Craig Brugi: Blower Door Test
By DAVID GREEN
Craig Burgi wasn’t expecting any trouble with this house. Not when he saw who handled the insulation job.
Burgi, who heads up the Energy Advisory Program for Steuben County (Ind.) Rural Electric Cooperative, had previously checked the energy efficiency for several houses insulated by Tom Henniger’s crew from Airtight Insulation in West Unity, Ohio.
Through the electric cooperative, Burgi provides the service free to all customers. Keith Walker and Sam Witt hired him to check the efficiency of the first two homes they’ve built on the grounds of the former Morenci Middle School.
Burgi uses what’s called a blower door test. After all the windows and doors are closed in the house, one door is opened and a plastic frame is inserted. A fan is attached to an opening in the frame and three gauges are connected.
Burgi enters data into a laptop computer, including information such as the size of the house, the heating source, the number of occupants and the cost of natural gas and electricity.
The fan is turned on and the atmosphere inside the house is de-pressurized as air is sucked out. When the top meter indicates a force of 50 Pascals—a unit of pressure—Burgi knows the artificial conditions he’s set up are equal to a 20 mile an hour wind striking the house on all four sides. With higher pressure outside the house, air flows in through unsealed cracks and openings. The final result produces the air infiltration rate of a structure.
At the Morenci home, the pressure doesn’t reach 50 Pa level immediately. Burgi attaches a ring to the fan to restrict the flow of air. That’s often needed in a tight house.
“If you get down to the second ring, you get a raise,” he says to Henniger’s crew—not that Burgi is the one paying wages.
A minute later he’s adding that second ring.
Burgi finally determines the house has a 2.5 rating.
“That means all the air in this house is exchanged two and a half times every hour,” he explained, “and that’s good.”
Any rating between 2.0 and 3.5 is considered well insulated. It’s possible to go too far in the air-tight direction, he said. If he comes up with a rating below 2.0, some extra ventilation might be in order since a natural exchange of fresh air is essential.
“This is a well-sealed house,” Burgi announces. “It’s going to be very energy efficient. Good job, guys.”
At this point in the test, Burgi and others move from room to room to look for air leaks. He doesn’t expect to find much with a 2.5 rating, and Henniger is proud of his company’s efforts to seal potential sources of leaks with caulk or foam.
In an older home, however, residents can easily track down leaks that lead to wasted fuel. A whistling sound will often be heard around electrical outlets, windows and plumbing fixtures.
Some states require blower door tests for new residences, Burgi said, but for his electric cooperative, the tests are available simply for the goal of helping customers save on fuel costs.
It doesn’t always work out the way he would like. It’s very frustrating, he said, to assist home owners in identifying leaks, then later find out they never followed up on the steps needed to make changes.
Henniger prefers a good cellulose insulation for fuel savings and for its sound deadening properties. He uses an insulation treated with boric acid for insect control.
Witt, one of the developers of the property, is willing to pay the initial heating and cooling costs at the two homes he’s built in Morenci.
“We’re so comfortable with our heating and cooling systems that we’ll guarantee the first year’s costs,” he said.
Based on the data obtained by Burgi, he convinced Walker to join him in paying the costs for the first year of a customer’s ownership.– September 20, 2006
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