Sustainable Energy Ireland (SEI)

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

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

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

© Sustainable Energy Ireland, 2009. 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 SEI Renewable Energy Information Office and MosArt Architecture. Cover images courtesy of Cooney Architects. Table of Contents

FOREWORD (i) SECTION FIVE: Upgrading of Typical Construction Types SECTION ONE: The ‘’ Walls 29 Random rubble and hollow block wall 29 Passive House and the Passivhaus Standard 1 Cavity walls 29 Definition of the Passivhaus Standard 1 Timber frame 35 Technical definition of the Passivhaus Standard for Ireland 2 Floor slab 37 Applications of the Passivhaus Standard in the EU and Ireland 3 Roof 42 Evolution of retrofitting dwellings to the Passivhaus Cold Roof / insulated at ceiling level 42 Standard in Europe 3 Sloped roof 43 Application of the Passivhaus Standard in Ireland 3 Dwelling Energy Assessment Procedure 3 Building Energy Rating 4 SECTION SIX: PHPP and DEAP 4 Case Study Retrofit Building - Theoretical

Dwelling description 49 SECTION TWO: Current heating and DHW system 50 Review of Building Stock in Ireland Use of PHPP and DEAP to prepare retrofitting strategy 52 Preparing a retrofitting strategy 52 Energy efficiency and dwelling age 7 Measures in detail 53 Fuel poverty source: Healy and Clinch (2002) 8 53 Windows and doors 53 Thermal bridges 53 SECTION THREE: Airtightness 53 Ventilation 54 Principles of Passive Houses Cost of retrofitting 54 Passive house verification 57 Passivhaus Planning Package 2007 - An essential design tool 11 Passive house certification 12 insulation 12 SECTION SEVEN: Optimising passive solar gain 12 Thermal bridging 13 Case Study of Completed Retrofitted Project Structural airtightness and draught proofing 13 Internal heat gains 13 Case study of completed retrofitted project 61 Passive House building systems 13 What happens in the event of a power failure? 13 Back-up heating system 14 Domestic hot water production 14

SECTION FOUR: Typical Phases of Retrofitting

Survey 17 Initial PHPP calculation 17 Changes in layout/design 18 Upgrade thermal envelope 18 Insulation 18 Internal insulation 19 External insulation 20 Insulating the roof space 20 Wall cavity insulation 20 Windows and doors 21 Airtightness 21 Thermal bridges 22 Upgrade ventilation and heating system 22 Ventilation system 22 Recommended ventilation rate 22 Mechanical heat recovery ventilation (MHRV) system 23 Insulation and positioning of work and vents 23 Heating system 23 Water to air 23 Compact unit with electrical 23 Wood pellet / Wood pellet stove / Wood log 24 Integrated controls for heating in a Passive House 24 Individual control 24 Site supervision 24

i Foreword

The Sustainable Energy Authority of Ireland, SEI, operates programmes and activities to advance the Government’s ambition for Ireland to become a world leader in sustainable energy as part of our transition to a low carbon economy. Thus, we seek to accelerate the development and deployment of cost effective low carbon technologies. Following the implementation of the EU Energy Performance of Buildings Directive, recent substantial improvements in Building Regulations energy standards and requirements for the use of renewable energy systems, we have seen substantial improvement in the energy performance required of new buildings.

For several reasons, attention must retrofitted PassivHaus projects in focus now on our existing buildings. continental Europe in the past three to The recent extension of the Building five years and it is expected that this Energy Rating to all buildings being trend will carry over to Ireland. sold or rented coupled with the introduction of a national residential These guidelines provide sound and energy efficiency programme, and the practical advice on how the knowledge that cost-effective retrofitting of older buildings could opportunities to reduce greenhouse potentially achieve a standard which gas emissions are most readily found will greatly increase comfort, cut in buildings are all combining to energy costs dramatically, and offer a provide an extraordinary impetus to home which is far more “future home energy saving. proofed”. There are over 1.5 million homes in Ireland that could each The PassivHaus standard is benefit from implementing even recognized in Europe as a progressive some of the measures contained in and advanced benchmark for this document. building energy performance. In 2008 SEI published ‘Guidelines for the Design and Construction of Passive House Dwellings in Ireland‘ which have been very well received, with some 5,000 copies now in circulation. These companion guidelines ‘Retrofitted Passive Homes - Professor J Owen Lewis Guidelines for Upgrading Existing CEO, Sustainable Energy Ireland Dwellings in Ireland to the PassivHaus Standard’ extend the available support and information for the upgrading of existing dwellings to achieve the ambitious PassivHaus Standard.

There has been a noticeable increase in the number of successfully

ii SECTION ONE

The ‘Passive House’ 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 all year-round comfort and construction standard for buildings good indoor environmental conditions which results in good comfort condi- without the use of significant active space tions during winter and summer, heating or cooling systems. The space without traditional space heating heat requirement is reduced by means of systems and without active cooling. passive measures to the point at which The primary focus in building to the MosArt Architecture there is no longer any need for a conven- Passivhaus Standard is directed towards tional space heating system; the air creating a thermally efficient envelope supply system essentially suffices to which makes the optimum use of free distribute the remaining space heat heat gains in order to minimise space requirement. A passive house provides a heating requirement. Structural air- very high level of and tightness (reduction of air ) whole-house even temperature. The and minimal thermal bridging are essen- concept is based on minimising heat tial. A whole-house mechanical heat losses and maximising heat gains, thus recovery ventilation system (MHRV) is enabling the use of simple building used to supply controlled amounts of services. fresh air to the house. The incoming MosArt Architecture The Passivhaus Standard is a construc- fresh air is pre-heated, via a heat tion standard developed by the exchanger, by the outgoing warm stale Passivhaus Institut in Germany air. If additional heat is required, a small (http://www.passiv.de). The standard can efficient back-up system (using a renew- be met using a variety of design strate- able energy source, for example) can be gies, construction methods and used to boost the temperature of the technologies and is applicable to any fresh air supplied to the house. building type. Renewable energy sources are used as much as possible to meet the resulting This publication outlines the require- energy demand (PEP, 2006), including ments in applying that standard to retro- that required for the provision of domes- fitting dwellings in Ireland and in all tic hot water (DHW). cases when referring to a passive house MosArt Architecture is describing a house upgraded to the The energy requirement of a house requirements of the Passivhaus retrofitted to the Passivhaus Standard is: Standard. These guidelines should be ■ Annual space heating requirement read in conjunction with the Guidelines of 15 kWh/(m2a) treated floor area; for the Design and Construction of Passive House Dwellings in Ireland ■ The upper limit for total primary published by SEI in July 2008 energy demand for space and water (www.sei.ie/phguidelines). heating, ventilation, electricity for fans and pumps, household appli- ances, and lighting not exceeding 120 kWh/(m2a), regardless of energy source; and

page 1 ■ Additionally, the air-leakage test Measure/Solution Retrofit Passivhaus Standard for the Case Study results must not exceed 0.6 air Semi-Detached House in the Irish Climate changes per hour (ac/hr) using 50 1. Super Insulation Pascal over-pressurisation and Insulation Walls U ≤ 0.10 W/(m2K) under-pressurisation testing. Insulation Roof U ≤ 0.09 W/(m2K) Insulation Floor U ≤ 0.10 W/(m2K) In order to maintain high comfort levels Window Frames, Doors U ≤ 0.8 W/(m2K) in any building, heat losses must be Window Glazing U ≤ 0.6 W/(m2K) replaced by heat gains. Heat losses Thermal Bridges Thermal bridges with a linear heat coefficient Ψ ≥ occur through the building fabric due 0.01 W/mK will be very common in most retrofit projects and will require calculating to transmission through poorly Structural Airtightness n50 ≤ 0.6 ac/hr @ 50 Pascal insulated walls, floor, ceiling and glazing as well as from uncontrolled 2. Heat Recovery/ Air Quality cold air infiltration through leaky Ventilation counter flow Heat recovery efficiency ≥ 85% air to air heat exchanger construction and poorly fitted windows Minimal Space Heating Post heating ventilation air/ Low temperature and doors. In a passive house, the heat heating losses are reduced dramatically Efficient small capacity heating system Biomass compact unit, gas etc. (through better insulation and airtight Air quality through ventilation rate Min 0.37 ac/hr or 30m3 /person/hr detailing) so that internal gains and Ventilation Supply Ducts Insulated Where applicable passive solar gain contribute a DHW Pipes Insulated Where applicable relatively high proportion of the total 3. Passive Solar Gain need. As a result of this, a smaller space Window Glazing Solar energy transmittance g ≥ 50% heating system is therefore required Solar Orientation Minimal glazing to north where possible compared to that needed in a conven- within Envelope Recommended tional poorly performing dwelling. 4. Electric Efficiency A semi-detached, two storey Irish house Energy Labelled Household Appliances A-Rated appliances Hot water connection to Recommended built in the mid 1970’s before the intro- washing machines/dishwashers duction of thermal insulation standards Compact Fluorescent or LED Lighting Recommended wouldbeexpectedtohaveaspace Regular maintenance ventilation filters Recommended heating requirement of over 200 Energy Efficient Fans/ Motors Recommended kWh/(m2a) and to have a total primary 5. On-site Renewables 2 energy demand of over 400 kWh/(m a) DHW Solar Heating Area to be dictated by house size and occupancy for all applications. The equivalent Biomass system Recommended house built to the requirements of TGD Photovoltaics Application in a case by case basis Part L 2007 would be liable to use 40-50 Wind Turbine Application in a case by case basis kWh/(m2a) delivered (useful) energy for Other including geothermal Application in a case by case basis 2 space heating and 90-95 kWh/(m a) Table 1. Technical Definition of the Passivhaus Standard for the Case Study Project Presented in Section 6 primary energy. The Passivhaus Source: MosArt Architecture Standard requirement for space heating is 15 kWh/(m2a). When compared to a 1.1.2 Technical Definition of the values for retrofit projects will often be house built in the mid-1970’s, with little Passivhaus Standard for far lower than for buildings that were, or no insulation and poor performing Ireland from the very outset, designed in strict glazing, a house retrofitted to the accordance with the Passivhaus Passivhaus Standard thus represents a InTable1arangeofU-values is specified Standard. The U-values included in saving of more than 90% on the space in order to meet the Passivhaus Table 1 have been tested for the case heating demand. Standard of annual space heating study house presented later in Section 6. requirement of 15 kWh/(m2a) for the One of the key benefits of a passive This case study house is a terraced two Irish climate. Specifying U-values is house is that it becomes affordable to storey house of compact form and with dependent upon many variables and the provide thermal comfort conditions optimal (rear) façade orientation of effect on energy performance can only around the clock at much reduced directly south. A detached bungalow be verified through testing the perform- energy consumption. This is a very house of sprawling form would likely ance of the dwelling design in the positive aspect of passive houses that is require even lower (better performance) Passive House Planning Package (PHPP) often forgotten. The energy consump- U-values than those specified in the software. In a typical retrofit situation, tion for heating an existing house table above in order to meet the Passivhaus principles such as orienta- around the clock would be significantly Passivhaus Standard. Readers familiar tion, position of glazing, thermal bridg- higher and much less affordable. with the SEI (new-build) Passive Homes ing and compactness will generally not Guidelines will recognise that the U- have been considered in the original values listed in the table above are design. For that reason, the required U- considerably lower (better performance)

