Hong Kong Polytechnic University (PolyU) has successfully developed the first solar powered air-conditioning system for use in the mainland. The project, commissioned by the Croucher Foundation, is a collaboration between PolyU and the Guangzhou Institute of Energy Conversion of the Chinese Academy of Sciences. Professor Leung Tin-pui, the project leader representing Hong Kong and PolyU vice-president, said the innovation aimed to use solar energy for air-conditioning and heat supply systems. It had gone through five main stages of development over 13 years. The integrated solar air-conditioning and hot water system is located in a 24-storey building in Jiangmen City, Guangdong, where construction work is being carried out. Technicians worked at combining a novel two-stage absorption chiller with a solar collector system. During the summer, the solar system provides cooling and, in cold weather, hot water or heating. The main components are the solar collectors, which turn energy from the sun's radiation into energy to heat water, or drive the absorption chiller for air-conditioning. Researchers at PolyU and Guangzhou Institute developed three types of collectors - evacuated tube collectors, heat-pipe vacuum collectors, and flat-plate collectors with V-corrugated film. The project has also contributed to the academic and technical development of both institutes. The first three stages of the development mainly focused on techniques in the field of solar-driven air-conditioning and a new two-stage absorption chiller which required lower heat source temperature for the cooling system. The gathering of data on solar radiation and a feasibility study of the absorption chiller and its accessories were conducted in the first stage. This was followed by the design and construction of an integrated solar air-conditioning system. The third stage was the development of the solar absorption chiller, which made use of low temperature energy sources for cooling. Successful results were then transferred for industrial and commercial uses. Professor Leung said the key techniques of developing the integrated solar cooling and hot water system, and the novel two-stage absorption chiller, would be adopted by China's State Committee of Science and Technology. 'This means the achievements have been highly evaluated and will be demonstrated in a large state project of practical solar application system,' he said.