Indirect Evaporative Air Conditioners Added to Existing RTUs

This report documents the results of a pilot field study designed to characterize performance for two indirect evaporative air conditioning products. These systems each utilize indirect evaporative heat exchangers that enable water evaporation to cool a building without adding moisture to the air that is supplied to the conditioned space. These air conditioners do not have compressors, and the only major energy consuming component is a fan. Unlike conventional vapor-compression air conditioners, indirect evaporative systems actually become more efficient as outdoor temperature increases. This study was performed in parallel and/or in sequence with four other studies, all of which assessed the performance of RTUs that employ evaporative technologies in different ways or configurations. These include: • A lab assessment of four direct evaporative condenser pre-coolers, and one air supply indirect evaporative pre-cooler. http://www.etcc-ca.com/reports/laboratory-testing-performance-enhancements-rooftop-packaged-air-conditioners • A field assessment of indirect evaporative cooling for a mall in Fairfield, CA in which a new RTU was retrofitted with a direct evaporative pre-cooler at the condenser inlet, and a water to air heat exchanger at the ventilation air inlet. http://www.etcc-ca.com/reports/indirect-evaporative-cooling-shopping-mall • A field assessment of an indirect evaporative unit, serving as a dedicated outside air supply (DOAS) at a restaurant in Rocklin, CA. http://www.etcc-ca.com/reports/indirect-evaporative-air-conditioning-restaurant • Lab and field assessments of a Munters hybrid unitary dedicated outside air supply (DOAS) system. Lab: http://etcc-ca.com/reports/munters-epx-5000-dedicated-outside-air-supply Field: http://etcc-ca.com/reports/climate-appropriate-cooling-grocery-store-hybrid-unitary-doas-system-san-ramon-ca