page 2 than those specified for the prototype tion of these savings (32%) coming from Rating certificate. This requirement, house in those guidelines. The reason for the built environment. perhaps above all other initiatives, is this is that there are often numerous likely to result in a rapid and dramatic In 2006, the residential sector accounted thermal bridges that have to be appreciation by homeowners of the for 25% of primary energy consumption compensated for in retrofitting an older importance of energy efficiency in older and used 2,990 ktoe of final energy dwelling compared to new-build. The dwellings. representing 23% of Ireland's Total Final case study dwelling is also partly shaded Consumption. With regard to CO The EU Parliment has proposed a which reduces passive solar gain, requir- 2 emissions, the average dwelling was binding requirement that all new build- ing a better insulated envelope. responsible for emitting approximately ings needing to be heated or cooled be 8.1 tonnes of CO . A total of 4.8 tonnes constructed to a‘passive house’or equiv- 1.2 Applications of the 2 CO (59%) was from direct fuel use, the ilant standard from 2011 onwards (refer- Passivhaus Standard in 2 remainder being the result of upstream ence European Parliament resolution of the EU and Ireland emissions from electricity usage. 31 January 2008 on an Action Plan for Energy Efficiency: A6-0003/2008). As the 1.2.1 Evolution of Retrofitting Examining CO emissions per dwelling, 2 energy efficiency of new-build dwellings Dwellings to the Passivhaus the average Irish dwelling in 2005 steadily improves, there may well be Standard in Europe emitted 47% more CO than the average 2 increasing pressure to reduce the energy dwelling in the UK. Emissions were 92% The Passivhaus Institut consumption of older homes in order higher than the average for the EU-15, (http://www.passiv.de) was founded in that they can compete for buyers atten- 104% more than the EU-27. Darmstadt, Germany in 1996 by Dr. tion on the open market. Wolfgang Feist as an independent Following the Government’s White Minister Gormley announced in July research institute. Since then, it has been Paper ‘Delivering a Sustainable Energy 2008 his ambition that all new domestic at the forefront of the Passive House Future for Ireland’ (DCMNR, 2007), and buildings be constructed to a ‘carbon movement in Germany and has been the subsequent Programme for neutral’ standard by 2012 or 2013. Such instrumental in disseminating the Government, the Building Regulations a move will likely result in a significant standard throughout Europe and Part L in respect of new dwellings have increase in the market penetration of overseas. The Institute developed the been strengthened to bring a 40% renewable electricity generating "Passivhaus Projektierungs Paket" (PHPP reduction relative to previous standards technologies which will, inevitably, spill - Passive House Planning Package), an in respect of primary energy consump- over in terms of application to the Excel worksheet used to determine the tion and associated CO emissions 2 second-hand housing sector. energy supply / demand balance for arising from space heating, water passive buildings (available in Ireland heating, ventilation, associated pumps Lastly, there are several grant schemes from SEI Renewable Energy Information and fans, and lighting energy usage. available through Sustainable Energy Office (www.sei.ie/resourcecentre). These provisions apply to dwellings Ireland at present which are focused where planning permission was submit- towards building energy efficient Since completion of the first certified ted after July 2008. This policy has dwellings and the deployment of renew- new-build passive houses in Darmstadt committed to a further review in 2010 able energy technologies including the in 1991, there has been an emerging with the aim of extending that improve- Greener Homes Scheme and the Low trend in recent years of retrofitting build- ment to 60%. Carbon Homes Scheme. In addition the ings to the Passivhaus Standard. Warmer Homes Scheme tackles the issue It is clear that the performance of both of energy efficiency in low income, older 1.2.2 Application of Passivhaus new build and existing housing stock dwellings and is of potential relevance to Standard in Ireland must be addressed if we are to achieve these Guidelines. In 2003, SEI estimated the objectives set out both at European The Kyoto Protocol came into force in that approximately 220,000 households and national level. The energy require- 2005 and the proposed targets of reduc- in Ireland live in either persistent or inter- ment of a house retrofitted to the ing greenhouse gas (principally CO ) mittent fuel poverty. 2 Passivhaus Standard is even lower than emissions by 8% compared to 1990 the 40% improvement that applies to all levels by the period 2008-2012 became 1.3 Dwelling Energy new dwellings in Ireland from July 2008. legally binding for EU Member States Assessment Procedure As inefficient existing dwellings repre- (UNFCCC, 1997). Within the EU burden sent the majority of the building stock, sharing agreement in this regard, 1.3.1 Dwelling Energy Assessment the retrofitting of existing stock to the Ireland's target limit of 13% above 1990 Procedure Passivhaus Standard represents a great levels had been reached in 1997, and it is potential for reducing energy consump- The Dwelling Energy Assessment likely that the limit will be overshot by tion. Procedure (DEAP) is the Irish official up to 37% by 2010. The EC Green Paper procedure for calculating and assessing on Energy Efficiency (EU, 2005) states From January 1st 2009, all existing the energy performance of dwellings. that it is possible for the EU-25 Member dwellings which are offered for sale or The procedure takes account of the States to achieve energy savings of 20% rent must undergo a building energy energy required for space heating, by 2010, and sees the greatest propor- assessment and have a Building Energy

page 3 ventilation, , associated 1.3.3 PHPP and DEAP pumps and fans, and lighting, and also References Whereas DEAP is the mandatory method takes into account savings from energy 1 for both producing a BER and for A passive house is a building, for which generation technologies. The DEAP demonstrating compliance with certain thermal comfort (ISO 7730) can be calculations are based on standardised achieved solely by post-heating or post- aspects of the Irish Building Regulations, occupancy and the procedure deter- cooling of the fresh air mass, which is the Passivhaus Standard and the associ- mines annual values for delivered required to fulfill sufficient indoor air ated PHPP is a voluntary design standard energy consumption, primary energy quality conditions (DIN 1946) - without a for achieving low levels of total energy consumption, CO emissions and costs. need for recirculated air. Source: 2 consumption within a dwelling. These values are expressed both in http://www.passivhaustagung.de/Passive_ House_E/passivehouse_definition.html terms of annual totals and per square While it is to be expected that a dwelling metre of total floor area of the dwelling. conforming to the Passivhaus Standard will comply with Irish Building As the national methodology, DEAP Regulations Part L, a separate calculation serves two primary functions. The first is using DEAP will be required to demon- to demonstrate compliance with certain strate both this and to determine its BER. provisions in the Building Regulations Additional Reading and the second is to produce a Building The Passivhaus Standard can be met Energy Rating (BER) for a dwelling. using a variety of design strategies, construction methods and technologies. European Commission (EC), 2005. “Green Paper on Energy Efficiency”. 1.3.2 Building Energy Rating In general, the low energy consumption [Internet] EC. Available at: required to meet the standard will result A BER is an objective scale of compari- http://ec.europa.eu/energy/efficiency/i in a dwelling achieving a favorable BER, son for the energy performance of a ndex_en.html provided that attention is paid to the building ranging from A1 to G (see European Commission (EC), 2006. “ advice outlined in later sections of these sample label below). Essentially a BER is Promotion of European Passive Houses guidelines. an asset rating, based on a standardised (PEP)”.[Internet] PEP. Available at: http://www.europeanpassivehouses.or occupancy and usage pattern, and is g/html calculated for a dwelling using DEAP. The rating is the annual primary energy Government of Ireland, Department of Communications, Energy and Natural consumption of the dwelling expressed Resources (DCMNR), 2007. Government 2 in terms of kWh per m of floor area. The “White Paper Delivering a Sustainable CO2 emissions associated with this Energy Future for Ireland”.[Internet] energy consumption are also reported DCERN. Available at: on the BER certificate and expressed in http://www.dcmnr.gov.ie/Energy/Energ 2 y+Planning+Division/Energy+White+P termsofkgofCO2 per m of floor area. aper.html O’Leary, F., Howley, M., and O’Gallachóir, B., 2006. “Energy in Ireland 1990-2004, Trends, issues, forecast and indicators”.Dublin. Sustainable Energy Ireland. O’Leary, F., Howley, M., and O’Gallachóir, B., 2008, “Energy in the Residential Sector: 2008 Report”. Dublin. Sustainable Energy Ireland. United Nations Framework Convention on Climate Change (UNFCCC), 1997. The Kyoto Protocol. [Internet]. UNFCCC. Available at: http://unfccc.int/resource/ docs/convkp/kpeng.html Guidebook on Energy Intelligent Retrofitting, Published by Intelligent Energy Europe Agency, February 2008.

Building Energy Rating Label. Source: Sustainable Energy Ireland.

page 4 SECTION TWO

Review of Building Stock in Ireland page 6 Review of Building Stock in Ireland

An overview of the current building was €1,767, an increase of 4% on 2005 stock in Ireland is provided below in and 70% on 1990 (3.4% per annum on In terms of real numbers, it is order to gain some impression of the average) – this increased to approxi- estimated that 930,000 houses in Ireland were built before the first ever potential application of these guide- mately €2,000 in 2008. building regulations in 1991, with lines. In 2006 the residential sector accounted approximately 1 million homes built There were an estimated 1.46 million for just under a quarter of all energy before the 1996 Building Regulations. permanently occupied dwellings in the used in Ireland and after transport it was 350,000 houses in Ireland have no wall insulation, 200,000 houses have State at the end of 2006. The most the second largest energy using sector. no roof insulation and 350,000 houses common house type in Ireland in 2006 The sector was responsible for 25% have single glazed windows. was the detached house which (11,896 kt CO2) of energy related CO2 accounted for 42.8% of the total, emissions. In 2006 the 'average' dwelling (DoEHLG). At the time of the survey, 57% followed by semi-detached houses at consumed a total of 25,304 kWh of of all dwellings had been built before 2 27.2% and terraced houses at 17.6% . energy based on climate corrected data. the introduction of the first Irish Building Regulations which came into force in Stock of Private Households in Permanent Housing Units - Types of Accommodation 1991. Approximately 750,000 homes DWELLING TYPE 2006 number 2006 % of Total were built prior to any thermal insula- tion requirements (introduced 1979) but Detached House 625,988 42.8 the survey indicates a degree of energy Semi-Detached House 398,360 27.2 Terraced House 257,522 17.6 improvement across the older housing Flat / Apartment[1] 139,872 9.6 stock. Nevertheless, in 2001 24% of all Bed-sit 8,751 0.6 households surveyed had no insulated Not Stated 31,803 2.2 walls (equating to 63% of pre-1940 built Total 1,462,296 100.0 houses), 18% had no insulated roof (40% Source: SEI of pre-1940 built houses) and 31% had no double glazing (49% of pre-1940 In 2006, the majority of dwellings (75%) This comprised 19,713 kWh (78%) in the built houses). were either owned outright or were in form of direct fossil fuels and the remain- the process of being purchased der as electricity. The percentage of dwellings with central (mortgaged) representing a slight heating had increased from 52% in 1987 Putting Irish dwellings into an interna- decrease on the 1991 proportion of 79%. to 91% in 2005. tional context. Examining CO2 emissions There have been historically high levels per dwelling, the average Irish dwelling Energy efficiency and dwelling of ownership in Ireland compared to in 2005 emitted 47% more CO2 than the age other European countries. For example average dwelling in the UK. Emissions in Austria the proportion of owner were 92% higher than the average for Pre-1940 dwellings were mainly solid- occupied dwellings was 51% in 2004 the EU-15, 104% more than the EU-27. wall construction, while during the and for the UK it was 69%. 1940s through to the 1970s, cavity-wall Focusing on the quality of the building construction was implemented. During Dwellings in Ireland are gradually stock in Ireland, The Economic and the 1980s, improved U-values for both increasing in size. For example, the Social Research Institute (ESRI) walls and attics were introduced in average floor area of new houses completed a study in 2002 titled ‘Irish various building regulations, increasing granted planning permission grew from National Survey of Housing Quality 2001 the thermal efficiency of dwellings, and 2 2 130m in 1990 to 161m in 2007 (an – 2002 (NSHQ)’ on behalf of the these U-values have since been further increase of 24%). In 2006 the average Department of the Environment, enhanced with the introduction of more annual spend on energy by households Heritage and Local Government stringent building regulations.

page 7 The graph across highlights the trend from 1972 to 2010 in terms of energy Energy rating of Irish housing: efficiency of dwellings in Ireland. The Indicative Trends over 4 decades most significant improvement in this 400 period was post 1979, when the first 350 Building Regulations were introduced. It would appear from this data, therefore, 300 that dwellings built pre-1979 would Primary Energy 250 benefit most from retrofitting to the kWh/(m2a) 200 Passivhaus Standard (amounting to approximately 750,000 dwellings). 150 100

Fuel Poverty SOURCE: 50 HEALY AND CLINCH (2002) 0 The study by Healy and Clinch highlights 1972 1979 1982 1992 2002 2008 Regs 2010 est. that older dwellings are more likely to be Construction standard/year occupied by those experiencing fuel poverty than newer dwellings, with the prior upgrading are most suited to retro- highest absolute numbers found in fitting to a significantly higher energy References homes built in the 1940s-70s, where performance standard (such as 2 Energy in the Residential Sector, 2008 some 111,000 households are affected. Passivhaus Standard) given their Report, by Fergal O’Leary, Martin Howley completion prior to introduction of As might be expected, those in newer and Dr. Brian Ó Gallachóir homes experience a lower level of fuel thermal insulation standards in the late poverty. Retrofitting older dwellings to 1970’s. Further, due to the age of these the Passivhaus Standard would there- dwellings, they may well require signifi- fore assist in addressing the issue of fuel cant upgrading of the building fabric poverty in Ireland. which often provides a stimulus to upgrade energy performance. Summary In short, the older the building the more It is likely that dwellings which are older effective would be retrofitting to the than 30 years and have had little or no Passivhaus Standard.

Source:MosArt Architecture

page 8 SECTION THREE

Principles of Passive Houses page 10 Principles of Passive Houses

The principles of passive houses will be of the PHPP software can be purchased and the proportion of insulation outlined below in brief. More detailed from SEI’s Renewable Energy occupied by structural elements. information is provided in Chapter 2 of Information Office (www.sei.ie/resource- ■ Windows – the orientation and size SEI’s Guidelines for the Design and centre). The verification requires the of all windows are entered into this Construction of Passive House Dwellings input of very specific and detailed data sheet, along with the U-values of the in Ireland (www.sei.ie/phguidelines). about the building design, materials and glass and frames as well as other components into the PHPP spreadsheets The building envelope consists of all technical specifications. and is then related to the climate data elements of the construction which for the region in which the house would ■ Annual Heat Requirement – this separate the indoor climate from the be retrofitted. The validity of the result value is calculated by determining outdoor climate. The aim of retrofitting to from this process is of course highly the heat losses through transmission the Passivhaus Standard is to upgrade the dependent upon the validity of the data and ventilation and subtracting the building envelope in order to minimise entered. total solar and internal heat gains. heat loss and optimise solar and internal The annual space heat requirement heat gain to reduce the space heating Some of the principal datasheets must be less than 15 kWh/(m2a). requirement to 15 kWh/(m2a). included in the software are listed below, along with their main functions: ■ Heat Load (W/m2) – the building’s The following parameters are funda- heat load is based on energy balance mental in this process: ■ Climate data – it is possible to calculations estimated by subtract- choose the climate for which the 1. Well insulated building envelope ing the minimum solar gains and passive house is being designed. internal heat sources from the 2. High energy performing windows This has a potentially significant maximum transmission and ventila- and doors impact on the U-values required to tion heat losses. achieve the threshold annual heat 3. Minimised heat loss through thermal requirement. The PHPP software is comprehensive bridging and detailed and therefore requires ■ Verification – this sheet collates the 4. Significantly reduced structural air some training prior to embarking on results of the overall evaluation of infiltration practical application to a real project. the building including the Space However, the software is also quite user 5. Optimal use of passive solar and Heating Requirement, Specific friendly and the verification page internal heat gains Primary Energy Requirement, Heat enables the user to check whether or not Load and Frequency of Overheating. 6. Introduce renewable energy such thresholds as space heating The user can see at a glance on this technologies such as solar thermal requirement are met. In the event that sheet whether or not the building the key Passivhaus Standard criteria are can be certified as a Passive House. not met, for example, the assessor will ■ Passivhaus Planning Package U-value – this sheet enables the firstly have to check to see if there are 2007 – An Essential Design assessor to specify the construction any fundamental errors in terms of data Tool of all the opaque (ie. does not entry. If this is not the cause of the include windows) elements of the problem, then the retrofitting strategy The Passivhaus Planning Package 2007 building envelope for the purposes will likely have to be modified in order to (PHPP) is a software package based on a of calculating the U-values of those achieve the required standards. In a series of extensive and interlinked Excel elements. The sheet requires the retrofit situation, this will typically data sheets which collectively allow input of the thermal conductivity (λ- involve improving the U-values of the building designs (including retrofit value) of the building materials building envelope. strategies) to be verified against the proposed as well as their thicknesses Passivhaus Standard. The latest version

