Field Evaluation of Remote Evaporative Condenser

Packaged rooftop air conditioning units (RTUs) are the predominant equipment used for space conditioning of small and medium-size commercial buildings. It is estimated that roughly 70% of space conditioning in commercial buildings is provided by RTUs. Due to the longevity of these RTUs (roughly 15-20 years in California), more and more companies are entering the market with products that are designed to improve the energy efficiency of existing RTUs. This project was designed to evaluate the performance of one of those products. An inordinate amount of energy is wasted each year as a result of the fact that packaged commercial air conditioners are designed as ‘one-size fits-all’ products that can function in any climate and are not designed to achieve maximum efficiency for a specific climate. Climate appropriate solutions recognize unique opportunities for efficiency that arise from the climatic patterns and characteristics in particular regions. In California, these solutions include technologies that use water evaporation strategically to achieve substantial gains in cooling efficiency. This report explores one such technology opportunity that has previously demonstrated in a slightly different application to achieve a seasonal full load condenser efficiency of 16.9 EER (German et al. 2012). The report presents results from a field assessment of two new RTUs that were retrofitted with a single evaporatively-cooled condensing unit (ECCU). The ECCU uses direct evaporative cooling to cool the condensing coil which is a significant departure from standard air-cooled condensers.