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Difference between a passive house window (above) and typical window: passive house window offers thermal comfort through warm surfaces. (PHI, VTT)

Both the appearance of the house and thermal comfort requirements for a modern building are high. Good thermal insulation and air tight structures contribute to draught-free indoor climate and desired indoor temperature. Thermal insulation layer need to be protected both from the inside by continuous air barrier and from the outside by continuous wind barrier. Both air and wind barrier perform adequately only if all discontinuities of the layer are sealed.

A Passive House has high inner surface temperatures due to high insulation level. Thermal bridges may cause cooling of a surface locally. Both draught and cold surfaces increase the need for comfort heating even though the room air temperature is adequate.

A proper and controlled ventilation quarantines good quality of indoor air. Fresh air preheating, e.g., in ground ducts, and heat recovery from exhaust air increase the temperature of supply air. If ventilation heating system is used, the ventilation does not cause any feeling of draught.

The heating demand of a Passive House is very low, and thus cold air leaks are experienced more easily as discomfort as, e.g., in a normal house with traditional radiator or floor heating system. Air leaks at the wall to floor connection are especially harmful, as there are no heat sources to compensate the cold draft on the floor level.