The Seifert House by Bau Kultur architects in Austria
The UK is going to require that new homes be carbon emissions neutral by 2016. One of the ways that this target can be achieved is by using passive solar building design (English Wikipedia page). This can be used to keep a house cool in summer and warm in winter with minimal energy inputs. There is also the term “Passive House” (not to be confused with passive solar design, though there are overlapping principles) refers to a design and construction standard that aims to drastically reduce heating requirements in homes so that conventional heating systems are no longer necessary.
In 1991 Wolfgang Feist (German Wikipedia Link) a physicist from Darmstadt Germany built the first passive heated home. Now the estimate is that 15,000 homes across Germany and Scandinavia have been built with the innovations Feist pioneered.
What’s different in a passive homes is ultrathick insulation very sophisticated doors and windows in an airtight design. That means virtually no heat comes out or cold getting in. The heat that is needed can come from simple warming by the sun, heat from appliances and the people and pets living inside. There is a provision for adding heat but the systems are small and used infrequently. The added energy efficiency adds about 5 to 7 percent to the construction costs in Germany.
Passive House in Europe
On January 31, 2008, the European Parliament called on the European Commission to propose a binding requirement that all new buildings needing to be heated and/or cooled be constructed to passive house or equivalent non-residential standards from 2011 onwards, and a requirement to use passive heating and cooling solutions from 2008.
A consortium of European partners, supported by The European Commission, is promoting the Passive House Standard because it has been demonstrated, through projects similar to CEPHEUS, that cost effective, non renewable energy savings is not only possible but also realistic. PEP, which stands for Promotion of European Passive Houses was established to promote this standard. You can visit their website www.Europeanpassivehouses.org for more information.
The Passive House Institute in Germany was founded in 1996 as a research / consulting firm to assist architects and engineers in the planning and designing of passive homes. Refer to their website at www.passiv.de (click on English flag) for a comprehensive overview of the Passive House concept. Most interesting is that in Germany the market is growing. Passive is popular as many more people are aware of the advantages. The doors, windows and ventilation systems and other parts have migrated to off the shelf markets for the do it your self crowd. New construction costs are dropping with the added market volume.
Ireland, as a member of the European Union, has a timber frame construction industry which has been influenced by the American Industry. As a member of the EU, Ireland must improve the energy performance of its housing stock and is promoting the Passive House Standard as one of the solutions to reach this goal. Sustainable Energy Ireland www.sei.ie has published guidelines called Passive Homes – Guidelines for the design and construction of Passive House dwellings in Ireland.
In the UK one of the organisations that is pushing to improve the sustainability of the built environment is the UK Green Building Council. Their aim is to help forge a new partnership between government, industry and other stakeholder groups. They are a membership organisation, primarily consisting of businesses from across the building industry. They bring together architects, engineers, investors, product manufacturers and many others involved in all the processes the building industry.
The Passive House Situation in the USA
In the U.S. designers and architects are specifying better insulation and high efficiency appliances plus adding energy with solar panels and wind turbines in an effort to close the utility bill gap that high efficiency can add to mortgage payments. A $100 per month saved in utilities can equal more investment in the home. The Passive House Institute US, PHIUS was established in Urbana, Illinois to promote the implementation of Passive House standards and techniques throughout the USA. You can visit their website www.passivehouse.us for more information.
The downside is that in the U.S. the prices are still much higher meaning construction would be higher than the falling 5% seen in Germany. Then there is the retrofit problem. In many U.S. homes no provision for forced air ventilation is available to retrofit.
The passive approach may be seeing more acceptance world over. The early attempts at tight homes suffered from stagnating air and susceptibility to molds as humidity would climb and air would settle to stillness. But now passive homes are being built with an ingenious central ventilation system. Inside air is expelled as outdoor air is drawn in with an exchange of the heat now up to 90% efficiency.
How Does a Passive House Work?
The strategy of a Passive House is to reuse “free” heat to heat the home. “Free” heat is generated from all electrical and gas appliances such ovens, refrigerators, computers and light bulbs. The building envelope of a Passive House must be extremely well insulated and air-tight so that this “free” heat can not accidentally escape out of the building.
- A mechanical ventilation system, with an air to air heat recovery component, is installed to simultaneously bring in fresh air and remove the same amount of stale air.
- The stale air leaving the house is carrying the “free” heat. It goes through the heat recovery ventilator, and transfers the heat, to the incoming fresh air, before it leaves the building.
- The cool, exterior fresh air comes into the heat recovery ventilator, picks up the “free” heat and goes into the home warm.
- A conventional heating system is not necessary.
A diagram from the Wikipedia website of a Passive House for a very cold climate. Passive Homes are designed according to their specific climate conditions. Triple pane windows are not always required. The ground heat exchanger is also optional.
Architect Nabih Tahan with 11 years of experience in Austria is building his family a passive home in Berkeley California. He is also heading up a group of 70 San Francisco Bay area architects and engineers working to encourage wider acceptance of the standards. “This is a recipe for energy that makes sense to people,” Mr. Tahan said. “Why not reuse this heat you get for free?”
Wolfgang Hasper, an engineer at the Passivhaus Institut in Darmstadt says, “We’ve found it’s very important to people that they feel they can influence the system.” The newest systems offer three settings, one down for being away; one up to circulate air for lots of occupants and the normal one.
Research is looking into the issues that are more American in nature, the cooling from air conditioning where a heat exchanger could be used in reverse, to keep cool air in and warm air out. Then there is the site issues, as passive needs correct positioning to get a sun facing wall for a heat driver.
Mona Vale House by architects Choi Ropiha in Australia
The key to the entire Passive House concept is that it makes many renewable energy systems viable because it reduces the amount of energy needed to heat and cool a home. It is clearly cheaper to transfer out stale air from a very tight house than to reheat or re-air-condition the air. It would be no huge matter for most forced air heating and air-conditioned homes to be fitted with an indoor to outdoor circulator as a worthy addition to a energy conservation program with goals of reducing heat loss through more insulation better windows and doors. Plus, these techniques could go a long way to making geothermal home heating smaller so making them much more affordable.
Guest post from HomeGardenGreen.com