Operation of passive stack systems in summer.

The ventilation rate in a building depends on many things, one of which is the air temperature. The air temperature in turn depends in part on the ventilation rate. The effects of this relationship are generally overlooked in both thermal and ventilation models. To study this effect a model has been developed which integrates the models GAINE and SILONA developed at CSTB. This allows the prediction of the natural ventilation rates caused by the actual temperatures in the building. It has been used for predicting summertime temperatures and ventilation rates for a range of different ventilation and thermal parameters. In particular the difference between night and daytime ventilation rates and pollutant levels has been examined. The extract flow is found to be more stable at night than in the day.