Passive House has long been hailed as the high end in high-performance building: capable of remarkable efficiency, but only available at a premium. But what if you could achieve the efficiency of Passive House at a price so low that the slight uptick in the owners’ mortgage payment was eclipsed every month by what they were saving in energy costs?
Not only has Roanoke, Va.-based Structures Design/Build achieved exactly that, but also the firm is doing it on a large production scale.
“This is not magic. This is not voodoo. This is real,” says Adam Cohen, the company’s co-owner, who says that the same tool that has allowed his firm to achieve such high efficiency goals is the same tool that has enabled it to cut back on costs.
“Passive House’s methodology is not prescriptive. It’s just a performance metric that you have to meet, and they give you tools to meet those goals. As a designer and builder the world is completely open to my creativity,” Cohen says.
Cohen has now been building low-energy buildings for 30 years and acts as vice chair of the Technical Committee of the U.S. Passive House Institute. However, when he first started building to Passive House standards, he used the Passive House Planning Package—a 30-page Excel spreadsheet that calculates the impact of individual elements on the building’s overall performance—not only to maximize efficiency but also to optimize for cost.
“I took all my cost codes for the previous 10 years and targeted which of the codes would change in a Passive House,” he says. It turned out to be no more than eight or 10. “I prioritized them and asked which cost codes had the potential to save the most.” From there, Cohen was able to start developing new building systems, such as a thermal-bridge free wall system, that allowed him to cut both costs and improve performance. “We were able to cut, cut, cut,” he says, adding that he recently developed a new ventilator that allows him to cut another $4K to $5K off the price of a home.
Now that he has a honed system, the builder is now working on a panelized system that other builders can use to achieve high performance at a low cost. He anticipates it will be available mid-2014. “We’re trying to move what we’ve learned into the mainstream.”