Virtually all manufactured housing units in the nation use forced air systems for heating and cooling distribution. The typical manufactured home air distribution system (ADS) wastes a significant amount of energy through leakage of conditioned air to the exterior. Reductions in this leakage have the potential to reduce a home's annual energy bills by up to 10 percent; making improving ADS performance the single most important strategy for saving energy in manufactured housing.

This report documents visits by building scientists to 16 manufactured home plants to develop and demonstrate techniques to build tighter duct systems and to train production personnel in these techniques. The three key steps in the ADS construction process that enabled individual plants to reach the target leakage levels were: cutting accurate holes for registers in floors and for duct connections by using templates, securely and mechanically fastening ADS components rather than using tape alone, and covering seams with proven durable sealants such as mastic or appropriate tapes. The scientists adapted standard duct leakage test protocols for use in the plant environment in order to quantify performance improvements. The training of plant staff and often the plant's Design Approval Primary Inspection Agency (DAPIA) was designed to enable the plant to maintain production of the improved ADS systems.

The lessons learned while working with the 16 plants was widely distributed to the industry through articles in TECHNOLOGIES and Modern Home, seminars and symposia at major industry trade events, and posting on the MHRA web site. As a result of this effort, the efficiency of the air distribution systems (ADS) constructed at 16 manufactured home plants whose parent companies produce over 85,000 homes per year was dramatically improved. The average rate of duct leakage to the outside was reduced to 3.7 percent from 13.6 percent observed in earlier studies of homes produced at some of these plants.