This paper reports the results of an investigation into the practical and economic viability of an integrated combined heating and cooling system in a supermarket. This system consists of a direct-drive screw compressor, which is powered by a throttle controlled gas engine. The waste heat from the engine is used to provide hot water for space heating and for general usage within the catering and toilet facilities in the supermarket. In this paper, the working principle of the novel system is first described. This details how the gas engine system may be integrated into the typical supermarket. The paper then describes a model, which is used to simulate the energy consumption of the supermarket. This is used to calculate the energy consumed by the conventional system and that used by a number of alternative combined heating and cooling system configurations, which are also described. The additional capital cost of each configuration is estimated and this is used to calculate the payback period. The results show that a payback period of 4.2 years may be achieved with a system that uses approximately 500,000 kWh per annum less primary energy than a conventional system. Finally, comparison between this system and a traditional Combined Heat and Power (CHP) installation is given.