News Treehugger Voices These Prefab Cabins Are a Conscious Consumer's Dream Low upfront carbon? Built on stilts? Cross-laminated timber? Check! By Lloyd Alter Lloyd Alter Facebook Twitter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. Learn about our editorial process Published August 3, 2022 09:42AM EDT Fact checked by Haley Mast Fact checked by Haley Mast LinkedIn Harvard University Extension School Haley Mast is a freelance writer, fact-checker, and small organic farmer in the Columbia River Gorge. She enjoys gardening, reporting on environmental topics, and spending her time outside snowboarding or foraging. Topics of expertise and interest include agriculture, conservation, ecology, and climate science. Learn about our fact checking process CABN.CO Share Twitter Pinterest Email News Environment Business & Policy Science Animals Home & Design Current Events Treehugger Voices News Archive A few years ago, I imagined my healthy and green home—an extreme dream edition. I wrote, "If I was still practicing architecture and a client came to me with a request to do the greenest and healthiest house possible, a new build on an open site, (which of course we shouldn’t do but it is a client, right?) in a temperate to cool climate, this is what I might propose." Among its many attributes, I would: Build it out of solid woodMeet the Passive House standardAvoid plastic wherever possibleGo all-electric with heat pumps and a heat recovery ventilatorBe built on stilts to avoid the use of concrete. But now I can leave my set squares and clutch pencils in the drawer because that's pretty much what Jackson Wyatt's new company CABN.CO is doing. In fact, times have changed since I thought up my dream home in 2016 so they go well beyond it, addressing the issues of upfront carbon emissions and going beyond net zero with solar systems. 2 bedroom house in city. CABN.CO Perhaps the most noticeable features of the models CABN featured on their site are the roof overhangs and solar shading. They are obsessed with it, "using shading, window placement, orientation, and wall and roof angles," and "these elements create a highly efficient structure for year-round comfort and energy generation." CABN doesn't use the Passive House model but developed its own Energy Informed Design (EID) system that is very picky about orientation. Wyatt tells Treehugger these units are designed in anticipation of continued climate warming, where overheating will be a major issue. "CABN.CO buildings are performance optimized for the heating and cooling of the building due to changes in solar gain (sun exposure). Through orientation, window optimization, and shade strategies, the CABN buildings minimize fluctuations in peak hot and cold temperatures and minimize energy consumption to maintain thermal comfort." Their EID model also accounts for location, occupancy rate, insulation, ventilation, infiltration, fenestration, and configuration. Whew! They write, "CABN is considered a Net-positive Energy Building when applying thermal bridge free components airtight construction, electric systems with heat exchange ventilation and on/site renewable energy generation within the building elements." CABN.CO The wall construction is very much like my dream house wall, which was used by Susan Jones in her wonderful Seattle house, where the structure is about 3 inches of cross-laminated timber (CLT) left exposed on the inside, which is wonderful for aesthetics, biophilia, sound, and moisture management. Jones used rock wool because wood fiber insulation was unknown in North America at the time, but CABN wraps the entire building in the stuff, with 8 inches of the standard board wrapped in another inch of water-resistant board. The parts of the home are panelized in the factory and delivered to the site in standard shipping containers so that they can go anywhere. Helical Piles. CABN.CO They also use my favorite footings: helical piles, which you just screw into the ground. This eliminates excavation and concrete, has a minimal impact on the landscape, and at the end of life of the building, they just unscrew again. Because the house is built on these stilts, one can wrap the wood fiber insulation right around the bottom of the house where the plastic foam usually goes and eliminate the thermal bridge where the house and the foundations usually meet. I love the wooden walls. CABN.CO There are a few minor technical quibbles; CABN is proposing R-744 (carbon dioxide) heat pumps, which deliver hot water, supplying heat to radiant floors. But in a warming world, it might make sense to use an R-290 (propane) heat pump that can also cool. We have also learned that radiant floors are overkill in a Passive House with so little heat loss; they rarely get warm enough even to be noticed on bare feet. BuildingGreen's Alex Wilson has written that “it’s a great heating option for a poorly designed house." We have shown Passive House designs not much bigger than these that are heated with a towel warmer. two bedroom unit plan. CABIN.CO The plans as shown are also problematic: When I was trying to promote a modern green prefab, I thought the hot model would be two bedrooms, around 750 square feet, as CABN shows. But almost everyone who came through the door wanted three bedrooms, two baths, and one level. In many municipalities, building under 900 square feet wasn't even legal. Wyatt acknowledges that this is where much of the market is and is developing designs for it. I came to realize why this was. Once people pay for the land, servicing, and the hard stuff like heat pumps and kitchens, a bit of extra space seems cheap, though less so with expensive walls and windows. CABN.CO And to be fair, CABN is just getting started, building their first model home this summer. They have plans for additional dwelling units (ADUs or ARUs in Ontario), garden suites, and affordable units. There will likely be a wide range of models. We have no word on cost other than noting: "The key purpose of sustainable building isto reach maximum energy efficiency and decrease costs. Traditional construction strategies focus on initial construction cost while ignoring the cost of the structure long-term in both environmental and monetary impact." This is a hard sell in the land of squarefootitis; these will not be cheap upfront, but will be in the full life cycle. In the Mountains. CABN.CO There is more to this than beautiful renderings of single houses in the mountains. In the end, Wyatt and CABN may not be overstating or overselling their case when they write, "Using our innovative prefabricated component construction strategy, combined with energy-modelled design and renewable technology, CABN.CO has created a new era in home design for the conscious and connected consumer." This really could be that green and healthy home, extreme dream edition, finally a reality.