What is a Passive House?
A Passive house is a house which is so energy efficient, it not does require a conventional heating system. A true passive house, or PassivHaus in German is a building, and not necessarily a house – it can be a pharmacy, a school, offices – anything in fact that meets the strictly defined criteria set down by the PassivHaus Institut in Germany to qualify for this title.
This is achieved by using insulation to prevent heat loss through the walls, floors and ceilings. Windows and doors are designed and positioned to maximise free solar gains and minimise losses.
Heat losses through air leakage are reduced to a minascule level by taking care to eliminate gaps in the construction.
Ventilation is especially critical in these buildings, because there aren’t accidental draughts to get rid of poor quality air, so a carefully designed ventilation system is installed. This will usually have a ducted system which recovers heat from exhaust air, to preheat the new fresh air, without mixing the two.
Careful attention is paid to how the different elements of wall, floors, roofs and windows meet, so that there is no cold junctions, or ‘thermal bridge’.
As a result, these buildings cost about 1/10th to maintain permanently comfortable conditions.