Ventilation strategies for energy-efficient production homes.

The Environmental Protection Agency's (EPA) ENERGY STAR® Homes program seeks to reduce greenhouse gas emissions by encouraging U.S. production home builders to voluntarily improve the thermal quality of their construction by minimizing infiltration, improving insulation, and right-sizing HV AC equipment. Tight homes need active ventilation to maintain indoor air quality, but mechanical ventilation increases initial home cost as well as operating costs. We were asked to recommend ventilation systems that minimize installation costs without jeopardizing occupant safety, indoor air quality, or operating cost savings. We evaluated nine ventilation systems in four climates by comparing annualized capital costs, annual operating costs, distribution of ventilation air within the home, potential for depressurization, and potential ventilation-related condensation in exterior walls. Based on our analysis, we recommend Multi-port supply ventilation in all but cold climates, because it provides the safety and health benefits of positive indoor pressure, as well as the ability to filter air. In cold climates we recommend that Multi-port supply be balanced by Single-port exhaust. We recommend that forced-air heating and cooling systems not be used for supply ventilation unless forced-air ducts are well-sealed and/or within conditioned space, the forced-air fan automatically operates at least IO minutes each hour for ventilation.