The Radiant Demonstration Program (RDP) was developed for the management association of a large retirement single-family housing community in the Northeast for the purpose of providing comparative data for heating system retrofit selection. Control and pre- and post-retrofit energy consumption data were monitored for two to four years in approximately 100 occupied units of 19 designs. The heating systems involved encompassed electric concealed ceiling radiant panels; fast-acting, ceiling surface mounted radiant panels; baseboard heaters; forced air furnaces; standard air, high-efficiency air, and geothermal heat pumps; and gas forced air high-efficiency furnaces. All units had a separate air-conditioning system. Significantly lower retrofit installed and maintenance costs were demonstrated for the fast-acting radiant panels. Comparative energy use of fast-acting radiant panels was less for the systems involved, with the range of savings apparently varying in relation to previous relative comfort and interest in practicing occupancy-based room temperature control.Units: I-P