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V O L . X X V N O. X I I I J U N E 2 4 , 2 0 1 9 18 E N E R G Y / E N V I RO N M E N T F O C U S a three-bedroom, 2,200-square-foot home. An open house for a home still under construction drew 50 people. "at's the level of interest," Muller says. "And that was only two hours on a Sunday. When we held another open house, after we finished it, we had another 50 people. We had a contract within five days." But there's still a long way to go. Asked how much demand he's seeing in Maine, Corson replies, "Not enough." He continues, "ere's little thought given to the building enve- lope, quality of the windows, level of thermal insulation, mechanical venti- lation, durability and longevity of the structure, and air-tightness." 10% cost difference Passive house construction costs about 10% more than standard construction. But the proponents say the difference is more than covered by savings in energy costs. "We tend to say, on a small scale like a house, that if people assume approxi- mately a 7% to 10% increase in con- struction costs, they're going to realize an 80% to 90% reduction in operation costs," says Timothy Lock, a man- agement partner with Belfast-based OPAL (the architectural division of Belfast-based GO Logic), lead designer for College of the Atlantic's planned passive-house Center for Human Ecology in Bar Harbor. "Typically, the return on that extra 10% in investment is in the six- to eight-year range. It's a pretty quick return because you're saving so much on energy." e first passive house in the U.S. was built in 2003, according to the nonprofit Passive House Institute US. Standards are based on climate-specific comfort and performance criteria — an estimated 60% to 85% more effi- cient than conventional construction, the institute says. In 2011, GO Logic built Maine's first passive construction, a dorm at Unity College. e technique has mainly been adopted for single-family homes, but there's a growing number of com- mercial projects, like Wright-Ryan Construction's Village Centre, a 48-unit development in Brewer. Not rocket science Passive construction standards are increasingly well-known in Maine as a highly insulated structure with air- tight envelopes, ventilation to provide a steady supply of fresh air, high- performance, triple-glazed windows and orientation of the structure to maximize solar gain. e concept is relatively simple, with some differences from conven- tional framing. Village Centre is wood-framed, which is conventional for housing, but the walls can accommodate 12 inches of cellulose insulation. Early on, materials needed to provide an airtight envelope, like air-seal membranes, were mainly sourced from manufacturers in Europe, where passive construction is a longstanding practice, says Steven Konstantino, owner of Performance Building Supply in Portland. Today, "almost any builder knows about the value of air sealing a structure. In 2002, nobody talked about it," he says. "A lot of the materials are becom- ing standardized," says Reggie Lebel, president of Emerald Builders in Bowdoinham, builders of net-zero and passive homes. Emerald's prac- tices includes frequent blower door Energy-saving construction includes: OFF THE GRID: Black Brothers Builders is installing a Tesla Powerwall battery in a Knox home. The home is far from the closest powerline; the cost of connection would have been $30,000. The Powerwall plus solar panels and standby generator cost $40,000 for an off-the-grid solution, generat- ing heat and electricity. "This system saves them money in the long run," says Brenan Black. During the day, solar panels produce energy; the battery stores excess energy for future demand. P R E FA B : Ecocor High Performance Buildings owner Chris Corson prefabricates panelized wall and roof assemblies to passive house standards. All materials, including tapes, adhesives and membranes, are natural, mainly wood, with zero volatile organic compounds. Wood comes from within a 200- mile radius from the factory to minimize transportation's carbon emissions. Focused on the residential market to date, Corson plans to expand into larger commer- cial projects, with a launch planned this summer of cus- tomizable assemblies. W O O D I N S U L AT I O N : GO Lab, a spin-off of passive-construction firm GO Logic in Belfast, is devel- oping wood fiberboard, batt and blown-in insulation from wood chip byproduct from lumber mills. Wood insulation has been used in Europe for a long time, says OPAL man- agement partner Tim Lock, a lead designer of College of the Atlantic's planned Center for Human Ecology, which will use wood insulation. "Being able to produce it domestically would be huge," he says. "But it's up to the large projects to show the material is viable here. Having a partner like COA will say, 'We can do this.'" » C O N T I N U E D F RO M PA G E 1 6 R E N D E R I N G / T E S L A . C O M R E N D E R I N G / C O U R T E S Y C O L L E G E O F T H E AT L A N T I C P H O T O / C O U R T E S Y U N I T Y H O M E S P H O T O / C O U R T E S Y DAV E M E N T I O N A N D E M E R A L D B U I L D E R S R E N D E R I N G / E C O C O R . U S P H O T O / G O L A B OPAL, a Belfast architecture firm, led the passive house design of College of the Atlantic's planned 29,000-square- foot Center for Human Ecology, in Bar Harbor. A 1,371-square-foot net-zero home built by Landicity Builders and Unity Homes, which plans 17 ultra-efficient homes for the Douglas Ridge development in Brunswick. Emerald Builders built this high-performance cabinet shop, which is super insulated and airtight.

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