A retrofit study is being conducted to investigate the airtightness, ventilation and energy impacts of tightening the exterior envelope and the heating and air conditioning system ductwork of a double section manufactured house. This report describes the results of the pre-retrofit assessment of building airtightness, ventilation, and energy consumption under both heating and cooling conditions. After the pre-retrofit data collection was finished, the house underwent retrofits to tighten the building envelope and to reduce ventilation system duct leakage. After completion of the retrofits,...