The Passive House Energy Standard
Passive House (or Passivhaus) is a housing energy standard created in Germany in the early 1990's. Through a combination of layered insulation and airtight construction, homes built to the Passive House standard use a fraction of the energy needed in traditional homes
Walls in a Passive House are significantly thicker than in traditional construction, as are the windows. The foundation is poured over thick insulation, and the entire house is built to prevent unwanted air leakage. As a result, passive heat loss is almost eliminated. When viewed with a thermograph, the differences between a Passive House and a traditionally built home are striking, even to the point of looking unreal.
Although the description of a house as hermetically sealed would normally carry connotations of stale air or claustrophobia, the Passive House design keeps the home bright and airy. Passive House homes tend to have a large number of windows (the majority facing south), and a layout which allows air to move freely about the house. Open the windows and that air movement becomes even greater; if the weather won't permit open windows, a ventilator can serve to help move the air. This prevents the air from taking on a 'stale' feel and evens out the ambient temperature, so that there is no noticeable change from one room to the next.
Spreading the Word
Passive House is growing in popularity across the globe, thanks in no small part to the efforts of Dr. Wolfgang Feist. One of the creators of Passive House, Dr. Feist has established the Passivhaus Institute to help educate builders and consumers about the advantages of super insulating construction techniques. Along with affiliate organizations in several countries (including the UK and the US) the Passivhaus Institute provides certification for home builders, listings of certified building materials, and resources for the efficiency-minded homeowner.
Selling the advantages of Passive House to homeowners carries its own challenges as well. Often builders catering to a “green” consumer will highlight some construction element which is visually striking, or fill the home with the latest in environmental gadgets. The Passive House standard is plain, nondescript, and not sexy at all... until that first electric bill shows up. Whereas other green building standards address everything from site location to water usage, the singular focus of Passive House brings dividends: while LEED specifications will generally reduce a home's energy consumption by 30%, Passive House reduces energy use by 70% (and by a staggering 90% of heating costs).
Like any standard, Passive House is not without its weak areas. The original standard was created in the colder climate of Germany, and it needs to be adapted to regions where cooling and dehumidification are more pressing concerns. Another early area of concern was the uniform, 'boxy' look of Passive Houses. As more Passive Houses are being built, the exterior appearance of the homes is receiving more attention. Getting away from the stereotype of its earlier days, architects are finding ways to integrate new builds into their surroundings, although the thick-walled construction still has a distinctive look.
Overall, Passive House is an exciting building standard which can have dramatic impact on the homeowner's monthly bills and energy consumption. For the right consumer, it's well worth considering, and will likely only grow in popularity as the movement towards green building continues.