Using EnergyPlus to Perform Dehumidification Analysis on Building America Homes

A parametric study was conducted using EnergyPlus version 6.0 to investigate humidity issues on a typical mid-1990s reference home, a 2006 International Energy Conservation Code home, and a highperformance home in a hot-humid climate. The impacts of various dehumidification equipment and controls are analyzed on the high-performance home. The study used the Walker and Wilson (1998) infiltration model to examine the combined effects of infiltration and mechanical ventilation with balanced and unbalanced mechanical ventilation systems. Indoor relative humidity excursions were examined-specifically, the number of excursions, average excursion length, and maximum excursion length. Space relative humidity, thermal comfort, and whole-house source energy consumption were analyzed for indoor relative humidity set-points of 50%, 55%, and 60%. The study showed and explained why similar trends of high humidity were observed in all three homes, regardless of energy efficiency, and why humidity problems are not necessarily unique in highperformance homes. Thermal comfort analysis indicated that occupants are unlikely to notice indoor humidity problems. The study confirmed that supplemental dehumidification should be provided to maintain space relative humidity below 60% in a hot-humid climate. All modeled supplemental dehumidification options successfully controlled space relative humidity excursions, yet the increase in whole-house energy consumption was much more sensitive to the humidity set-points than the chosen technology option.