By Dr Wolfgang Feist, Founder of the Passive House Institute, Germany
Energy Efficient Passive Houses – Reducing the Impact of Global Warming
The February 2007 report of the Inter-Governmental Panel on Climate Change
(IPCC) has shown that climate change is already a very serious global issue. The
negative effects it will have on the ecosystem, the world economy and on living
conditions are anticipated to be on a massive scale.
Climate change is caused largely by human behaviour due mainly to the use of
fossil fuels as our main source of energy generation. The magnitude of future
climate changes is closely linked to worldwide CO2 emissions into the earth’s
atmosphere. The worst effects of global warming, such as a thawing of the entire
land-borne ice in Greenland and Antarctica, can still be prevented. However, this
requires a substantial reduction in worldwide CO2 emissions far below the
There is hardly any doubt that an energy system ready for the future will have to
be sustainable. Sustainable development is economic development that can be
continued in the future without causing significant problems for other people,
the environment and future generations.
Passive Housing can play a major role in reducing the impact of global warming.
The energy requirement of a passive house is so low that a family will never again
need to worry about energy price hikes. Passive Houses are virtually independent
of fossil sources of energy and can be fully supplied with renewable energy if a
compact heat pump unit is used in combination with an ecological electricity
supplier. Due to the low energy requirement of passive houses the regionally
available renewable energy sources are sufficient to provide a constant supply of
energy for everyone.
Ireland’s mild climate puts it in a favourable position to introduce Passive Houses
to mainstream construction compared to the more severe climates prevalent in
Sustainable Energy Ireland is Ireland’s national energy agency, set up to support Irish government energy
policy objectives. Following the introduction of new legislation, most notably the European Community
Directive on the Energy Performance of Buildings and the recent announcement of the intent to regulate
and require the use of renewable energy systems in new buildings, we are seeing the emergence of
extraordinary standards of energy performance for building construction in Ireland, as well as a rapid
increase in the uptake of renewable energy technologies for building services.
Ireland is facing a number of serious challenges including houses and facilitate the further development of this
rising energy costs and meeting our emissions obligations standard here in Ireland SEI commissioned ‘Guidelines for
under the Kyoto protocol. These and other factors have the Design and Construction of Passive House Dwellings in
given rise to a fundamental rethink in the way we design, Ireland‘. These detailed guidelines for self-builders and
construct and operate buildings. As we move forward, it is architects focus on new build houses and cover both
becoming clear that building ‘green’ has evolved and is fast conventional block construction and timber frame
becoming the preferred choice, providing high quality, high construction methods. They will ultimately become part of
efficiency, dynamic and cost effective solutions for a suite of guidelines to cover, for example, multiple
consumers and businesses. The passive house is the dwellings, non-residential buildings, extensions,
ultimate low energy building. The passive house standard is renovations etc.
recognised in Europe as the most advanced in terms of
energy performance of buildings and going forward the The guidelines cover the rationale and definition of the
European Commission is set on implementing the passive passive house standard, how to design and specify a passive
house standard and also on setting more stringent house along with, construction options, associated services,
requirements for the refurbishment of existing buildings. cost considerations and lifestyle issues. SEI hopes they will
be useful in increasing awareness and understanding of the
Today, the passive house offers one of the most desirable key principles and techniques in designing, constructing
technological and economical solutions for comfortable and operating the ultimate low energy building – the
living and working. It can be applied to new and existing passive house.
buildings in the commercial, industrial, public and
residential sectors. With close to 10,000 passive houses built
in Europe, this well proven and tested innovative standard is
now attracting significant interest in Ireland with pioneers
like MosArt and Scandinavian Homes leading an emerging
movement in the construction industry.
In response to the need to educate professionals and their David Taylor
clients on how to design, specify and construct passive CEO Sustainable Energy Ireland
The ‘Passive House’
1.1 Passive House and the 1.1.1 Definition of the Passivhaus
Passivhaus Standard Standard
A passive house1 is an energy-efficient The Passivhaus Standard is a specific
building with year-round comfort and construction standard for buildings with
good indoor environmental conditions good comfort conditions during winter
without the use of active space heating and summer, without traditional space
or cooling systems. The space heat heating systems and without active
requirement is reduced by means of cooling. Typically this includes
passive measures to the point at which optimised insulation levels with minimal
there is no longer any need for a thermal bridges, very low air-leakage
conventional heating system; the air through the building, utilisation of
supply system essentially suffices to passive solar and internal gains and
distribute the remaining heat good indoor air quality maintained by a
requirement. A passive house provides mechanical ventilation system with
very high level of thermal comfort and highly efficient heat recovery. Passive house in Ghent, Belgium (2004).
Source: Passiefhuis Platform vzw.
provision of whole-house even Renewable energy sources are used as
temperature. The concept is based on much as possible to meet the resulting
minimising heat losses and maximising energy demand (PEP, 2006), including
heat gains, thus enabling the use of that required for the provision of
simple building services. The domestic hot water (DHW). It should be
appearance of a passive house does not noted that the primary focus in building
need to differ from a conventional house to the Passivhaus Standard is directed
and living in it does not require any towards creating a thermally efficient
lifestyle changes. Passive houses are envelope which makes the optimum use
light and bright due to large glazed of free heat gains in order to minimise
Passive house in Oberosterreich, Austria (2000).
areas designed to optimise solar gains, space heating requirement. While there Source: IG Passivhaus Osterreich Innovative Passivhaus
as well as healthy buildings in which to are also limitations on the amount of projekte.
live and work due to fresh air supply primary energy that can be used by a
through the ventilation system. dwelling for such uses as DHW, lighting
and household appliances, this will not
The Passivhaus Standard is a be the primary focus of these guidelines.
construction standard developed by the That is not intended to imply that such
Passivhaus Institut in Germany energy uses are insignificant, however.
(http://www.passiv.de). The Standard can In fact, a passive house will have the
be met using a variety of design same DHW requirements as any typical
strategies, construction methods and house in Ireland and given the low
technologies and is applicable to any energy required for space heating the
building type. energy demand for DHW will represent a
This publication outlines the relatively high proportion of the overall
requirements in applying that standard consumption. In order to address this,
in Ireland and in all cases when referring some guidance is provided on strategies
to a passive house is describing a house to ensure that renewable energies are
built to the requirements of the employed as much as possible for Interior of passive house in Oberosterreich, Austria
(2000). Source: IG Passivhaus Osterreich Innovative
Passivhaus Standard. production of DHW. Passivhaus projekte.
Measure/Solution Passivhaus Standard for the Prototype House
in the Irish Climate
1. Super Insulation
Insulation Walls U < 0.175 W/m2K
Insulation Roof U < 0.15 W/m2K
Insulation Floor U < 0.15 W/m2K
Window Frames, Doors U < 0.8 W/m2K
Window Glazing U < 0.8 W/m2K
Thermal Bridges Linear heat Coefficient Ψ < 0.01 W/mK
Structural Air Tightness n50 < 0.6/ air changes per hour
2. Heat Recovery/ Air Quality
Ventilation counter flow Heat Recovery Efficiency > 75%
air to air heat exchanger
Minimal Space Heating Post heating ventilation air/ Low temperature
Passive house in Hannover, Germany (2004). heating
Source: IG Passivhaus Deutschland Innovative Efficient small capacity heating system Biomass, compact unit, gas etc.
Passivhaus projekte. Air quality through ventilation rate Min 0.4 ac/hr or 30m3/pers/hr
Ventilation Supply Ducts Insulated Applicable
Air-leakage (or infiltration) is the 3. Domestic Hot Water Biomass, compact unit, gas, heat pump, etc.
uncontrolled penetration of outside DHW cylinder and pipes well insulated Applicable
air into a building. It takes place Solar thermal system Recommended
through openings, primarily through
inadequate and imperfect sealing 4. Passive Solar Gain
between window frames and walls, Window Glazing Solar energy transmittance g > 50%
between the opening sections of the DHW solar heating Area to be dictated by house size and
window and along the joints of the occupancy
building envelope. Solar Orientation Minimal glazing to north
Thermal Mass within Envelope Recommended
5. Electric Efficiency
Energy labelled Household appliances A rated appliances
Thermal bridging refers to a material,
Hot water connection to washing Recommended
or assembly of materials, in a machines/ dishwashers
building envelope through which Compact Fluorescent Lighting Recommended
heat is transferred at a substantially Regular maintenance ventilation filters Recommended
higher rate (due to higher thermal Energy Efficient fans Recommended
conductivity) than through the
surrounding materials. Junctions 6. On-site Renewables
between window or door and wall, Solar thermal system Recommended
wall and floor, and wall and roof Biomass system Recommended
should be designed carefully to avoid Photovoltaics Application in a case by case basis
Wind Turbine Application in a case by case basis
thermal bridging. A thermal bridge
Other including geothermal Application in a case by case basis
increases heat loss through the
Table 1. Technical Definition of the Passivhaus Standard for Ireland.
structure, and in some extreme cases
may cause surface condensation or
interstitial condensation into the Structural air-tightness (reduction of air treated floor area (TFA), and
construction. Surface mould growth infiltration) and minimal thermal
• The upper limit for total primary
or wood rot may be the consequences bridging are essential. A whole-house
energy demand for space and water
of a thermal bridge. mechanical heat recovery ventilation
heating, ventilation, electricity for
system (MHRV) is used to supply
fans and pumps, household
controlled amounts of fresh air to the
appliances, and lighting not
house. The incoming fresh air is pre-
exceeding 120kWh/(m2year), regard-
heated via a heat exchanger, by the
less of energy source.
outgoing warm stale air. If additional
heat is required, a small efficient back-up Additionally, the air-leakage test results
system (using a renewable energy must not exceed 0.6 air changes per
source, for example) can be used to hour using 50Pa overpressurisation and
boost the temperature of the fresh air under-pressurisation testing.
supplied to the house.
In order to maintain high comfort levels
The energy requirement of a house built in any building, heat losses must be
to the Passivhaus Standard is: replaced by heat gains. Heat losses occur
through the building fabric due to
• Space heating requirement (deliver-
transmission through poorly insulated
ed energy) of 15kWh/(m2year)
walls, floor, ceiling and glazing as well as
Standard of space heating requirement
(delivered energy) of 15kWh/(m2year) for
the Irish climate. Specifying U-values is
dependent upon many variables and
can only be verified through testing the
performance of the dwelling design in
the PHPP software. The U-values
included in Table 1 have been tested for
the prototype passive house presented
later in Section 3. This prototype house is
a semi-detached two storey house of
very compact form. A detached
bungalow house of sprawling form
would require much lower U-values to
meet the Passivhaus Standard. Due to
the mild Irish climate, it is possible to use
U-values for walls in the prototype
house that are higher than those
typically recommended by the
Comparison of delivered energy in conventional house and in house built to Passivhaus Standard.
Source: Passivhaus Institut. http://www.passiv.de. Passivhaus Institute for colder central
A sensitivity analysis was undertaken
using different U-values for the
Building Regulations 2005
(TGD) Part L prototype house in order to see, for
example, whether it would be possible
60 to relax the building fabric requirements
e.g. double glazing, in Ireland and still
achieve the Passivhaus Standard. The
40 results of this analysis are included in
1.2 Applications of the
Passivhaus Standard in
the EU and Ireland
1.2.1 Evolution of the Passivhaus
Standard in Europe
Delivered space heating energy comparison, Building Regulations (TGD) Part L and Passivhaus Standard. The Passivhaus Standard originated in
Source: UCD Energy Research Group.
1988 by Professor Bo Adamson of the
University of Lund, Sweden and Dr.
from uncontrolled cold air infiltration needed in a conventional dwelling.
Wolfgang Feist of the Institute for
through leaky construction and poorly
A new built semi-detached, two-storey Housing and the Environment. The
fitted windows and doors. In a typical
Irish house built to comply with the concept was developed through a
dwelling, such heat losses have to be
requirements of Building Regulations number of research projects and first
balanced by heat gains mostly
Technical Guidance Document (TGD) tested on a row of terraced houses by Dr.
contributed by a space heating system.
