Passive House

I have really enjoyed watching Grand Designs over the years, and one of the great ideas used occasionally is the passive house.  Passipedia defines a passive house as:

"... a building, for which thermal comfort (ISO 7730) can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”

Often having a thermal mass, such as concrete slab floors that are heated by the sun, help to heat and keep the temperature stable.  The result is very efficient buildings that require very little energy to heat or cool the living space.