Energy recovery ventilator free cooling strategies across the U.S

High-performance buildings are gaining prevalence to combat grid load and save utility costs for residential customers. ERVs could save energy by enabling bypass mode when outdoor conditions are lower than indoor conditions during the cooling season. During these times, bypass mode reduces thermal loads added to the building, reducing heat pump operation. We compared the normal operation of an ERV to two forms of bypass control, temperature-based and enthalpy-based, using a tuned TRNSYS model of NIST’s Residential Test Facility. Simulations were performed for 15 cities in the United States. Temperature-based control saves between 1% and 4.7% of HVAC energy in hot/dry climates and marine climates. Enthalpy-based control limits latent loads but diminishes free-cooling potential, with between −1.5% and 1.7% of HVAC energy saved. The temperature-based control reduced PMVs beyond ± 0.5 by at least 3% in hot-and-dry climates and up to 60% in marine climates. The enthalpy-based control resulted in PMVs beyond ± 0.5 from 0.3% more and up to 40% less time for marine climates. Our temperature-based control provides more ventilation, improves thermal comfort across all climates, and saves energy in hot, dry, or marine climate zones.