page 11 record of adjustment of the ventilation achieved with U-values for walls, floors system, declaration of the construction and roofs ranging from 0.09 to 0.15 supervisor and photographs of the W/(m2K) and average U-value for complete building must also be submit- windows (including glazing and window ted. Upon examination of received frames) in the region of 0.60 to 0.80 documentation the applicant receives W/(m2K). Typically triple glazed window the results of the examination from the units are used in passive houses in certifying party. If the necessary verifica- Central and Northern Europe. tions have been found to be correct and These U-values are far below (i.e. better the above criteria have been met the than) the limits set under the Irish ‘Quality Approved Passive House’ certifi- Building Regulations. cate is issued (PHPP 2007, pp.28). According to the current Technical A wider European passive house certifi- Guidance Document Part L 2007 the cation scheme was developed within the required U-values are 0.27 W/(m2K) for Intelligent Energy Europe walls, 0.16 – 0.22 W/(m2K) for roofs, 0.25 project (2005-2007) “Promotion of W/(m2K) for ground floor slab, 0.15 European Passive Houses, PEP” W/(m2K) for ground floor slab with under (http://www.europeanpassivehouses.org). floor heating and 2.0 W/(m2K) for This certification scheme is applicable to windows, rooflights and external doors. Passivhaus Institut Certificate example, Quality ‘an emerging market scenario’ (i.e. Approved Passive House. countries with a small number of passive Source: Passivhaus Institut, Germany. house buildings), aims to ensure that the design of a particular passive house can Optimising passive solar gain Extracts from the PHPP software are deliver the specific energy requirements The optimal approach to the design of a included later in Section 6 pertaining to in accordance with the PHPP and passive house is to avoid an excessive the retrofit case study house. confirms the airtightness of the area of north facing glazing and place completed building. This certification relatively large windows facing south. Passive House Certification scheme involves the verification of the This is in order to minimise heat losses 'as built' design (i.e. that reflects the At the time of writing these Guidelines, a through the north facing elevation, actual construction, incorporating any passive house in Ireland can be certified which receives no direct sunlight during modifications made during construction) by the Passivhaus Institut in Darmstadt, most of the heating season, while in accordance with the PHPP and confir- Germany (http://www.passiv.de) or maximising ‘free’ solar heat gains on the mation of the airtightness of the certifying body approved by the south. Achieving the optimal distribu- completed building by a pressurisa- Passivhaus Institut. For further informa- tion of glazing when dealing with exist- tion test performed in accordance with IS tion on certification of passive houses in ing dwellings will often be very EN 13829. Ireland contact SEI’s Renewable Energy challenging and in many instances it will Information Office or the Passivhaus simply not be possible to increase Institut directly. The evaluation criteria passive solar gain due to the aspect of for the certification (Source: PHPP 2007, Building Envelope Insulation the dwelling. A detached house in its pp.23) are: own grounds might provide some scope There are several different methods and for alteration and provision of south- - Specific Space Heat Demand materials available to upgrade the 2 facing windows, but an east-west facing max. 15 kWh/(m a) performance of the building envelope in mid-terrace house will not have the dwellings to the Passivhaus Standard - Pressurisation Test Result n50 same scope. The PHPP software can be and the most typical scenarios likely to max. 0.6 used to determine whether or not the be encountered are illustrated in the Passivhaus Standard can be reached - Entire Specific Primary Energy next Section. Continuous insulation of 2 with any given aspect and it will typically Demand max. 120kWh/(m a) includ- the entire thermal envelope of a build- be possible to compensate for lack of ing domestic electricity. ing is the most effective measure to passive solar gain by increasing the level reduce heat losses in order to meet the The above criteria have to be verified of insulation of the building envelope. with the PHPP 2007, and the required list Passivhaus Standard. Achieving this in a of documentation for the passive house retrofit situation is more challenging Extensive areas of glass on the south quality approval certificate, construction than for a new-build. facing façade in a well insulated and air- tight dwelling might well lead to drawings and technical specification Insulation of the building envelope can overheating on warm sunny days. The with product data sheets, must be be divided into four distinct areas: exter- PHPP software will alert the designer to submitted to the certifying party nal wall, floor, roof and windows/doors. any risk of overheating by calculating (including PHPP calculations). Also, Existing passive houses in Central and the frequency of overheating and verification of the airtight building Northern European countries have been envelope according to IS EN 13829, a expressing this as a percentage of the

page 12 year in which the internal temperature in The airtight construction required any auxiliary space heating needs, the house rises above 25 degrees C. should reduce the penetration of radon expected to be small. Typical fuel in to the building. Radon which can still sources for the back-up system Thermal Bridging be detected inside of the building will be include biomass, heat pump, gas, partly contributed from outside air as and in some instances electricity (for Thermal bridging (i.e. un-insulated joints well as off-gassing from building materi- example ‘green electricity’ from between walls, floors/ walls, ceilings/ als. To mitigate against effects of low renewable sources). The back-up adjacent walls, windows/walls etc) are radon concentrations recommended air system is also used to provide hot weak points of thermal resistance in the changes of 25 to 30 m3/person provided water, either throughout the year or building envelope and cause unwanted by a mechanical ventilation system are during winter if a solar water heating losses of energy. A thermal bridge sufficient3. system is used during summer. increases heat loss through the struc- ture, and in some extreme cases this The Radiological Protection Institute of An airtight house requires a well- may cause surface condensation or Ireland (RPII) (www.rpii.ie) and the Irish designed mechanical ventilation system interstitial condensation in the structure. Building Regulations provide advice to provide good . A Surface mould growth or wood rot may about the treatment of radon in the built passive house is ventilated using a be the consequences of a thermal environment. mechanical system which incorporates bridge. Special care must be taken to air to air heat recovery (mechanical heat ensure that retrofit measures do not recovery ventilation, or MHRV). Exhaust increase the likelihood of creating such air is extracted from rooms that typically Internal Heat Gains problems which can affect the health produce heat, moisture and unwanted and longevity of the building. A passive house is very efficient at utilis- smells such as kitchens and bathrooms. ing‘free’internal heat gains from domes- Before this air is expelled to the outside The Passivhaus Standard for linear tic household appliances, kitchen and it passes through a heat exchanger thermal transmittance should not utility equipment, electronic equipment, where the heat is transferred to the exceed 0.01 W/(mK). This requires the artificial lighting, and occupants. Heat separate stream of incoming fresh air, building designer to identify and locate losses from stoves or also thereby eliminating the need to all potential thermal bridging in the contribute towards the overall space completely heat the fresh air as it enters construction, applying careful specifica- heating requirement as long as they are the building. tion and detailing of those elements positioned within the building envelope. providing where possible a continuing It is important that attention is paid to Occupants of the building also layer of insulation as well as taking care regular replacement of air-filters for both contribute to meeting the heat load; a to execute those elements on site as per incoming and exhaust air. Filters are typical adult human continuously emits design details. The impact of thermal used not only to provide clean air for the 100W of heat when stationary. A family bridging can be tested and verified in occupants but also to ensure that the of five persons, therefore, can emit up to the PHPP software as the design of the heat exchanger is not clogged with dust 0.5 kW of heat. This may seem like a retrofitting scheme is being developed. and other matter. If the filters are not small amount but it equates to approxi- regularly replaced (for example every six mately two thirds of the total space heat to twelve months) and become clogged load for the case study passive house with dirt the MHRV will have to work retrofit project presented in Section 6. Structural Airtightness and harder to provide the same volume of air Draught Proofing to the house, thereby increasing the Building an airtight or leak-free structure speeds of the fans and, ultimately, using is imperative to achieving the Passivhaus Passive House Building more energy. In retrofitting a dwelling to Standard. If there are gaps in the build- Systems include MHRV, occupants will likely have ing structure then uncontrolled no experience of the maintenance As indicated earlier a passive house does amounts of cold external air can infil- requirements involved with the system. not need a conventional space heating trate the building. Achieving a high level system of radiators or underfloor of air-tightness eliminates cold draughts heating to maintain a comfortable and associated comfort losses. It also indoor climate. Instead, due to the small What happens in the event of prevents condensation of indoor moist, space heating requirement involved, the a power failure? warm air penetrating the structure, and following building services are sufficient possible structural damages due to If there is a loss of electricity (and the in a passive house: decay, corrosion and frost. The air tight- dwelling has no back-up generator) the ness of a building can be accurately (IS ■ Mechanical ventilation system with ventilation system will stop working and EN 13829) measured by carrying out a heat recovery which provides most the supply of fresh air will be cut off. If blower-door test and the Passivhaus of the space heat requirement. power is lost for a short while (for Standard is reached when there are less example a few hours), then there is likely ■ Back-up system capable of heating than or equal to 0.6 air changes per hour to be no noticeable difference in indoor the air passing through the dwelling @ 50 Pascal pressure. air quality. However, if the loss of power is via mechanical ventilation to meet

page 13 prolonged, the simple solution is to open The heat load, on the other hand, has ■ The optimal orientation is due south the windows and to create natural cross been reduced from 80 W/m2 (6.64 kW for and deviation from this will reduce flow ventilation through the building. 83m2)to9W/m2 (0.74 kW for 83m2). This the contribution of the collectors to amount of energy could be provided by DHW production. In places where Additional details on MHRV aspects are a very small wood chip / pellet there is no south facing roof, then provided in SEI’s publication Guidelines boiler/stove compared to what might be expected orientation losses can be for the Design and Construction of typically required in a family home. overcome by increasing the collector Passive House Dwellings in Ireland. area. The most common method of ‘heating’ in a passive house is by post-heating the ■ The optimal tilt of the solar panels fresh air after it has already been for DHW is approximately 45 Back-up Heating System warmed by the exhaust air in the MHRV. degrees. (In a pitch that is greater As previously highlighted in these There are a number of ways in which the than 45 degrees the potential annual guidelines, the space heating require- temperature of the air can be boosted, output is compromised somewhat). ment in a passive house is so low that including: ■ There are two main types of solar there is no need for a traditional space ■ Water to air heat exchanger; collectors typically used, namely flat heating system. Space heating demand plate panels and evacuated tubes. in a passive house is typically met ■ Compact unit with electrical heat through passive solar gains (40 – 60%), pump; and internal heat gains (20 - 30%) and the ■ Wood pellet/wood log boiler/stove remainder (10 - 40%) needs to be with integral back boiler. provided from building systems. The optimal way to transfer the small An overview of the typical back-up amount of required heat throughout the heating systems used in passive houses house is through the mechanical ventila- to provide thermal comfort3 is provided tion system. in Section 4.4.

The PHPP software will accurately predict the following two measure- ments for each retrofit passive house Domestic Hot Water References design: Production 3 Translated from Protokollband Nr. 30, Lueftung bei Bestandssanierung: ■ Annual Space Heat Requirement – As in any type of dwelling, the passive Loesungsvarianten, Dr. Wolfgang Feist this measures the amount of energy house requires a system that provides Passivhaus Institut that is needed to maintain a domestic hot water (DHW). As with comfortable indoor temperature, space heating, it is important that the specified in kilowatt hours per system is energy efficient, well square metre of treated floor area controlled and has an adequate capacity Primary energy, in kWh/year: This per year, or kWh/(m2a). to meet demand. Generally the DHW includes delivered energy, plus an system in a passive house is combined allowance for the energy “overhead” ■ Heat Load – this measures the with a heat source such as a wood stove, incurred in extracting, processing and capacity of the space heating system transporting a fuel or other energy , compact unit or required to maintain comfortable carrier to the dwelling. For example, heat pump for space heating. Most indoor temperatures at any one in the case of electricity it takes passive house examples encountered time, specified in Watts per square account of generation efficiency at have utilised solar thermal collectors as metre of treated floor area, or W/m2. power stations. SEI, Dwelling Energy they reduce the use of primary energy Assessment Procedure (DEAP), 2008 For the retrofit case study the annual and CO2 emissions. It is important to version 3, pp. 31. space heat requirement (without losses note, however, that the Passivhaus of the heating system) is 15 kWh/(m2a) Standard is indeed achievable without Delivered energy, in kWh/year: This reduced from an initial 214 kWh/(m2a). solar based water heating. The introduc- corresponds to the energy consump- Including the losses the so called final tion of the BER system as an indication of tion that would normally appear on energy (post retrofitting) is 30 the energy performance of dwellings in the energy bills of the dwelling for the assumed standardised occupancy and kWh/(m2a) equating to approximately Ireland, together with the mandatory end-uses considered. 2,490 kWh over an entire year (the house requirement in the Building Regulations measures 83m2 in treated floor area). Part L 2007 in relation to renewable Annually, this would equate to 230 litres energy provision is likely to increase the of oil, 240 m3 of mains gas or 450 kg installation of solar technologies. (0.45 tonne) of bagged wood pellets. In terms of specifying a solar collector system, the following outline guidance should be considered:

page 14 SECTION FOUR

Typical Phases of Retrofitting page 16 Typical Phases of Retrofitting

4.1 Survey note. It will also be necessary to ascer- tain the extent of the shading surround- A detailed survey of the building to be ing the building by surveying the retrofitted is an important basis for a position, shape and height of adjacent good low-energy design. obstacles such as buildings and trees.

