To design and build an energy efficient home can be quite a challenge. No matter what architectural style and design options are chosen, energy efficient new construction entails having a tightly-sealed thermal envelope with a high R-value and controlled ventilation, which in turn means lower heating and cooling bills. Thermal envelope means everything about a house which serves to shield the interior from the outside, including walls and roof assembly, insulation, doors and windows, weather-stripping, finishes, and air and vapor retardants. There are advanced alternatives to conventional wood stud framed walls and roof assemblies, which act to enhance the house’s thermal envelope. Energy efficient houses have much higher insulation R-values than most standard building codes require. For example, a house in the Northeastern U.S. might have R-11 fiberglass insulation in its exterior walls and R-19 in its ceiling; and foundation walls and floors might not be insulated at all. A similar house which is well designed and built would have a range of R-20 to R-30 in the wall and foundation insulation, and R-50 to R-60 in the ceiling.
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