Part L 2005, Conservation of Fuel and Wolfgang Feist in 1991 in Darmstadt,
The internal heat gains from occupants
Energy), uses approx. 75kWh/m2 Germany. The Passivhaus Institut
and other sources such as household
delivered energy for space heating and (http://www.passiv.de) was founded in
appliances as well as passive solar gains
159kWh/m2 primary energy. The Darmstadt, Germany in 1996 by Dr.
contribute a relatively small proportion
Passivhaus Standard requirement for Wolfgang Feist as an independent
of the total overall need in a
space heating is 15kWh/(m2year) research institution. Since then, it has
conventional dwelling. In a passive
delivered energy. When compared, the been at the forefront of the Passive
house, the heat losses are reduced so
reduction in space heating demand House movement in Germany and has
dramatically (through better insulation
represents 80%. been instrumental in disseminating the
and airtight detailing) such that the
standard throughout Europe and
same internal gains and passive solar
1.1.2 Technical Definition of the overseas (more details in Section 2).
gain now contribute a relatively high
Passivhaus Standard for Ireland
proportion of the total need. As a result
of this, a smaller space heating system is In Table 1, a range of U-values are
therefore required compared to that specified in order to meet the Passivhaus
Dwellings built to the Passivhaus and 27% of energy related CO2
Standard have been constructed all over emissions (11,376 kt CO2), the second
Europe in recent years but most largest sector after transport at 32%. The
especially in Germany and Austria where average dwelling emits approximately
the Passivhaus Standard was first 8.2 tonnes of CO2 emissions, 5 tonnes
applied.2 Over 10,000 dwellings have from direct fuel use and 3.2 tonnes from
been built to the standard throughout electricity use (O’Leary et al, 2006) and
Europe, including 4,000 in Germany and Irish dwellings have a higher
Austria, Norway, Sweden, Denmark and consumption of energy, electricity and
Belgium and this number is continuing energy related CO2 emissions per
Passive house in Guenzburg, Germany (2006).
to grow. CEPHEUS3 (Cost Efficient Passive dwelling compared to the average of the
Source: UCD Energy Research Group. Houses as European Standards) was a EU-15 (EC, 2005).
research project (1998–2001) that
The Government White Paper ‘Delivering
assessed and validated the Passivhaus
a Sustainable Energy Future for Ireland’
Standard on a wider European scale. The
(DCMNR, 2007) highlighted that
project was sponsored by the European
amendment to the Building Regulations
Union as part of the THERMIE
in 2008 would bring a further 40%
Programme of the European
energy reduction and related CO2
Commission, Directorate-General of
emissions in new build construction. The
Transport and Energy. Under CEPHEUS,
recent Programme for Government has
14 housing developments were built,
brought forward that amendment to
resulting in a total of 221 homes
2007 and committed to a further
Passivhaus Eusenstadt, Austria.
constructed to the Passivhaus Standard
amendment in 2010 to 60% below
Source: Construct Ireland Issue 2, Vol 3. in five European countries. Another
project supported by the European
Commission, Dictorate General for It is clear that the performance of both
Energy and Transport is PEP, which new build and existing housing stock
stands for ‘Promotion of European must be addressed if we are to achieve
Passive Houses’ (http://www.european the objectives set out both at European
passivehouses.org). PEP is a consortium and national level. The energy
of European partners aiming to spread requirement of a house built to
the knowledge and experience on the Passivhaus Standard goes beyond the
passive house concept throughout the proposed 40% energy reduction and
professional building community, related CO2 emissions in new build
beyond the select group of specialists. construction.
Multy family dwelling, ‘Hohe Strasse’, Hannover, 1.2.2 Application of Passivhaus A study completed by UCD Energy
Germany. Source: UCD Energy Research Group.
Standard in Ireland Research Group quantified the potential
reduction for space heating energy and
The Kyoto Protocol came into force in
CO2 emissions when the Passivhaus
2005 and the proposed targets of
Standard for space heating of
reducing CO2 emissions by 8%
15kWh/m2year is applied to the Irish new
compared to 1990 levels by the period
build residential construction market
2008–2012 became legally binding for
(Brophy et al. 2006). Five scenarios of
EU Member States (UNFCCC, 1997).
varying levels of application were
Ireland’s target under the Kyoto Protocol
investigated. The tool used in this study
to limit green house gas emissions to
was a computer based model,
13% above 1990 levels by that period
developed as part of the “Homes for the
was reached in 1997, and it is likely that
21st Century” study (Brophy et al. 1999),
the target will be overshot by up to 37%
which profiled the existing national
(74Mt CO2) by 2010 (O’Leary et al, 2006).
dwelling stock by dwelling form,
The EC Green Paper on Energy Efficiency
insulation characteristics and heating
(EC, 2005), states that it is possible for
system types. The model was used to
the EU-25 Member States to achieve
predict the energy consumption and
energy savings of 20% by 2010, and sees
CO2 emissions of dwellings with a typical
the greatest proportion of these savings
floor area of 100m2, constructed to 2002
Kronsberg Passivhaus Complex Hannover, Germany. (32%) coming from the built environ-
building regulation standard. This
Source: UCD Energy Research Group. ment.
provided national common practice
In Ireland the residential sector accounts energy consumption and CO2 emissions
for 26% of primary energy consumption figures. It was found that a typical Irish
dwelling consumes 9,722 kWh/year of
The EU Energy Performance of Buildings Directive (EPBD) was transposed into Irish
delivered energy on space heating and
law on 4th January 2006. This states that when a building is constructed, rented or
as a result releases 2,855 kgCO2/year
sold a Building Energy Rating (BER) certificate and label must be made available to
into the atmosphere. The space heating
prospective buyers or tenants. The BER is expressed in terms of kWh of primary
requirements for the same size of energy/m2/year. A passive house would achieve an A2 rating (UCD Energy Research
dwelling built to Passivhaus Standards Group).
was found to be only 1,500 kWh/year of
delivered energy which equates to 176
kgCO2/year. (It was assumed 50:50 split Percentage (and number) of new Potential energy and CO2 Potential energy and CO2
dwellings built to Passivhaus emissions savings per emissions savings in
between the use of gas and wood Standard year 20 years
pellets for space heating energy source
as typically used in passive houses). The 3.29 GWh 0.691 TWh
difference in delivered energy 1.07 ktCO2 5.02 MtCO2
consumption and carbon dioxide 16.44 GWh 3.453 TWh
emissions between the two construction 5% (2,000)
5.36 ktCO2 25.10 MtCO2
types for a single building over one year
65.78 GWh 13.813 TWh
was therefore 8,222 kWh/year and 2,680 20% (8,000)
kgCO2/year. Applying potential energy 21.44 ktCO2 100.41 MtCO2
and CO2 emissions saving rates to the 20 164.44 GWh 34.533 TWh
year average new build dwelling 53.59 ktCO2 251.03 MtCO2
construction rate of 40,000 homes per Table 2: Potential for space heating energy and carbon dioxide savings.
year the following results were
calculated. The results showed that
substantial savings are achievable
through the application of the
Passivhaus Standard in Ireland (Table 2).
The Passivhaus Standard was first
introduced in Ireland by the Swedish
architect Hans Eek at the ‘See the Light’
conference organised by Sustainable
Energy Ireland (SEI) in June 2002. Tomás
O’Leary of MosArt Architects, a delegate
at the conference, was so enthused by
Mr Eek’s presentation that he decided on
the spot to sell his townhouse, buy a site
in the countryside in Co. Wicklow and
build a passive house. The O’Leary family
has been living in the “Out of the Blue”
house since Spring 2005. This house is
the first Irish passive house to be
certified by the Passivhaus Institute in
Germany, and has been the focus of a
research, demonstration and energy
monitoring project funded by
Sustainable Energy Ireland. MosArt
Architects, the Passivhaus Institute of Dr
Wolfgang Feist and the UCD Energy
Research Group are partners in the
project. The project is instrumental in
establishing the basis for the
deployment of the Passivhaus Standard
in Ireland in different ways:
• it has provided a learning experience
for professionals involved in the
design, specification, construction
and servicing stages
• it will provide a scientific basis for
performance assessment through Building Energy Rating Label. Source: Sustainable Energy Ireland.
monitoring and evaluation
• it is an excellent demonstration tool
Brophy, V., Clinch, J.P., Convery, F.J., and has been the focus of many
Healy, J.D., King, C. and Lewis, J.O., 1999 visits, presentations and journal
“Homes for the 21st Century - The Costs
& Benefits of Comfortable Housing for
Ireland”. Dublin. Report prepared for
Energy Action Ltd.
Brophy, V., Kondratenko, I., Hernandez,
P., Burke, K., 2006 “Potential for Energy
and CO2 Emission Savings through
application of the Passive house
Standard in Ireland”. Published in the
Passive House Conference 2006 pp. 119-
124. Hanover, Germany. Ireland’s first Passive House, Wicklow.
Source: MosArt Architecture.
European Commission (EC), 2005.
“Green Paper on Energy Efficiency”.
[Internet] EC. Available at:
European Commission (EC), 2006.
“Promotion of European Passive Houses
(PEP)". [Internet] PEP. Available at:
Government of Ireland, Department of
Communications, Energy and Natural
Resources (DCMNR), 2007. Government The O’Leary’s embark on their passive house project.
Source: MosArt Architecture.
"White Paper Delivering a Sustainable
Energy Future for Ireland". [Internet]
DCERN. Available at: A passive house is a building, for which
http://www.dcmnr.gov.ie/Energy/ thermal comfort (ISO7730) can be
Energy+Planning+Division/Energy+ achieved solely by post-heating or post-
White+Paper.html cooling of the fresh airmass, which is
required to fulfill sufficient indoor air
O’Leary, F., Howley, M., and O’Gallagher,
quality conditions (DIN 1946) - without a
B., 2006. “Energy in Ireland 1990-2004,
need for recirculated air. Source:
Trends, issues, forecast and indicators”.
Dublin. Sustainable Energy Ireland.
Pa s s i v e _ H o u s e _ E / p a s s i v e h o u s e _
United Nations Framework Convention definition.html
on Climate Change (UNFCCC), 1997. 2
The Kyoto Protocal. [Internet]. UNFCCC.
Available at: http://unfccc.int/resource/ See http://www.passiv.de/07_eng/ news/
S ECTION T WO
How to Design & Specify a Passive House in Ireland
How to Design & Specify a Passive House in Ireland
This section introduces the passive sky. It may happen that the best views volume, and size of the house. This will
house building design process as well as from the site are to the north suggesting provide an early indication of whether
explaining the balance between energy the placement of large glazing areas on the Passivhaus Standard is being
losses and gains. It also provides an the northern façade in order to optimise achieved. If the space heat requirement
overview of the various building systems the best view. All orientation options is significantly above the threshold of
and technologies typically employed in must be considered by the designer at 15kWh/(m2year) then the building will
a passive house and presents the PHPP this stage - the house must not only have to be modified whether in terms of
software used for energy balance function well in terms of energy improved U-values, reorganisation of
calculations. The design and efficiency but also in terms of optimising glazing or adjustment of form. The
specification of the example prototype the potential of the site and its designer should intuitively know how
passive house in the Irish climate surroundings. improvements can best be achieved
developed as part of these guidelines while broadly remaining true to the
will be covered in greater detail in Sketch Design agreed sketch design. If the space heat
Section 3. The next phase of the design process is requirement is significantly less than the
to develop a sketch design for the house. threshold level, then it might be possible
2.1 Building Design Process The basic principles of passive house to increase the U-values and therefore
for a Passive House design will greatly inform the save on insulation costs. Care should be
Client’s Brief development of the initial design. An taken to note other performance
The design of a passive house will ideal approach would be to have the indicators calculated by the software,
typically commence with developing a longest façade of the house facing such as frequency of overheating, for
brief with the Client, whether this is a south, a bias of glazing towards the example.
family wishing to build a single rural southern elevation with reduced glazing
area on the northern elevation and a Detailed Design and Specification
dwelling, a Local Authority progressing a
compact form in order to minimise The design of the house is next
housing scheme or a commercial
surface to volume ratio. Shading devices developed to the level of detail required
developer proposing a mixed residential
may be required in order to protect to apply for planning permission.
project. The brief would typically outline
against the risk of overheating in Typically this would not require all
the Client’s practical requirements in
summer and the aesthetic integration of construction details but it is wise to
terms of space functions and density
these are essential. In terms of internal consider the various technologies at this
and also their preferred image or
layout, it is preferable to organise, where stage in order to avoid difficulties later
concept for the building(s). Clients
possible, family rooms and bedrooms on on. The type of construction will need to
interested in building a passive house
the southern elevation with utility room be considered, whether timber frame,
will often have carried out a
and circulation spaces on the northern concrete, externally insulated masonry,
considerable amount of research on the
elevation where availability of sunlight is insulated concrete formwork, straw bale,
subject and so will already be relatively
not so critical. etc as well as the space required for
well informed regarding the benefits of
services such as solar panels, large
living in a passive house.
