I am planning to build a new house. I want one that is very energy efficient, but still livable. I know that standard stick-built is not the most efficient. What construction methods do you recommend?—Pete S.
While building a small, simple house with thick insulation and very few windows would save a lot of energy, it would not suit most American families. You should balance a home’s energy-efficient aspects with comfort and convenience.
The typical “to-code” stick-built house—a home constructed entirely or largely onsite—is not very energy efficient. However, with adequate insulation that exceeds building codes, high-quality windows and doors, and attention to construction details such as sealing all the vapor-air barriers, a typical lumber-framed house can be very efficient. For efficiency, make sure it’s ENERGY STAR home construction certified. Go to www.energystar.gov.
Several alternative construction methods can be much more efficient than a stick-built house. These methods include round panelized, geodesic dome, steel-framing, foam block/concrete, and structural insulated panels (SIPs).
A round house is particularly energy efficient for several reasons. A circle provides the greatest amount of indoor floor space with the least amount of exterior wall surface area. Since heat loss (or gain) from a house is directly related to wall surface area, less wall area results in less potential loss.
Circles, domes, and steel
A circular panelized house uses a series of 8-foot-wide flat panels to create the round house. A combination of insulation inside the hollow panels (filled at the building site with the customer’s choice of insulation) and thick rigid foam sheathing on the exterior results in a high level of insulation. The panels, built in a factory, fit perfectly together for an airtight house.
Geodesic dome houses are the ultimate in circular design for the least overall exterior surface area, but the interior living space is quite different from a typical house. The most efficient and strongest homes are made of a combination of 7-inch rigid triangular expanded polystyrene foam pieces covered with steel-reinforced concrete.
Although it seems counterintuitive because metal conducts heat, steel-framed houses can be very energy efficient. The most efficient steel-framed houses use large steel-framing members (called red iron) spaced very far apart. Special radiant barrier wraps used around the steel help prevent heat leakage.
More energy-efficient options
Foam blockhouses are assembled somewhat like hollow Legos. The lightweight expanded polystyrene foam blocks are stacked to create walls. When blocks are stacked, channels are created throughout them, and steel reinforcement bars are placed within the cavity. Concrete is pumped into the top and flows throughout the wall. The foam blocks provide high insulation levels.
SIPs are strong panels containing thick insulating foam. With high insulation levels and few joints needed between the panels, houses built with SIPs are efficient.