Investigation of ventilation conditions in naturally ventilated single family houses.

The reason for the present project is the need for more reliable information about the actual ventilation conditions in naturally ventilated, detached houses. The aim has been to quantify the ventilation and humidity conditions and to establish a better basis for elaborating directions and guidelines on proper ventilation of detached houses. A national questionnaire survey covering more than 2100 households has been carried out, together with detailed investigations in about 150 houses. The investigations comprised measurements of the average outdoor air supply and the average relative humidity. The main bedroom was investigated separately. The measurements were performed during the heating period. Passive measurement techniques were used. Results show that the air change rate on average is about 0.35 h^-1. In more than 80 per cent of the houses the air change rate is lower than the recommended rate of 0.5h^-1. The relative humidity is on average 0.45 in the living-room and 0.53 in the bedroom.