Initial Evaluation of Energy Performance domestic hot water tank, mechanical
Site Visit Once the sketch design has been ventilation equipment with supply and
A site visit is important to (thus reducing approved by the client, it is important to exhaust ducting. The specification of
the potential for achieving a glazed test the energy balance of the house such services might be outside the
south facing façade) identify the design using the Passive House Planning expertise of the house designer and it
presence of structures, landform or Package (PHPP). The essential elements may be required to commission the
evergreen trees which might cast of the design are entered into the services of a Mechanical and Electrical
shadows on the house during the short spreadsheet U-values of walls, floors, Engineer. It is also critically important to
winter days when the sun is low in the roof and glazing as well as orientation, plan ahead in terms of airtightness and
cold bridging detailing as these often level of airtightness, as this is greatly
Areas of Heat Loss in Homes
represent the most challenging aspects affected by the quality of craftsmanship
Roof Loss 30%-35% of passive house design. The detailed on site. The challenge becomes all the
design should be re-tested in the PHPP more difficult if the building contractor
25%-30% Loss 25% software to ensure that the Passivhaus has no prior experience of building to
Standard is achieved. At this stage all the the Passivhaus Standard. More
required data fields have to be challenging again is the common
completed as accurately as possible practice of the house built by ‘direct
(details of the PHPP tool datasheets is labour’ and without an experienced
outlined in section 2.3.1). This might supervisor with overall responsibility to
Window Loss 15%
require some minor redesign of the achieve the high standards set.
initial house design. The Client should
Floor Loss 7%-10% It will usually be necessary to engage
be kept informed at all times of the
Comparison typical building fabric heat loss patterns specialist Sub-Contractors to supply and
in a detached dwelling, excluding ventilation and decisions being made by the design
install such elements as the ventilation
infiltration. Source: SEI. team and have the opportunity to
equipment, solar system, back-up
suggest alterations should the need
heating systems and controls.
Post Construction Testing
Tender Documents and Drawings
This is the final stage to determine
Once planning permission has been
whether the constructed dwelling
granted, a more detailed set of technical
actually meets the air-tightness
drawings will be required in order to
requirements of the Passivhaus
enable the construction of the house. As
Standard. The air-leakage must not
highlighted above, the emphasis will be
exceed 0.6 air changes per hour using
on detailing of junctions between
50Pa overpressurisation and
different elements of the building,
underpressurisation testing. An
practical requirements for minimising
independent inspection and testing
heat loss through cold bridging,
body should conduct the testing
planning for airtightness and the
activities. It is important to undertake
location and routing of services. The
this test as soon as the airtight layer is
sizing of the ventilation equipment,
complete so that any leaks can be
back-up space heating, solar domestic
rectified. When the house does not meet
hot water system, as well as details of
the requirements further testing may be
controls for space and water heating and
ventilation, will have to be specified at
this stage. The detailed drawings and 2.2 General Principles: Heat
specification can then be issued for Energy Losses & Heat
tender to competent contractors. Energy Gains
Thermographic image illustrating difference in heat 2.2.1 Passive House Building
loss through building envelope in a conventional and The detailed design of the passive house
passive house building. must now be realised on-site and quality
Source: UCD Energy Research Group. The building envelope consists of all
control is paramount to achieving the
standard envisaged in the PHPP elements of the construction which
software. The most challenging aspect separate the indoor climate from the
Thermal transmittance (U-value) outdoor climate. The aim of the passive
will typically be achieving the required
relates to a building component or
structure, and is a measure of the rate 0.3
TGD Part L
at which heat passes through that
component or structure when unit 0.25
temperature difference is maintained
between the ambient air temper-
U-value W/m2 K
atures on each side. It is expressed in Passive House
units of Watts per square metre per
degree of air temperature difference
Source: Building Regulations Technical 0.05
Guidance Document, Part L Conserv-
ation of Fuel and Energy 2005. 0
Figure depicting 2005 Building Regulation standard required for insulation and required insulation to meet the
Passivhaus Standard in Ireland. Source: UCD Energy Research Group.
house is to construct a building temperature, therefore warm objects
envelope that will significantly minimise stand out well against cooler Irish Building Regulations, Elemental
heat loss and optimise solar and internal backgrounds. In the passive house some Heat Loss Method (Building
Regulations Technical Guidance
heat gain to reduce the space heating heat is lost through windows but heat
Document Part L, Conservation of
requirement to 15KWh/(m2year). lost through the external wall is very low.
Fuel and Energy 2005).
In the conventional building, on the
The following building envelope Maximum average elemental U-value
other hand, there is heat loss from the
parameters are fundamental in this W/(m2K)
entire building envelope, especially
process: • Pitched roof, insulation horizontal
through windows. at ceiling level 0.16
1. Well insulated building envelope • Pitched roof, insulation on slope
Insulation of the building envelope can
2. High energy performing windows 0.20
be divided into four distinct areas:
and doors • Flat roof 0.22
external wall, floor, roof and windows.
3. Minimised heat loss through thermal • Walls 0.27
Existing passive houses in Central and
bridging • Ground Floors 0.25
Northern European countries have been
• Other Exposed Floors 0.25
4. Significantly reduced structural air achieved with U-values for walls, floors • Windows and roof lights 2.20
infiltration and roofs ranging from 0.09 to 0.15
*Regulations due to be updated in 2008
5. Optimal use of passive solar and W/(m2K) and average U-value for
internal heat gains windows (including glazing and window
frames) in the region of 0.60 to 0.80
Building Envelope Insulation
W/(m2K). These U-values far exceed
Many building methods can be used in
those currently required under the Irish
the construction of a passive house,
Building Regulations, with the most
including masonry, lightweight frames
marked difference pertaining to
(timber and steel), prefabricated
windows, wall and floor.
elements, insulated concrete formwork,
straw bale and combinations of the A sensitivity analysis using the Passive
above. The prototype house presented House Planning Package (PHPP), v2004,
in this publication (details in Section 2 software was undertaken using a range
and 3) illustrates both masonry and of U-values for the timber frame and
timber frame construction as masonry constructions of the prototype
representative of most typically used house using climate data for Dublin. In Light filled room in a passive house.
building methods for dwellings in all options tested the same data was Source: MosArt Architecture.
Ireland. input into PHPP for air-tightness
0.6ac/h@50Pa, ventilation and
Continuous insulation of the entire
minimised thermal bridging. Various
thermal envelope of a building is the
parameters were tested in order to
most effective measure to reduce heat
determine, for example, the required
losses in order to meet the Passivhaus
level of U-values for the building
envelope in the Irish climate, and to
A thermographic image is used to ascertain whether it would be possible
illustrate the difference between the to use double glazing and still achieve
well and poorly insulation levels in a the Passivhaus Standard in Ireland. The
house. Heat loss through the building results are: Option 1 being the most
envelope is highlighted by the green, energy efficient house and Option 8 Light, bright and airy.
yellow and red colouring. The amount of being the least energy efficient. An Source: MosArt Architecture.
radiation emitted increases with outline description of each of the eight
Comparison of the interior surface temperature depending on the type of glazing. Windows on the northern elevation should ideally be
Source: Internorm, fenster–Lichtund Leben catalogue 2007/2008, pp.91. small. Source: MosArt Architecture.
Option U-Values of U-Values of U-Value of Space heating
U-Values of roof
ext. wall floor windows and requirement
1 0.10 W(m2K) 0.10 W(m2K) 0.10 W(m2K) 0.80 W(m2K) 8 kWh/( m2a)
2 0.15 W(m2K) 0.15 W(m2K) 0.15 W(m2K) 0.80 W(m2K) 13 kWh/( m2a)
3 0.10 W(m2K) 0.10 W(m2K) 0.10 W(m2K) 1.10 W(m2K) 13 kWh/( m2a)
4 0.175 W(m2K) 0.15 W(m2K) 0.15 W(m2K) 0.80 W(m2K) 15 kWh/( m2a)
5 0.27 W(m2K) 0.16 W(m2K) 0.25 W(m2K) 0.80 W(m2K) 22 kWh/( m2a)
6 0.10 W(m2K) 0.10 W(m2K) 0.10 W(m2K) 2.20 W(m2K) 28 kWh/( m2a)
7 0.15 W(m2K) 0.15 W(m2K) 0.15 W(m2K) 2.20 W(m2K) 34 kWh/( m2a)
8 0.27 W(m2K) 0.16 W(m2K) 0.25 W(m2K) 2.20 W(m2K) 45 kWh/( m2a)
Table 3: Sensitivity analysis of the passive house prototype house in Ireland outline test results for eight options. Source: MosArt Architecture.
options analysed is provided. Only the W(m2K) for all other building
first four achieve the Passivhaus envelope elements, coupled with Note: Results presented here are
Standard set for space heating triple glazed windows. The result is indicative only and should be used as
(delivered energy) of 15 kWh/(m2year) exactly at the threshold of the starting point for specification of a
treated floor area: Passivhaus Standard but was not passive house dwelling in Ireland.
used for the prototype house as there Meeting the Passivhaus Standard must
• Option 1 - U-value 0.10 W(m2K) for all be tested and verified with the PHPP
is no margin in site operations.
building elements combined with software for the specific dwelling
triple gazed windows with average • Option 5 - U-values for walls, roof design.
U-value (including glazing and and floor employed in the Irish
window frames) of 0.80 W(m2K) Building Regulations, Elemental Heat
results in space heating requirement Loss Method (Building Regulations Thermal Conductivity
significantly below the standard TGD Part L, Conservation of Fuel and Thermal conductivity ( -value) relates to
required of 15 kWh/(m2 year). Energy 2005) combined with triple a material or substance, and is a measure
glazed windows, failing to achieve of the rate at which heat passes through
Note: Advantages and disadvantages the required standard. a uniform slab of unit thickness of that
of using triple glazed windows are material or substance, when unit
discussed in detail in section ‘Windows • Option 6 - also a failure is the temperature difference is maintained
& Doors’) combination of U-value 0.10W(m2K) between its faces. It is expressed in units
for building fabric in combination of Watts per metre per degree (W/mK),
• Option 2 - (This is the option that has with standard double glazed units. (Building Regulations Technical
been used in the design of the Guidance Document Part L,
• Option 7 - U-values 0.15 W(m2K) for
prototype passive house in Ireland as Conservation of Fuel and Energy 2005).
walls, roof and floor as the prototype
part of these Guidelines), with U- Insulation materials for walls, roofs and
house but with standard double
value 0.15 W(m2K) for all building floors vary in terms of thermal
glazing U-value 2.20 W(m2 K) which
envelope elements combined with conductivity. Typical conductivities for
comes way above the Passivhaus
triple glazing. The results show space different insulation materials are
heating requirement below the included below as well as the
Passivhaus Standard. • Option 8 - U-values for walls, roof approximate thickness required in order
and floor employed in the Irish to achieve a U-value of 0.15 W(m2K) and
• Option 3 - All building envelope
Building Regulations, Elemental Heat 0.10W(m2K). (Table 4)
elements with U-value of 0.10
Loss Method (Building Regulations
W(m2 K) combined with an efficient Typical insulation materials used in
TDG Part L, Conservation of Fuel and
double glazed unit with low U-value Ireland include mineral wool,
Energy 2005) and standard double
1.1 W/(m2 K) achieves the Passivhaus polystyrene, polyurethane, polyiso-
glazed units underachieving the
Standard. cyanurate, sheep wool and hemp.
Different insulation materials suit
• Option 4 - U-value 0.175 W(m2K) for
different types of construction
external walls and U-value 0.15
application and it is important to use the the optimum balance of glazing for each the thermal comfort level in the house.
material best suited for the situation. For passive house design can be reached.
Typically triple glazed window units are
example, cellulose insulation is suitable
It has been illustrated above that the use used in passive houses in Central and
for use in an open attic space where it
of windows and doors with average U- Northern Europe. The Passivhaus Institut
will fill completely between ceiling joists
values of 0.8 W/(m²K) can be combined has certified a range of glazing and door
in comparison with rigid insulation
with U-values for opaque elements of units suitable for use in passive house
where there is a high risk of thermal
0.15 W/(m²K) to comfortably achieve the buildings. Although it is not a
bridging unless cut perfectly to fit
Passivhaus Standard in Ireland. There are prerequisite to use certified passive
snuggly between the joists. Conversely,
a number of advantages in using house products (http://www.passiv.de) in
a high density rigid insulation is better
windows with average U-values of 0.8 a passive house, choosing approved
suited under a floor slab compared with
W/(m²K) as well as highly insulated products means the validity of technical
insulation that easily compress or are
doors, principally the assurance of a data has been tested and verified by an
affected by moisture.
comfortable indoor climate due to the independent certifier. The principle
The U-value of the construction is lower cold radiation heat transfer at the characteristics and advantages of using
determined by the conductivity of surface of the glass. One will not sense a triple glazed windows in a passive house
materials and components used from drop in temperature standing are listed below, for both window
the internal surface to the external immediately adjacent to this standard of glazing and frames:
surface of the thermal envelope. window, unlike the experience of Glazing
Examples of typical construction standing next to a conventional double • Three panes of glass separated by
methods and materials used for the glazed unit with U-value, for example of special low-conductivity spacers
prototype passive house in Ireland are 2.2 W/(m2 K). An added benefit of using eliminates the risk of condensation at
illustrated later in Section 3. highly energy efficient windows and the bottom of the glass in cold
Windows & Doors doors includes significant draught weather (which may lead to rotting
The recommended approach to the reduction due to the fact that they have of timber frames over time).
design of a passive house is to have typically two seals or gaskets (compared
with conventional double glazed units • High solar energy transmittance (g
avoid excessive area of north facing
which often have only one) as well as 50) which allows solar radiation to
glazing and place relatively large
excellent sound insulation. Finally, penetrate the glass and contribute
windows facing south or due south. This
natural convection which is driven by towards heating of the dwelling.
is in order to minimise heat losses
through the north facing elevation, temperature difference between the • A low emissivity (low-e) coating on
which receives no direct sunlight, while inside face of the glass and the room the inside of the outer two panes
maximising ‘free’ solar heat gains on the interior is much reduced with which in which reduces solar re-radiation back
south. An advantage of large windows is turn will reduce cold air flows and out through the glass. It should be
an increase in interior day light levels thermal discomfort. noted that a ‘soft coat’ has slightly
which in turn reduces the need for use of better U-value but a ‘hard coat’
The sensitivity analysis for a passive
electricity for artificial lighting and also glazing has higher solar trans-
house dwelling in Ireland (showed in
ensures a more pleasant natural light- mittances.
