Interior view of Passive House in Darmstadt-Kranichstein, Germany

Photo: Pfäffinger

The term "Passive House" refers to a construction standard. The standard can be met using a variety of technologies, designs and materials. It is a refinement of the low-energy house (LEH) standard.
"Passive Houses" are buildings which assure a comfortable indoor climate in sum-mer and in winter without needing a conventional heating system.
To permit this, it is essential that the building’s annual demand for space heating does not exceed 15 kWh/(m²a). The minimal heat requirement can be supplied by heating the supply air in the ventilation system – a system which is necessary in any case. Passive Houses need about 80% less heating energy than new buildings designed to the standards of the 1995 German Thermal Insulation Ordinance (Wärmeschutzverordnung).
The standard has been named "Passive House" because the passive heat inputs – delivered externally by solar irradiation through the windows and provided internally by the heat emissions of appliances and occupants – essentially suffice to keep the building at comfortable indoor temperatures throughout the heating period.
It is a part of the Passive House philosophy that efficient technologies are also used to minimize the other sources of energy consumption in the building, notably electricity for household appliances. The target of the CEPHEUS project is to keep the total final energy demand for space heating, domes-tic hot water and household appliances below 42 kWh/(m²a). This is lower by at least a factor of 4 than the specific consumption levels of new buildings designed to the standards presently applicable across Europe.