Solar cooling

In this contribution a picture is drawn on general issues for using solar thermal energy for air-conditioning of buildings. Subsequently to a brief overview on thermodynamic limits, the state-of-the-art of available technologies is highlighted. Although the system components are generally market available, the application of solar thermal air-conditioning is still far from market penetration. Although the functional capability of the applied technologies was proven in realised intallations in Europe, the experiences reveal also potential for improvements mainly in design and control of the systems. A glance at new developments and future perspectives on solar thermal air-conditioning is given in the final section. Summer air-conditioning represents a growing maret in building services world-wide in both commercial and residential buildings. Main reasons for the increasing energy demand for summer air-conditioning are the increased thermal loads, increased living standards and occupant comfort demands as well as building architectural characteristics and trends, like an increasing ration of transparent to opaque surfaces in the building envelope to even the popular glass buildings. Different heat driven cooling technologies are available in the market, which can be used in combination with solar thermal collectors. The main obstacles for large scale applications, beside the high first cost, are the lack of practical knowledge on design, control and operation of these systems. For small scale systems, many years no appropriate technology was available on the market. However, recently several mainly European companies started development of water chillers in the power range below 50 kW down to 5 kW, and first commercial systems are now available. But still the further development of small capacity cooling and air-conditioning systems remians of high interest.