Option 3), achieves the Passivhaus
filled living environment.
Standard yearly space heating • Insulating gases between the glass
There is, however, a balance to be requirement with extremely efficient panes, typically argon or krypton,
achieved between heat losses through double glazed windows with a U-value which help to reduce heat escaping
the glazing and solar heat gains through no greater than 1.1 W/(m²K). When used through the glass.
the south/east/west facing windows. in a passive house, however, they must
When designing a passive house, PHPP be used in conjunction with very low U-
• The frame must be well insulated and
software should be used to calculate the values for all other elements of the
also be thermally broken. Even wood
heat losses and heat gains taking into building envelope. This may negate any
conducts heat and a thermally
account building orientation, areas of financial saving in not using more
broken timber window frame will
glazing and specific types of glazing so efficient glazing as well as compromise
result in much lower heat losses than
Insulation Material Thermal Thickness for Thickness for a solid one.
Type conductivity W/mK U-Value of 0.15 U-Value of 0.10
W(m2K) W(m2K) • There will typically be two weather
Polyisocyuranate or gaskets on triple glazed windows
0.023 145mm 220mm used in a passive house dwelling, the
Polystyrene, sheep wool 0.035 220mm 340mm primary function of the outer one
Cellulose, Hemp and being for weathering with the inner
0.04 250mm 400mm
Rockwool one serving to improve airtightness.
Wood 0.13 825mm 1,250mm The majority of these types of
Table 4: Conductivity of insulation materials and approximate thickness to achieve specific U-value for external windows open outwards which is
walls. Source: MosArt Architecture. common place in Continental Europe
however, there are models of inward transferred throughout the house via
opening windows being developed the mechanical ventilation system. This
which will soon be available in the has the added benefit of enabling
Irish market. One advantage of unobstructed use for placing furniture
outward opening windows is that against all external walls.
they don’t intrude in the room space
which may be important in more
Thermal bridging (i.e. un-insulated joints
between walls, floors/walls, ceilings/
• Triple glazing window frames are adjacent walls, windows/walls etc) are
typically much wider and stronger weak points of the building envelope
construction than their conventional and cause unwanted losses of energy
double glazing counterparts. which should be eliminated or
significantly reduced to a degree that
• Triple glazed windows with low- the associated heat losses become
emissivity coating and insulated negligible.
window frames will have improved
A thermal bridge increases heat loss
U-values compared to double glazed
through the structure, and in some
Cross section though a triple glazed insulated window windows, resulting in less heat loss.
and frame. Source: MosArt Architecture. extreme cases this may cause surface
However with triple glazing the solar
condensation or interstitial conden-
energy transmittance (gs), that is, the
sation in the structure. Surface mould
amount of solar energy entering
growth or wood rot may be the
through that glazing, is somewhat
consequences of a thermal bridge.
reduced compared to double glazing
Typical effects of thermal bridges are:
due to the effect of the additional
layer of glass. The requirements of • Significantly increased heat losses.
the Passivhaus Standard is to use • Decreased interior surface temper-
glazing with minimum solar ature which may result in high
transmittance of 50% or higher. humidity in parts of the construction.
The use of larger areas of glazing on the • Mould growth cause by warm
south elevation is helpful in maximising internal air condensing on cold
the amount of sunlight available in the surfaces.
short days of winter. It must be All of the above situations can be
remembered, however, that highly avoided in houses built to the
energy efficient windows allow less Passivhaus Standard. The Passivhaus
daylight (visible light transmittance) into Standard for linear thermal trans-
a building than a normal double glazed mittance (ψ) should not exceed 0.01
windows without e-coating. Light W/(mK). This requires the building
transmittance is an optical property that designer to identify and locate all
indicates the amount of visible light potential thermal bridging in the
The risk of internal condensation is dramatically
being transmitted through the glazing. construction, careful specification and
reduced. Source: MosArt Architecture.
It varies between 0 and 1 (0 to 100% detailing of those elements providing
light transmitted) with the higher the where possible a continous layer of
The quantity which describes the heat light transmittance value the more light insulation, as well as care being taken to
loss associated with a thermal bridge is is transmitted. A double glazed window execute those elements on site as per
its’ linear thermal transmittance (ψ). with low-e coating will transmit 72% of design details.
This is a property of a thermal bridge visible light. A triple glazed energy
and is the rate of heat flow per degree Designing and building a passive house
efficient window will transmit 65% of
per unit length of bridge that is not in Ireland requires the development of
visible transmittance (these are
accounted for in the U-values of the construction details that go far beyond
indicative values only - actual values
plane building elements containing guidance provided (to avoid excessive
depend on the manufacturer’s specific-
the thermal bridge. heat losses and local condensation) in
Building Regulations Technical Guidance
Source: SEI, Dwelling Energy Assess-
ment Procedure (DEAP) 2005 edition, In a conventionally constructed house in Document Part L, Conservation of Fuel
version 2, pp.55 Ireland radiators are typically positioned and Energy 2005. Building practitioners
under windows in order to heat the cold could refer to the accredited con-
air entering through the single or struction details specifically developed
double glazing. In a passive house for passive house building published in
locating radiators beneath windows is Germany “Thermal Bridge-Free Con-
simply not required as the heat load is struction” (PHPP 2007, pp.96). Thermal
bridging can be tested and verified in leaks in the envelope are very minor and
the PHPP software as the design of the therefore difficult to locate. In these
passive house building is being situations it is typical to reverse the
developed. direction of the fan and suck air into the
house putting it under positive pressure.
Structural Air-Tightness and Draught-
Odorless smoke can then be released
into the building and leaks can be
Building an airtight or leak-free structure
observed from the outside where the
is imperative to achieving the Passivhaus Infrared image of the interior of a passive house
smoke appears through the envelope. It
Standard. If there are gaps in the window. All surfaces (wall structure, window frame,
is important to notify the fire service if and the glazing) are pleasantly warm (over 17°C). Even
building structure then uncontrolled
you are carrying out such a test in case it at the glass edge, the temperature does not fall below
amounts of cold external air can 15°C (light green area).
is mistakenly reported as a house fire by Source: Passivhaus Institut, http://www.passiv.de from
infiltrate the building. Achieving a high
passers by. the passive house Kranichstein).
level of air-tightness eliminates cold
draughts and associated comfort losses. The Passivhaus Standard is reached
It also prevents condensation of indoor when there are less than or equal to 0.6
moist, warm air penetrating the air changes per hour @50Pa pressure.
structure, and possible structural
The most critical issue regarding testing
damages due to decay, corrosion and
for airtightness is timing during the
building process. It is important that
Air-tightness is achieved by careful remedial measures can be carried out in
application of appropriate membranes order to remedy any leaks or cracks. The
For comparison, a typical older double glazed window
and tapes or wet plastering in concrete test should be carried out before second is shown. The centre of glass surface temperature is
construction within the building fix carpentry, for example, when there below 14°C. In addition, there are large thermal
bridges, particularly where the window meets the
envelope. A great deal of attention must are no skirting boards or window boards external wall. The consequences are significant radiant
be paid to detailing and workmanship in fitted and where the junctions covered temperature asymmetry, drafts, and pooling of cold air
in the room. IR-photography: Passivhaus Institut.
order to ensure that the airtight layer is by such materials are still accessible and Source: Passivhaus Institut, http://www.passiv.de from
continuous all round the building, can be sealed. The test should also be the passive house Kranichstein).
especially around junctions between carried out after all mechanical and
walls and floors, roof, windows, doors, electrical services, that need to
etc. Penetrations of the airtight layer by penetrate the building envelope, have
mechanical and electrical services must been installed. Otherwise, installing
be properly sealed. such services after the test could
severely compromise the airtightness of
The air-tightness of a building can be
accurately measured by carrying out a
blower-door test. The test involves In a typical Irish house built in
placing a powerful fan suspended in a accordance with building regulations
canvas sheet within a door opening and TGD Part F 2002 the method in which
operating the fan at very high speeds habitable rooms are ventilated is usually
thereby creating either negative or via a hole in the wall or ventilator in the
positive pressure within the house. By windows of 6,500mm2 fitted with a
sucking air out of the house, for controllable grille. Such means of
example, a negative pressure is created ventilation can result in large amounts of
with the result that external air will be cool external air infiltrating the building
sucked in through any gaps or cracks in depending on wind speed and pressure.
the building envelope. The pressure In a passive house, on the other hand,
used for such tests is 50 Pascal which can the supply of fresh air is provided by a
be accurately set by the blower door whole house mechanical ventilation
equipment. system with heat recovery which
negates the necessity for openings in
When undertaking the test it is usually
the wall or windows. Thereby draughts
quite easy to identify major leaks due to Timber Frame I-Beam construction reducing thermal
are eliminated and structural air- bridging. Source: Passivhaus Institut, Germany.
the presence of a strong draught which
tightness is not compromised.
can be felt by the hand or, for smaller
leaks, can be detected by a In developing the building design it is
thermographic camera. The cause of very important to anticipate differential
these draughts can then be sealed with movement and decay of adhesives and
appropriate materials as the test is being chemical bonds by detailing junctions
undertaken. It may also happen that the which will assist in maintaining an
airtight layer for the life of the building. Internal Heat Gains
Many excellent details, for example, can A passive house is very efficient at
be found at the website of the Scottish utilising ‘free’ internal heat gains from
Ecological Design Association domestic household appliances, kitchen
(www.seda2.org/dfa/index.htm). It is also and utility equipment, electronic
important to use membranes and equipment, artificial lighting, and
plasters that are both airtight but also occupants. Heat losses from stoves or
vapour diffusing which allow moisture boilers also contribute towards the
within the structure to escape to the overall space heating requirement as
outside thereby reducing the risk of long as they are positioned within the
interstitial moisture and the threat of rot building envelope. Occupants of the
and decay over time. building also contribute to the heat load
Correctly insulated house avoiding thermal brid.
Source: Passivhaus Institut, Germany.
- a human continuously emits 100W of
Passive Heat Gains heat when stationary. A family of five
Passive heat gains in a passive house are persons, therefore, can emit 0.5KW of
a result of the combination of solar gains heat. This may seem like a small amount
and internal gains. but it equates to approximately one
third of the total space heat load for the
Solar Heat Gains prototype passive house presented in
Passive solar gain is optimised by Section 3.
providing an east-west alignment to the
building, if possible on the site, resulting Risk of Overheating
in the longest façade facing south, and Placing extensive areas of glass on the
by placing the majority of the glazing south facing façade in a well insulated
towards the south. Very high quality and air-tight dwelling may lead to
windows (average U-value 0.8W/m2K) overheating in warm sunny days. The
facing south will have a positive thermal PHPP software will alert the designer to
Continuous Airtight Membrane.
balance - it will have more heat gain any risk of overheating by calculating
Source: IG Passivhaus Osterreich Innovative Passivhaus
projekte. than heat loss throughout the year. the frequency of overheating expressing
Results of a recent parametric study by J. this as a percentage of the year in which
Schnieders of the Passivhaus Institut the internal temperature in the house
“Climate Data for Determination of rises above 25oC. If frequency of
Passive House Heat Loads in Northwest temperatures over the comfort limit of
Europe” illustrates the relationship 25oC exceeds 10% of the year, additional
between the area of south facing glazing measures for reducing overheating
and the space heat demand for a passive should be included in the dwelling. To
house dwelling located in Ireland prevent uncomfortable indoor
(measured climate data for Birr used). temperature in a passive house dwelling
The parametric study uses the first it is recommended to specify shading
passive house built by Dr. Wolfgang Feist devices (blinds, overhangs or awnings,
of the Passivhaus Institut as a case study etc.) which allow low sun to enter the
building, shown below. It can be seen home in winter but prevent the high sun
that the space heating demand initially entering in summer.
decreases quite steeply with increasing
In the first Irish passive house in Wicklow
south facing glazing. There are
shading was not in place on the south
diminishing returns from increasing the
facing glazing during the first summer
Timber frame house pre-cladding fitted airtight area of south facing glass, however, and
and the house did overheat. A balcony
membrane. Source: Passivhaus Institut, Germany. there eventually comes a point where
was installed ahead of the second
there is little or no benefit in providing
summer, which significantly reduced the
more south facing glass as the net heat
There are two measurements used to frequency of overheating. In mid-
loss is greater than the heat gains over
define airtightness, namely cubic summer when the daylight hours are
metres of air per square metre of the year.
long the sun only enters the building
external envelope per hour (m3/m2h) or later in the day while during winter
air changes per hour (ac/h). While the There is no optimal ratio of glazing to
when the daylight hours are short the
measured result for the former is floor area that can be used as a rule of
low sun completely illuminates the
generally 20% greater than that of the thumb in deciding what proportion of a
entire interior of the building.
latter, the difference is practice greatly given façade should be glazed. The area
depends on the building form. of glass has to be determined as part of In the temperate climate in Ireland
the design verification procedure using where external temperature rarely
the PHPP software. exceeds 25oC, the risk of overheating
22 Ireland - Birr
Space Heat Demand / Heat Load
6 U-Value Wall = 0.175 W/(m2K)
U-Value Window = 0.85 W/(m2K) Space Heat Demand [kWh/(m2a)]
2 Heat Load [W/m2]
0 10 20 30 40 50 60
Area South Facing Windows [m2]
Climate Data for the Determination of Passive House Heat Loads in Northwest Europe.
