What is a Passive House? design process

The design philosophy behind Passive House buildings is simple: the energy performance requirements of the Passive House Standard specify a maximum permissible amount of annual heating and cooling energy in any building. The designer then works to define each component of the building, in order to meet the overall energy target.  

In normal buildings the designer asks a mechanical contractor or engineer to size an appropriate heating system for a finished design, but in Passive House buildings this is reversed: the architect designs the building to ‘fit’ a very small heating system.

This iterative design procedure will be recognizable to anyone who’s designed an   R-2000 house; individual building components can be adjusted and optimized within the software program until the desired energy target is achieved.

However the PHPP’s scope of engineering and building science detail in describing a low-energy building far exceeds that of other energy modeling tools

This PHPP analysis, together with detailed design drawings, becomes the basis for the Passive House Certification, should that be a client objective.  

In practice, Passive House-compliant buildings need to be designed with maximum design heat loads of around 10 Watts per square metre of floor area (i.e. 1 Watt per square foot). This is around one tenth of the heating power output required by a conventional building.

This produces a requirement to superinsulate all parts of the building, as well as eliminating most thermal bridging, and by the use of exceptionally high- performance components, including windows.