Grid Magazine April 2012 [#36]
"The Passive House standard specifies very high insulation values and aggressive air sealing techniques, which, compared with a typically constructed building, will reduce the heating and cooling loads on the building by 90 percent. The remaining 10 percent can then be provided by on-site renewable energy sources. In the case of Ridge Flats, that will be a 300-kilowatt solar array."
Passive House @ Wikipedia