The Air-Conditioning and Refrigeration Institute
This document presents a rigorous methodology for determining the efficiency of energy recovery ventilation systems. This is based on the standard calculation of useful energy delivered by a process divided by the energy consumed in that process. To distinguish it from similar calculations of energy efficiency ratio or EER for unitary equipment, a new term, recovery efficiency ratio (RER) is introduced. In the case of energy recovery ventilation this is a measure of useful space conditioning energy recovered over the extra fan energy required to move the two airstreams through the energy recovery device (an air-to-air heat exchanger).