Secondary Author(s)

Withers Jr., Charles; McIlvaine, Janet; Chasar, David; Beal, David

Report Number




Moisture; Heat Pumps; Ventilation; Hot Humid Climates; HVAC


The well-sealed, highly insulated building enclosures constructed by today's home building industry coupled with efficient lighting and appliances are achieving significantly reduced heating and cooling loads. These low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. Even if fixed-capacity equipment can be properly specified for peak loads, it remains oversized for use during much of the year. During these part-load cooling hours, oversized equipment meets the target dry-bulb temperatures very quickly, often without sufficient opportunity for moisture control. The problem becomes more acute for high-performance houses in humid climates when meeting ASHRAE Standard 62.2 recommendations for whole-house mechanical ventilation. This additional latent load coupled with the diminished sensible load of a high-performance thermal envelope makes the moisture-removal capacity of space-conditioning equipment more critical than ever. This project consisted of laboratory and field studies. For the field studies, two types of houses built by Habitat for Humanity were monitored in two Florida locations. Each affiliate employed different space-conditioning and ventilation strategies in highly efficient homes that met the DOE Zero Energy Ready Home program requirements. This material is based upon work supported by the Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Building Technologies Office under Award Number(s) EE0007056. DOE/EE-1702.

Date Published


Local Subjects

Heat Pumps; Hot Humid Climates; Buildings - HVAC; Buildings - Moisture; Buildings - Ventilation


FSEC Energy Research Center® Collection



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