Whole-house leakage and heating energy use of electric forced-air and room-heater-equipped homes in the Northwest are compared. More than 800 homes were tested to study energy savings from a proposed code. Air leakage was measured using fan pressurization and tracer gas. Energy use was submetered; inside-to-ambient temperature differential was monitored. Two home groups were tested: energy-efficient "MCS" homes and a "control" group of current practice homes.

Ducted and unducted heating systems were compared within homogeneous subsets of homes. Air leakages were compared using 4 Pascal air infiltration, effective leakage area, specific leakage area, and 50 Pascal ach. Heating energy was compared using specific K factor (Btu/h•°F•ft2).

Ducted forced-air homes were leakier and used more heat than unducted homes. Ducted control homes were 26% leakier than unducted controls and used 40% more heating energy. Ducted MCS homes were 22% leakier and used 13% more heating energy than unducted MCS homes.