A new technology that cuts heating and cooling costs
Structural insulated panels could make sky-high energy bills a thing of the past
Heating and cooling costs are uppermost in the minds of homeowners these days, whether they live in the frigid Northeast or the simmering Southwest.
In the Pacific Northwest, Donna Shirey of Shirey Contracting Inc. thinks she's found a remedy for skyrocketing energy bills. Her company builds homes with structural insulated panels (SIPs).
The panels consist of a thick layer of rigid foam insulation (compressed expanded polystyrene, the stuff found in foam cups) laminated between two sheets of wood.
They have been likened to a huge ice-cream sandwich that never melts. It's an apt description for what some people in the building industry are calling the wave of the future.
In a study by the Oak Ridge National Laboratory in Oak Ridge, Tenn., walls constructed of SIPs were found superior to traditional stick-frame walls in retaining their thermal properties.
Where regular insulation loses 30 percent of its R-value to wall studs, nails, wiring, switching boxes, and the like, the thermal integrity of a foam-filled SIP wall, which has a built-in channel for wires, loses only 3 percent.
Aside from their energy efficiency, foam-insulated panels offer better soundproofing and are sturdier than conventional wood-framed walls.
From the outside and inside, houses built of foam panels look like any other home. And because they're basically solid, mounting a shelf doesn't require searching for studs. Panels can be made in any thickness, but most often come in standard wall, floor, and ceiling thicknesses, with wall sections usually finished over with gypsum wallboard, as are many stick-frame walls.
The Structural Insulated Panel Association says that SIPs generally cost the same as more conventional building materials when all is said and done. Upfront, however, they may cost more than stud-style construction.
Bill Wachtler, the new executive director of the Gig Harbor, Wash.-based association, says he's still working on coming up with a side-by-side cost comparison, which can vary by region. But he notes that panelized construction saves on job-site labor and dump fees.
The real savings, however, come later - in the form of lower heating and cooling costs.
"In this building," Mrs. Shirey says of her company's foam-panel constructed offices in suburban Seattle, "if it's 30 degrees outside, we might turn on the heat for five or 10 minutes in the morning, and that's it. And in the summer, it keeps the heat out like a Styrofoam cooler. What if it adds $10 to your mortgage? In five years you may have saved 60 percent in your energy costs, and those savings are ongoing."
Mr. Wachtler jokes that with SIPs you can heat with a match and cool with an ice cube. While that's an exaggeration, he mentions a Michigan homeowner who spends $22 a month to heat a 3,000-square-foot house.
Despite this, SIPs are probably used in less than 1 percent of new homes, says Mark Nowak of the National Association of Home Builders. The reason: Builders are often reluctant to try something new.
"Because this [material] is new and different, the issue is awareness," Wachtler says. "But quality works in our favor: SIPs are perfectly straight and flat" - making them ideal to work with.
SIP technology has been embraced in suburban San Diego, Dallas, and Phoenix, where homeowners are concerned about air-conditioning costs.
Although SIP construction accounts for only a small corner of the current home-building market, manufacturers are struggling to keep pace with growing demand. Annual industry growth is estimated at 30 percent, causing some construction companies to build their own panel plants.
Another bump in demand may be on the horizon, since three of the nation's largest home builders are actively looking into using SIPs.
Shirey believes SIPs hold great promise for addressing two major industry problems: a shrinking pool of skilled labor and declining lumber quality. "The average age of carpenters in the United States is 55," she says. "Who's going to be building houses in 20 years? I don't know. There are fewer people coming into the trade. With SIPs, you can have one journeyman carpenter and others who are not as skilled."
Shirey says that panels also help solve dilemmas of building-material availability and quality.
"Studs are terrible today," she says. "SIPs eliminate [problems with] poor-quality dimension lumber." Stud construction depends on the quality of individual boards, which are now cut from younger trees, as old-growth forests have disappeared. This wood is susceptible to warping and shrinkage.
Structural insulated panels, on the other hand, are usually cloaked in oriented strand board (OSB), manufactured from bits of scrap wood fused into sheets. Besides being stable, these sheets use quick-growth trees, a highly renewable resource.
From a builder's perspective, SIP construction does not require new equipment or retraining carpenters. Panelized construction also speeds the building process and lessens job-site pilferage, since the panels are too bulky to tempt most thieves.
It reduces the number of subcontractors required to finish a job, making scheduling easier and delays less frequent. And because the panels are built in climate-controlled factories, weather delays are avoided.
With prefabricated panels, cut off-site, it's important that drawings be carefully checked so window and door openings, for example, arrive in the right places. "You have to make sure you've got the right panels with everything in the right location," says Mr. Nowak.
"It's rare a mistake is made because of the double- and triple checking that occurs," Wachtler says, "but if a mistake is made, you don't have to send the panels back to the factory. Things can be fixed on site."
Because SIPs are still relatively new technology, panels differ slightly from manufacturer to manufacturer, especially in how they are joined. Within a year, Wachtler predicts, the industry will achieve standardization.
Some people may wonder if the panels make a house too airtight. "We recommend mechanical ventilation," Wachtler says of the air-exchange systems that are common in today's tight homes.
SIPs are perhaps more impervious to high winds than traditional wood-built walls, and, as fans of their energy savings will tell you, their beauty is definitely more than skin-deep.
For more information on companies that produce structural insulated panels, visit www.sips.org.
(c) Copyright 2001. The Christian Science Publishing Society