Ventilation rates and energy losses due to window opening behaviour.

This paper describes one of the results of the IEA-annex 8 "Inhabitants behaviour with regard to ventilation". Annex 8 has shown that the occupants can play a rather important role with regard to the ventilation rates inoccupied buildings. This paper gives some practical 'rules of thumb' for estimating air flow rates through open windows. An overview of measured and estimated ventilation rates in houses is given from which a simplified approach is derived that takes into account the air tightness of the building and the behaviour. The second part of the paper deals with heat losses and seasonal heating demand due to window use. The effect of house type and insulation level is analysed as well as the variation in window use. This parameter study indicates that the effect of the window use on the energy consumption can be very important in apartments and well insulated houses.