Passive cooling of a wood frame house

A two-storey wood frame house for the experimental study of hybrid residential ventilation was built in the campus of the Brno University of Technology in 2003. The house is fitted with a demand controlled hybrid ventilation system assisted with solar chimneys. Demand control of the system is based on the monitoring of carbon dioxide concentrations in rooms. There is a data acquisition installed in the house that monitors a number of parameters related to the performance of the house and the ventilation system. A passive cooling strategy making use of solar chimneys has been developed for the hybrid ventilation system. The passive cooling mode is activated when the indoor air temperature reaches the cooling set point, and at the same time outdoor air temperature is lower than indoor air temperature. All air supply inlets as well as the solar chimneys are fully open in the passive cooling mode. One of the solar chimneys contains heat storage mass for night operation. Even though passive cooling is not considered a very suitable technique for wood frame houses, the passive cooling strategy revealed itself to be quite effective. It was possible to keep the indoor air temperature below the outdoor air temperature during daytime when the passive cooling experiments were performed in hot summer. The most important factors contributing to good results of passive cooling are good insulation properties of the building envelope, proper shading of windows, relatively high mass of gypsum plasterboards used for internal finishes, and demand controlled ventilation reducing the ventilation heat gain. The phase change materials will be employed for cool storage in the next stage of investigations.