A combined heat and cold system driven by a gas industrial engine was set up and tested. The experimental results showed that the primary energy rate of the combined system was about 1.90. The comparative saving of primary energy demand of the combined system reached 40.9% compared to conventional separate systems of cold and heat supply (direct fired absorption chiller for cooling and gas boiler for heating). When the speed of the gas engine reduces, the refrigerating capacity of the combined system and heat recovered from the gas engine also reduce, but the primary energy rate of the combined system increases. The experimental procedure also confirmed the reliability of the combined system. (c) 2006 Elsevier Ltd. All rights reserved.