July 5, 1999


Energy efficient homes are inherently airtight and require ventilation for acceptable indoor air quality. Recognizing this fact, two building code jurisdictions, the federal department of Housing and Urban Development and the State of Washington, require mechanical ventilation for homes. The state of Minnesota will soon enact regulations for mechanical ventilation in homes, and it is expected that this trend will continue. Of all the options currently available, the low cost and low maintenance central fan-integrated ventilation approach is the most acceptable to large production builders and manufactured home producers. In this approach, fresh air is filtered and ducted to the return air side of the central system fan. The central system fan and ducts then distribute the ventilation air throughout the living space. This is a resource and energy efficiency strategy that utilizes the existing air ducts and the normal cycling of the fan, in response to demand from the thermostat, to distribute ventilation air and conditioned air at the same time. The patented AirCycler™ control can be used to automatically operate the fan if the fan has been inactive for a period of time, and to control a motorized outside air damper to limit the intake of ventilation air independent of fan operation.