Evaluation of Five Simple Ventilation Systems Suitable for Houses without Forced-Air Heating

Houses without forced-air heating systems may not experience adequate distribution of their outdoor air supply. This project examined five simple ventilation systems suitable for such houses. Four were exhaust-only, using either only local exhaust fans in the kitchen and bathrooms or the local exhaust fans supplemented with a partially distributed exhaust system with pickups in each bedroom. Each approach was tested with deliberate passive inlet vents (both distributed and centralized) both open and closed. The fifth system was a supply and exhaust system with small-sized ducts supplying outdoor air to each room and the local exhaust fans providing the exhaust. The five ventilation systems were installed in a two-story house that also has an electric forced-air heating system. Using tracer gas techniques, the air distribution patterns provided by each system for a wide range of weather conditions were measured and compared with similar reference measurements in the house with no mechanical air exchange with the outdoors and with only the forced-air furnace fan operating to circulate the air within the house. The local exhaust fan system with no passive inlet vents was found to provide inadequate distribution of the outdoor air supply, only marginally better than simple air leakage alone.more » With the distributed passive inlet vents open, the local exhaust fan system was found to distribute more outdoor air to the ground-floor rooms than the upper-story bedrooms. The partially distributed exhaust system was effective at improving the ventilation air distribution to the bedrooms. The minimal ducted supply system provided the best outdoor air distribution to all the habitable rooms.« less