Passive house
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{{For|passive solar houses|passive solar building design}}
[[Image:Passivhaus Darmstadt Kranichstein Fruehling 2006.JPG|thumb|300px|One of the original Passive Houses at [[Darmstadt]], [[Germany]]]]
[[Image:Passivhaus Darmstadt Kranichstein Schnee 2005 Feb.jpg|thumb|300px|One of the original Passive Houses at Darmstadt]]
The term '''passive house''' ('''''Passivhaus''''' in [[Germany|German]]) refers to the rigorous, voluntary, Passivhaus standard for energy use in buildings. It results in [[Low-energy house|ultra-low energy building]]s that require little energy for space heating or cooling.<ref>[http://www.passivhaustagung.de/Passive_House_E/passivehouse_definition.html Definition of Passive House]</ref> A similar standard, ''MINERGIE-P'', is used in [[Switzerland]] <ref> [http://www.minergie.ch/fr/index.php?standards-6 Minergie-Standard] </ref>. The standard is not confined only to houses. Several [[office building]]s, [[school]]s, [[kindergarten]]s and a [[supermarket]] have also been constructed to the standard. Passive design is not the attachment or supplement of architectural design, but an integrated design process with the architectural design.<ref name="plainiotis">Ji Yan and Plainiotis Stellios (2006): Design for Sustainability. Beijing: China Architecture and Building Press. ISBN 7-112-08390-7</ref> Although it is mostly applied to new buildings, it has also been used for refurbishments.
The first Passivhaus buildings were built in [[Darmstadt]], [[Germany]], in 1990, and occupied the following year. In September 1996 the ''Passivhaus-Institut'' was founded in Darmstadt to promote and control the standard. Since then, more than 6,000 Passivhaus buildings have been constructed in Europe,<ref>[http://www.passivhaustagung.de/elfte/english/01_start_home.html Passive House Conference]</ref> most of them in Germany and [[Austria]], with others in various countries world-wide. In North America the first Passivhaus was built in Urbana, Illinois in 2003, <ref>[http://www.e-colab.org/ecolab/SmithHouse.html First US Passive House]</ref> and the first to be [[Product certification|certified]] was built at [[Waldsee (camp)|Waldsee]], [[Minnesota]], in 2006. <ref>[http://www.waldseebiohaus.typepad.com/ Certified US Passive House]</ref>
==Origins of the passive house==
{|align="right"
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|[[Image:Bo Adamson.jpg|thumb|250px|Prof. Bo Adamson, co-originator of the concept]]
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|[[Image:Wolfgang Feist.jpg|thumb|250px|Dr Feist, founder of the ''Passivhaus Institut'' and co-originator of the concept]]
|}
The Passive House standard originated from a conversation in May 1988 between Professors Bo Adamson of [[Lund University]], [[Sweden]], and Wolfgang Feist of the ''Institut für Wohnen und Umwelt'' (Institute for Housing and the Environment <ref>[http://www.iwu.de/homep_e.htm Institute for Housing and the Environment]</ref>). Their concept was developed through a number of research projects <ref>[http://www.passivhaustagung.de/Kran/First_Passive_House_Kranichstein_en.html Evaluation of the First Passive House]</ref>, aided by financial assistance from the German state of [[Hesse]]. The eventual building of four [[row house]]s (terraced houses) was designed for four private clients by [[architect]]s [[professor]] Bott, Ridder and Westermeyer.
After the concept had been validated at Darmstadt, with space heating 90% less than required for a standard new building of the time, the 'Economical Passive Houses Working Group' was created in 1996. This developed the planning package and initiated the production of the novel components that had been used, notably the windows and the high-efficiency ventilation systems. Meanwhile further passive houses were built in [[Stuttgart]] (1993), [[Naumburg, Hesse]], [[Wiesbaden]], and [[Cologne]] (1997) <ref>[http://www.buildingforafuture.co.uk/winter05/1-29.pdf European Continental Passive Houses ]</ref>.
The products developed for the Passivhaus were further commercialised during and following the [[European Union]] sponsored [[CEPHEUS]] project, which proved the concept in 5 European countries over the winter of 2000-2001.
While some techniques and technologies were specifically developed for the standard, others (such as [[superinsulation]]) were already in existence, and the concept of [[passive solar building design]] dates back to antiquity. There was also experience from other [[low-energy building]] standards, notably the German ''Niedrigenergiehaus'' (low-energy house) standard, as well as from buildings constructed to the demanding energy codes of Sweden and [[Denmark]].
==The standard==
[[Image:Passivhaus thermogram gedaemmt ungedaemmt.png|thumb|300px|The dark colours on this [[thermogram]] of a Passive house (right) show how little heat is escaping compared to a traditional building (left).]]
The Passivhaus standard requires that the building fulfills the following requirements:<ref> [http://www.cepheus.de/eng/index.html Passive House Requirements]</ref>
* The building must not use more than 15 [[Watt-hour|kWh]]/[[Square metre|m²]] per year (4746 [[btu]]/[[Square foot|ft²]] per year) in heating energy.