Source: J. Schnieders, Passivhaus Institut.
should be avoided by careful throughout the year or during winter
consideration of shading devices, if a solar water heating system is used
provision of openings for natural during summer.
ventilation in combination with thermal
mass inside the dwelling (exposed Each of these items is dealt with
concrete floor; masonry wall, etc.). In separately in greater detail below.
some cases the mechanical ventilation
Given the lengths to which the designer No more than 0.6 air changes/hour at 50 Pascal
system could be used to distribute fresh pressure should be observed in accordance with the
and builder go to in terms of ensuring a
air throughout the building by switching Passivhaus Standard. This should be checked for
highly insulated building envelope, compliance with a blowerdoor test which will
to a ‘summer bypass’ setting. This immediately highlight leaky areas. Air-tightness can be
excellent air-tightness and minimal
however should be avoided where achieved through the use of membranes, roofing felts
thermal bridging, it is important that the and plasters combined with sealants and vapour
possible as the ventilation system will
building services in a passive house are diffusing resistant materials.
consume electricity resulting in Source: UCD Energy Research Group.
as energy efficient as possible. This is
increased primary energy. The dwelling
especially critical in the case of the
designer should employ ‘passive’ cooling
mechanical ventilation heat recovery
strategies to minimise overheating.
system. Therefore, the required
2.2.2 Passive House Building efficiency of the mechanical ventilation Deep roof overhang shades
Systems system with heat recovery for a passive
house dwelling is 75%. It is also very
As explained earlier a passive house
important to consider comfort, health
does not need a conventional space
and safety issues in the design of the
heating system of radiators or
building services for a passive house,
underfloor heating to maintain a
ensuring for example that the back-up Balcony shades
comfortable indoor climate. Instead, downstairs windows
heating system is adequately sized to
typically, the following building services
deal with extreme weather conditions;
are required in a passive house:
that filters in the ventilation equipment Location of overhang and balcony.
are replaced regularly and that there is a Source: MosArt Architecture.
• Mechanical ventilation system with
heat recovery which provides most of fresh air supply for any combustion
the space heat requirement. devices such as a boiler. These and other
issues are dealt with in greater detail
• Back-up system capable of heating below.
the air passing through the dwelling
via mechanical ventilation. Typical Mechanical Heat Recovery Ventilation
fuel sources for the back-up system (MHRV)
include biomass, gas, and in some An airtight house requires a well-
instances electricity (for example designed mechanical ventilation system
‘green electricity’ from renewable to provide good indoor air quality. A
sources). Since the demand for space passive house is ventilated using a
heating in a passive house dwelling is mechanical system which incorporates
very low, the back-up system is used air to air heat recovery (mechanical
Lighting contributes towards internal heat gains.
to provide hot water, either ventilation heat recovery, or MVHR). Source: MosArt Architecture.
Photo depicting how the low winter sun enters the
room below the overhang/awning/balcony.
Source: MosArt Architecture.
Graph depicting how mechanical ventilation ensures a good indoor air quality by removing the high concentrations
of tracer gas that were inserted into the house under test conditions. Source: UCD Energy Research Group.
Exhaust air is extracted from rooms that space heating that may be required in a
typically produce heat, moisture and passive house. The aim is to use the
unwanted smells such as kitchens and warm exhaust air to raise the temper-
bathrooms. Before this air is expelled to ature of the cool fresh air to provide for
the outside it passes through a heat thermal comfort all around the house.
exchanger where the heat is transferred On a night where outside temperatures
to the incoming fresh air, thereby are below freezing, the fresh air should
eliminating the need to completely heat be raised to, for example, 18oC, having
the fresh air as it enters the building. It is passed through the MVHR. The
important to highlight that the stale efficiency of sensible heat recovery
exhaust air and clean fresh air do not mix should exceed 75% for the nominal
Photo depicting how the house is shaded from the high
in the heat exchanger and therefore range of flow rates specified for the unit
summer sun by the overhang/awning/balcony. there is no risk whatsoever of what when measured in terms of the supply-
Source: MosArt Architecture. might be referred to as ‘sick building air side temperature ratio as described in
syndrome’. Rather, the stale air and clean EN 13141-7:2004.1 Specifiers and
air is channelled through closely spaced designers should be wary of products
but separate narrow sleeves in the core claiming extraordinary efficiency rates of
of the heat exchanger. 95% or higher. The safest route is to
install equipment that has been
The benefits of having a whole-house
independently tested and verified by
mechanical heat recovery ventilation
such bodies as the Passivhaus Institute.
system (MHRV) are many, including:
• Constant supply of the correct The graph above is based on actual
amount of fresh air to all habitable testing of the first Irish passive house in
rooms thereby reducing CO2 levels Wicklow. It illustrates, for example, how
and removing the cause of stuffiness mechanical ventilation ensures good
and tiredness. indoor air quality by removing the high
• Simultaneous extraction of moisture- concentrations of a tracer gas that was
Schematic of the supply air ducts, the extract air ducts laden air from bathrooms, utility deliberately released into the house as
and the heat exchanger within mechanically part of the test procedure. In less than
rooms and kitchens as well as
ventilated house. Source: Passivhaus Institut.
ventilating noxious gases and 1.5 hours the air quality in the house had
unwanted smells if present. returned to normal.
• A lowering in humidity levels
Recommended Ventilation Rate
reducing mould and fungus that may
According to the Passivhaus Institut, the
appear over time and decreasing
appropriate air change rate for dwellings
dust mite levels.
is between 0.3 and 0.4 times the volume
System Efficiency of the building per hour, with a general
The efficiency of the heat exchanger in recommendation of leaning toward the
the MHRV determines the amount of lower rate. This maintains high indoor air
heat that can be recovered from the quality while ensuring a comfortable
exhaust air and, therefore, has a very level of humidity and maximizing
The sommer-bypass can be used for cooling in the
summer if needed. Source: MosArt Architecture. significant influence on the additional energy savings.
The PHPP software suggests that 30m3 Winter and Summer Mode
per person per hour should be provided There are generally two ventilation
to dwellings to ensure good air quality. modes in a passive house: Summer
These two measurements can be used to Mode and Winter Mode. In winter, the
choose an appropriately sized machine MHRV uses the heat in the exhausted air
for different dwelling designs. Taking the to warm the incoming fresh air. In
prototype house presented later in summer, a bypass in the equipment can
Section 3 as an example, an occupancy be set to open automatically (controlled
of 5 persons would require 150m3 of by thermostats) such that the incoming
fresh air delivered to the house per hour. fresh air is not heated. Alternatively in
In terms of extract, the PHPP software summer natural cross ventilation may be
uses the following rates for different used and the MHRV system can be
room types as default values, kitchen = switched off.
60m3h, bathroom = 40m3h, shower =
20m3h and WC = 20m3h. In the prototype Insulation and Positioning of Duct Work
house these total 140 m3h which is close and Vents
to the supply volume which will ensure Iit is very important to adequately
that the whole house system will be insulate the supply air ducting so that
balanced. The supply and extract there is minimal loss of temperature in
volumes can be accurately set by using a delivering warm air around the house.
The thickness of insulation generally A pellet stove is at the hearth of an Irish passive house.
digital anemometer and adjusting the Source: MosArt Architecture.
valves on the vents in each room as used in passive houses is between 6cm
required. and 10cm for ductwork. It is also
preferable to locate the ducting within
Adjustment of Fan Speed and Exchange the thermal envelope and to keep pipe
Rate runs as short as possible by ideally
Most MVHR machines have different positioning the MVHR unit in the centre
settings for different circumstances. of the house. This requires careful
These are often referred to as a ‘party’ planning at a very early stage of building
setting, where there are a lot of people design.
in the house and where additional fresh
air is required, and ‘holiday’ setting, Vents are normally placed in the ceiling
where the house is being left vacant and but can also be placed in the wall if
the flow of air is reduced. The former of necessary. The air inlets are typically
these settings will use more energy and designed to spread the air horizontally
also decrease the level of humidity across the ceiling, minimizing down-
ward drafts. There should be a gap either The ventilation system can be used in a sealed closet to
whereas the latter will use less energy
dry clothes. Source: MosArt Architecture.
and perhaps lead to an increase in under or over the door of each room to
humidity. enable the easy movement of air from
one room to the next. If doors are fitted
It is not advisable to constantly run the
tight without such a gap, rooms with
equipment on the lower setting just to
exhaust vents would be under negative
save energy when the house is
pressure and rooms with supply air
occupied. MHRV machines uses
under positive pressure.
surprisingly little energy given the
important role that they play in the Noise
passive house. The PHPP software uses Fan and valve noises can be almost
standard value 0.45Wh for every m3 Ceiling air supply vent.
completely eliminated by sound control Source: MosArt Architecture.
transported air software in the measures (e.g. vibration isolation
calculation of electricity due to MHRV. mounts, low air speed and acoustic
When designing a passive house in lining in ducts). The grilles on vents
Ireland the specific fan power should be generally guide incoming air along the
carefully considered as the electricity ceiling from where it uniformly diffuses
consumed for fans has direct impact in throughout the room at velocities that
terms of primary energy performance are barely perceptible. If the ventilation
and energy labelling, the Building equipment is operating on a high
Energy Rating (BER), recently introduced setting (‘Party Mode’) the noise of the
to Ireland. Therefore, specific fan power equipment and the air flow may be more
for fans should be less than 1w/l/s. noticeable. MVHR machines are Supply air ducts should be well insulated.
generally housed in a well insulated Source: MosArt Architecture.
casing and noise should not be a critical ventilation system. This section of the
issue. guidelines will provide an overview of
the typical back-up heating systems
Maintaining Good Air Quality
used in passive houses to provide
It is important that attention is paid to
thermal comfort .
regular replacement of air-filters for both
incoming and exhaust air. Filters are Space heating demand in a passive
used not only to provide clean air for the house is typically met through passive
occupants but also to ensure that the solar gains (40–60%), internal heat gains
Used air filter.
Source: MosArt Architecture. heat exchanger is not clogged with dust (20–30%) and the remainder (10–40%)
and other matter. If the filters are not needs to be provided from building
regularly replaced (for example every six systems.
to twelve months) and they themselves
The PHPP software will accurately
become clogged with dirt the MHRV will
predict the following two measure-
have to work harder to provide the same
ments for each passive house design:
volume of air to the house, thereby
increasing the speeds of the fans and, • Annual Space Heat Requirement -
ultimately, using more energy. In this measures the amount of energy
countries where this system is relatively that is needed to maintain a
new, occupants may not be aware of this comfortable indoor temperature,
What a clean filter looks like. maintenance need and indoor air quality specified in kilowatt hours per square
Source: MosArt Architecture.
may suffer as a consequence. Equipment metre of treated floor area per year,
differs with respect to the types of filters or kWh/(m2year).
used, some have to be replaced while
• Heat Load - this measures the
others can be washed and reused.
capacity of the space heating system
Sometimes the extractor hood in the required to maintain comfortable
kitchen is connected to the MHRV indoor temperatures at any one time,
equipment to extract kitchen smells and specified in Watts per square metre of
to use the waste heat from cooking to treated floor area, or W/m2.
warm the incoming fresh air. In such For the prototype house the annual
instances, it is very important that the space heat requirement is
hood is fitted with a high quality filter 15kWh/(m2year) equating to approx-
that can easily be cleaned or replaced in imately 1,650 KWh over an entire year
order to prevent the built up of grease in (the house measures 110m2 in treated
the ducting system which could be a fire floor area). This would equate to 155
Water to air heat exchanger unit. hazard. litres/year of oil, 160m3/year of mains gas
Source: MosArt Architecture.