The existing build-up (in terms of materi- Lastly, the completion of a detailed als, performance and dimensions) of the survey will provide the opportunity to different elements of the thermal locate potentially harmful or toxic envelope and details of junctions, possi- substances such as asbestos. These ble thermal bridges, windows and doors substances should be replaced with have to be accurately recorded. In many more suitable material during the build- cases, the precise build-up of the ing process. envelope will not be known to the owner of the dwelling (for example Initial PHPP Calculation whether external walls are of cavity block, hollow block or solid block) and in It is recommended to do a PHPP calcula- these situations it will be necessary to tion of the existing building and to create an inspection opening to clarify compare the ‘theoretical’ with the actual the construction type. energy consumption. If there is a consid- erable difference between both Details of the heating and DHW system airtightness test. estimates (for example greater than as well as data on energy consumption Source: MosArt Architecture 10%), it would first be important to over a three year period are also critically dwellings will perform considerably verify the comfort levels of the important as a means of verifying the poorer than this. occupants. thermal performance of the existing building fabric. In parallel with this, it is The National Standard Authority of The initial testing of the dwelling in the also important to consider the comfort Ireland (NSAI) recently introduced a PHPP software will quickly determine its levels experienced by the dwelling registration scheme for service providers current performance compared to the occupants. Low energy bills could be involved in the Air Tightness Testing of Passivhaus Standard and will provide a misinterpreted as a reflection of an Domestic dwellings to IS EN 13829:2000. good indication of the extent of upgrad- efficient dwelling when in fact the This scheme should ensure high ing works that would be required. For occupants might have been living in standards in terms of independence and example, the current space heating some considerable discomfort during quality of testing and evaluation. requirement of the case study retrofit the heating season due perhaps to lack The use of a thermal imaging camera of resources (fuel poverty) or malfunc- can also be very helpful in locating weak tioning heating systems. points in the thermal envelope but such A blower door test would be helpful to a procedure is not necessarily manda- ascertain the current level of airtightness tory especially if the survey and assess- and to identify where cold air may infil- ment is being undertaken by someone trate the building fabric in the heating with experience in retrofitting. season. The Passivhaus Standard Given the importance of maximising requires an airtightness performance of passive solar gain, the overall aspect of 0.6 air changes per hour measured at 50 the building facades as well as area and Thermographic Image Pascal pressure and the majority of older orientation of glazing is important to Source: GreenBuild Building Information Services

page 17 house presented in Section 6 was If it is proposed to change the overall ance of the thermal envelope is estimated in the PHPP as 214 kWh/(m2a) form of the dwelling, care should be provided below, considering the follow- which is approximately 14 times less taken to bear in mind the important ing aspects: efficient that the 15 kWh/(m2a) required principles of achieving compactness ■ Insulation (internal and external); by the Passivhaus Standard. (reducing the surface to volume ratio), maximizing the proportion of exposed ■ Windows and doors; glazing to the south, east and west (to ■ Airtightness; and be tested and verified in the PHPP), and 4.2 Changes in layout/design avoiding unnecessary recesses and ■ Thermal bridges. In some cases, it might be possible to projections that might cause shading. alter the dwelling layout and / or An iterative process should be estab- 4.3.1 Insulation arrangement of glazing in order to lished between the architectural re- One of the key challenges in upgrading increase overall energy efficiency. Given design of the dwelling and cross-check- overall insulation levels in dwellings is to that the existing building is already ing the overall energy performance in choose from the wide variety of materi- modelled in the PHPP, any changes that the PHPP. For instance, existing windows als available on the marketplace. Above are being considered to the building to the south, east and west of the build- all, the insulation has to be appropriate form and orientation of glazing can be ing could possibly be enlarged in order to its application. Some insulation tested during the design process regard- to increase solar gain and thereby products are suited to use for fill in cavity ing the effect on energy performance as reduce the space heating requirement. walls, for example, whereas others are well as the risk of overheating (which not. Some are load-bearing for use might arise if a dwelling has an excess of under concrete floors whereas others south-facing glazing without a screen to 4.3 Upgrade Thermal Envelope are ‘soft’ and better suited to fitting in keep the high summer sun out). the attic space. Some products have very As highlighted earlier, a key perform- When considering a major retrofit low thermal conductivity values ((λ) ance threshold given by the Passivhaus project, the owners might also consider lambda values) - which means they have Institut is the maximum specific space using the opportunity to extend their high insulating properties and can heat requirement of 15 kWh/(m2a). For home or to modify the internal layout or provide a higher level of insulation for a all retrofit projects (and especially for arrangement of rooms. In such given thickness compared to lesser older dwellings), it will inevitably be instances, it should be remembered that performing products. Insulation types required to significantly upgrade the larger homes, no matter how energy will also vary on price, fire safety issues insulation performance of the thermal efficient, will undoubtedly consume and amount of processing and / or envelope and install highly efficient more energy than smaller houses of a chemicals involved in their manufacture. windows and doors and mechanical similar specification. There has been a heat recovery ventilation system in order Different thicknesses and thermal tendency for dwellings in Ireland to to reach the above threshold. conductivities of insulation products can become larger over the years and easily be tested in the U-value sheet in homeowners should consider very The heat recovery system will be the PHPP. Dependent on the overall carefully the extent of space that their discussed in Section 4.4. If no heat recov- retrofit strategy, the additional insula- families really need. Minimising the area ery is included in the retrofit scheme, the tion might be placed on the outside of of extended floor space will reduce build energy savings that it would have the structural building shell (sometimes cost and perhaps leave additional funds brought to a project would have to be referred to as ‘outsulation’), the inside for enhancing the overall retrofit specifi- compensated for by an even more (so-called ‘dry-lining’) and/or within the cation. efficient building fabric. construction envelope (eg. filling the Guidance on upgrading the perform- cavity space created by two leaves of APPLICATION OF DIFFERENT INSULATION TYPES Roof Ceiling Floor Wall Façade Perimeter Mineral wool x x x x x Polyurethane x x x x x Polyisocyuranate x x x x x Phenolic x x x x x EPS x x x XPS x1 xx Wood fibre x x x x x Wood wool x x x Calcium silicate x2 Cork x x Cocos fibre x x Foam glass x3 xxx x Cellulose x x x x Maximise passive solar gain Notes: 1 Cold roof construction, 2 Internal insulation, 3 Flat Roof, Sedum Roofs. Source: MosArt Architecture

page 18 In every case, it is critically important as not having to use scaffolding and INSIDE OUTSIDE that the retrofit designer makes sure not being dependent on reasonable that the proposed insulation strategy weather to carry out the works. will not cause more interstitial ■ In terms of thermal comfort, a room condensation in the structure that can which is internally insulated will be evaporated to the exterior over the typically heat up much quicker due course of one year. The amount of to the avoidance of having to heat condensate that can potentially build up up massive external walls. within the envelope of a building is influ- enced by climate (temperature and Considering disadvantages, the follow- ) and internal air conditions ing are highlighted: (high or low occupancy, internal average

INSIDE ■ Internal insulation will reduce the OUTSIDE temperature and humidity). All calcula- usable net floor area of rooms with tions in these Guidelines are based on (a) external walls. In the case of the climate conditions for Dublin and (b) low semi-detached retrofit house occupancy (according to BS EN ISO presented later, this reduction would 13788, Annex A). ). The danger of inter- be approximately 20% (300 mm stitial condensation is that it is, by defini- insulation) of the total net usable tion, hidden within the structure and floor area for insulation with a therefore may be reducing the thermal thermal conductivity value of 0.035 performance of the envelope unknown W/mK (such as mineral wool or cellu- to the homeowners, potentially causing lose) and 14 % for an insulation with In the top diagram, the risk of creating a thermal structural defects in the medium to long a thermal conductivity value of 0.025 bridge is greatly reduced using external insulation. term as well as health risks from result- Source: MosArt Architecture W/mK (such as polyisocyuranate). ing mould growth. There is free software Related to this, any surface mounted external and internal blockwork or, in available which can be used to test the services located on the internal face the case of timber frame between the risk of causing interstitial condensation of external walls, such as electrical wall studs). with different insulation strategies and switches and sockets, will have to be application of such tools is strongly Ideally, the insulation layer should be re-mounted on the new surface. recommended herein. continuous all around the building ■ Inevitably thermal bridges will be fabric without any breaks. While this is 4.3.1.1 Internal Insulation created for example at relatively easy to achieve with a new- external/internal-wall-junction or build project, avoiding breaks in the There are advantages as well as disad- external-wall/ceiling-junction. As a insulation layer is considerably more vantages of internally insulating the result of this, additional insulation challenging when retrofitting. building envelope which need to be may be necessary along internal considered at an early stage of the retro- The location of insulation relative to the elements such as walls and ceilings fitting strategy. structural envelope can have a signifi- to reduce the effect of the thermal cant influence on thermal bridges. In terms of advantages, the following bridges with all details having to be External insulation, for example, is attributes are highlighted: studded very carefully to avoid any typically the most effective in reducing condensation in joints. ■ The external facade of the building thermal bridges, whereas internal will remain untouched by the ■ Usually there has to be a vapour insulation would be the least effective. upgrading works which would be barrier on the warm side of the beneficial when dealing with certain insulation. When fixing paintings or external finishes which homeowners cupboards with nails or screws this might be reluctant to cover with vapour barrier could be penetrated external insulation, such as tradi- which would compromise its tional brick, or natural stone. performance and result in a higher risk of mould growth and damages ■ Internal insulation may be cheaper in the wall construction through when compared to external insula- condensing water. A service cavity tion because of certain savings, such may be necessary to avoid penetra- tion of the vapour barrier. This again reduces the treated floor area.

Internally insulating on the top of an existing concrete floor slab would create a number of practical knock-on-effects. For example, the clear height of internal Testing of various insulation strategies for risk of creating interstitial condensation. Source: MosArt Architecture

page 19 and external doors and windows would Insulating the Roof Space be compromised by the higher finished When considering insulating the roof floor level, the balustrade height of space, the first decision to make is to windows or railings might be too low and determine the position of the thermal the height of the lowest riser of an inter- envelope of the dwelling. In most nal staircase might not be consistent with homes, the thermal envelope will be on the height of the other risers which would the horizontal and just above the be unacceptable from a health and safety plastered ceiling comprising of insula- point of view. tion rolled out between the roof joists. In other situations, such as where there is a 4.3.1.2 External Insulation vaulted ceiling for example, the thermal External insulation should be External insulation is typically used with envelope will be within the sloping roof fitted to run past the level of the internal floor slab in order to masonry construction types but might comprising of insulation fitted between minimise thermal bridging also be considered as an option for the roof trusses. In the case of where the (lower sketch) upgrading timber frame dwellings. The former scenario exists, it might be worth key principle behind this insulation considering changing the position of the method is to completely wrap around insulation to the sloping part of the roof the entire structural building envelope which would result in extending the thereby significantly reducing thermal heated volume of the dwelling. This has bridges which can otherwise arise where the advantage of creating a heated attic Source: MosArt Architecture external walls and foundations connect space into which it might be possible to likely the hardcore there under before to internal walls and the floor slab. If position some of the service equipment placing a damp-proof membrane, a layer external insulation is being proposed for typically found in passive houses, includ- of insulation and a new floor screed. Just a cavity wall construction, then it would ing a large solar hot water tank as well as as externally insulating a roof, this would be imperative to also fill the cavity with the mechanical heat recovery ventila- be costly, hugely disruptive for insulation in order to avoid thermal tion equipment. By positioning this homeowners and might not be justifi- looping occurring from the ‘cold’ equipment within the (extended) able in terms of cost and return on unheated cavity through the internal thermal envelope, transmission heat investment. block leaf to the inside of the dwelling. losses will be minimised. Furthermore, If it is decided not to excavate the This would also reduce the visible thick- not having to lay thick insulation within ground floor slab to provide an insula- ness of insulation required externally. and above the roof joists might facilitate placing a floored surface in the attic tion layer, some compensation will be There are two options of external wall which would provide additional storage provided by externally insulating the insulation, as follows: space for the homeowners. A leaky attic external walls down as far as the founda- tion. Externally insulating external walls ■ The so-called ‘composite system’ or hatch would also be avoided when the as far as the foundation will marginally ‘single-skin system’ is where insula- sloped section is insulated. reduce the heat loss from internal floors tion is either stuck or mechanically Shifting the thermal envelope to the as well as marginally reduce thermal fixed directly to the external face of sloping roof should be verified in the bridges emanating from the rising walls. masonry wall, reinforced with for PHPP software and the load-bearing example a plastic or glass fibre mesh capacity of the roof trusses should be 4.3.1.3 Wall Cavity Insulation and then rendered. To avoid compli- checked prior to placing additional cations regarding damages or loads thereon. Cavity wall insulation in Ireland is now warranty it is important to use commonplace and involves filling the components of one building system In dwellings where sloping ceilings are cavity between the inner and outer leaf only. This composite system is used found, the implications of placing of concrete blocks with appropriate widely on Continental Europe as a additional insulation underneath the insulation material. It is quite likely that technique to upgrade existing build- roof trusses should be evaluated with insulating the cavity alone, however, will ings to the Passivhaus Standard. respect to clear head height. There may not be enough to achieve the required With this single skin construction be insufficient space internally to place U-values for the Passivhaus Standard. In type, care should be taken that the additional insulation, in which case it such cases, cavity insulation will have to system has Agrement Certification might be required to place the insula- be combined with internal and / or for insurance purposes. tion externally (above) the roof trusses. external insulation to achieve the This is only likely to be economically targeted U-value identified in the PHPP ■ Thesecondsystemiswhereinsteadof feasible if the roof coverings (tiles or software. the above single-skin system a venti- slates) are in very poor condition and lated cavity is created between the need upgrading or replacing. The proper installation of cavity insula- external cladding and the insulation, tion can be proven by using a thermal the latter of which is otherwise fixed To externally insulate a ground floor slab imaging camera which will immediately to the exterior of the existing walls in a would require completely removing the highlight parts of the construction that similar manner to the other option. existing concrete slab and more than have not been fully insulated due to

