The vast majority of the energy that can ever be saved in a home is saved before ground breaking, during the home's design. If you are planning a new home, take time to learn about energy efficient design principles appropriate for your area. Your local library, book store and the Internet are good starting points. Most carry books with information about energy efficient construction and home plans tailored to your climate zone. You might also check phone listings for home designers or builders specializing in energy efficient homes. Other sources include your state energy office or local building officials.
The four most critical factors that will influence the home's energy efficiency are its siting, the thermal integrity of its shell (insulation levels and especially tightness), the efficiency of the selected heating, cooling, water heating and other energy-using equipment, and the use of natural cooling and passive solar designs to minimize the need for heating and cooling.