Think Big About Energy-Efficiency Measures, but Plug the Little Leaks

New windows can improve energy efficiency. Cold air streaming in around the doors and windows can be eliminated with caulk and weatherstripping.
New windows can improve energy efficiency. Cold air streaming in around the doors and windows can be eliminated with caulk and weatherstripping. (By Mary Ann Chastain -- Associated Press)
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By Katherine Salant
Saturday, February 21, 2009

Most of the discussion about energy efficiency has focused on new construction and major renovations. Now it's time to shine the spotlight on existing houses and their often abysmal energy-use profiles.

Houses built to the standard of the most recent building code revisions -- the 2006 International Energy Conservation Code -- are reasonably energy efficient. But the efficiency of the roughly 80 million built before then ranges from acceptable but not great to marginal to truly awful when you get to the millions of houses built before 1970. Antiquated, nonexistent or inadequate energy saving measures can send as much as 50 percent of a household's heating and cooling energy directly to the great outdoors.

To get a sense of the enormous differences in energy consumption between old and new houses, take a look at their Home Energy Rating Systems (HERS) scores. The Energy Department uses HERS scores to determine Energy Star qualification for new houses.

A house built to the 2006 International Building Code standards will receive a HERS score of 100. A house with a HERS score of less than 100 uses less energy and is more efficient. To qualify for the Energy Star rating, a new house must score 85, which means it's 15 percent more efficient than that standard. A house built before 1970 will often have a HERS score of more than 200, which means it uses more than twice as much energy as the 2006 house, and a house built to the standards of the 1980s and '90s will often score between 130 and 140, said Nate Kredich of the U.S. Green Building Council.

What is the best way to address this problem?

You might assume that it's getting a new furnace or a condenser for central air conditioning, especially if your house is 30 years old and still has the original heating and cooling equipment.

But green building experts urge you to start with the low-hanging fruit and your "building envelope," or all the surfaces exposed to the outside. First, get an energy audit of your house from an energy specialist. (For more on this, go to Home Improvement at the Energy Star Web site, Some things can be done by handy homeowners, but many require professionals.

Every hole in the wall, including those for light switches, outlets and ceiling light fixtures, is an opportunity for air to get in and out. As much as 25 percent of your heating and cooling energy can be lost through these often tiny, pinhole-size leaks.

"In 99 of 100 houses in the U.S. on a cold, windy day, you can put your hand in front of a light switch or outlet and feel cold air coming in," said Ron Jones, editorial director of Green Builder magazine and a life member of the National Association of Home Builders board of directors.

Green building consultant David Johnston and his wife lit lots of candles for their first dinner party after moving to Boulder, Colo., in 1993. Within five minutes, drafts in his 1972 house had blown them all out. He began addressing the problem the next week.

Air leaks in the walls can be plugged with caulk or an expansive foam sealant, Johnston said. The cold air streaming in around the doors and windows can be eliminated with a combination of caulk and weatherstripping. This is one cure that most homeowners can do themselves.

The duct system used with forced-air furnaces and central air conditioning can also have leaks. These can account for as much as 25 percent of total household energy consumption. In older houses, the ducts can be sealed from the inside, using special equipment that sprays a liquid resembling latex paint, Johnston said.

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