Impact of shading air-cooled condensers on the efficiency of air-conditioning systems

Shading is a technique used to reduce the cooling demand in buildings and save energy. This paper investigates the possibility of reducing the electrical demand and saving energy by shading the condensers of air-conditioning (A/C) equipment. A limiting analysis compares the performance of several A/C systems with ideal shade to those with ideal solar heat gain. The comparison is based on a theoretical model and data from equipment catalogs. The results show that the theoretical increase in the coefficient of performance (COP) due to shading is within 2.5%. Furthermore, this small improvement in ideal efficiency decreases at higher ambient temperatures, when enhancements to efficiency are more needed. A sensitivity analysis shows that the small COP enhancement is not significantly affected by assumed variables. The actual efficiency improvement due to shading is not expected to exceed 1%, and the daily energy savings will be lower. The findings indicate that condenser shading alone, without evapo-transpiration, is not an effective measure to improve efficiency or save energy. (C) 2010 Elsevier B.V. All rights reserved.