Here is a long article with some details on the passive house standard, which promises order of magnitude energy use reductions in buildings. It was invented in the United States, forgotten/ignored in the United States, adopted in Europe, and now is finally filtering back from Europe into the United States.

The passive house standard requires a tightly sealed and heavily insulated building envelope to ensure optimum energy efficiency. The minimum airtightness level allowed is 0.6 air changes per hour under 50 pascals of pressure. To ensure that a house is in compliance with this limit and that there are no leaks, the building’s designers conduct an on-site blower door test. “The biggest challenge is the sealing,” says Priputen, adding, “If you have a weak spot you have to make all of the other areas stronger in terms of insulation and air sealing.”

The other main pillar of passive house construction is a compact air and heat exchange system that conserves energy by transferring heat and/or moisture between incoming and outgoing streams of air. Designers specify one of two systems, depending on the site’s climate: heat recovery ventilators (HRVs), which transfer only heat, or energy recovery ventilators (ERVs), which transfer both heat and moisture.