Tuesday, November 12, 2013

Passive House- what is it?

By Michelle Harris

What comes to your mind when you hear the words, passive house? An apathetic house? Perhaps more accurately, a house using passive solar strategies? There are a few approaches to passive house design and construction that are universally true, minimal active heating and cooling, with use of solar energy. The standard for passive house construction is systemized through the Passive House Institute. Passive House Institute is a non-profit  organization that certifies contractors, engineers and architects to design passive houses to a verifiable standard. The headquarters for Passive House Institute is located in Urbana- Illinois. There are over 300 certified designers throughout the U.S. Passive House Institute operates as an authority at the forefront of quality ‘sustainable’ design.
Passive house construction methods were pioneered in the U.S. and Canada in the late 70’s as a response to the oil embargo of 1973. In 1986, William Shurcliff, a physicist, published in the Energy Review the core elements of passive house: Thick insulation, airtight construction, prevention of moisture migration into cold regions within the walls and other regions where much condensation could occur. Shurcliff’s work though brilliant were not holistically embraced in the U.S.. However, in Europe, the concept of passive housing has been easily adopted and taught as a practical construction practice in schools. The founder of Passive House Institute U.S., Katrin Klingenberg, moved from Germany to pursue passive housing in the states. Eventually, there was a spilt of construction standards between Passive Haus Institute (European Coalition) and Passive House Institute (U.S. & Canadian Coalition) due to complications in formula property rights, measuring standards and disagreements on climate zoning. While the two groups are unique each other, in a few ways, the two standards also inform each other.
An example of a passive house construction from Europe is the BedZED in London, UK. This housing development is collaboration between sustainability consultants, engineering and quantity surveyors. It was the first zero carbon development in the UK fully completed in 2002. The aim of BedZED was to reduce electricity consumption compared to the UK average by 33%, to reduce space heating needs compared to the UK average by 90% and to eliminate carbon emissions due to energy consumption. In 2003, Passive House Institute U.S., founded by Katrin Klingenberg also set out to construct a passive house as a prototype. Her design, the Smith House, established for the U.S. a competitive take on passive house construction.
The Smith House is regulated by energy recovery ventilators that maintain the energy created in the house versus venting it out. Thus energy losses are minimized. Necessary components in the Smith House are triple pane windows, thermal bridge free and airtightness design strategies, vapor retarders,  a 100 ft earth tube and 40 sq. ft. in-floor electrical radiant heating. The discussion of an energy recovery ventilator versus a heat recovery ventilator is covered in the below references. As are more specifics of the Smith House  specific passive house construction.
While passive house may mean many things, the construction speaks for itself. A passive house goes beyond average construction standards in energy conservation. Passive House Institute is partnering with the government’s U.S. Challenge Home, as well as Franhoffer IBP to create a standard that is both stringent and effective through new goals and formulas. Because of these updates to what originally caused strife between the continents, Passive House is even more a competitor with other standards, such as LEED and USGBC. While there is benefit in all, the successful use of minimized energy consumption is the point, and the construction will ultimately speak for itself.

Passive House History: http://passivehouse.us/blog/?p=693
Passive House Institute Facts: http://www.passivehouse.us/passiveHouse/FAQ.html

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