Energy efficiency gets the 'green' light The NAHB is urging builders to use more products and technologies designed to lower electric, gas, and water consumption and slash costs. Builders are responding by using innovative products such as photovoltaic roof shingles, which use solar energy; geothermal heat pumps; energy-efficient windows, which block excessive sunlight and prevent air from leaking in or out of a structure; and Energy Star-rated appliances. NAHB President David Pressly says, "The green market is growing by leaps and bounds. And as the market expands, we will see prices come down, making energy-efficient choices much more accessible."