This paper discusses a study undertaken to analyze the performance of house and heating system alternatives commonly used in the Pacific Northwest and the Southeast of the U.S. using the SP43 simulation model. The SP43 program was upgraded with the addition of simplified electric baseboard and electric heat pump heating submodels to facilitate modeling of a wider variety of heating systems than was previously possible with the SP43 program. In the Pacific Northwest, gas furnace heating systems in a variety of house envelopes and with several different duct systems were compared with electric baseboard heating systems in houses built according to local building codes. It was found that the gas furnace systems performed well on an energy cost basis in comparison with the electric heating cases. In the Southeast, gas furnace systems were compared to several different heat pump alternatives. The gas heating systems performed comparably to the heat pump systems on an energy cost basis.