* With the building de-pressurised to 50 [[pascal (unit)|Pa]] ([[newton|N]]/[[square metre|m²]]) below atmospheric pressure by a [[blower door]], the building must not leak more air than 0.6 times the house volume per hour (n<sub>50</sub> ≤ 0.6 / hour).
* Total [[primary energy]] consumption (primary energy for [[Central heating|heating]], [[Water heating|hot water]] and [[electricity]]) must not be more than 120 kWh/m² per year (3.79 × 10<sup>4</sup> btu/ft² per year) <!-- seems not consistent with http://www.cepheus.de/eng/ph-was.html which specify 42kWh/m2*y ,changed recently? -->
* Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 [[Watt|W]]/m² (3.17 [[btu]]/ft² per hour).
These standards are much higher than houses built to most normal building codes. For comparisons, see [[Passive house#International comparisons|the international comparisons section]] below.
National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally.<ref>[http://www.europeanpassivehouses.org/ europeanpassivehouses(PEP)]</ref>
===Space heating requirement===
By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume [[heat recovery ventilation]] system that is required to maintain air quality, rather than by a conventional hydronic or high-volume [[forced-air]] heating system, as described in the [[Passive house#Space heating|space heating]] section below.
==Construction costs==
In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German [[building code|building standards]], as was done with the Passivhaus apartments at [[Vauban, Freiburg]] <ref>[http://www.passivhaus-vauban.de/passivhaus.en.html Cost Efficient Apartment Passive House]</ref>.
Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in [[Northern Europe]] above 60° [[latitude]] <ref>[http://erg.ucd.ie/pep/pdf/Henk_Kaan.pdf Passive Houses in High Latitudes]</ref> <ref>[http://erg.ucd.ie/pep/pdf/Tor_Helge_Dokka.pdf Passive Houses in Norway]</ref>.
==Design and construction==
[[Image:Passivhaus section en.jpg|thumb|350px|The passivhaus uses a combination of [[:category:low-energy building|low-energy building]] techniques and technologies.]]
Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design is carried out with the aid of the 'Passivhaus Planning Package' (PHPP) <ref>[http://www.passiv.de/07_eng/phpp/PHPP2004.htm Passivhaus Planning Package]</ref>, and uses specifically designed [[computer simulation]]s.
To achieve the standards, a number of techniques and technologies are used in combination:
===Passive solar design===
Following [[passive solar building design]] techniques, where possible buildings are compact in shape to reduce their surface area, with windows oriented towards the equator (south in the northern hemisphere and north in the southern hemisphere) to maximize passive solar gain. However, the use of [[solar gain]] is secondary to minimizing the overall energy requirements.
Passive houses can be constructed from dense or lightweight materials, but some internal [[thermal mass]] is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible over-heating in spring or autumn before normal solar shading becomes effective.
===Superinsulation===
Passivhaus buildings employ [[superinsulation]] to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings. A wide range of [[Building insulation|thermal insulation]] materials can be used to provide the required high [[R-value (insulation)|R-values]] (low [[U-value]]s, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating [[thermal bridge]]s.
A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.
In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).
===Advanced window technology===
[[Image:Passivhaus Fenster Beispiele.png|thumb|200px|Typical Passivhaus windows]]
To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-pane [[insulated glazing]] (with a good solar heat-gain coefficient, [[low-emissivity]] coatings, [[argon]] or [[krypton]] gas fill, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally-broken window frames.
In [[Central Europe]], for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.
===Airtightness===
Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. Air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations through it are all used to achieve this.
Airtightness minimizes the amount of warm (or cool) air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.
===Ventilation===
Mechanical [[heat recovery ventilation]] systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated (ECM) motors, are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system. Since the building is essentially airtight, the rate of air change can be optimized and carefully controlled at about 0.4 air-changes per hour. All ventilation ducts are insulated and sealed against leakage.
Although not compulsory, [[Ground-coupled heat exchanger|earth warming tubes]] (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)) are often buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents [[ice]] formation in the heat recovery system's [[heat exchanger]].
Alternatively, an earth to air heat exchanger, can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air. This avoids the risk of condensation, mold growth and associated health risks with the earth warming tubes.
===Space heating===
[[Image:Passivhaus heating de Kompakt.png|thumb|200px|In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.]]
In addition to using passive [[solar gain]], Passivhaus buildings make extensive use of their intrinsic heat from internal sources – such as waste heat from lighting, [[white goods]] (major appliances) and other electrical devices (but not dedicated heaters) – as well as body heat from the people and animals inside the building. Together with the comprehensive [[energy conservation]] measures taken, this means that a conventional [[central heating]] system is not necessary, although they are sometimes installed due to client scepticism.
Instead, Passive houses sometimes have a dual purpose 800 to 1,500 [[Watt]] heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.
The air-heating element can be heated by a small [[heat pump]], by direct [[solar thermal energy]], [[annualized geothermal solar]], or simply by a [[natural gas]] or [[oil burner]]. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.
Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m² <ref> [http://www.passivhaustagung.de/zehnte/englisch/texte/PEP-Info1_Passive_Houses_Kronsberg.pdf Passive House Estate in Hannover-Kronsberg p72]</ref>.
Because the heating capacity and the heating energy required by a passive house both are very low, the particular [[List of energy resources|energy source]] selected has fewer financial implications than in a traditional building, although [[renewable energy]] sources are well suited to such low loads.
===Lighting and electrical appliances===
To minimize the total primary energy consumption, low-energy lighting (such as [[compact fluorescent lamp]]s), and high-efficiency electrical appliances are normally used.
==Quality of life==
By their design, passive houses usually have the following traits:
*the air is fresh, and very clean. Note that for the parameters tested, and provided the filters (minimum F6) are maintained, [[HEPA]] quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO<sub>2</sub>, flushing of indoor air pollutants) and any greater, excessively dry (lack of humidity <40%). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from [[formaldehyde]]s, [[Volatile organic compound|VOC]]'s, etc. The use of a mechanical venting system also implies higher positive ion values. This can be counteracted somewhat via opening the window for a very brief time, plants and indoor fountains. However, it should be noted that failure to exchange air with the outside during occupied periods is not advisable.
*because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.
*since there are no radiators, there is more space on the rooms' walls.
*inside temperature is homogeneous; it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked slightly to alleviate this when necessary.
*the temperature changes only very slowly - with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.
*opening windows for a short time only has a very limited effect - after the windows are closed, the air very quickly returns to the "normal" temperature.
==International comparisons==
*In the [[United States]], a house built to the Passive House standard results in a building that requires space heating energy of 1 [[BTU]] per square foot per heating [[degree day]], compared with about 5 to 15 BTUs per square foot per heating degree day for a similar building built to meet the 2003 Model Energy Efficiency Code. This is between 75 and 95% less energy for space heating and cooling than current new buildings that meet today's US energy efficiency codes. The Passivhaus in the German Language Village, [[Waldsee]], in Minnesota uses 85% less energy than a normal house of its size.
*In the [[United Kingdom]], an average new house built to the Passive House standard would use 77% less energy for space heating, compared to the [[Energy efficiency in British housing|Building Regulations]].<ref>[http://erg.ucd.ie/pep/pdf/Energy_Saving_Potential_2.pdf Energy Saving Potential of Passive Houses in the UK]</ref>
*In [[Ireland]], it is calculated that a typical house built to the Passive House standard instead of the 2002 Building Regulations would consume 85% less energy for space heating and cut space-heating related [[carbon emissions]] by 94%.<ref>[http://erg.ucd.ie/pep/pdf/Irena_Kondratenko.pdf Passive Houses in Ireland]</ref>
==Comparison with zero energy buildings==
{{main|Zero-energy building}}
A net zero-energy building (ZEB) is a term for a related approach to creating buildings that use substantially less energy. A ZEB requires the use of onsite [[renewable energy]] technologies like [[Building-integrated photovoltaic|photovoltaic]] to offset the building's primary energy use.
==See also==
{{EnergyPortal}}
{{Portal|Sustainable development|Sustainable development.svg}}
*[[CEPHEUS]]
*[[Energy-plus building]]s
*[[Low-energy building]]s
*[[List of low-energy building techniques]]
*[[Renewable heat]]
*[[Self-sufficient homes]]
*[[Thermal conductivity]] for an explanation of how thermal conductivity, thermal conductance, and thermal resistance are related
==References==
{{reflist|2}}
==External links==
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{{Commons|Category:Passivhaus|Passive house}}
===Passive House information===
* [http://www.passivhaustagung.de/Kran/First_Passive_House_Kranichstein_en.html History of the Passivhaus]
* [http://www.passivhaustagung.de/zehnte/englisch/texte/PEP-Info1_Passive_Houses_Kronsberg.pdf Passive House Estate in Hannover-Kronsberg] (4.3MB) Construction details and performance
* [http://www.passivehouse.com/07_eng/news/CEPHEUS_final_long.pdf CEPHEUS Final Report] (5MB) Major European Union research project. Technical report on as-built thermal performance.
* [http://www.passive-on.org "Passive-On Project"] Research and dissemination to promote Passive Houses in warm climates.
* [http://www.passivehouse.us Passive House Institute US] Promotion and certification of Passive House construction in North America.
===Passive House examples===
*[http://www.passivehouse.com/English/Kranichstein.HTM The original Darmstadt Passive Houses]
*[http://www.passivhaustagung.de/Passive_House_E/Examples_passive_houses.html German & Austrian residential Passive House examples]
*[http://www.passivehouse.co.uk/content/view/18/91/ Ty-Kama House], One of the first Passive Houses in the United Kingdom.
*[http://www.granback.se/welcome-to-passiv-house-granback Passive house Granbäck, Sweden] Stockholms first passive house
*[http://www.kjellgrenkaminsky.se/index.php?blp=25 Prefabricated Passive House examples, Sweden]
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[[Category:Low-energy building]]
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