Abstract

The substantial reduction of required heating load in passive house buildings has led to an integration of heating in the ventilation system by post-heating the supply-air, called air-heating. The incorporation of heating in the ventilation system constitutes a departure from a well-established customary practice of strictly separating heating and ventilation in the indoor climate design. It is therefore imperative to thoroughly investigate and evaluate air-heating with regard to effects on the indoor air quality (IAQ) and thermal comfort. Simulations and laboratory measurements suggest that air-heating has no adverse effects on IAQ and thermal comfort. The purpose of this paper is to investigate the acceptability and suitability of air-heating from the occupants' point of view. A comprehensive literature study is performed in order to assess the perception of IAQ, thermal comfort and general experiences with the operation of air-heating in comparison to other heating strategies. The evaluation is based on studies on multifamily passive house buildings in temperate and continental climates. No proof for the general unsuitability of air-heating in residential passive house buildings with regard to perceived IAQ and thermal comfort was found, but clear limitations were determined in buildings where the heating is based on air-heating only. Based on the findings it is suggested that air-heating always should be supplemented with an extra heat source in bathrooms and it should be possible to adjust the supply-air temperature in the bedroom independently from other rooms.