page 20 their detection as being colder than the amount of solar gain. DEFINITION OF fully insulated areas. It also should be considered that as the VAPOUR BARRIER AND U-value of the glass components, e.g. VAPOUR CHECK/ VAPOUR 4.3.1.4 Windows and Doors double glazing / triple glazing improve, CONTROL LAYER: The greatest heat losses in a dwelling the glass will let through less solar and µ value is the vapour resistance factor typically occur through windows and light gains in addition to reductions due of a material (see also IS EN 12524) doors. The better the thermal perform- to increased frame, mullion and d is the thickness of a layer stanchion proportions. However, ance of these elements, therefore, the sd is the equivalent air layer thickness less insulation will be necessary in walls, improved U-values will provide a net i.e. a vapour barrier with an sd of 1500 floors and roofs. decrease in energy consumption. m is equivalent to 1500 m thickness of still air in terms of vapour resistance There is a growing range of windows The joints between windows and doors and is calculated as follows : and doors available in Ireland which are to walls and floors have to be sensibly sd [m] = µ x d [m] suitable for passive house design. Many detailed. Ideally, an external insulation vapour check: 0.5 m < sd < 1,500 m of these will have insulation integral to layer would be used to overlap the vapour barrier: sd > 1,500 m the frame so that thermal bridging from window or door frame by at least 65 mm BRE IP 2/05 Modelling and Controlling the exterior to interior surface is in order to reduce potential thermal Interstitial Condensation in Buildings. minimised. Specifiers and homeowners bridges to a minimum. Furthermore the regards to protection from the dangers should be aware that mullions and above joints have to be vapour proof on of interstitial condensation. For example, stanchions (glazing bars) will reduce the the inside and weather proof externally. in certain instances a vapour check area of glass and, accordingly, the To prevent overheating in summer it membrane with a relatively low resist- might be worth considering shading ance factor might be sufficient (i.e., devices such as overhangs, balconies or allowing some moisture to pass through bris soliel which block direct sunlight the wall), whereas in other situations, a when the sun is high in the sky in the complete vapour barrier might be summer time. In winter, when the sun is required which totally prevents any lower in the sky, passive solar gain will moisture entering the construction. be provided by the sun’s rays passing There are currently vapour membranes underneath the shading device. available on the market which are so- called ‘intelligent’ insofar as their vapour 4.3.1.5 Airtightness resistance can change depending on the relative difference in vapour pressure The Passivhaus Standard requires a between internal and external environ- maximum hourly air change rate of 0.6 ments. They can thus ‘close’ or ‘open’ as at an under and over-pressure of 50 Pascal. That means the entire air volume of the dwelling changes through gaps, cracks and other openings in the build-

Traditional sash window with mullions and stanchions ing fabric at a maximum of 0.6 times in which reduce solar gains and create a thermal bridge one hour at an air pressure of 50 Pascal. from outside to inside Source: MosArt Architecture Compared to the current Part L, this level of airtightness is quite a high perform- ance standard but is nevertheless achievable when both design detailing and site operations have been well executed.

The airtight membrane or layer should always be located on the warm side of

the insulation and should be continuous Source: Passivhaus Institut around the building fabric without any break. In masonry buildings, the plastered internal face of walls is regarded as the ‘airtight’ layer, whereas a separate membrane would be required if the wall construction is comprised of timber or steel frame.

Different construction configurations Externally insulated window frame reducing heat loss will require different strategies with Source: Optiwin GmbH Use of rubber gasket to seal a penetration of the airtight membrane. Source: MosArt Architecture

page 21 appropriate. Whichever membrane is construction. This kind of thermal bridge ventilated in a number of ways, includ- used, it must be remembered that it will can be calculated in the PHPP by enter- ing through controlled means by extract function as the airtight layer and must ing the percentage of the insulation fans, vents in the wall with adjustable be treated with great care during the layer occupied by the material (such as grills and openable windows or by construction process. timber studs) as well as the thermal simply by uncontrolled means through conductivity of that material. Repeating drafts and leaky construction. As The timing of carrying out an airtight- thermal bridges are thus accounted for highlighted in the previous section, ness test (commonly referred to as a within the normally quoted U-values for however, it is vital for the Passivhaus ‘blower door test’) is very important in walls, roofs and ground floors. An extract Standard that a very high level of the overall retrofit procedure. It is impor- from the PHPP software is included airtightness is achieved in order to tant to carry out the test prior to the below to illustrate how repeating minimise heat loss. Airtight construc- completion of final finishes so that if the thermal bridges can be calculated. tion, in turn, is accompanied in the test fails then any gaps or cracks in the Passivhaus Standard with mechanical airtight layer can be precisely located Linear thermal bridges, on the other heat recovery ventilation systems. This and accessed for repairs. The use of hand, can be found at junctions of inter- next section of the guidelines will smoke puffers / pencils / sticks can be nal and external walls, at the eaves provide an outline of considerations very useful to precisely identify leaks where there is little or no space for necessary in planning such a system in while the building is pressurised or de- insulation and even around opes for the context of retrofitting a dwelling. pressurised. The test should ideally be windows and doors. These bridges were carried out once the airtight layer has not accounted for at all until they were Recommended Ventilation Rate been completed but while it is still recognised in recent versions of the exposed, including most especially the building regulations. The calculation of According to the Passivhaus Institut, the taped joints between the windows and thermal bridges is a specialist field that appropriate air change rate for dwellings doors to the building envelope as well as will probably require assistance from a is between 0.3 and 0.4 times the volume joints between different elements of the professional. of the building per hour at normal dwelling (ceiling, walls and floors). All pressure, with a general recommenda- The linear thermal transmittance (ψ) persons working on the site must make tion of leaning toward the lower rate. values have to be verified in accordance sure not to subsequently compromise This maintains high indoor air quality with EN ISO 10211. The ψ values for the airtight layer which can easily while ensuring a comfortable level of several products certified by the happen, for example, where services humidity and maximizing energy Passivhaus Institut can be found on their such as cables or pipes have to savings. website (www.passiv.de) or on their penetrate the barrier. product certificates. Compliance with the Irish Building Regulations Part F might require more 4.3.1.6 Thermal Bridges air changes per hour than the Passivhaus The concept of thermal bridges has Institut recommends. It is possible to 4.4 Upgrade Ventilation and been introduced earlier in Section 3. enter a higher air change rate into the Heating System PHPP which consequently leads to a There are two types of thermal bridges The upgrading of the ventilation and slight increase of the energy consump- of interest to these Guidelines, namely heating system is the second step in tion. (a) repeating thermal bridges and (b) retrofitting dwellings to the Passivhaus linear thermal bridges. The PHPP software suggests that 30m3 Standard. per person per hour should be provided Repeating thermal bridges would to dwellings to ensure good air quality. include studs or rafters in the insulation Ventilation System These two measurements can be used layer or indeed wall ties in masonry The dwelling to be retrofitted might be to choose an appropriately sized machine for different dwelling designs. Taking the retrofit case study presented later in Section 6 as an example, an occupancy of 2.4 persons would require 71 m3 of fresh air delivered to the house per hour. In terms of extract, the PHPP software uses the following rates for different room types as default values, kitchen = 60m3/h, bathroom = 40m3/h , shower = 20m3/h and WC = 20m3/h. In the case study house these total 100 m3/h which is close to the supply volume which will ensure that the whole house system will be balanced. Source: MosArt Architecture The supply and extract volumes can be

page 22 accurately set by using a digital Insulation and Positioning of Duct large for the retrofitted dwelling which anemometer and adjusting the valves Work and Vents could have a heat load demand of less on the vents in each room as required. than 20% of that of the original need. It is very important to adequately Another strategy would be to retain the Mechanical Heat Recovery insulate the air ducting so that there is pipes and radiators already existing in minimal loss of temperature in deliver- Ventilation (MHRV) System the dwelling but to replace the older ing warm air around the house. The larger boiler with a smaller and more The efficiency of the heat exchanger in thickness of insulation generally used in efficient one that can serve not only the MHRV determines the amount of passive houses is between 6 cm and 10 space heat requirements but also heat that can be recovered from the cm for ductwork. It is also preferable to domestic hot water production. One exhaust air and, therefore, has a very locate the ducting within the thermal advantage of keeping the radiators significant influence on the additional envelope and to keep pipe runs as short results in the homeowner being able to space heating that may be required in a as possible by ideally positioning the control individual room temperatures by passive house. The efficiency of sensible MHRV unit in the centre of the house. heat recovery should exceed 75% for the adjusting the valves manually to suit nominal range of flow rates specified for Vents are normally placed in the ceiling their needs or using Thermostatic the unit when measured in terms of the but can also be placed in the wall if Valves (TRV) to set the room supply-air side temperature ratio as necessary. The air inlets are typically temperatures. Even if the original radia- described in IS EN 13141-7:20044. designed to spread the air horizontally tors are being retained as the primary Specifiers and designers should be wary across the ceiling, minimising downward heating system, there will still be a need of products claiming extraordinary draughts. There should be a gap (10mm for a MHRV system which will now not efficiency rates of 95% or higher. The is sufficient) either under or over the only supply fresh pre-heated air to the safest route is to install equipment that door of each room to enable the easy dwelling but will also distribute the heat has been independently tested and movement of air from one room to the generated by the radiators throughout verified by such bodies as the Passivhaus next. If doors are fitted tight without the house. A further issue to consider in Institut. such a gap, rooms with exhaust vents debating whether or not to retain the (See www.sap-appendixq.org.uk). would be under negative pressure and original radiators is the fact that they will rooms with supply air would be under probably have to be moved if internal Current accreditation testing procedures positive pressure. insulation is proposed for the dwelling. for mechanical ventilation systems often produce unrealistically positive test There are a number of MHRV products Water to Air Heat Exchanger results. If reliable measured values are available on the market that have been not available, or a certificate is not specifically developed for retrofitting to This method involves using a heating presented, then the values are calcu- the Passivhaus Standard. device placed immediately on the fresh lated by subtracting 12% from accredita- air supply outlet of the MHRV. If the tion test results. Heating System house needs additional heat (which is In DEAP a default efficiency of 0.66 is determined by a ) then hot The most common method of ‘heating’ assumed for mechanical heat recovery water is circulated through the device, in a passive house is by post-heating the systems and the default Specific Fan hence the title of ‘water to air heat fresh air after it has already been Power (SFP) is assumed to be 2W/[l/s]. exchanger’. The hot water is heated, in warmed by the exhaust air in the MHRV. This default value is considerably less turn, by using a number of energy There are a number of ways in which the than is achievable in practice (as verified sources including a stove or boiler (for a temperature of the air can be boosted, by institutes such as the Passivhaus larger house) in combination with solar including those listed below: Institut). hot water panels or evacuated tubes. ■ Water to air heat exchanger; The Passivhaus Standard can be Compact Unit with Electrical Heat achieved without a heat recovery system ■ Compact unit with electrical heat Pump pump; and as well. However, when eliminating the This system is so-named as it incorpo- MHRV system the savings foregone in ■ Wood pellet/wood log boiler. rates all of the technology required for a recovering the thermal energy have to passive house in a relatively small unit, These three options are explored in be compensated by other measures such namely the MHRV, the DHW and the outline only below with additional as additional insulation of the thermal heating power for the home, in this case details provided in SEI’s Guidelines on envelope. This could turn out to be a false powered by an electrical heat pump. It is Passive Homes. It may well be possible economy, therefore. As a practical therefore very suited to smaller homes to continue to use the existing heating example, if a MHRV system was omitted where space might be limited for large system in the dwelling (for example, oil in the case study building (Section 6), the tanks, stoves and storage for wood. It is boiler with radiators) albeit in many space heating requirement would important to use a heat pump with the cases it might not be an efficient model double the maximum allowed by the highest possible efficiency (coefficient of and might be at or near the end of its Passivhaus Standard. performance or COP). useful life. In addition, the design output of the heating system is likely to be too