What happens in the event of a power or 350kg/year of wood pellets (in bags)
failure? at a cost of approximately €92/year
If there is a loss of electricity (and the when using oil, €55/year when using gas
dwelling has no back-up generator) the (without standing charges for gas or
ventilation system will stop working and €345/year with standing charges) or
the supply of fresh air will be cut off. If €97/year when using wood pellets. Unit
power is lost for a short while (for price: heating oil 5.62c/kWh; mains gas
example a few hours), then there is likely 3.39c/kWh standing charges €256/year;
to be no noticeable difference in indoor wood pellets - in bags 5.92c/kWh.
air quality. If the loss of power is Source: SEI, Dwelling Energy Assessment
prolonged, the simple solution is to Procedure (DEAP) 2005 edition, version
open the windows and to create natural 2, Manual pp. 84.
cross flow ventilation through the The heat load, on the other hand, is
building. approximately 1,800 W, or just 1.8 kW.
This amount of energy could be
Back-up Heating System
provided by a very small stove / heater /
As previously highlighted in these
boiler compared to what might be
guidelines, space heating requirement
typically required in a family home.
in a passive house is so low that there is
no need for a traditional space heating The most common method of 'heating'
system. The optimal way to transfer the in a passive house is by post-heating the
Compact unit including ventilation heat recovery and small amount of required heat through- fresh air after it has already been
air to water heat pump. Source: Drexel und Weiss. out the house is through the mechanical warmed by the exhaust air in the MVHR.
There are a number of ways in which the
temperature of the air can be boosted,
including those listed below:
• Water to air heat exchanger.
• Compact unit with electrical heat
• Compact unit with natural gas.
The first two of these is explored in
outline below. The compact unit with
natural gas, while used in Central Europe
is virtually unheard of in Ireland and
would have to be approved for use by
the appropriate authorities.
Water to Air Heat Exchanger
This method involves using a heating
device placed immediately on the fresh
air supply outlet of the MVHR. There is a
small radiator inside this device and it is
heated by hot water connected to the
domestic hot water tank. If the house
needs additional heat (which is
determined by a thermostat) then hot
water is circulated through the device, Schematic of mechanical system that can be used for back-up heating in a passive house.
hence the appropriate title of ‘water to Source: Passivhaus Institut, Germany (http://www.passiv.de).
air heat exchanger’. Once the house has
reached the programmed temperature,
the hot water stops circulating and the
air is no longer heated. The water in the
domestic hot water (DHW) tank is
heated, in turn, by using a number of
energy sources including a stove or
boiler (for a larger house) in combination
with solar hot water panels. The
principle advantage of this system over
the compact unit system described
below is that when fueled by a
combination of firewood and sunshine it
is carbon neutral.
Compact Unit with Electrical Heat Pump
This system is so-named as it
incorporates all of the technology
required for a passive house in a Sunlight amounts for Ireland.
relatively small unit, namely the MVHR, Source: Green Design, Sustainable Building for Ireland, pp. 28.
the DHW and the heating power for the
the most common boiler based systems • Separate and independent auto-
home, in this case powered by an
using a timer and a cylinder thermostat, matic time control of space heating
electrically powered heat pump. It is
sometimes even room thermostats been and hot water;
therefore very suited to smaller homes
absent. New building regulations Part L
where space might be limited for large • Shut down of boiler or other heat
(2005) recommend minimum levels of
tanks, stoves and storage for wood. source when there is no demand for
control, installing equipment to achieve
Compact units are becoming more either space or water heating from
widespread in use in passive houses that source.
built in Central and Northern Europe. • Automatic control of space heating
Additional control features can be
on the basis of room temperature;
Integrated controls for heating in a incorporated to a heating system so the
Passive House • Automatic control of heat input to overall system performance improves.
Heating systems in Ireland have stored hot water on basis of stored One example is the ‘weather com-
traditionally been very simple, perhaps water temperature; pensation’ feature, which is the ability to
adjust the output of the system based Room based temperature controls for will reduce the contribution of the
on the measured external temperature. temperature differentiation between collectors to DHW production. In
The main advantage of using weather different rooms may be necessary if places where there is no south facing
compensation is that the heating system individual comfort requirements are set roof, additional panels over the m2
closely monitors external temperature for different rooms. In a centralised area which might otherwise be
trends and adjusts the output ventilation heating system, however, the needed can be fitted to east or west
accordingly. If, for example, the external supply air temperature is constant for facing roofs.
temperature starts to drop rapidly, the the whole house and this would be
• The optimal tilt of the solar panels to
system can ‘anticipate’ that the dwelling typical for most houses built to the
meet approximately 50% of the
may come under pressure to maintain its Passivhaus Standard.
annual heating demand for DHW is
current internal temperature and can
Domestic Hot Water Production approximately 45 degrees (at a pitch
verify whether there is sufficient power
As in any type of dwelling, the passive greater than 45 degrees the potential
to generate the back-up heat that might
house requires a system that provides annual output is compromised
domestic hot water (DHW). As with somewhat).
The preferred internal temperature can space heating, it is important that the
• There are two types of solar
be set using an internal thermostat. If system is energy efficient, well
collectors typically used in Ireland,
the internal temperature goes below the controlled and has an adequate capacity
flat plate panels and evacuated
thermostat setting, the system will to meet demand. Generally the DHW
tubes. A comparison of the
automatically start to heat the fresh air system in a passive house is combined
performance of these types, based
passing through the ventilation with a heat source such as a wood stove,
on 5m2 collector area, along with
equipment. The principle function of the solar thermal collector, compact unit or
consideration of orientation and
heating control system is to ensure that heat pump for space heating. Most
angle of incidence is provided here.
there is always sufficient heat in the passive house examples encountered
The calculation was developed for
buffer tank to deliver the heat load have utilised solar thermal collectors as
the prototype passive house using
required to maintain the comfort levels they reduce the use of primary energy
the calculation methodology for
set by the occupants. In the case of the and CO2 emissions. It is important to
solar water heating in Dwelling
Out of the Blue house, if there is note, however, that the Passivhaus
Energy Assessment Procedure DEAP
insufficient heat in the buffer tank, and Standard is achievable without solar
2005, version 2.
the solar input can not provide the heat based water heating. The introduction of
demand at that particular time, the Building Energy Rating system as an
Three different inclinations of solar
pellet stove can be ignited automatically indication of the energy performance of
panels (30o, 45o, 60o) and three different
to provide the back-up required. The dwellings in Ireland is likely to increase
orientations were calculated, with the
pellet stove will then cut out when there the installation of solar technology as it
following specification: standard
is sufficient energy available. A similar influences the energy rating of a home,
number of 3.6 occupants according to
control system is found in the Compact and in particular CO2 emissions.
DEAP assumption; water storage tank
Units, except that a heat pump is used Domestic Water Heating - Solar Input 300 lit., with 150 lit. dedicated to solar,
instead of a pellet stove. It is reasonable to expect that an and 50mm factory insulation; with
optimized solar based system (flat plate thermostat control.
The amount of heat delivered to the
of 5–7m2 area or evacuated tubes) will
fresh air by the heat exchanger is • As a general rule of thumb, the area
produce up to 60% of total annual hot
regulated by the internal and external of solar panels is roughly 1 to 2m2 of
water demand the Irish climate and they
temperatures. The control system is collector area per person. The system
have a relatively shorter pay back period
usually set up to deliver a relatively high should be capable of providing up to
when taking into account available
heat load if the temperature outside is 50 litres of DHW per person per day
grants, in comparison to other re-
very cold, or alternatively a low heat load in season.
newable energy technologies such as
if it is not too cold.
wind turbines or photo voltaic panels. In • In terms of sizing a solar tank, a
It would also be possible to use an Ireland the amount of solar irradiation minimum of 80 and preferably 100
‘instantaneous’ system eliminating the received each year is approximately litres storage per m2 of collector
need for a large buffer tank. Such 900–1,150 KWh/m². This is the equival- should be provided. In a typical Irish
systems do not typically suit the use of a ent of close to 100 litres of oil. Many home this could mean installing a
pellet boiler, however, as the boiler people would be surprised to learn that tank of between 300 and 500 litres
would have to switch on and off for Dublin receives the same amount of capacity. It is important to use a
short periods of time to maintain an irradiation as Paris. proper solar water tank which is very
even temperature in the house. well insulated. Insulation of hot water
In terms of specifying a solar collector
pipes is also important for energy
Individual Room Temperature Control system, the following outline guidance
conservation, using at least 1 time
Different rooms may have different should be considered:
and preferably 1.3 times the pipe
temperatures due to solar gains, • The optimal orientation is directly diameter.
occupation and internal heat loads. due south and deviation from this
5 square meters of FLAT PLATE collectors (η0=0.75 and a1=6)
No obstructions: Primary energy, in kWh/year: This
includes delivered energy, plus an
Solar Input kWh/year allowance for the energy “overhead”
Tilt of collector
South SE/SW E/W incurred in extracting, processing and
1264.9 1246.3 1191.2 transporting a fuel or other energy
carrier to the dwelling. For example, in
45O 1264.2 1240.4 1167.9
the case of electricity it takes account
60O 1248.5 1221.3 1137.0 of generation efficiency at power
Solar input to demand ratio stations.
Tilt of collector
South SE/SW E/W Source: SEI, Dwelling Energy Assess-
30O 49% 48% 46% ment Procedure (DEAP), 2005 version
45O 49% 48% 45% 2, pp. 28.
60 48% 47% 44%
5 square meters of EVACUATED TUBE collectors (η0=0.6 and a1=3) Delivered energy, in kWh/year: This
No obstructions: corresponds to the energy con-
Solar Input kWh/year sumption that would normally appear
Tilt of collector on the energy bills of the dwelling for
South SE/SW E/W
the assumed standardised occupancy
30O 1324.3 1300.7 1231.5 and end-uses considered.
45O 1323.4 1293.2 1202.5
Source: SEI, Dwelling Energy Assess-
60 1303.4 1269.1 1164.4 ment Procedure (DEAP), 2005 version
Solar input to demand ratio 2, pp. 28.
Tilt of collector
South SE/SW E/W
30 51% 50% 48%
45O 51% 50% 47%
60O 50% 49% 45%
Domestic solar water heating - solar input (flat plate collectors and evacuated tube) for the prototype passive house
(described in Section 3), calculated with the Dwelling Energy Assessment Procedure DEAP 2005 version 2.
Source: UCD Energy Research Group.
The 40% or more of DHW needs that are appropriately to the heat load of the cannot generally be used for whole
not provided by solar energy can be met house. This will be defined by the house heating.
by several means including biomass ‘Verification page’ in the PHPP
boilers or stoves, immersion heaters or software. Taking the prototype house • Wood (whether logs, chipped or in
natural gas. An outline of the first of presented in these guidelines, a stove pellets) is bulky and a considerable
these is provided below. It must be of 3kW output would be sufficient for volume is required for storage
remembered that space heating in a all space heating and DHW needs. especially if it is purchased in bulk to
passive house is often provided by using keep costs to a minimum.
hot water to heat the air passing • A combustion air supply must be
provided to any stove or boiler in a • Most wood stoves are highly efficient
through the ventilation system. In such
passive house bearing in mind the (up to 90%) and when burning
cases, hot water production is essential
level of airtightness that has to be pellets there is very little ash
in the heating season when solar panels
achieved. The provisions of an air remaining following combustion. A
on the roof will not be sufficient to meet
supply and flue for stoves or boilers flue will be required to take exhaust
the demand for heating the hot water.
will generally not adversely impact gas emissions safely away from the
Accordingly, many passive houses will
on airtightness or the balancing of house, as with any typical stove.
have a biomass stove burning either
natural logs or wood chip or pellets. The ventilation flows due to the 'closed'
Electricity Consumption in a Passive
advantage of the latter two of these is nature of their construction. Air
that they are more easily automated so required for combustion is drawn in
The Passivhaus Standard primary energy
that they fire up and switch off in the through a relatively small diameter
requirement has a limit of 120 kWh/(m2
same way as a conventional gas or oil duct and expelled through the flue.
