On a cold day in Tacoma, thermography shows house-warming, heart-warming results
It was a record cold day in Tacoma, and a bright sun could not ease the chill of the light wind that wrapped itself around the dozen tidy homes of Larabee Terrace.
The cold snap provided the first big test of the heating systems, insulation and construction techniques used by the Habitat for Humanity volunteers and low-income homeowners who built these homes. Conditions were ideal for a quick course in thermography and weatherization. It was a great opportunity for Habitat staff members to learn to use their new Fluke TiR1 thermal imager.
Thermographer, and Sr. Product Manager, Michael Stuart had driven down from Fluke headquarters for the orientation. The Washington State University team, representing the Department of Energy Building America program, was there with their blower door setup. A blower door test used in conjunction with some thermal imagers from Fluke in one of the newly-built homes would reveal any gaps in the way they were built and point the way to greater energy efficiency.
Volunteers and partners
The homes at Larabee terrace step down a west-facing hillside in an old Tacoma neighborhood of smaller homes. It's the latest project of Tacoma Pierce County affiliate of Habitat for Humanity International. Habitat works in partnership with people in need to build and renovate decent, affordable housing. The houses then are sold to those in need at no profit and with no interest charged.
Since 1985, Habitat has built more than 162 homes in Pierce County, providing home ownership opportunities to households making 30 percent to 60 percent of the Area Median Income. And the benefits extend beyond the homeowners and their neighborhoods. The volunteers who devote their time to building the homes enjoy the warm feeling of giving back to their community. Each Habitat family must complete 500 hours of "sweat equity" through work on their and other people's homes or other work that helps the Habitat run. Habitat is a partnership that builds houses together with the families who will live in them.
"Our goal is to try and make these homes more energy-efficient and more affordable to live in," said Gomer Roseman, Site Development Director, Tacoma Pierce County affiliate of Habitat for Humanity International. "If we can reduce the utility bill by $25 a month, somebody who earns $25,000 a year would be very happy about it."
Modest in size (averaging 1500 square feet) and affordably priced, the Larabee Terrace homes are built to save energy. Their heating systems, designed by a retired Boeing engineer, get double duty from an on-demand gas water heater used to warm domestic water and provide under-floor radiant heat. Foam exterior sheathing boosts wall insulation from a standard R20 to R30.
"That shows up in the infrared imaging," said Mike Lubliner, Sr. Building Sciences Specialist for the WSU Extension Energy Program. "You don't see the distinct heat loss normally caused by the studs in the walls." As Stuart demonstrated its use, the imager made other construction details and areas for possible future improvement surprisingly easy to see. The infrared scans revealed the normally expected cooler areas where walls and ceilings come together—and were even sensitive enough to see where sheetrock screws were under the paint.
Infrared reveals opportunities
After a quick thermography introduction, the WSU team set up a blower door in a recently completed home. The door-mounted fan drew air from the structure, reducing the interior pressure and pulling in cold outside air through openings visible and unseen.
Though the house performed well, some fixes were needed. In the imager's scan, some electrical outlets in outside walls took on a cooler blue tint where air infiltration was occurring through the electrical chase. In another area, cool "air fingers" lightly streamed from a ceiling fixture -- evidence that cooler air was coming in through the fixture and cooling off her surface of the ceiling around it. A few areas even showed where a little more attention could have been given to the placement of the fiberglass bat insulation in the upper part of some wall cavities. Roseman said the results will help produce a better, more efficient, Habitat house by indicating where improvements can easily and inexpensively be made during the construction process and afterward.
"Everything that we've seen as a result of this test indicates something we could be doing differently that would give us a better result," said Roseman. "What we've learned today is that we need to provide better sealing around our electrical penetrations in the walls, and we need to pay more attention to the connection at the top plate. Those are things we're going to work on now and try and build a tighter house.
"If we can build a better house for the same price, and it results in a saving for the owner, we've accomplished something. Tools like this allow us to see the hidden movement of air, things that aren't visible to the naked eye—things that enable us to do a better job without spending a lot of money."
According to Lubliner, infrared testing could be even more productive as Habitat moves into rehabilitating existing homes, built without the energy-conscious techniques of today. "I believe there will be more and more focus on existing homes," he said. "I think the infrared technology and blower door technology will get us more low-hanging fruit in the existing sector than they will in new homes."