cooling

Especially in modern buildings with small capacity of humidity storage it is necessary to reduce the humidity in the supply air. Normally a refrigeration system containing CFC s is used. There are some alternative fluids available, but mostly they show a high global warming potential. These systems all need electrical energy to be driven and therefore it is necessary to consider other possibilities with alternative systems. The most promising systems are sorptive systems which are used in open cycles.

For the planning of "silent cooling" systems built by free convective coolers, it is necessary to support characteristic data for the cooling performance and the effect of different installation and operating parameters on the cooling performance. At the "Institut für Angewandte Thermodynamik und Klimatechnik" at the University of Essen measurements of the cooling performance of free convective coolers were carried out by using a testing chamber as well an enlarged and modified testing room with dimensions near to practise.

The material presented in this paper highlights some aspects of""two research projects, The control of natural ventilation , and Night cooling strategies . The research has led to the development of generic control strategies. These have evolved from consideration of the control strategies used in naturally ventilated buildings utilising Building Management Systems (BMS) control together with experience obtained from monitoring three naturally ventilated buildings. The site monitoring has also led to recommendations being provided for commissioning and fine tuning procedures.

A significant amount of the electrical energy used to cool non-residential buildings equipped with all-air systems is drawn by the fans that transport the cool air through the thermal distribution system. Hydronic systems reduce the amount of air transported through the building by separating the tasks of ventilation and thermal conditioning. Due to the physical properties of water, hydronic systems can transport a given amount of thermal energy and use less than 5% of the otherwise necessary fan energy.

Elevated temperatures in urban 'heat islands' increase cooling energy use and accelerate the formation of urban smog. Urban shade _trees and light-colored surfaces can offset or reverse the heat island and conceive energy. Implementation of heat island mitigation measures is now a prominent part of President Clinton's Climate Change Action Plan to control the emissions of greenhouse gases, necessitating a better understanding of the quantitative benefits of these control measures.