page 23 ■ An independent combustion air stored hot water on basis of stored supply must be provided to any water temperature; stove or boiler in a passive house ■ Separate and independent bearing in mind the level of airtight- automatic time control of space ness that has to be achieved. It is heating and hot water; important to check if your chosen product can accommodate direct ■ Shut down of boiler or other heat connection to the external air. source when there is no demand for either space or water heating from ■ Most wood boilers/stoves are highly that source. efficient (up to 80 – 90%) and when burning pellets there is very little ash The above levels of control should be remaining following combustion. A incorporated into any dwellings retrofit- will be required to take exhaust ted to the Passivhaus Standard. gas emissions safely away from the Additional control features can be incor- house, as with any typical Water to air heat exchanger unit. Source: MosArt porated to a heating system so the overall Architecture boiler/stove. This flue must comply system performance improves. One A 3D model of a typical compact unit is with Part J of the building regula- example is the ‘weather compensation’ illustrated below. tions. feature, which is the ability to adjust the Wood pellet/Wood pellet stove/Wood ■ A stove or boiler that directs most of output of the system based on the log boiler the heat output to the DHW tank is measured external temperature. The main essential if the hot water is to be advantage of using weather compensa- A boiler is typically located in a separate used to heat the ventilation air as tion is that the heating system closely plant room whereas a stove is located in described above. If there is a need to monitors external temperature trends and an internal room for example a living back-up the MHRV the stored hot adjusts the output accordingly. room. Wood pellet stoves/log boilers can water will be used to re-heat the The preferred internal temperature can serve as an auxiliary or back-up source of fresh air. heat as well as for domestic hot water be set using an internal thermostat. If production. The following issues should ■ As previously indicated, it will often the internal temperature goes below the be remembered when considering be logical for such units to be used thermostat setting, the system will installing a wood stove or boiler: for not only auxiliary space heating automatically start to heat the fresh air but also for auxiliary water heating. passing through the ventilation equip- ■ Pellet boilers are available in types ment. loaded automatically or manually, ■ Although the demand for wood fuel whereas wood log boilers and wood will be low, a dry space for storage Individual Room Temperature Control pellet stoves for domestic use are has to be provided. Wood (whether Different rooms may have different only manually charged. logs, chipped or in pellets) is bulky temperatures due to solar gains, occupa- and a considerable volume is ■ tion and internal heat loads. Room The equipment must be sized appro- required for storage especially if it is based temperature controls for temper- purchased in bulk to keep costs to a ature differentiation between different minimum. Storage underground is rooms may be necessary if individual also possible in special containers. comfort requirements are set for differ- Wood pellets need to be kept dryer ent rooms. In a centralised ventilation than chips or logs. heating system, however, the supply air Integrated controls for heating in a temperature is relatively constant (20 Passive House degree C) for the whole house and this would be typical for most houses retro- Heating systems in Ireland have tradi- fitted to the Passivhaus Standard. tionally been simple, with among the most common boiler based systems DHW is produced typically by the back- Compact unit including ventilation heat recovery and being a timer and a cylinder thermostat, up heating system, supported by solar air to water heat pump. Source: Drexel und Weiss and with sometimes even room thermo- collectors. Hot water can also be stats being absent. However, the produced electrically but this will priately to the heat load of the Building Regulations Part L require increase the primary energy consump- house. This will be defined by the minimum levels of control, installing tion and therefore adversely affect the ‘Verification page’ in the PHPP equipment to achieve the following: BER. software. Taking the prototype ■ Automatic control of space heating house presented in these guidelines, 4.4 Site supervision a stove of just 7 kW output would be on the basis of room temperature; sufficient for all space heating and An overview of the various works ■ Automatic control of heat input to DHW needs. required to achieve the Passivhaus

page 24 Standard has already been provided, …) may appear. The opportunity should including emphasising the different be taken to remove these and replace insulation methods that could be used, with harmless materials. the importance of minimising thermal bridges, the risks associated with unwit- tingly creating interstitial condensation For further information on asbestos and the need to achieve a high level of removal - www.epa.ie. airtightness. It is vitally important that both the contractor(s) carrying out the work as well as the energy advisor inspecting the works must be suitably experienced in all of the above issues in order that a successful result is achieved References for the homeowner. 4 IS EN 13141-7:2004, Ventilation for There is a rather high margin for error in buildings/ performance testing of retrofitting to the Passivhaus Standard components/products for residential and care should be taken at every step of ventilation. Performance testing of a the way. mechanical supply and exhaust ventila- tion units (including heat recovery) for During the construction while opening mechanical ventilation systems wall, floor or ceiling constructions intended for single family dwellings. harmful substances (Asbestos, pollutant emitting materials, respirable glass fibre

page 25 page 26 SECTION FIVE

Upgrading of Typical Construction Types page 28 Upgrading of Typical Construction Types

This section illustrates many of the most Readers should also note that a change plastered with an approved render common construction types in Ireland in external finishes may require planning system. and various means of upgrading their permission. In many situations, random rubble walls performance to the Passivhaus or hollow block walls will already be Standard. It must be appreciated that 5.1.1 Random Rubble and Hollow insulated internally (commonly referred there are many different construction Block Wall to as ‘dry-lining’). If the wall is already dry types as well as numerous techniques Walls constructed of random rubble or lined, the plasterboard and plastic sheet- and materials available to reduce hollow block are often found in very old ing should be removed in order to check thermal losses and to deal with all the dwellings and, accordingly, are often not the condition of the timber or metal permutations and combinations would insulated. studs as well as the existing insulation. If not be possible within these Guidelines. these are not in good condition, they It is hoped that the variety of examples If the stone used in the dwelling is should be replaced or upgraded and covered below, however, provide as exposed and of high aesthetic quality, closed with OSB and an airtight layer/ useful guidance for most scenarios that homeowners might well be reluctant to vapour control layer. As has been will be encountered by persons inter- clad over this with external insulation stressed earlier, great care has to be ested in retrofitting. which would completely alter the taken when insulating internally in order character of the building. In situations It must be stressed that readers to avoid causing interstitial condensa- where this is not the case, however, should not copy techniques from tion. A membrane with a high vapour external insulation might be considered. these guidelines without checking the resistance (vapour ‘barrier’) may help to suitability of the building being When insulating externally there are two prevent the build up of condensation, upgraded! For all parts of the thermal possible options, either using a loose but this should be proven by calculation. envelope, the risks of interstitial insulation type with a ventilation cavity It is recommended to create an insulated condensation have to be calculated or using a single skin insulation type. service cavity for cables and pipes and verified. Furthermore, there may Using loose external insulation typically running along the external walls in order be other issues such as structural requires a substructure comprising to protect the vapour control layer from stability and fire safety considera- wooden battens which are fixed to the being penetrated by nails or screws. tions to be considered. wall and bear the load of the new façade. Depending on the thickness of It is possible to mix both external and Retrofitters should only use IAB the insulation required, it might be internal insulation techniques but there approved products with installation by necessary to counter batten externally is likely to be more costs involved due to specialist contractors only to ensure to the first layer of battens to provide additional labour and materials. insurance by Home Bond. enough depth. An oriented strand board A number of 3D images are provided to (OSB) or a wood fibre board is then fixed 5.1 Walls illustrate different possible approaches to the external side of the battens to significantly upgrading the energy The following Section explains how to followed by a breather membrane. performance of random rubble and upgrade different wall constructions Thereafter, a ventilation cavity is formed hollow block walls. These sketches are which are common in Ireland. with vertical battens which can be clad not exhaustive. Rather, they serve as with appropriate materials. For all construction types care has to be examples of the kind of approach that taken when externally insulating at the The other option is to insulate externally might be used. base of walls. The insulation here should with insulation boards which create a be a type of material which is suitable for a single skin structure (ie. no ventilation 5.1.2 Cavity Walls humid environment. Furthermore the cavity). In this case, the insulation of When dealing with cavity walls, it is detail has to be developed in that way so required thickness can be mechanically usually best to full-fill the cavity with no moisture can infiltrate the construction. fixed to the structural wall and thereafter

page 29 Existing Standard Random Rubble Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Random Rubble Exterior Wall Upgraded to Passivhaus Standard - Internal “Loose” Insulation

Source: MosArt Architecture

page 30 Dry Lined Hollow Block Exterior Wall Upgraded to Passivhaus Standard

Source: MosArt Architecture

page 31 Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Dry Lined Hollow Block Exterior Wall Upgraded to Passivhaus Standard - External “Loose” Insulation

Source: MosArt Architecture

page 32 Existing Standard Hollow Block Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Hollow Block Exterior Wall Upgraded to Passivhaus Standard - Internal “Loose” Insulation

Source: MosArt Architecture

page 33 Existing Standard Hollow Block Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Hollow Block Exterior Wall Upgraded to Passivhaus Standard - External “Rigid” Insulation

Source: MosArt Architecture

page 34 insulation in order to reduce the thick- As for the random rubble and hollow sation is considered in the detailing and ness of the additional insulation that will block wall, there are two means of exter- design. As before, it is recommended to inevitably be required. This is normally nally insulating, namely with a (new) remove existing insulation and airtight done by injecting suitable insulation ventilated cavity construction or as a layers where they exist and upgrade (such as beads) into the cavity. single skin construction. It is likely that these in best practice manner including the insulation layer does not have to be service cavity as described in Section Make sure when filling the cavity that as thick as for the random rubble or 4.3.1 and 5.1.1. the insulation material does not transmit hollow block wall because of the better water coming from driving rain to the thermal performance of the cavity wall. 5.1.3 Timber Frame inner leaf (there is a variety of certified products available on the market so If it is decided that the wall should be Typically in Ireland, the structural part of please ensure the installer is IAB certified insulated internally, care should be timber frame constructions is built with (Check www.nsai.ie). taken that potential interstitial conden- OSB on the outside, insulation in

Existing Standard Cavity Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Cavity Exterior Wall Upgraded to Passivhaus Standard - External “Loose” Insulation Source: MosArt Architecture

page 35 Existing Standard Cavity Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Cavity Exterior Wall Upgraded to Passivhaus Standard - External “Rigid” Insulation

Source: MosArt Architecture

page 36 between the studs and a layer of the internal or external face of the accuracy than on-site assembled polyethylene on the inside. It is more construction. constructions. Another advantage is that than likely that the polyethylene sheet- the footprint of the building would not Only certified insulation systems which ing will not have been installed as an extend as much as it would if the do not transmit water from the outer to airtight layer. Therefore the sheeting has concrete leaf was retained and the inner leaf should be used. to be taken off and the condition of the additional insulation were placed insulation checked and possibly There are again the same possibilities to exterior to that. Such considerations replaced by a better performing type. upgrade the timber frame construction might be important with buildings that Opening the wall will also provide a to the Passivhaus Standard externally are very closely spaced. This option is good opportunity to check the condi- and internally as mentioned above for not illustrated below but the build up tion of the studs as there might be the masonry wall constructions. Some of will be similar as for external upgrade damage caused over the years by these options are illustrated below. with loose insulation material. A disad- penetrating water. In the worst-case vantage that must be considered is the Another option to upgrade a timber scenario parts of the structure may have cost and waste associated with remov- frame construction is to remove the to be changed. ing the outer masonry leaf. outer leaf of concrete block or brick and The existing cavity (between the timber insert a new insulated timber frame wall 5.2 Floor Slab structure and the external concrete in its place. The principal advantage of block leaf) should be filled with insula- this approach is that large parts of the Floor construction types in Ireland tion to reduce the inevitable additional walls can be pre-fabricated and there- typically comprise of either a suspended insulation that will be required either on fore produced with a much higher timber floor, power floated concrete

Existing Standard Timber Frame Exterior Wall

outside

Note: Only the use of IAB approved products are inside premitted and installation by specialist contractor only

Timber Frame Exterior Wall Upgraded to Passivhaus Standard - External “Loose” Insulation Source: MosArt Architecture

page 37 Existing Standard Timber Frame Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Timber Frame Exterior Wall Upgraded to Passivhaus Standard - External “Rigid” Insulation

Source: MosArt Architecture

page 38 Existing Standard Timber Frame Exterior Wall

Note: Only the use of IAB approved products are premitted and installation by specialist contractor only

Timber Frame Exterior Wall Upgraded to Passivhaus Standard - Internal “Loose” Insulation

Source: MosArt Architecture

page 39 floor or concrete floor with a screed with and can be upgraded by removing the thermal conductivity will increase up finish. The thermal performance of these the floor covering, insulating between to approximately 0.02 W/mK. It should is typically not sufficient to achieve the the joists, fixing a vapour control layer be noted that at the time of print this Passivhaus Standard and will thus and covering this with a new floor finish. product does not have Agrment certifi- require upgrading. Unfortunately, floor Make sure that the vapour control layer cation. constructions are difficult to upgrade is not penetrated. If the U-value of the above upgrade because most often the finished floor An option of upgrading concrete floor options is still not low enough (as deter- level cannot be changed (considering slabs with a screed finish is to take off mined by the PHPP software) or if there clear heights at doors, first steps at stairs, just the screed and insulation and is a power floated concrete floor slab it is height of balustrades etc.). exchange the existing insulation with a worth thinking about completely replac- For bungalows it is worth thinking about better performing insulation. Vacuum ing the floor construction with highly high performance vacuum insulation insulation, for example, has a thermal insulated floor slab as described in (see performance details below) plus a conductivity (λ) value of 0.004 W/mK, i.e. Section 4.3.1.2. new build up on top of the screed. The approximately 10 times more efficient The installation of a radon barrier should knock-on effects of rising the finished than either mineral wool or cellulose. completed in accordance with the Irish floor level has to be considered very For more information please visit the Building Regulations. carefully. Internal doors may have to be following website: http://www.vip- cut at the bottom and special detailing bau.de/e_pages/start_e.htm would be required at the threshold of Vacuum insulation has to be handled external door(s). with extraordinary care (like glass). If the Suspended floors are the easiest to deal foil wrapping of the boards is penetrated

Existing Standard Suspended Timber Ground Floor

Suspended Timber Ground Floor Upgraded to Passivhaus Standard

Source: MosArt Architecture

page 40 Existing Standard Concrete Ground Floor

Note: Excavation Required to allow for additional Thickness of Insulation to Engineers Detail. Note: Only the use of IAB approved Products are Permitted & Installation by Specialist Contractor Only

