What do you get when you put a new spin on a traditional concept? If you’re talking about the world of framing, then one answer is Boise Cascade’s Conditioned Airspace HVAC Framing System. It’s a long name, but it accurately describes the company’s answer to an age-old dilemma.
In conventional framing systems, most HVAC ductwork is run through crawlspaces and attics, while the air handler or furnace itself sits in the garage. That means the intake air often contains whatever odors and pollutants that might be lingering nearby—gas cans for the lawnmower, half-used paint cans, bottles of weed killer—and pumping it straight into the living area. It also means the incoming air is usually the wrong temperature; stifling in the summer when you’re trying to cool things down and frigid in the winter when occupants most want to be warm. The traditional pathways for ductwork also translate into wasted energy costs in the form of leaks of expensive conditioned air into unoccupied spaces.
Enter Boise Cascade’s new framing system. It addresses the energy-gobbling drawbacks of conventional framing methods that run ductwork in unconditioned space, while simultaneously offering builders an option with more sustainable manufacturing methods and innovative design practices that cut down on waste and lessen environmental impact.
Testing Ground: VISION House LA
One home taking advantage of Boise’s new framing concept is Green Builder’s own VISION House Los Angeles, a demonstration home created to serve as a research and training ground offering information to builders, architects and consumers.
Los Angeles-based Structure Home is the project’s builder, and Mark Sapiro, Structure’s co-founder, says he chose Boise Cascade’s engineered wood products because they’re certified green engineered, a good match for this project. “I know that the products are manufactured with sustainability in mind,” he says.
Sapiro evaluated the product’s stability and potential to decrease callbacks, along with the system’s efficiency and waste reduction features. Result: He’s become a believer. “We really love the product and we hope to incorporate it, not just in this one VISION Home,” Sapiro says. “We’re hoping that Boise Cascade will be one of those manufacturers that we’ll continue to use and incorporate into future projects.”
Sourcing, Tracking and Planning
The sustainability of Boise’s system starts with the raw materials. “Boise Cascade demands full forest certification of all wood fiber used,” says Denny Huston, general sales manager of Boise Cascade Engineered Wood Products. “The company doesn’t own forests, but buys wood fiber in compliance with forest certification standards, such as the Sustainable Forestry Initiative (SFI) and Forest Stewardship Council (FSC).” Huston says that Boise Cascade utilizes a chain-of-custody tracking system that documents the sourcing of all wood fiber purchased, which ensures that only material from acceptable sources makes its way into Boise’s inventory. Through the use of this comprehensive, documented system, Boise Cascade engineered wood products are eligible for credits toward either LEED or National Green Building Standard certification.
Once the trees have been turned into EWP, Boise takes another opportunity to reduce waste. Instead of shipping standard-length lumber out to each job site, the designers at Boise use a suite of software applications including BC Calc to precisely plan out the location of each framing component, along with HVAC duct and trunk lines. The BC Framer software creates a floorplan identifying every I-joist, beam and rim board, along with locations for all necessary duct penetrations.
“It tells you the length and size of the joists and where everything is placed,” says Mike Carver, area manager of the engineered wood products division at Boise Cascade, “and you can see the whole duct schematic laid out with the I-joist schematic--it’s all been rolled into one.”
Carver explains that the plan is then evaluated in BC Calc, to ensure the floor joists will perform to the builder’s expectation. “BC Calc calculates and makes determinations on a couple different things: Are the joists going to be structurally sound? Are they properly sized for the job? And then how are they going to perform?” Because floor performance is of critical importance, especially in a high-end home, Boise’s designers evaluate not only the structural integrity of the framing system but also how the floor will feel to the homeowner.
After the plan has been through a final analysis, the lumber is then cut to match the plan exactly and sent on to the contractor. Because there are no extra materials or too-long boards being shipped, transportation costs and environmental impact is minimized. Job site efficiency is improved, too.
“When an I-joist package is delivered to a job site, it’s already precut,” Carver says. “There isn’t extra weight being taken to the job site like dimensional lumber, and where you’re typically cutting and pulling out bad boards, you don’t have that with engineered wood products.”
Boise Cascade’s system offers builders a range of benefits over traditional framing practices. Sapiro appreciates the product’s stability, which helps to prevent squeaks and shrinkage.
“[It’s] very easy to work with and very consistent in size and moisture content, which really does help prevent moving around, shrinking and expanding,” he says. “It’s also going to prevent a lot of damage to the ductwork that we’ll typically see in attics, where ductwork can get kinked, tangled, and damaged. Ducts are typically not as well-protected as this when they are run in the joist bays, which is pretty common.” He also appreciates the system’s ability to support shorter duct runs, and says the shift to using conditioned space for ducting is a significant move forward. “I think one of the big points is that they have the ability to cut out large sections of the web and actually run heating and air conditioning ducts through the floor joists,” Sapiro says. “We’re able to run our air conditioning ducts in conditioned air space as opposed to unconditioned space.
Huston says that Boise’s system “merges HVAC design and optimization with structural floor design and optimization for a solid, well-engineered solution that keeps the builder in charge of how homes are designed and built.” And home designers can work closely with HVAC contractors to create highly detailed plans that provide “optimum performance and least waste.”
He also says the improved design capabilities of the system offer builders the chance to reduce material and installation costs through more accurately specified ducting requirements and the potential to install only one H/C unit instead of two.
A well-engineered, sustainable product can also be a strong selling point when it’s time to lure homeowners. “It is a competitive advantage for a builder to be able to produce homes capable of consuming up to 40% less energy than homes being produced by competitive builders,” Huston says. “There aren’t many places a contractor can go to find that kind of month-in, month-out savings for homeowners.”
Carver agrees, and adds that IAQ should also be a talking point with homeowners. “If the builder’s able to say, ‘We’ve got a system that’s much cleaner and safer as far as air quality is concerned,’ that’s a pretty emotional appeal right there.” He says that builders who understand the advantages of the system “have a really good story to tell that’s going to differentiate them from other builders.”
To view this article as presented in our October 2011 issue, with additional photos and sidebars, please visit our Magazine Archive.
Product featured in VISION House Los Angeles.