PNNL

Abstract

Dedicated Outdoor Air Systems (DOAS) with Energy Recovery Ventilators (ERVs) are increasingly popular in new buildings and have the potential to greatly reduce building energy consumption through elimination of zone-level summer reheat and free pre-conditioning of outdoor ventilation air through energy recovery with building exhaust air, often using an enthalpy wheel heat exchanger. In practice, many of these systems, however, are run sub-optimally, or are designed with complex and counterintuitive configurations that require detailed engineering analysis to understand optimal control sequences. Three real-world case studies from commercial building re-tuning are presented where control deficiencies in DOAS systems with ERVs lead to excess energy consumption. An analysis of the potential energy savings from correcting these deficiencies as well as a discussion of how each analysis was performed during the re-tuning audit is included. Energy savings can vary significantly based on the climate and the baseline system’s specific sub-optimal operation, however opportunities for saving energy amounting to up to 2.2% of annual building energy consumption have been documented in these case studies.