Passive House is a fabric first building approach with super insulated walls, floor and roof and also air tight requiring only a minimal amount of heating. Most of the heating requirement is provided by solar gain and incidental gains from showering, cooking and appliances.
A passive house is designed to have minimal energy requirements for space heating and cooling and have excellent indoor air quality making it extremely comfortable to live in.
A passive house not only has lots of insulation, but careful detailing to eliminate thermal bridging that allows heat to transfer directly through building junctions or gaps in insulation. A passive house must also achieve a very strict level of air tightness to remove heat loss through draughts. Fresh air is then supplied to individual rooms in the house through a heat exchanger, transfering heat energy from the warm, damp stale air extracted from kitchens and bathrooms.
The Passivhaus standard originated in Germany in 1996 and was developed by the Passivhaus Institut (PHI). Gaining Passivhaus certification is not a requirement to building a low energy home but shows that there has been independent verification that a house meets the passive principals.
Its great advantage is that it eliminates the performance gap between designed and built performance. The build is checked and measured against the designed proposal and signed off by an independent certifier.