year), regardless of energy source for all
burner. • A stove or boiler that directs most of space and water heating, ventilation,
The following issues should be the heat output to the DHW tank is electricity for fans and pumps,
remembered when considering essential if the hot water is to be used household appliances, and lighting
installing a wood stove or boiler: to heat the ventilation air. A model energy requirements of the house. This
that simply radiates all the heat into limit means that in a passive house the
• The equipment must be sized the space in which it is located efficiency of household appliances and
all electrical systems is crucial to meet of course highly dependent upon the requires some training prior to
this challenging requirement. This is validity of the data entered. embarking on practical application to a
emphasised with the fact that the real project. However, the software is
Some of the principle datasheets
primary energy factor for electricity also quite user friendly and the
included in the software are listed
taken in the PHPP software (as well as in Verification page enables the user to
below, along with their main functions:
the DEAP, Dwelling Energy Assessment check whether or not such thresholds
Procedure) is 2.7. Therefore 1kWh • Climate data - it is possible to choose such as Space Heating Requirement are
electricity used in a passive house the climate which the passive house met. In the event that the key Passivhaus
accounts for 2.7kWh of the primary is being designed for which has a Standard criteria are not met, for
energy. significant impact on the U-values example, the assessor will firstly have to
required to achieve the threshold check to see if there are any funda-
When designing a passive house, the
annual heat requirement. mental errors in terms of data entry. If
PHPP software is used to calculate the
this is not the cause of the problem, then
electricity balance. The first step is to • Verification - this sheet collates the the building will likely have to be
calculate the electricity requirement in results of the overall evaluation of the modified in order to achieve the
the house including all household building including the Space Heating required standards. This will typically
appliances and lighting. In order to Requirement, Specific Primary involve improving the U-values of the
achieve the Passivhaus Standard it is Energy Requirement, Heat Load and building envelope, or altering the
necessary to specify refrigerators, Frequency of Overheating. The user proportion and orientation of glazing.
freezers, cookers, artificial lighting, can see at a glance on this sheet
washing machines, dryers, etc. with the whether or not the building can be Extracts from the PHPP software are
highest energy efficiency available on certified as a Passive House. included later in Section 3 pertaining to
the market (i.e. category ‘A’ energy rated the prototype passive houses.
household appliances). The second step • U-value - this sheet enables the
is calculating the auxiliary electricity assessor to specify the construction 2.3.2 Passive House Certification
requirement, in which electricity of all the opaque (i.e. does not
At the time of writing these Guidelines, a
consumption is specified for mechanical include windows) elements of the
passive house in Ireland can be certified
ventilation system fans and controls, building envelope for the purposes
by the Passivhaus Institut in Darmstad,
DHW circulation pumps, and any other of calculating the U-value of those
Germany (http://www.passiv.de) or
present in the dwelling. Calculation elements. The sheet requires the
certifying body approved by the
results are presented in primary energy input of the lambda value of the
Passivhaus Institut. For further infor-
kWh/(m2year) and included in the PHPP building materials proposed as well
mation on certification of passive
‘Verification page’. as their thicknesses and the
houses in Ireland contact the SEI
proportion of insulation occupied by
2.3 Energy Balance Renewable Energy Information Office or
Calculations and Passive the Passivhaus Institut directly. The
House Specification • Windows - the orientation and size of evaluation criteria for the certification
all windows is entered into this sheet, (Source: PHPP 2007, pp.23) is:
2.3.1 PHPP Software and
along with the U-values of the glass - Specific Space Heat Demand
and frames as well as other technical max. 15kWh/(m2year)
An introduction to the Passivhaus specifications which have discussed - Pressurisation Test Result n50
Planning Package (PHPP) was provided earlier in this chapter. max. 0.6ac/h
at the beginning of this chapter within a
• Annual Heat Requirement - this value - Entire Specific Primary Energy
discussion of the building design
is calculated by subtracting the heat Demand max. 120kWh/(m2year)
process for passive houses. PHPP is a
losses through transmission and including domestic electricity.
software package based on a series of
elaborate and interlinked Excel data ventilation from the total solar and The above criteria have to be verified
sheets which collectively allow building internal heat gains. The Annual Heat with the Passive House Planning
designs to be verified against the Requirement must be less than Package 2007 and the required list of
Passivhaus Standard. The latest version 15kWh/(m2year). documentation for the passive house
of the PHPP software can be purchased • Heat Load - the building's heat load is quality approval certificate, construction
for a nominal fee from SEI Renewable based on energy balance calculations drawings and technical specification
Energy Information Office. The estimated by subtracting the with product data sheets, must be
verification requires the input of very minimum solar gains and internal submitted to the certifying party
specific and detailed data about the heat sources from the maximum (including PHPP calculations). Also,
design, materials and components into transmission and ventilation heat verification of the airtight building
the PHPP spreadsheets and is then losses. envelope according to DIN EN 13829, a
related to the climate data for the region record of adjustment of the ventilation
in which the house would be built. The The PHPP software is very com- system, declaration of the construction
validity of the result from this process is prehensive and detailed and therefore supervisor and photographs of the
complete building must also be occupants. Also, an approach to
submitted. Upon examination of certification of products and tech-
received documentation the applicant nologies used in passive house designs
receives the results of the examination has been developed. (Source: PEP
from the certifying party. Promotion of European Passive Houses,
passive house building certification,
A wider European passive house
certification scheme has been
developed within the Intelligent Energy Lifestyle Issues
Europe project (2005–2007) “Promotion It is a very common misconception that
of European Passive Houses, PEP” windows cannot be opened in a passive
(http://www.europeanpassivehouses. house. They can indeed be opened but
org). This certification scheme is they don’t have to be opened. In a
applicable to ‘an emerging market passive house the ventilation system
scenario’ (i.e. countries with a small ensures that a constant controlled
number of passive house buildings), amount of fresh air is circulated around
aims to ensure that the design of a the house so a stuffy or uncomfortable
particular passive house can deliver the atmosphere is avoided. If the occupants
specific energy requirements in would prefer to have the windows open
accordance with the Passive House at night or provide natural cross
Planning Package (PHPP) and confirm ventilation during a hot summer’s day Passivhaus Institut Certificate example, Quality
the air-tightness of the completed then it is entirely possible to open Approved Passive House.
Source: Passivhaus Institut, Germany.
building. This certification scheme whatever windows or doors one
involves the verification of the ‘as built’ chooses. The MVHR should be switched
design (i.e. that reflects the actual off if there are a lot of windows or doors
construction, incorporating any being left open as it would be an
modifications made during con- unnecessary waste of electrical energy.
struction) in accordance with the Passive
Living in a passive house encourages a
House Planning Package (PHPP) and
greater interest in and awareness of
confirmation of the air-tightness of the
weather patterns and the impact they
completed building by a fan
have (or don’t have) on indoor climate.
pressurization test performed in
The passing of cloud cover brings with it
accordance with EN 13829.
instant brightness and rising tem-
Since the above assessment criteria peratures on the display panel for the
apply to the ‘as built’ design details and solar collectors. A very hard frost will
the completed building, there is a sometimes leave a veil of ice crystals on
significant risk that any non compliances the outside pane of the glazing which
due to fundamental errors will be rapidly melts in the morning sunshine.
difficult to correct when the building is Extremely cold clear weather usually
complete. It is therefore recommended means that the back-up heating is not
that the design is checked against the required during the day due to the high
PHPP before construction is started to levels of solar irradiation available. Dull
confirm that the criteria for the specific muggy days, on the other hand, while
heating and primary energy require- not especially cold, may well require the
ments are met; the construction on site use of the pellet stove due to the lack of
should be checked to ensure that the sunlight. Windows may have to be flung
dwelling design has been realised; air open to cool the house on New Years Eve
permeability measurements are night depending on how many friends
recorded during the construction and neighbours you manage to attract
process so that air leakage problems can to join the celebrations!
be identified and remedied while access
As an illustration of the indoor
to the air-tightness membranes etc is
temperature comfort,2 monitoring
results of the room temperatures in the
Since the actual performance of the passive house in Wicklow and site
building is very dependent on the measured temperature is shown on
correct operation and maintenance by page 26. The graph represents measured
the occupant, it is recommended that average indoor and outdoor tem-
adequate written information and peratures from January 2006 to
instructions are provided to the November 2007.
Januray 2006 - November 2007 OUT OF THE BLUE TEMPERATURES
20 Bathroom Down
10 External Temperature
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average daily temperatures, January 2006 – November 2007, monitoring results for the first passive house in Wicklow. Source: UCD Energy Research Group.
The above diagram illustrates just 2kW. As a result, those rooms on
temperature variation in different parts the northern side of the house were
of the house and cooler average below thermal comfort levels for the
temperatures in the first heating season first few months of 2006. This went
(early 2006) compared to the second largely unnoticed by the family due
and third heating seasons (late 2006/ to the fact that the rooms in question
early 2007 and late 2007 respectively). are not used.
The reasons for these variations are
• In the autumn of 2006, a water-to-air
interesting and warrant some
heat exchanger was fitted to the
MVHR equipment which enabled
• The three coolest rooms (‘office’, heating the fresh air as it passes
‘garage’ and ‘bathroom down’) are throughout the house. This was
each on the north side of the actively used for the first time in
building, receive no direct sunlight December 2006 which resulted in
during the winter months and are raising the temperatures in all rooms
You can open windows and doors in passive houses! very infrequently used compared to (even those three on the north side)
Source: MosArt Architecture. the remainder of the house. The first to well within the normal comfort
two of these spaces have three level. In late 2007 the temperatures
external walls and so are more prone have improved yet again.
to heat losses compared with the rest
• There is still in evidence a
of the house.
temperature gradient (increasing in
• The three warmest rooms (‘kitchen’, temperature) from north to south
‘main bedroom’ and ‘stairs’) all open and from first floor to ground floor.
out to the south of the house and so
The specification of materials and very
receive the maximum amount of
high quality build creates a strong sense
solar gain in winter. Furthermore,
of living in a well-built house that will
they are occupied for significant
last the test of time. The heavy doors and
parts of the day and / or night.
windows close with a reassuringly solid
• In the first few months of 2006, the ‘clunk’ and keep out draughts and
only back-up heat source in the reduce external noise. The walls are thick
house was a pellet boiler in the and substantial and are packed full of
sitting room. This alone was insulation to keep out the cold and the
insufficient to heat the entire house heat in. There is no condensation on the
Comfort levels all year round in a passive house.
Source: MosArt Architecture. as its direct output into the room is internal glazing early on a cold morning.
The health aspects of living in a
mechanically ventilated house are also References
readily apparent, with no lingering Passive House Planning Package 2007,
odours, little or no condensation in “Protokolband 16: Waermedruecken-
washrooms after showering and an freis Konstruiren (Thermal Bridge-Free
overall sense of high indoor air quality Construction)”, pp.96. PHPP 2007
throughout. Changing the filters on the Technical Information PHI-2007/1(E),
ventilation system is always an eye Passive House Institute, Dr. Wolfgang
opener - seeing what dust and dirt is Feist.
taken out of the incoming air and what is Passive House Planning Package 2007,
extracted from the indoor air. “Certification of Passive Houses”, pp.28.
Passive houses provide a stable environment for house PHPP 2007 Technical Information PHI-
Living in a house that has a low carbon plants. Source: MosArt Architecture.
2007/1(E), Passive House Institute, Dr.
footprint can bring about other changes Wolfgang Feist.
in lifestyle that are positive for the 1
EN 13141-7:2004, Ventilation for European Commission (EC), 2006.
environment, including growing your buildings/ performance testing of
“Promotion of European Passive Houses
own food and reducing the impact of components/products for residential
ventilation. Performance testing of a
(PEP)”. [Internet] PEP. Available at:
travel whether by car or by plane. http://www.europeanpassivehouses.or
mechanical supply and exhaust
Raising children in a passive house will g/html
ventilation units (including heat
also bring about positive change for the recovery) for mechanical ventilation
next generation who will expect to Schnieders J. 2006, “Climate Data for
systems intended for single family
dwellings. Determination of Passive House Heat
improve even further on what their
Loads in Northwest Europe”. Darmstadt,
parents achieved. 2
Thermal comfort is defined in British Germany, Passivhaus Institut.
Standard BS EN ISO 7730 as: ‘that
Perhaps the overall lifestyle benefit of condition of mind which expresses
living in a passive house is that it satisfaction with the thermal environ-
provides very high levels of overall ment.’ It is affected by the key environ-
comfort without compromising the mental factors as air temperature,
radiant temperature, air velocity and
environment and at a fraction of the cost humidity.
of living in a so-called ‘normal’ house.
