In order to investigate the energy performance of air-to-air heat Pumps for residential heating in the Black Sea region of Turkey, an experimental set-up was constructed. An electrically driven air-to-air heat pump was used for heating a laboratory building with a floor of 75 m2. The experimental results were obtained for December, January, February, March, April and May of the 1991-2 heating season. The experimentally obtained results are used to calculate the heat pump's coefficient of performance (COP). Actual experimental performance data were used to generate third-order polynomials relating the heat pump's COP to the outdoor air temperature. Also, economic comparisons were made of the heat pump's performance with electrical resistance, oil, gas and coal-fired heating systems, using an annualised life-cycle costing method. This showed that the heat pump offers economic advantages over the oil and coal-fired boiler systems, but is not an economic alternative to the gas-fired heating system. Because the unit price of the gas is 3.84 times less than that for electricity, to become competitive with a gas-fired boiler, either the capital cost of the heat pump must be substantially reduced or its seasonal COP increased by about 60%: it should also be driven by a gas engine rather than an electric engine.