, Dwelling supply air ducts should be insulated and Electrical Services Energy Assessment Procedure (DEAP) in order to minimise heat losses, even 2005 edition, version 2, Manual pp. 84. if they are located within the thermal The final design of the prototype passive envelope. house is presented below in plan, The heat load, on the other hand, is elevation, section and, finally, a 3D approximately 1,800 W, or just 1.8 kW. • Solar panels (measuring 7.5m2) are model. A number of mechanical and This amount of energy could be positioned on the south facing roof electrical features are highlighted which provided by a very small stove/ which is pitched at the optimal angle have been included specifically in the heater/boiler compared to what of 45 degrees. These have been sized development of the passive house might be typically required in a in accordance with the needs of such prototype: family home (there are several such a house and could include either flat ‘small’ boilers on the market which plate collectors or evacuated tubes. • In terms of mechanical ventilation, an average air flow rate of range in output from 2.4 to 8kW, with Other aspects of the design which are approximately 115m3/h would be approximate efficiency of 90%). The not related to the mechanical or required providing an approximately pellet stove in the prototype house electrical services are listed below: air change of 0.4 per hour. A fresh air has been positioned in the sitting room, but space has also been left in • All windows in the prototype house outlet is provided to the living room, the utility room as this might be are triple glazed with low emissivity dining room, double height sun preferable for users. The pellet stove coating, thermally broken frames and room (at ground floor level) and can be filled manually as the need gaskets especially designed to bedrooms whereas an extract vent is arises, or could be automatically fed minimise air infiltration. A passive provided in WC’s and bathrooms as using an underground pellet storage house triple glazed window is well as the kitchen, the utility room ‘bunker’ located underground to the typically four times more energy and the upper part of the sun room. public road side of the house for ease efficient than a standard double The mechanical ventilation with heat of delivery. While a house of this size glazed unit and, if south facing, will recovery unit is located in the utility could probably manage without an take in more energy in a year than it room and will recover the majority of automatic feed from a bunker (given lets out. The use of such glazing the heat from the extracted air to an average use of approximately ensures high thermal comfort in cold warm the incoming fresh air. An 15kg of pellets per week), the weather through minimal temper- airing cupboard is located on the first advantage of such a system is in the ature difference between internal floor along with the washing space saved from having to store glass pane surface and room temper- machine. This space is connected to pellets in the house or garden shed. ature. the ventilation system and can function as drying cabinet for drying In positioning the pellet stove in the • A balcony is provided at first floor clothes in the winter. Sound sitting room, there is an aesthetic level, the primary function of which is attenuators should be used in order benefit to be gained from visibility of to shade the extensive area of glass to minimise noise travelling along the flames coupled with the delivery on the south elevation. This balcony ducts and air filters should be of some heat directly into the sitting can be accessed via the gallery which changed as required in order not to room. Care must be taken to use a overlooks the double-height sun compromise indoor airflows and / or stove that delivers most of the heat room. A wooden pergola is provided air quality. output to the hot water tank and not overhead the balcony to shade the directly into the room in which it is upper story windows. A possible • A pellet stove is proposed for the located. It is also critically important alternative to this pergola could be a back-up space and water heating that the pellet stove has its own fresh deep roof overhang but the steep- system.4 For the prototype house the air supply, given the airtight nature of ness of the pitch in the prototype annual space heat requirement is the construction, and that an house would mean that this latter 15kWh/(m2year) equating to approx- appropriate flue for venting of solution would restrict high level imately 1,650 KWh over an entire year exhaust gases is provided. Such views from the upper storey. (the house measures 110m2 in systems are common place in passive treated floor area). This would equate houses and will not adversely affect • The internal party walls can be to 155 litres/year