Concrete Ground Floor Upgraded to Passivhaus Standard

Source: MosArt Architecture

page 41 5.3 Roof Usually the airtightness layer (or rather connected – otherwise, while each room the vapour control layer) - if existent – itself might have a sealed ceiling, the 5.3.1 Cold Roof / Insulated at will not be installed correctly to achieve partition walls will severely compromise Ceiling Level the Passivhaus Standard. For example, the overall airtightness of the dwelling. the joints between different sheets will Alternatively, it might be possible to Where there is a cold unused attic space typically not be taped. The first task, install the airtight layer on top of the the insulation will typically be found therefore, is to remove the existing joist which is an easier option. If choos- within the joists just above the plaster- plasterboard and exchange it with a ing this option, however, be aware that board ceiling to the attic. layer of OSB. On the internal face of the the insulation must be installed above As suggested earlier, in the long term OSB a vapour control layer has to be this membrane which will reduce the the homeowner might consider convert- fixed. Installing this vapour control layer available head height in the attic space. is difficult work as the membrane needs ing the attic space to a living space or A service cavity should thereafter ideally to be seamless under the entire insula- might be used to locate some of the be created by battens and plasterboard tion layer. In the case of houses with passive house mechanical plant which on the internal side of the airtight layer. masonry internal walls, each room can should be sited within the thermal This will lower the ceiling height, be sealed individually as the membrane envelope, such as the ventilation system. however, and it has to be clarified by the can be taped to the four walls which are, In these cases it is recommended in designer if this is acceptable to the themselves airtight. In situations where terms of cost and good building practice occupants. to create a ‘warm’ attic which means that partition walls are constructed of timber, the sloped section of the roof is however, the creation of a full seal is insulated (see Section 5.3.2). more challenging. The membranes in all individual rooms need to be properly

Existing Standard Ceiling to Attic Space with Insulation on the Flat

Note: Excavation Required to allow for additional Thickness of Insulation to Engineers Detail. Note: Only the use of IAB approved Products are Permitted & Installation by Specialist Contractor Only

Ceiling to Attic Space with Insulation on the Flat Upgraded to Passivhaus Standard

Source: MosArt Architecture

page 42 5.3.2 Sloped Roof is recommended. The rafters have to be When the external parts of the roof are increased in size by adding another in good condition the insulation could If it is necessary to insulate the sloped rafter on top of them. On top of that an be added to the inside. The build up is in section of a roof there are two options, OSB or wood fibre board is fixed and principle the same as the external insula- either insulation on top of the rafter then battens, counter battens and slates tion except that there is no OSB or wood (externally) or below the rafter (inter- are added. fibre board on top of the rafter. Note that nally). an additional internal build up will Insulation will also be placed between If the roof slates or tiles as well as exter- reduce the clear head height and with it the rafters and internal to this will be an nal weathered parts of the roof construc- the usable floor area. OSB layer, vapour control layer, battens tion are in poor condition it is probably to create a service cavity and, finally, wise to replace these as part of the plasterboard. upgrade. In this case external insulation

Existing Standard Pitched Roof With Insulation on the Slope

Note: Ceiling Heights may Restrict this Build Up

Pitched Roof with Insulation on the Slope Upgraded to Passivhaus Standard

Source: MosArt Architecture

page 43 The thermal performance of buildings is costs also have to be considered. There The following two sections show possi- not only dependent on carefully are many options and strategies that can ble solutions for the upgrade of a block designed build up of walls, roof and floor be used to retrofit to the Passivhaus work and timber frame wall construc- slab. When retrofitting buildings to the Standard and to show every single tion. Passivhaus Standard the correct design option for the upgrade of the building of junctions in terms of insulation, envelope would go beyond the scope of thermal performance, airtightness and these guidelines.

Additional insulation applied in attic space and ventilation tile installed.

Airtight layer sealed to wall.

Existing windows removed and replaced with new tripled glazed thermally broken windows.

Existing conc. window cills removed and replaced with pressed metal cills with external insulation returned to underside of cill.

Additional insulation applied using ‘beads’ to create a full fill cavity.

Airtight layer to continue through floor cavity.

External insulation fixed to existing render returned to meet the window frame.

External windows removed and replaced with new tripled glazed thermally broken windows.

Existing conc. window cills removed and replaced with pressed metal cills with external insulation returned to underside of cill.

Airtight layer to be sealed at floor slab.

Addition of perimeter insulation from rising wall to underside of external insulation to reduce impact of cold bridging.

Standard Cavity Wall Construction Retrofit for Cavity Wall Construction

NOTE: Source: MosArt Architecture Only the use of IAB approved products is permitted & installation by specialist contractor only.

page 44 Additional insulation applied in attic space and ventilation tile installed.

Airtight layer sealed at all joints and to all walls, floor and external opes.

Additional insulation applied using new internal stud work and returned to meet window frame.

Existing windows removed and replaced with new tripled glazed thermally broken windows.

Existing conc. window cills removed and replaced with pressed metal insulated cills and 2 No. courses of brick laid to match existing.

Optional service cavity.

Insulation fitted into floor cavity with airtight layer continuing through.

Existing windows removed and replaced with new tripled glazed thermally broken windows.

Existing conc. window cills removed and replaced with pressed metal insulated cills and 2 No. courses of brick laid to match existing. Additional insulation applied using new internal stud work and returned to meet window frame. Airtight layer to be sealed at floor slab.

Floor screed cutback to allow additional for insulation.

Addition of perimeter insulation at rising wall to reduce impact of cold bridging.

Standard Timber Frame Construction Retrofit for Timber Frame Construction

NOTE: Source: MosArt Architecture Only the use of IAB approved products is permitted & installation by specialist contractor only.

page 45 page 46 SECTION SIX

Case Study Retrofit Building - Theoretical page 48 Case Study Retrofit Building - Theoretical

This Section will illustrate a theoretical The construction of the walls, floor and case study in how to approach the ceiling is summarised in the Table below. upgrading of a semi-detached house to The windows were replaced in 2004 the Passivhaus Standard. A description from single glazed units with wooden of the construction type and thermal frames to double glazed PVC. Attic performance of the property will first be insulation was also fitted in 2004 which provided. Thereafter, it will be shown added considerable comfort to the how the specialist software PHPP was dwelling. used to determine such critical issues as Thermographic images of the house the level of insulation required for the were taken at pre-dawn in late Passivhaus Standard along with sizing of September 2008, with an outside mechanical systems and prediction of temperature of 11 degrees C and an annual space heating requirement. internal temperature of 18 degrees C. Schematic drawings are included in The low energy performance of the order to illustrate various means of building fabric can be easily appreciated achieving a highly efficient thermal from these images, highlighting uninsu- envelope as well how to deal with lated external walls with thermal bridg- challenging issues such as thermal ing, heat loss through ventilation grills, bridging and excellent air-tightness. An uninsulated external door, poorly approximate estimate will be provided insulated hot water pipes connecting to of the projected savings in terms of radiators and inadequately sealed attic energy for both heating and DHW hatch. production. A blower door test was also carried out Dwelling Description on the same day to determine the level of airtightness of the dwelling. The result The dwelling chosen as a case study is a of this test was 6.39 air changes per hour semi-detached / terraced house built in at 50 Pascal, or 6.6m3/(hm2). The principal the late 1970’s and located in north weakness of the envelope in terms of County Dublin. airtightness is the ground floor, compris- The house comprises three bedrooms ing wooden flooring on timber joists and one bathroom upstairs with an over a ventilated void. According to the Source: MosArt Architecture entrance hall, sitting room, kitchen and occupant, there are often severe drafts dining area at the ground floor level. The CURRENT BUILDING ENVELOPE DETAILS (FROM INTERIOR TO EXTERIOR) total accommodation comprises 83m2. Walls Floor Ceiling Windows and Doors In addition to this is an unheated, exter- 100mm inner 25mm wooden 12mm plaster nally accessed, single storey, flat roofed concrete block floor covering board garage attached to the western side of 40mm cavity 150mm joists 100mm ceiling joist the dwelling. uninsulated uninsulated with 100mm mineral wool insulation In terms of aspect, the front of the house 100mm exterior 150+ mm open faces north and the rear of the house concrete block ventilated space faces south. There are no east facing Overall U-value Overall U-value Overall U-value Overall U-value of = 1.69 W/(m2K) = 1.47 W/(m2K) = 0.43 W/(m2K) windows = 1.85 windows but three windows which face W/(m2K) and doors west. = 3.0 W/(m2K)

page 49 blowing up from the open space below the ground floor creating severe thermal discomfort. A number of the windows and both external doors are insuffi- ciently sealed as can be seen from the smoke test carried out during the blower door test. Other weaknesses include wiring which passes from the first floor through to the attic space as well as a poorly sealed attic hatch. Front (north) elevation illustrating significant heat loss Heat loss depicted in black and blue colouring created through the upstairs front bedroom external wall by an uninsulated front door. Note how the cold Current Heating and DHW System (Bedroom 2). The red glow located between the two migrates inward along the floor. windows is created by heat loss from a wall mounted Source: GreenBuild Building Information Services radiator at that position. The house is currently heated using a Source: GreenBuild Building Information Services relatively new natural gas boiler of approximately 80% efficiency. The boiler heats six radiators (two downstairs and four upstairs) which are controlled by a thermostat located in the kitchen. There is also a wall mounted electrical heater in the upstairs bathroom and a portable electric heater in the living room.

The house currently has no DHW tank. Hot water is provided on demand at the Rear (south) view of Bedroom 3 highlighting in red Heat loss (depicted in grey line) from an under floor hot kitchen sink (using electricity) and in the significant heat losses through the uninsulated exter- water pipe feeding a radiator. upstairs bathroom with an ‘electric nal wall from a wall mounted radiator positioned Source: GreenBuild Building Information Services under the window. shower’. The primary control for heating Source: GreenBuild Building Information Services aside from the kitchen thermostat is a time clock.

Heat loss depicted in blue colouring created by cold air Poorly sealed attic hatch displaying heat loss around entering the corner of a bedroom through a ventilation the perimeter (in dark blue colouring). grill. Source: GreenBuild Building Information Services Source: GreenBuild Building Information Services

Smoke test clearly highlights poorly sealed windows Smoke test illustrating air leakages below a window sill Leaky floor construction Source: MosArt Architecture Source: MosArt Architecture Source: MosArt Architecture

page 50 Source: MosArt Architecture

page 51 Use of PHPP and DEAP to Prepare PERFORMANCE OF THE EXISTING DWELLING ACCORDING TO PHPP AND DEAP7 Retrofitting Strategy PHPP DEAP Annual space heating 214 KWh/(m2a) 160 KWh/(m2a) All the relevant details concerning the requirement existing building dimensions, thermal Annual primary 441 KWh/(m2a) including 356 KWh/(m2a) (only includes envelope performance, level of airtight- energy use all household electricity electricity for lights, pumps & fans) ness, orientation and shadowing as well Building Energy Rating N/R E2

2 2 as electrical elements, heating system CO2 Emmissions 94 KgCO2eq/(m a) 37 KgCO2eq/(m a) are entered into both the PHPP and the Space Heat Requirement DEAP software. erftSesRtoi tp Retrofit Steps Retrofit Steps Retrofit Steps As can be seen from the Table above, the 6 dwelling as it is currently constructed has an annual space heating require- 5 ment of approximately 14 times that of 4 the Passivhaus Standard. Further, with an existing BER of E2, there is consider- 3 able scope for improvement to bring the 2 overall energy efficiency to what would be required by the revised 2008 Part L 1

Building Regulations (a BER of approxi- 0 mately B1). 0 50 100 150 200 250 Taking the current annual space heating Source: MosArt Architecture kWh/(m2a) demand and multiplying this by gas and electrical prices, it should, theoretically Primary Energy Requirement (according to the PHPP), cost the owner in the order of €900 per year on gas and 6 €570 per year on electricity, totalling approximately €1,500 per year. This 5 estimation is very close to the actual 4 amount spent on heating by the occupant of the house as determined 3 from a review of their energy bills. 2