S ECTION T HREE
Passive House Prototype for Application in Ireland
Passive House Prototype for Application in Ireland
This section of the guidelines 3.1.1 Combining Aesthetic and of the prototype passive house.
demonstrates the practical application Energy Performance in House
3.1.2 Decision Support using Passive
of Passivhaus Standard to a prototype Design
House Planning Package (PHPP)
house designed especially for this
The design of a passive house is strongly Software
project and suitable for the mass
influenced by the need to minimise heat
housing in Ireland. The house type The Passive House Planning Package
loss through the building fabric, to
demonstrated is a semi-detached two (PHPP v2004) has been introduced
maximise solar gains and to cater for the
storey house with a floor area of already in these guidelines. It is an Excel-
various building services. Form and
approximately 110m2. The house is based software that can be used to ‘test’
function played equal roles in the design
depicted in plan and elevation below. the energy performance of a building as
of the prototype passive house. The
The house is typical in most aspects of its it is being designed. It includes Irish
overriding principle used in the design
design, comprising three bedrooms climatic data which is very useful in
of the prototype house was that it
upstairs (including one ensuite and ensuring that buildings are not over-
should be broadly similar in character to
family bathroom) and a living room, specified in terms of thermal per-
contemporary housing, thus maximising
dining room, kitchen/utility and formance. Key aspects of the emerging
ease of acceptance to the current
wheelchair accessible WC down-stairs. prototype passive house were entered
housing market in Ireland.
There are also some non-conventional into the software with a view to ensuring
elements included, including a double- As has been described in some detail in that the design achieved the minimum
height sun room, solar panels, pellet the preceding sections, much of the requirements of (a) yearly space heating
boiler and shading pergola. These are all ‘free’ energy required to heat a passive delivered energy demand of 15 kWh/m2
described in greater detail below. house comes directly from the winter treated floor area (TFA3), and (b) upper
sun through south facing windows. It is limit for total primary energy demand
The final part of this section examines
therefore typical (though not essential) for space and water heating, ventilation,
the capital construction costs associated
to have a bias in terms of placement of electricity for fans and pumps, house-
with the passive house.
glazing on the southern elevation. hold appliances, and artificial lighting
3.1 Design and Specification Combined with such glazing is the need not exceeding 120kWh/(m2year), regard-
to prevent overheating in summer and less of energy source.
The two most common residential
this is easily ensured through the use of
construction methods in Ireland were The thickness of insulation required in
shading, in this case with a balcony and
used in the design and specification of the walls, floor and roof is strongly
pergola. The walls of a passive house are
the prototype passive house, namely guided by the PHPP software, as is the
typically thicker than those of
timber frame1,2 and masonry. It is specification and positioning of the
conventional construction due to the
demonstrated below that the Passivhaus windows, the sizing of the back-up
need for additional insulation and this
Standard can be easily achieved in space heating system, the consideration
must be borne in mind in the early
Ireland using both of these construction of thermal bridges and many other
stages of design development. The other
methods and that there are no major aspects of the design. The design is thus
key issue to consider when developing
advantages of one method over another an iterative process. Different insulation
the design of a passive house is the need
in terms of thermal performance. Both types can be tested in the software, with
to minimise thermal bridges including
passive house construction types can be higher performance materials (in terms
that created between the foundation
built using mostly conventional of lower Lambda values) requiring
and internal walls, for example. Bearing
elements as can be seen from the thinner walls than other less efficient
in mind the above principles of glazing
detailed wall sections provided in materials.
orientation, wall thickness and
minimised thermal bridging, the Two extracts from the PHPP software are
designers commenced the development included below in order to give an
insight into how the software can be details a timber frame wall with an intended to be diagram only. They
used to assist the designer. Passive insulated service cavity and the third should not be used as a basis for
House Verification Sheet deals with table illustrates the depth of insulation detailed construction drawings.
annual heat requirement based on a required in the roof. The partial thermal
The following key issues can be noted
balance of heat losses (transmission and bridge caused by the timber studs is
from the detailed wall sections:
ventilation) pitched against heat gains taken into account in the software by
(solar and internal) in order to calculating the proportion of the • Thicker than normal wall sections are
summarise the Annual Heat Require- insulated wall occupied by timber (in designed in order to accommodate
ment. The annual space heat require- this case 10%). the required depth of insulation.
ment of 15kWh/m2 is achieved. There is also substantial insulation in
3.1.3 Prototype Passive House both the roof and under the floor.
The second illustration provides an
External Wall Sections
insight into how the U-values of major • The insulation at the junction of roof
building elements are calculated. The The wall sections for both construction and wall, as well as wall and floor,
first table provides details on how a U- types are illustrated also. It should be overlap in order to minimise therma
value of 0.15W/(m2K) is achieved for a noted that no dimensions are included l bridging at these critical locations.
concrete cavity wall, the second table on the sections below as they are The window frame is also partly
Passive House Verification for the prototype passive house, concrete block construction.
Source: MosArt Architecture.
bedded in insulation in order to • Blockwork with a low thermal
reduce heat loss. conductivity is used in the rising
walls to reduce thermal bridging
• Membranes and specialist tapes are
between foundations and walls.
used to create an airtight envelope.
This is especially critical at junctions
between different elements, such as
around windows, and also where the
first floor penetrates the external wall
• A service cavity is proposed, internal
to the airtight layer in the timber
frame wall, in order to accommodate
mechanical and electrical fittings. A
similar cavity is proposed in the
underside of the ceiling at first floor IFC, Insulated Concrete Forms. Externally insulated concrete block wall.
level for both house types. Source: UCD Energy Research Group. Source: MosArt Architecture.
Passive House Verification for the prototype passive house, timber frame construction.
Source: MosArt Architecture.
U-value of building elements for the prototype passive house, concrete block construction. Source: MosArt Architecture.
U-value of building elements for the prototype passive house, timber frame construction. Source: MosArt Architecture.
3.1.4 Prototype Passive House charges €256/year; wood pellets - in heat exchanger. In this regard, all
Design including Mechanical bags 5.92c/kWh. Source: SEI, Dwelling supply air ducts should be insulated
and Electrical Services Energy Assessment Procedure (DEAP) in order to minimise heat losses, even
2005 edition, version 2, Manual pp. 84. if they are located within the thermal
The final design of the prototype passive
house is presented below in plan, The heat load, on the other hand, is
elevation, section and, finally, a 3D approximately 1,800 W, or just 1.8 kW. • Solar panels (measuring 7.5m2) are
model. A number of mechanical and This amount of energy could be positioned on the south facing roof
electrical features are highlighted which provided by a very small stove/ which is pitched at the optimal angle
have been included specifically in the heater/boiler compared to what of 45 degrees. These have been sized
development of the passive house might be typically required in a in accordance with the needs of such
prototype: family home (there are several such a house and could include either flat
‘small’ boilers on the market which plate collectors or evacuated tubes.
• In terms of mechanical ventilation, an
average air flow rate of range in output from 2.4 to 8kW, with Other aspects of the design which are
approximately 115m3/h would be approximate efficiency of 90%). The not related to the mechanical or
required providing an approximately pellet stove in the prototype house electrical services are listed below:
air change of 0.4 per hour. A fresh air has been positioned in the sitting
room, but space has also been left in • All windows in the prototype house
outlet is provided to the living room,
the utility room as this might be are triple glazed with low emissivity
dining room, double height sun
preferable for users. The pellet stove coating, thermally broken frames and
room (at ground floor level) and
can be filled manually as the need gaskets especially designed to
bedrooms whereas an extract vent is
arises, or could be automatically fed minimise air infiltration. A passive
provided in WC’s and bathrooms as
using an underground pellet storage house triple glazed window is
well as the kitchen, the utility room
‘bunker’ located underground to the typically four times more energy
and the upper part of the sun room.
public road side of the house for ease efficient than a standard double
The mechanical ventilation with heat
of delivery. While a house of this size glazed unit and, if south facing, will
recovery unit is located in the utility
could probably manage without an take in more energy in a year than it
room and will recover the majority of
automatic feed from a bunker (given lets out. The use of such glazing
the heat from the extracted air to
an average use of approximately ensures high thermal comfort in cold
warm the incoming fresh air. An
15kg of pellets per week), the weather through minimal temper-
airing cupboard is located on the first
advantage of such a system is in the ature difference between internal
floor along with the washing
space saved from having to store glass pane surface and room temper-
machine. This space is connected to
pellets in the house or garden shed. ature.
the ventilation system and can
function as drying cabinet for drying In positioning the pellet stove in the • A balcony is provided at first floor
clothes in the winter. Sound sitting room, there is an aesthetic level, the primary function of which is
attenuators should be used in order benefit to be gained from visibility of to shade the extensive area of glass
to minimise noise travelling along the flames coupled with the delivery on the south elevation. This balcony
ducts and air filters should be of some heat directly into the sitting can be accessed via the gallery which
changed as required in order not to room. Care must be taken to use a overlooks the double-height sun
compromise indoor airflows and / or stove that delivers most of the heat room. A wooden pergola is provided
air quality. output to the hot water tank and not overhead the balcony to shade the
directly into the room in which it is upper story windows. A possible
• A pellet stove is proposed for the located. It is also critically important alternative to this pergola could be a
back-up space and water heating that the pellet stove has its own fresh deep roof overhang but the steep-
system.4 For the prototype house the air supply, given the airtight nature of ness of the pitch in the prototype
annual space heat requirement is the construction, and that an house would mean that this latter
15kWh/(m2year) equating to approx- appropriate flue for venting of solution would restrict high level
imately 1,650 KWh over an entire year exhaust gases is provided. Such views from the upper storey.
(the house measures 110m2 in systems are common place in passive
treated floor area). This would equate houses and will not adversely affect • The internal party walls can be
to 155 litres/year of oil, 160 m3/year of the balanced ventilation system. constructed as per a conventional
mains gas or 350kg/year of wood house as long as it is within the
pellets (in bags) at a cost of • The domestic hot water tank (550 boundaries of the building envelope.
approximately €92/year when using litre)5 is located adjacent to the
• The hatch to the attic should be very
oil, €55/year when using gas (without mechanical ventilation unit, in the
well insulated and completely
standing charges for gas or utility room. The back-up heating
airtight to minimise cold air
€345/year with standing charges) or system, in this case, is provided by
€97/year when using wood pellets. heating the fresh air circulating
Unit price: heating oil 5.62c/kWh; around the house by the hot water in • Ceiling insulation is placed
mains gas 3.39c/kWh standing the ‘buffer’ tank using a water to air horizontally on the attic floor in the
prototype passive house. It would efficient light bulbs and household
also be possible to place this appliances. Included in their analysis Approximately 17% of houses built in
Ireland are semi-detached.
insulation between the rafters, albeit was an allowance for the foregone costs
with design and construction associated with ‘conventional’ house According to the Irish Timber Frame
implications. features such as a fireplace and boiler Manufacturers’ Association (ITFMA) the
number of timber frame house
with radiators. Gardiner and Theobald completions has grown from a market
• The timber frame option depicted in
undertook their analysis for both timber share of 15% in 1999 to a market share
these guidelines is ventilated with an
frame and the concrete block of 30% in 2006.
construction methods. 3
The TFA is the living area within the
• Energy efficient light fittings should thermal envelope. Any rooms or areas
be used which use less primary The additional ‘extra over’ cost beyond the boundaries of the thermal
energy (they will also reduce internal associated with building the prototype envelope are not considered.
heat gains). It is also preferable to use house to the Passivhaus Standard was 4
Other sources of heat such as gas or heat
energy efficient appliances. estimated at approximately €25,000 for pumps can also be used.
both construction methods, including 5
Various building methods can be used in Estimated heating requirement for hot
VAT and design fees. Approximately 60% water (incl 50% SWH) + space heating =
the construction of a passive house, of this cost can be attributed towards 3200 kWh = c.650 kg pellets/year =
including, insulated concrete formwork improvement of the building shell 10–15 kg/week.
and externally insulated concrete block (enhanced insulation, higher grade
wall. The prototype house presented in windows, improved airtightness and
this publication illustrates masonry and reduced thermal bridging) with the
timber frame construction as References
remaining 40% covering building
representative of most typically used systems including MVHR, solar thermal Passive House Planning Package, PHPP
building methods for dwellings in system, low energy lighting and wood 2004, Technical Information PHI-
Ireland. pellet boiler. 2004/1(E). Darmstadt, Germany.
Passive House Institute, Dr. Wolfgang
3.2 Cost Considerations Feist.
Gardiner and Theobald next sought to
An analysis of additional costs express the additional passive house
associated with construction of the costs as a proportion of conventional
prototype house to the Passivhaus construction costs. The cost of a
Standard was carried out by Gardiner conventional house varies considerably
and Theobald Cost Consultants. The according to the quality of finishes
additional cost of the key items required. An average cost of €196,000
including enhanced insulation, glazing, was proposed as representing a mid-
airtightness and thermal bridging was grade finish, including VAT and design
estimated, along with the cost of such fees. The additional cost of €25,000 thus
technologies as MVHR, solar panels for represents approximately 12.5% of
DHW, a pellet stove as well as energy current conventional costs.
Prototype passive house, front, back and side elevations (not to scale). Source: MosArt Architecture
Prototype passive house, 3D model (not to scale). Source: MosArt Architecture
Sustainable Energy Ireland
Renewable Energy Information Office
T. +353 23 42193 email@example.com
F. +353 23 54165 www.sei.ie
SEI is funded by the Irish Government under the
National Development Plan 2007 - 2013 with
programmes part financed by the European Union.