Humidity controlled exhaust fan in a natural ventilated single family house.

A humidity controlled exhaust fan have been tested during the winter season 1991/2. The test have been carried out in a detached one storey house with a flat roof. The relative humidity (RH) have been measured in the following modes: * natural ventilation only* wall mounted fan, setpoint 70% RH, and natural ventilation * fan in the exhaust duct, setpoint 70% RH.The relative humidity levels have been monitored in the shower room and in the other part of the dwelling. The temperatures have been measured in the exhaust duct and in four places in the dwelling. It is concluded that a wall mounted fan can keep the relative humidity close to 50% RH, causes backdraught in the exhaust duct, and usually has to be switched off manually. A fan mounted in the exhaust duct gives a higher average RH than natural ventilation only.