While energy-efficient home builders compete for the same business, those who flourish adhere strictly to the fundamentals of their trade. The fundamentals are solid construction and controlled ventilation, plus high-efficiency heating, cooling, appliances, doors, and windows. The job is to blend these with wall and roof assemblies, insulation, caulking, and weather-stripping to build a residence within a “thermal envelope” of comfort and energy conservation.
First of all, wood is the most dependable material for framing a green home, and today’s construction techniques use wood only where it is most effective. Since windows can rob a house of more than 25 percent of its heat, energy-efficient home builders in predominantly hot climates install the fewest windows possible in rooms facing north, east, and west. Total window space in each of these rooms should not exceed 9 percent of the floor area.
Proper insulation is vital, and green homes invariably have higher insulation R-values than those required by local codes. R-value is the measure of a material’s resistance to the transfer of heat; the higher the R-value, the lower the transfer. Carefully applied foam insulation, wet spray cellulose, and fiberglass are ideal for insulating wall cavities. Walls and slabs of a house’s foundation should be as well insulated as those in its living space.
A significant threat to the structure of any house is water vapor condensation. One solution is the vapor retarder, a material that inhibits the movement of water vapors. Another is the air retarder, which restricts airflow in and out of a home’s thermal envelope. Based on location and other factors, energy-efficient home builders will know the most effective way to proceed. Heat recovery ventilators can also save up to 70 percent of your utility bill by replacing stale exhaust air with fresh air flowing through the ventilator’s heat exchanger.
Residences built to energy-efficient standards usually require heating systems of less than 50,000 BTU per hour. One BTU is the amount of electricity needed to raise the temperature of one pound of water by 1° Fahrenheit-roughly equivalent to the burning of a single match. With minimal support from a furnace, electric heat pump, or standard water heater, energy-efficient home builders may produce a residence that needs only sunlight as its primary source of heat.
Keep in mind that any appliance yielding waste creates “waste heat,” which increases the need for fans and air conditioners. If an air conditioner is needed, a small unit may be sufficient.
As a result of these principles and constant flow of innovation, energy-efficient residences are more popular than ever. Taut construction and extra insulation keep interior walls at a consistent temperature, stabilizes humidity, reduces irritating drafts of cold and heat, and quiets the entire building. Clearly, energy-efficient home builders can produce structures with exceptional comfort, significantly lower operating costs, and enhanced market value.