One of the most useful documents available to contractors working on deep energy retrofits is the Mass Save Deep Energy Retrofit Builder Guide. Created by Betsy Pettit, Ken Neuhauser, and Cathy Gates of Building Science Corporation, the compendious tome starts with a thorough discussion of the principles of deep energy makeovers, and then moves on to a comprehensive set of building details developed (and in many cases field-demonstrated) by Building Science Corporation.

There's just one problem, says New York architect Ken Levenson: Nearly all of the building details in the guide are based on spray foam. Levenson, along with partner Floris Buisman, founded the New York-based distributor 475 High Performance Building Supply to bring advanced European air-sealing and vapor-management materials to the U.S. market. Most of these high-tech membranes and tapes are designed to work in conjunction with a low-tech insulation: dense-blown cellulose. But the details can be complicated. So Levenson and his team have set out to create a suite of details for retrofit and new construction that will accomplish the air-sealing and insulation they're aiming to achieve, but without the foam.

Several excerpts from the detail set appear in "Details for Foam-Free Superinsulated Construction." The full set is still a work in progress; updates are being posted at this 475's page "Construction Details" page.

475 sales rep Oliver Klein is quick to shake off the "anti-foam" label. At an Efficiency Vermont conference in January, Klein said, "We don't reject the use of spray foam. We'll specify it where it's appropriate." Levenson agrees: "We're not allergic to it," he says. "On many of our projects we work with foam." But in a blog post on July 3, 2013, Levenson issued a manifesto titled "A Declaration of Independence from Foam Plastic Insulation," a long list of foam's alleged offenses in the style of founding father Thomas Jefferson's original Declaration. He's intentionally taking a strong stance about foam's limitations and drawbacks, says Levenson: "We think somebody has to go out on a limb and make the case, and we're willing to be the ones to do it."

New York Passive House consultant Cramer Silkworth takes a more moderate position. "I am not quite that against foam," he says. "I know it does have its applications when used competently and intelligently by a qualified contractor. But I have seen it done very poorly in a Brooklyn brownstone renovation. Somebody did it, and they didn't get a great job done, and they had to go back and fill a lot of little gaps. "

"With cellulose," Silkworth goes on, "if your cellulose guy didn't get it quite right, you can just fire up the machine again and pack in a little more. if it got really screwed up, you slice the netting, pull it all out, and start again. it's really easy to fix situations that occur, as opposed to the spray foam, where you gotta call the guy back, he's gotta bring the truck, start the rig, suit up, get everybody else out …."

And I have just not had a project where I felt like spray foam was the only good solution for it," says Silkworth. "I've got what I need in the cellulose. It's a nice inert product that doesn't depend on a contractor on site getting a chemical reaction just right. Nobody has to wear a full body suit, a chemical respirator, all that other stuff."