Dodging The Draft Even Newer Homes Can Be Tightened Up To Save On Heat That Slips Through The Cracks Crevices

Imagine building a home with thick insulation, good windows and an efficient heating system, then leaving the back door open all winter.

It sounds silly. But that’s what many homeowners do, in effect, when they fail to insist that their new home be tested for tightness, according to David Hales.

“Builders think they’re building tight homes, but they’re not as tight as the (building) codes intended them to be. That’s why we’re not getting the performance we should,” says Hales, of the Washington State University Cooperative Extension Energy Program.

“When we look at houses with high energy costs, the problem is most often related to air leakage especially in newer homes,” says the building-science and energy specialist. (Older homes may also have inadequate insulation and substandard windows.)

Cold outdoor air sneaks indoors through a variety of small openings. Anywhere a cable-TV wire, stove pipe, gas line or recessed light fixture punctures a home’s “envelope,” that creates an opportunity for leaks. Ill-fitting weatherstrip around doors and windows also contributes to the problem.

Particularly costly, says Hales, is leaky furnace ductwork that allows pressurized air to escape in unheated areas of the house, such as an attic or crawl space.

Viewed individually, leaks in a home’s envelope and ductwork may appear minor. But add them up, and they can significantly compromise energy efficiency.

Hales admits it’s hard to estimate how serious the problem is, since the houses he studies typically have been performing below expectations.

But based on his 18 years of experience, here’s Hales’ best guess:

A study done in the late 1980s showed new Northwest homes having an average air-exchange rate of about 0.4 an hour. That means if you closed a house up tight, all the indoor air would leak out and be replaced by outdoor air every 2.5 hours. That’s important if you have to heat all that incoming air to stay comfortable.

Building codes adopted in the late ‘80s and early ‘90s intended for new homes to have an air-exchange rate of below 0.2 an hour. Once houses were tightened up, then fresh air would be mechanically introduced, bringing the exchange rate up to a healthy 0.35 an hour. And, in theory, when the temperature outside got really cold say, lower than 10 degrees mechanical ventilation could be stopped, reducing the home’s heat loss.

Good idea, Hales says, but that’s not how things have worked out. Since builders aren’t required to demonstrate that they’ve achieved a certain tightness, yet they are required to install mechanical ventilation systems, Hales believes the code’s tight-home strategy has backfired.

“Houses today are significantly different than before the code,” he acknowledges. Better insulation.

Better windows. “But they’re not as different as the code would have them. Air-leakage control is what builders consistently fail on.”

And since builders aren’t required to install shutoff dampers in their ventilation systems - a $60 item, says Hales - homeowners may not have the ability to control ventilation when outdoor temperatures plunge.

The reason new homes aren’t tested for tightness, says Hales, is money. There’s the cost of the test - $100 to $150 - plus the cost of plugging holes once they’re found. Total bill: $500-$1,000.

But Hales says the payback is fairly quick. With a 2,000-square-foot house, you can expect an annual energy savings of from $90 (with gas heat) to $216 (with electric).

Predictably, not everyone agrees with Hales.

Kootenai County building official Dave Daniel says new homes “are as energy-efficient as you can economically make them right now.”

He agrees with Hales that builders have no way of knowing how tight their product is without testing. But other factors affect energy performance, too, Daniel points out - especially the lifestyle of a home’s occupants. “A married couple with five kids is going to generate a lot more air changes (by opening and closing doors) than will a retired couple sitting in front of the television.”

Based on current Kootenai County and Washington state building codes, says Daniel, “I don’t think testing for tightness would accomplish that much. In most cases, it would be a waste of $150.”

The public seems to agree. One contractor who used to evaluate tightness with something called a “blower-door test” has gone out of business, and numerous telephone inquiries failed to locate others offering the service.

The Spokane-based WSU Cooperative Extension Energy Program will help homeowners find a private contractor to conduct a residential blower-door test. If one can’t be found, the Energy Program will conduct the test for around $100. But it’s then up to the homeowner or a private contractor to eliminate leaks.

Plugging leaks is easier to accomplish early in the construction process, before insulation is installed. But older homes can benefit from a blower-door test, too, Hales says.

Besides offering better energy performance, tight homes tend to be quieter. And they’re more comfortable, thanks to the elimination of drafts.

“People frequently ask me if they should invest in innovative technologies like ground-source heat pumps or radiant floor heat,” says Hales. “There’s a lot of wonderful technology out there, and you can’t beat it for operating cost.

“But the price of installing these systems is so high that the equipment won’t last long enough to pay for itself.

“The most cost-effective thing most homeowners can do today,” insists Hales, “is to build a tight envelope, or do air-leakage control on an existing home.”

Michael Guilfoil can be reached at (509) 459-5491 or by e-mail at mikegu@spokesman.com.