Many things make a home more energy efficient than others

By Ken Sheinkopf | Mcclatchy Newspapers • Published November 15, 2008

• Comments (0)

Question: What really makes one home energy-efficient and another one not? We've done a few things over the years to save energy in our home, but I know there are still a lot more things we can do to make it even better. Just how much has to be done before a home can really be called efficient?

Answer: There really aren't any specific levels of efficiency that need to be met before a home can be called truly energy-efficient. Rather, I think there are different degrees of efficiency in which one home can be seen as more efficient than another based on the amount of potential energy savings. Commercial buildings have some guidelines that are more specific (such as earning a LEED designation based on the number of points they get for different efficiency strategies), but about the only way to quantify a home's level of efficiency is to have an energy rater perform a detailed audit and give the house a rating (see www.natresnet.org for great information on home energy rating systems).

Note that you really can't tell if a home is energy-efficient just by looking at it. While some features can be easily seen (such as roof overhangs and exterior shading devices), many are part of the basic construction and aren't readily visible (such as the amount of insulation in the walls or a radiant barrier in the attic).

One of the best sources of information on what makes a home energy-efficient can be found from the U.S. Department of Energy (www.eere.energy.gov). Check out this site for explanations of building features that can save you money while making your home more comfortable.

While there might not be specific goals to reach to make your home efficient, there are many things you can do to significantly cut your energy use. Consider a research project by the National Renewable Energy Laboratory a couple of years ago that concluded that a 2,600-square-foot home in Sacramento, Calif., could have its energy use cut by 44 percent if it had just $9,729 in improvements added to the basic home. The major improvements they proposed, along with their costs, included a solar hot water system ($2,654), upgrading the walls from 2x4 studs with R-13 insulation batts to 2x6 studs with R-19 batts along with 2-inch foam sheathing ($1,748), having an R-10 slab perimeter insulation ($1,371), air sealing improvements ($1,408), relocating ducts within the thermal envelope ($829), and assorted other measures such as using Energy Star-rated appliances and upgrading the air conditioner to a higher-rated SEER unit.

Interestingly enough, two of the measures proposed that would be possible because of the other energy-saving features — would actually save money rather than costing anything extra. These are now being able to downsize the air conditioner to a 2-ton unit (saving $681) and downsizing the furnace to 50,000 Btuh (saving $108).

Finally, there's another valuable Web site that allows you to compare your home's energy use to other similar homes around the country.

Go to www.energystar.gov and fill out the Home Energy Yardstick.

You simply enter basic information about your home and your energy use and the site gives you a great deal of information to help determine your home's level of energy efficiency.

Ken Sheinkopf is a communications specialist with American Solar Energy Society (www.ases.org). Send your energy questions to askken@ases.org.