Passive House - Traits of Passive Houses

Traits of Passive Houses

Typically, passive houses feature:

• Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO₂, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.
• Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.
• Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.
• Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.
• Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.