Passive solar heating in cold, sunny climates can be very effective. One square foot of vertical south facing glass is equal in heat production to a gallon of oil during an entire heating season. Geothermal heating and cooling is also feasible in nearly every geographical location. Water is circulated down into deep wells, where it assumes the temperature of the soil – about 52oF. This stored heat is collected using a water furnace and then distributed throughout the building, usually in radiant tubes under the floor.

An array of photovoltaic (PV) panels can easily produce enough electricity to meet the needs of a properly designed house. In the state of California wind turbines produce the energy equal to 4.4 million barrels of oil per year. Many small turbines are available for private homes. In many locations, trees can be properly harvested, dried, and cut into firewood to be used in woodstoves capable of heating an entire house.

All renewable energy sources should be investigated and incorporated into a building design whenever possible. Once the energy is sustainably produced, it The Quaqiutl indigenous Americans of the Pacific Northwest built walls so thick that they could actually walk inside them. Similarly, the traditional Japanese engawa, usually on the south side of the house is, effectively, a sun room that helps warm a house with solar heat. Exterior walls should be thick, doubled and filled with insulation. When possible, exterior walls should also be multi-functional and integrated with halls, stairs, closets, pantries, and entrance foyers to insulate better; or, when on the south side, with sun rooms and greenhouses to warm the house. All large windows should include insulated shades and be triple glazed. Thermal masses of stone, ceramic tile or water columns are important features of a good passive solar building design. In warm climates, shading devices should be used, as well as cross and vertical ventilation to keep the building naturally cool.

Renewable energy is precious and must be conserved.