We had a presentation by a local construction company (Pheasant Hill Homes) who build passive homes, but what is a passive house?
I am going to quote Wikipedia which defines a passive house as:
"Passive house is a rigorous, voluntary standard for energy efficiency in a building, which reduces the building's ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in Switzerland."
So what this really means is that a home built to Passive House standards requires the least amount of energy to heat it and it retains the heat. This effectively requires the home to be more or less air tight with abundant insulation, triple glazed windows and with a HRV (heat recovery ventillation) system.
With regard to the insulation the amount will obviously depend on where you are building, as a house in Nunavut will be different to Vancouver Island as they are in different climate zones.
As the home is air tight you do still need air flow which is where the HRV system is used. The system removes air from inside the home and replaces it with fresh air from outside. However, you also do not want to remove the heat from the home so the HRV system takes the heat out of the expelled air and heats the incoming air with it and modern HRV systems are very efficiant with minimal heat loss.
The other aspect of a passive home is the design in that you do not want to use large amounts of electricity or gas to heat the home. Therefore they are designed to maximise the heat from the sun in the winter, when the sun is lower, but also not get too much heat from the sun in the summer when it is higher in the sky. Therefore they are usually designed to be south facing, to help heat the home in the winter when the sun is lower, but with good sized roof overhangs to help in the summer when the sun is higher.
This is brief description but there is good video to watch HERE.