of oil, 160 m3/year of the balanced ventilation system. constructed as per a conventional mains gas or 350kg/year of wood house as long as it is within the pellets (in bags) at a cost of • The domestic hot water tank (550 boundaries of the building envelope. approximately €92/year when using litre)5 is located adjacent to the • The hatch to the attic should be very oil, €55/year when using gas (without mechanical ventilation unit, in the well insulated and completely standing charges for gas or utility room. The back-up heating airtight to minimise cold air €345/year with standing charges) or system, in this case, is provided by infiltration. €97/year when using wood pellets. heating the fresh air circulating Unit price: heating oil 5.62c/kWh; around the house by the hot water in • Ceiling insulation is placed mains gas 3.39c/kWh standing the ‘buffer’ tank using a water to air horizontally on the attic floor in the 38
  • 42. prototype passive house. It would efficient light bulbs and household 1 also be possible to place this appliances. Included in their analysis Approximately 17% of houses built in Ireland are semi-detached. insulation between the rafters, albeit was an allowance for the foregone costs 2 with design and construction associated with ‘conventional’ house According to the Irish Timber Frame implications. features such as a fireplace and boiler Manufacturers’ Association (ITFMA) the number of timber frame house with radiators. Gardiner and Theobald completions has grown from a market • The timber frame option depicted in undertook their analysis for both timber share of 15% in 1999 to a market share these guidelines is ventilated with an frame and the concrete block of 30% in 2006. external cavity. construction methods. 3 The TFA is the living area within the • Energy efficient light fittings should thermal envelope. Any rooms or areas be used which use less primary The additional ‘extra over’ cost beyond the boundaries of the thermal energy (they will also reduce internal associated with building the prototype envelope are not considered. heat gains). It is also preferable to use house to the Passivhaus Standard was 4 Other sources of heat such as gas or heat energy efficient appliances. estimated at approximately €25,000 for pumps can also be used. both construction methods, including 5 Various building methods can be used in Estimated heating requirement for hot VAT and design fees. Approximately 60% water (incl 50% SWH) + space heating = the construction of a passive house, of this cost can be attributed towards 3200 kWh = c.650 kg pellets/year = including, insulated concrete formwork improvement of the building shell 10–15 kg/week. and externally insulated concrete block (enhanced insulation, higher grade wall. The prototype house presented in windows, improved airtightness and this publication illustrates masonry and reduced thermal bridging) with the timber frame construction as References remaining 40% covering building representative of most typically used systems including MVHR, solar thermal Passive House Planning Package, PHPP building methods for dwellings in system, low energy lighting and wood 2004, Technical Information PHI- Ireland. pellet boiler. 2004/1(E). Darmstadt, Germany. Passive House Institute, Dr. Wolfgang 3.2 Cost Considerations Feist. Gardiner and Theobald next sought to An analysis of additional costs express the additional passive house associated with construction of the costs as a proportion of conventional prototype house to the Passivhaus construction costs. The cost of a Standard was carried out by Gardiner conventional house varies considerably and Theobald Cost Consultants. The according to the quality of finishes additional cost of the key items required. An average cost of €196,000 including enhanced insulation, glazing, was proposed as representing a mid- airtightness and thermal bridging was grade finish, including VAT and design estimated, along with the cost of such fees. The additional cost of €25,000 thus technologies as MVHR, solar panels for represents approximately 12.5% of DHW, a pellet stove as well as energy current conventional costs. 39
  • 43. Prototype passive house, floor plans (not to scale). Source: MosArt Architecture 40
  • 44. Prototype passive house, floor plans (not to scale). Source: MosArt Architecture 41
  • 45. Prototype passive house, cross section (not to scale). Source: MosArt Architecture 42
  • 46. Prototype passive house, front, back and side elevations (not to scale). Source: MosArt Architecture 43
  • 47. Prototype passive house, 3D model (not to scale). Source: MosArt Architecture 44
  • 48. Sustainable Energy Ireland Renewable Energy Information Office Shinagh House Bandon Co. Cork Ireland T. +353 23 42193 renewables@reio.ie F. +353 23 54165 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.