Air leaks can increase home energy bills by 30 pct

Associated Press Modified: September 14, 2009 at 12:33 pm •  Published: September 14, 2009

Fall is the time when most homeowners begin to think about how well their home will shelter them from winter's blast and how much it's going to cost to stay warm.

The Department of Energy estimates only 20 percent of homes built before 1980 have adequate insulation. Even homes constructed 10 years ago may only have the minimum required by code. And, no matter how well a home's insulation performs, air can still escape through cracks around windows, gaps under exterior doors or entry points for utility wires and pipes. Leaks can account for as much as 30 percent of a home's annual heating cost.

The optimal way to find chinks in your home's armor is with an energy audit and blower door test. Generally they cost around $300, though the amount can vary depending on the size of the home, region of the country and complexity of the report. Testers are certified; many also offer good suggestions for solutions and will even do the work.

As an alternative to an energy audit, the Department of Energy suggests a visual inspection of the exterior. Their site,, also has instructions to check for leaks on the interior. Additionally, some local utilities offer free visual inspections.

—Small Fixes, Big Impact

Millard Blakey, an energy auditor and remodeler who owns WreckCREATIONS in Lexington, Ky., finds most consumers don't know what to repair first or what will bring the best return for dollars spent. Most want to replace windows, but it is one of the last fixes he recommends since the payback period is so long. Instead he looks for simple solutions like insulating behind outlets on exterior walls which, he says, can bring surprising savings.

Retailer Lowe's estimates that a 1/8 inch gap between a standard exterior door and its threshold is equivalent to having a two-square-inch hole in the wall. Door sweeps, the strip along the bottom of a door that seals the space between the door and the threshold, wear out quickly as does weather stripping. Both are easy and inexpensive to replace for $20 or less. Any interior door that leads to an unheated or colder space such as a basement should also be sealed with weather stripping.

Small cracks and crevices around doors and windows should be caulked or filled with a foam sealant specifically formulated for that job ($3 to $5 a can). Just these small steps could result in a 15 percent savings on heating and cooling costs according to Lowe's.

Leaky windows can also be tightened up with self adhesive weather stripping between the sashes. There is also a product that can be applied to the spaces in the frame where windows slide up and down, officially called the V Channels.

Another trouble zone that often turns up in energy audits are band joists along the top of foundation walls in basements. These wooden joists rest on top of the foundation and run perpendicular to floor joists. Even in newer homes they can be uninsulated. A professional will often spray into the area an expanding foam insulation such as Icynene, which is made from castor oil; DIYers often use fiberglass insulation.

—Slow the Flow

Whether the material is fiberglass, cotton, cellulose (recycled newspaper) or foam, insulation works by slowing the natural flow of heat from warmer to cooler spaces. This thermal resistance is expressed as an R-value, and the higher the better.

Some products are better for certain parts of the house and how they are installed contributes to effectiveness. "It's not a magic blanket between you and the cold. All insulation products must be installed correctly to perform at their rated R-value," cautions Charles Cottrell, vice president technical services for the North American Insulation Manufacturers Association.

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