Enterprises. The sample houses are rather typical for the area, but they nonetheless may hold the future of cost and health conscious ventilation and other energy design features -- not just for the cold Rocky Mountain winter climate but everywhere else as well.

McStain is a member of the Consortium for Advanced Residential Buildings -- CARB, for short -- one of five Building America teams sponsored by the Department of Energy and the National Renewable Energy Laboratory to identify cost savings in labor, material and equipment that can be applied to improvements in energy efficiency, comfort and occupant health.

The six plans integrate the houses' structural and mechanical components using value-engineered framing and "inside the envelope" duct work configuration that reduces labor and materials costs without sacrificing comfort. Blending design and engineering ensures that the various systems work together to cut heating and cooling demand so a smaller, more efficient and less expensive HVAC plant can be used in place of the normal size unit.

McStain's existing product line already earns a four-star rating from Energy Rated Homes of Colorado. But the whole-building approach taken with the new models is expected to achieve a 30-40 percent reduction in energy costs when compared to houses built to the current standards of the national Model Energy Code.

In Colorado, constructing houses with "tight" building envelopes for a minimum of unwanted air infiltration is a top priority. At the same time, however, air tight homes that are under-ventilated do a poor job of removing indoor air pollutants such as carbon dioxide and carbon monoxide as well as airborne irritants from cleaning solutions, residual dry cleaning chemicals and volatile organic compounds released by paints, finishes, adhesives and fabric treatments.

In an enclosed space that's poorly ventilated, any combination of these pollutants can result in a potentially unhealthy indoor environment -- and not just to people who are more sensitive than average.

To address this problem, CARB and McStain have devised a ventilation strategy that delivers an appropriate amount of fresh air to the living space at all times. An exhaust fan pulls airs from the bath and powder rooms, while an outside air duct provides a path for fresh replacement air to be brought into the house.

A regulator on the main duct maintains appropriate air flow under varying pressure conditions, and a manual damper is included so the duct can be closed during extremely cold winter weather. Operating schedules can be programmed to meet changing seasonal demands, or simply left on default settings for easier operation.

In carefully controlling the amount of fresh air that's introduced into the house and minimizing out-gassing by using environmentally benign paints, finishes and adhesives, CARB and McStain hope to improve indoor comfort as well as air quality.

To help in that regard, sealed combustion furnaces, water heaters and fireplaces are specified to be certain that other gases are not released into the living space. Furthermore, carpeting, decking, siding and floor joists are all made from recycled or resource-efficient materials, and sprayed cellulose insulation made from recycled newsprint is used in exterior walls.

Pat Murphy, McStain's construction vice president, says to many builders have been "underestimating the sophistication" of the home-buying public. "People are looking for the same level of technological innovation that they see in other aspects of their lives," he warns.

Murphy says working under the CARB banner has enabled his company to take its commitment to consumer comfort and well-being "to a whole new level." And for him personally, it means "creating an appropriate balance between durability, cost and resource efficiency, aesthetics and good health."

Published: July 3, 2000

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