Design Architecture Keep It Simple With Prefab Passivhaus Panels By Lloyd Alter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. our editorial process Facebook Facebook Twitter Twitter Lloyd Alter Updated March 27, 2019 ©. Simple Life Share Twitter Pinterest Email Design Tiny Homes Architecture Interior Design Green Design Urban Design The Simple Life shows that building healthy, efficient buildings isn't complicated. Building a decent wall is tough, particularly when people, both builders and occupants, don't understand how a wall works. Everybody talks about R-Value and the amount of insulation that they have, but few talk about the whole wall as a system, and about the amount of heat loss through leaks. Wall assemblies built on site require serious care and attention to get it right and minimize air leakage. Building codes never even used to set a standard for air leakage in houses, and builders used to think that a sheet of 6 mil poly stapled over the studs was enough. Now we know better, and many codes now demand a certain level of airtightness. In Ontario, Canada, it's 2 Air Changes per Hour (ACH) under 50 pascals of pressure, and is tested with a blower door. That sounds tight, but you still have to heat or cool twice the entire volume of your house every hour. Jeremy Clarke of Simple Life Homes with panel/ Photo Lloyd Alter/CC BY 2.0 Passivhaus designs are even tighter, permitting only 0.6 ACH. We recently showed a house that got down to a remarkable 0.13 ACH. This is really hard; you have to build a perfect wall. That's why I like prefabricated walls like Jeremy Clarke builds at The Simple Life in Port Hope, Ontario, which I learned about in the Green Building Learning Zone. Wall panel / Lloyd Alter/CC BY 2.0 Each panel is a giant 12" deep box filled with cellulose insulation for an R-value, sealed up on the outside with Mento Plus, which does not explode in contact with Coke. It's a "reinforced, airtight, 4-ply, vapor open, weather resistive barrier and roof underlayment. This highly durable membrane is designed to replacing sheathing, and can be used as netting for dense-packing insulation." © Simple Life Inside, a 3/4" layer of plywood acts as the air and vapour retarder. There is no more cheap layer of plastic film that is so easily perforated. Inside that, there are 2x6 studs where all the wiring can run, so that the air retarder is never drilled or punched. And you can fill that with even more insulation. © Simple Life The prefab wall components are erected on site, fastened together with the joints taped over. The result is one very tight, well insulated structure, made mostly of wood and old newspapers. Eighteen-inch-thick walls also make very nice window seats. It's like being in two places at once. © Simple Life Jeremy also tells builders and clients that they will get their job done more quickly because he builds the walls in his shop. We help reduce your on site time by delivering pre-fabricated panels as soon as the foundation is ready. There's no need to retrain your team, slow for weather, or worry about costly mistakes, and you can rest easy knowing you've delivered the highest performing house available. Simple Life is not the first company we have shown doing this; Ecocor is doing it in Maine, and Quantum Passivhaus is doing it further north in Minden, Ontario, both places with cold long winters. In many parts of Ontario, people are having trouble affording heat because of high electricity prices, so building to Passivhaus standards can actually pay for itself. Of course, it's a tough sell, convincing people to spend money on insulation and quality that you can't see when gas is so cheap they can't give it away. In Texas, the price is actually negative right now, and we are burning more of it than ever. We are in a crazy upside-down world. But Passivhaus quality buildings are comfier and healthier, and gas won't be free forever.