Preparing a Retrofit Strategy 1

There are quite a number of aspects of 0 the current dwelling that cannot be 0 50 100 150 200 250 300 350 400 450 500 altered to any significant degree, includ- Source: MosArt Architecture kWh/(m2a) ing, for example, orientation and surface to volume ratio. Other aspects that Heat Load might be improved, albeit with some difficulty and therefore relatively high 6 cost, include thermal bridges and amount of south facing glazing. The 5 most cost effective means of making 4 considerable improvements to overall energy performance include (a) signifi- 3 cantly upgrading the insulation value of 2 the entire thermal envelope, including windows and doors, (b) considerably 1 improving the level of airtightness, (c) 0 installing a mechanical heat recovery ventilation system and (d) fitting renew- 0 102030405060708090 able energy technologies such as solar Source: MosArt Architecture W/m2 collectors for DHW and improving the efficiency of the gas boiler. overall result of the upgrading strategy met, reducing the current energy is provided hereunder: use by 93% from the current level of The steps used to gradually upgrade the 214 kWh/(m2/a) according to the case study dwelling are detailed in the ■ The space heating requirement PHPP calculations. Referring to DEAP table on page 55. A summary of the target of 15 kWh/(m2a) has been

page 52 the ‘heat use’ has been reduced from those were upgraded to the same layer as the cavity to continue the 160 kWh/(m2a) to 9 kWh/(m2a) (also a Passivhaus Standard, there would be insulation layer. reduction of 93%) a reduction in annual emissions of CO by 2MTCO eq/(m2a). Thermal Bridges ■ Achieving the Passivhaus Standard 2 2 required very significantly upgrad- ■ Lastly, the Building Energy Rating of In general thermal bridges are reduced ing the U-values of the building the case study dwelling in achieving by using external insulation. Perimeter envelope. The poorest performing the Passivhaus Standard would be insulation should be continued on the element of the dwelling is the walls an A3, a very significant improve- outer face all around the building (U-value of 1.69 W/(m2K)) which ment from its E2 BER. approximately 500 mm to 1,000 mm into would need to be upgraded to 0.10 the ground, dependent on the depth of W/(m2K). The windows and doors Measures in Detail the foundation. Furthermore, the frames would have to be replaced with high of windows and doors should be As mentioned above all proposed performance triple-glazed elements, overlapped by the external insulation (at measures have to be checked and be airtightness improved from 6.39 air least 60 mm thickness) to reduce approved for each individual project. changes per hour at 50 Pascal to 0.6 thermal losses. air changes per hour, use of a MHRV Thermal Insulation The most significant thermal bridges system with an efficiency of 85%, would occur at the concrete canopy over increasing the area of south facing The existing house was built in tradi- the front door, the concrete columns on glass from 7.38m2 to 9.05m2 and tional un-insulated cavity wall construc- either side of the front door and at the replacing the gas boiler with a unit tion, with a U-value calculated at 1.69 joint of wall and roof of the adjacent with 90% efficiency and installing W/m2K. A 40 mm fulfilled cavity with garage. It would probably be best to 5m2 of solar collectors (flat plate or blown insulation beads and rendered remove the existing concrete canopy as evacuated tube) on the south-facing 300 mm EPS insulation on the outer leaf well as the columns. If there is still a need roof. will bring the U-value down to 0.10 for a canopy it could be constructed as- W/m2K. As shown in Section 5 there are a ■ The primary energy demand includ- new, yet structurally separated from the number of options available to upgrade ing for DHW, heating, cooling, auxil- house. a wall such as that described above. iary and household electricity was The uninsulated cold wall of the garage reduced in the PHPP analysis from The flat ceiling to the attic has to be should ideally be disconnected from the 457 kWh/(m2a) to 105 kWh/(m2a) and insulated with 100 mm mineral wool house and the resulting gap insulated in DEAP from 375 kWh/(m2a) to 55 between the joists. Additional insulation (some means of structurally anchoring kWh/(m2a) will be required, however, in order to the garage wall back to the house will achieve the target U-value (if using ■ The heat load for the dwelling was likely be required). The roof of the mineral wool insulation, for example, reduced by 90% from the current garage is easier to deal with as it is 400 mm would be required. If other size of 80 W/m2 to 9 W/m2. Taking mainly made from timber and therefore insulation products with lower thermal that the dwelling is 83m2 in size, the its thermal conductivity is not that high. conductivity (λ) values are being consid- size of boiler required for space Besides, additional insulation can easily ered, less depth would be needed). In heating alone could be reduced be fitted above and under the rafters to order to keep the attic accessible, it from 6.6 kW output to just 0.8 kW. reduce the thermal bridges. would be advantageous to construct a ■ Frequency of overheating remains raised floor above this additional insula- Thermal bridges can also be created at unaltered at 0%. tion using OSB, for example. the party wall with the neighbour if they do not insulate their building. These ■ Referring to the CO calculations in The existing ground floor slab is a 2 thermal bridges can be reduced by DEAP, the CO2 emissions have been suspended floor construction and it 2 insulating internally. reduced from 160 kgCO2eq/(m a) to would have been extremely difficult to 2 12 kgCO2eq/(m a), representing a reduce the U-value down to the required Lastly, the hatch to the attic has to be 93% reduction. In real terms, given 0.10 W/m2K. It was decided, therefore, well insulated and sealed airtight. the house size of 83m2, there would that the best option in this case would be an annual saving in CO2 be to remove the existing floor and Airtightness emissions of over 12,000 Kg, or construct a new 150 mm concrete floor A continuous airtight layer has to be approximately 12 tonnes. In 2004, slab with 300 mm insulation under- created in the building. As render is the ‘average dwelling in Ireland was neath. airtight, there is typically no difficulty in responsible for emitting approxi- achieving airtightness over wall areas. mately 8.2 tonnes of CO . If the case Windows and Doors 2 Windows and doors should be taped study house was retrofitted to the airtight with a suitable tape to the wall. Passivhaus Standard, it would emit In terms of glazing, it is proposed to use Following that the reveals can to be just 1 tonne per year. It is estimated triple glazed windows with an average plastered. that approximately 750,000 houses U-value (glass and frame) of Uw average=0.9 W/m2K and doors with a U- in Ireland were built before the first The layer of foil underneath the concrete value of Ud=0.8 W/m2K. The windows ever Building Regulations. If 25% of floor slab serves two purposes. and doors should be installed in the

page 53 The first duty is to prevent the concrete unit are located in the ‘box room’ on the same dwelling completely from new. It seeping into the gaps between the first floor. The ventilation ducts are must be stressed that such works are insulation boards while pouring it. The passed through the ceiling void and most economically viable when dealing second function is to create the airtight supply the fresh air to the habitable with an old dwelling which, irrespective layer. This foil has to be taped airtight at rooms such as bedrooms and down to of energy performance, needs to be the edges to the walls. the ground floor in two shafts to the completely upgraded. The case study family and living room. The air is dwelling presented in the following All joints of joists or rafters to walls have extracted in the kitchen, hall, box room chapter is an example of where such an to be taped airtight to the walls. If there and bathroom. overhaul was needed. In that case, the is no render in the ceiling level at the extra over costs to reach towards walls these spaces have to be rendered The heat recovery unit is calculated with Passivhaus Standard (i.e. over the above or spanned with a vapour barrier an efficiency of 85% and as a ‘back-up costs of new kitchen, extension, conven- membrane. heating’ the existing heating system tional builder’s work and so forth) was in with radiators is retained. Underneath the insulation of the first the region of 14%. floor ceiling a vapour barrier has to be Room temperatures are controlled with Until such time as more projects get installed. It is very important to carry out time control, external temperature underway in Ireland, it is difficult to a blower-door-test before the closing sensors and . estimate what retrofit costs will be. the access points to joints and junctions. It will typically happen that the first test Cost of Retrofitting result exceeds the 0.6 air changes per The cost of the above proposed works hour. During the test leakages can be has not been estimated for this ‘theoret- located and sealed. ical’ case study. However, experience on Continental Europe suggests that retro- Ventilation Heating System fit costs to the full Passivhaus Standard In the case of the example dwelling, the typically equate to approximately 60% ventilation system and heat recovery of what it would cost for to build the

page 54 250 kWh/(m2a)

200

150

100

50

0 Current Space Part L 2005 Part L 2007 Retrofitted Heat Passivhaus Requirement Standard

Space heating energy comparison, Current use in case study dwelling, Building Regulations (TGD) Part L 2005 and 2007 and the Passivhaus Standard. Source: MosArt Architecture

PHPP CALCULATIONS DEAP CALCULATIONS

Step Description Space Heat Primary Heat Load Frequency of Primary Heat use CO2 Building Requirement Energy (DHW, Overheating Energy (Space Heat emissions Energy Rating Heating, Cooling, Requirement) Auxiliary and Household Electricity):

2 2 2 2 2 2 Units of Measurement kWh/(m a) kWh/(m a) W/m % kWh/(m a) kWh/(m a) kgCO2eq/(m a) Passive House threshold 15 120 10 10 - - - -

Current performance 214 457 80 0 375 160 79 E2

1 Insulation of building fabric 49 178 26 4 177 51 39 C2 (walls, ceiling, floor), reduction of thermal bridges - improve U-value walls from 1.69 to 0.10 W/(m2K), U-value ceiling from 0.43 to 0.09 W/(m2K), U-value floor from 1.47 to 0.10 W/(m2K)

2 Change from double to triple 35 154 20 5 153 38 34 C1 glazed windows, change doors -improve average U-value windows from 1.85 to 0.91 W/(m2K), U-value doors from 3.00 to 0.80 W/(m2K)

3 Airtightness - improvement from 6.39 29 145 13 15 125 22 28 B3 to 0.6 airchanges per hour @ 50 Pascal

4 Balanced whole-house-ventilation system, 16 126 9 0 108 9 25 B2 with Heat Recovery Unit, efficiency 85%

5 Increase window sizes of south facing 15 126 9 0 108 9 25 B2 windows,from 7.38 to 9.05 m2

6 Condensing Gas boiler for heating 15 105 9 0 55 9 12 A3 and DHW- efficiency of 90%, DHW not electric anymore, 5 m2 Solar panels, 300 l hot water storage

Source: MosArt Architecture

page 55 Externally Insulated Building Envelope and Heat Recovery Venilation System in Retrofitted Dwelling

Source: MosArt Architecture

page 56 Copy of the PHPP 2007 verification sheet for theoretical case study pre retrofitting

page 57 Copy of the PHPP 2007 verification sheet for theoretical case study post retrofitting

page 58 SECTION SEVEN

Case Study of Completed Retrofitted Project page 60 Case Study of Completed Retrofitted Project

This project is one of Casethe first in IrelandStudy in The of existing Completed double glazed windows Retrofittedachieved. Testing Project with a thermal retrofitting a conventional built dwelling were replaced with thermally broken imaging camera is also available. This towards a Passivhaus Standard. The triple glazed windows throughout and can detect any cold bridges in the exter- clients visited MosArt's demonstration triple glazed roof lights were installed in nal fabric of the building. Strict on site passive house ‘Out of the Blue’ in 2006 the roof. supervision is required throughout the and were inspired to convert their home construction works by the designer. The to the same standard of comfort and site foreman or main contractor should energy efficiency. The existing roof was a standard tiled also be made aware of the importance of roof with pre-fabricated timber trusses strict on site supervision by them of all The existing external walls were with insulation on the flat. As the alter- trades to achieve an airtight building. On constructed as a standard cavity wall ations to the existing house included an completion the house should have one with a 100 mm brickwork outer leaf, 100 additional bedroom in the roof space final blower door test. mm cavity and 100 mm concrete block- the insulation had to be changed to on work inner leaf. Upon inspection the the slope to accommodate this. cavity was found to have no insulation Additional timber rafters were installed The retrofitted building was occupied in installed and the walls had been dry to accommodate additional higher May 2008 and at the time of print, the lined internally with timber studs with density insulation in the roof space heating season is approximately 50% rock wool insulation between, polyethyl- between the timbers, airtight vapour complete. The actual annual energy ene vapour barrier and plasterboard barrier was added and new plasterboard consumption cannot be verified before with skim finish. with skim finish. May 2009 at the earliest. A comparison As the exterior leaf was brickwork we between the modelled and achieved The existing heating system was were restricted in how we could improvement of the energy perform- replaced with a MHRV unit and heat upgrade the fabric to the Passivhaus ance of this project is yet not possible, pump with a gas condenser boiler as Standard. We achieved this by fully filling therefore it is anticipated that the annual back-up and solar collectors to the roof the cavity with blown in insulation, the space heating requirement will be for hot water supply. existing dry lining was removed inter- reduced by 80%. nally and replaced with larger timber It is important to note that the The extra-over cost to achieve the studs and higher density insulation programme for a passivhaus build differs Passivhaus Standard according to the between, a higher quality airtight to that of a conventional build. Time cost plan on this project was 14%. It vapour barrier was installed and taped should be allowed for the installation of should be borne in mind that this house on all joints with specific care taken to the airtight layer, this airtight layer underwent a major retrofit and exten- junctions at floors, ceilings and around should then be tested (blower door test) sion programme and thus the above windows and doors and new plaster- for leaks prior to any plasterboard being percentage extra over costs should in no board and skim finish was installed. All installed. Should any leaks be detected way be taken as a general guide for existing wall vents were blocked up they should then be rectified and the retrofit projects. internally and a MHRV unit was installed airtight layer should be re tested until throughout the house. the required level of airtightness is

Improvement of U-values

Envelope elements Pre-retrofit U-values Post retrofit U-values External cavity wall 0.28 W/(m2K) 0.19 W/(m2K) Floor slab 0.58 W/(m2K) 0.18 W/(m2K) Roof 0.13 W/(m2K) 0.11 W/(m2K) Windows 2.90 W/(m2K) 0.81 W/(m2K)

page 61 All proposed retrofit measures must be properly detailed to enable construction and well as to verify performance in the PHPP software

page 62 Before commencing any retrofit works, a full survey will be required to establish current insulation standards

While the red brick facade remained untouched, all the windows were upgrad- ed to triple-glazed Passivhaus Standard units (U-value of 0.81 W/(m2K) for entire window)

These special triple glazed roof lights were used on the south facing rear elevation (U-value of 0.91 W/(m2K) for entire window)

Retrofitting to reduce energy consumption also provides a valuable opportunity to enhance the aesthetics of the interior

The mechanical heat recovery ventilation system was installed in an accessible part of the warm attic space

page 63 This water to air heat pump is connected to a low-temperature under- floor heating system and is anticipated to provide 85% of the space heat requirement (COP = 3.4)

The existing building envelope was dry-lined internally with high performance insulation

Locations such as this where large services exit the building envelope are very difficult to seal properly in terms of airtightness

The south facing rear of the house on comple- tion, with 15m2 of flat plate solar thermal collectors which are expected to contribute 65% of DHW demand

page 64 page 65 Sustainable Energy Ireland Renewable Energy Information Office Unit A, West Cork Technology Park Clonakilty Co Cork Ireland T. +353 23 8863393 [email protected] F.+353 23 8863398 www.sei.ie

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