One of the primary goals of the 2012 International Energy Conservation Code (IECC) is to increase the energy savings in residential and commercial buildings by 30% compared to the 2006 code. This latest version builds upon the 2009 IECC, which calls for 12% energy savings over 2006, and whose residential requirements focus on significantly tighter and more efficient envelopes and HVAC systems.
Meeting the standards set by the 2009 or 2012 codes—along with complying with Energy Star Version 3, which went into effect on Jan. 1, 2012—would challenge almost any builder. And standards are only going to get more rigorous. “Advocates are pushing for codes that would be 70% to 100% more efficient [than the 2006 code] by 2030,” cautioned Bill Wachtler, executive director of the Structural Insulated Panel Association. That’s the same year the U.S. Department of Energy is calling for affordable net-zero homes and the 2030 Challenge wants all new homes to be carbon neutral.
Wachtler made these observations during an informative panel discussion he moderated at the recent International Builders' Show on energy code compliance using advanced building systems such as structural insulated panels (SIPs) and insulated concrete forms (ICFs). He also pointed out that the 2012 code requires all new houses to undergo blower-door tests that achieve an air infiltration rate of between three and five air exchanges per hour, depending on the climate zone. And Energy Star Version 3’s HERs score standard is 64. To achieve either of these via stick framing would require considerably more insulation and sealing than is currently common in most residential construction.
Wachtler and his fellow panelists—Frank Baker, the founder of Riverbend Framing Timber and Insulspan, who has been using advanced building systems for 30 years; and Don Ferrier of Ferrier Custom Homes in Fort Worth, Texas, who has been using SIPs in his construction since 1985—offered a detailed and sometimes highly technical argument in favor of advanced building systems. Such systems, they asserted, are more efficient and can help builders meet the new energy code standards because they provide an envelope with continuous insulation, no thermal bridging, and near-perfect air sealing. Advanced systems can also reduce builders’ labor expenses.
Baker conceded that, from a strictly materials standpoint, SIPs can be more expensive to install than stick framing. The 2012 code calls for six- to eight-inch SIPs for walls and 10- to 12-inch SIPs for roofs. “Greater thickness translates into higher costs.” He also pointed to the two Zebra Alliance Research Homes in Kentucky, whose thermal performance is being monitored by the Oak Ridge National Laboratory. One of the houses was built using optimal value framing, the other with six-inch SIPs. The SIPs home cost between $8,000 and $10,000 more. But it also saves 21% more energy and attained 40% greater air tightness. Perhaps even more important to builders in the audience, the envelope of the SIPs house went up in five days, compared to 15 for the stick-framed house.
Baker noted that a recent R.S. Means “time and motion” study found that using SIPs can cut framing labor costs by as much as 55% over stick framing, and 11% on electrical rough-ins.
Baker isn’t a fan of prescribing how builders achieve energy efficiency in their construction; he much prefers the “performance” method that measures the end result and pays less attention to how it’s achieved. This performance method, he said, is more likely to take a whole-house approach to energy efficiency than might a prescriptive method that measures each component’s efficiency individually. “Whole-house modeling also sometimes requires thinner panels and takes into account air infiltration,” he said.
He argued, too, that houses built with advanced building systems are less wasteful than stick-built construction, and often require smaller HVAC systems and shorter ductwork runs.
Ferrier lent his practical experience to Baker’s thesis when he noted that SIPs have become part of his marketing arsenal aimed at his two primary customer groups—retiring baby boomers and young professionals—who “are either looking for cost savings or green.”
He showed the audience some of the construction methods he’s used to reduce air infiltration, which mostly emphasize sealing before installation. Ferrier has found that SIPs work better on gable roofs than conventional plywood-and-truss construction because the cuts are more precise and easier to seal. It’s been his experience that SIPs are four to six times stronger than conventional stick-built walls, and are more adaptable to architectural designs, especially when it comes to window cutouts.
Ferrier was quick to note, however, that a given market’s labor costs will ultimately determine the relative cost benefits of using SIPs. He also noted that any efficiency measurement of advanced building systems is likely to depend on the orientation of the house to the sun, as well as the house’s air tightness and insulation. “These are the bases of our efficient homes,” he said.
John Caulfield is senior editor for Builder magazine.