This paper deals with the technical, economic and environmental performance of a 40 kWe CHP plant, located within the Queens Building at De Montfort University. Conventional analysis gives the overall efficiency as 77% with a 7.1 year payback period. By examining the thermal and casual gains, a novel alternative analysis gives an effective plant efficiency of 104%. Environmental analysis shows that the CHP-generated energy produces half the carbon dioxide emissions of separately imported electricity and heat from a boiler plant. The scheduling of plant utilisation has an effect on thermal efficiency due to thermal capacitance. The economic and environmental benefits of small-scale CHP plants are demonstrated.