An energy-efficient home is more comfortable and costs less to heat and cool. The elements of design in the energy-efficient house begin with the thermal envelope which is all of the parts of the house that keep the weather out: walls, windows, doors, roof and foundation. Other considerations are orientation on the lot, ventilation, heating and cooling, appliances and lighting, and points of water use.

Interior walls, traditionally built

• Determine the type of wall construction that will work best with your house plan. There are advanced framing techniques that provide strong structure with energy efficiency. Optimum value engineering, or OVE, uses less lumber and can reduce material costs 42 cents per square foot and labor costs 3 to 5 percent, as well as save up to 5 percent on heating and cooling. Structural insulated panels (SIP) are preformed panels with insulation between plywood or OSB (oriented strand board) sheets to created walls 4 to 8 inches thick.
• ICF, or insulating concrete form, walls are steel-reinforced concrete poured between layers of insulating extruded foam board, creating walls that exceed code requirements for hurricane- or tornado-prone areas.

Use traditional finishes.

• Plan interior wall finishes with energy efficiency in mind. The airtight drywall approach, or ADA, creates a continuous air infiltration barrier over insulated framing with caulking and gaskets along walls, as well as where walls meet ceilings, floors and windows. This system also seals seams where the subfloor, floor joists, headers, sill plate and foundation meet, creating an airtight house with traditional stick-built construction.
• Choose windows that will add to the energy efficiency of your home. It's common for a home to lose 25 percent of its heat through the windows. Awning and casement-style windows are the most efficient because they close completely.
• Position the windows for the climate. In cold climates place less glass on the north, east and west sides of the house and more on the south for winter solar gain. Windows should not exceed 8 to 9 percent of a room's floorspace, unless you're using southern exposure for solar gain. Appropriate roof overhang will allow winter solar gain while shading the summer sun from overheating your house.
• Choose windows and doors with Energy Star® labels. If you want solar gain and you'll have summer shading overhangs, choose your south facing windows with high Solar Heat Gain Coefficients (SHGC) to allow the winter sun to freely warm your home. The west, east and north windows should have low SHGC to block the summer sun from overheating your home.
• Plan your heating and cooling units with your tight house in mind. Because the energy-efficient home doesn't have the air leaks of a typical home, smaller capacity heating and cooling appliances can be used. The energy-efficient house usually requires a heat recovery ventilator (HRV) or an energy recovery ventilator (ERV) that use heat exchangers attached to the forced air system to bring fresh, preheated air into the home.
• These systems can also use a separate duct system if there's no existing duct system. In hot climates, using light colors on the roof and exterior walls can save up to 15 percent of cooling costs.
• Use energy-efficient appliances and lighting to further reduce energy costs. When buying new appliances check the energy rating on the Energy Star® appliance, and buy the most energy efficient you can afford. Check out motion sensor lights for rooms like bathrooms that are used for short periods.
• Plan your home to use water wisely. If you group your water-using rooms together, you'll save on construction costs and water. The farther your shower is from the hot water heater, the more water will stand in the pipes, cooling until you turn on the hot water tap. Consolidate the bathrooms, laundry and kitchen in one area to make water conservation part of your energy-efficient home.