Maine custom builder Don Pendleton is a pioneer of sorts, having adopted panelized construction a decade ago to ensure quality control and job-site efficiency. Pendleton Homes builds three or four custom homes per year, many in the $500,000-and-up range, often sited on oceanfront lots owned by the customer. Pendleton builds the panels at his shop near Augusta then trucks them to the home site and hoists them into place with a crane. His new passion is energy efficiency and the net-zero energy home. But, like other builders who are concerned with the costs associated with achieving net- or near-net-zero, he’s not attempted one. Until now.
Instead of doing his R&D on a customer’s home, however, Pendleton is building a two-unit townhouse apartment building on land he owns adjacent to his shop and residence. Each unit of the building, which he describes as modern industrial in design, is approximately 1,200 square feet, with living space and kitchen on the first floor, two bedrooms and a bath/laundry room on the second and an attached one-car garage. He intends to rent each apartment for $1,200 a month, including utilities.
“I’ve done a lot of reading, studying,” he says. In doing so, he learned quickly that what can get a builder to net-zero in, say, Southern California, Florida, or Arizona wouldn’t get him anywhere near that in Maine. But he had no idea how close he could get or how others have fared. There is, it seems, a lack of data about net-zero building in the state.
According to Ashely Richards, executive director of the Maine Home Builders and Remodelers Association, no one in the state knows how many net-zero or net-zero ready homes have been built in the state or how they were built. Robert Howe, a former state legislator (and net-zero energy home owner) who serves as CEO of the Maine Association of Building Efficiency Professionals, said there are "a few dozen, maybe.” He added, “However, the number of highly-efficient homes is much higher than that.”
Here’s the challenge: Maine is the third coldest state in the nation, according to the National Climatic Data Center in Asheville, N.C. At the winter solstice, there is less than nine hours of sunlight each day, which limits the efficiency of passive solar technology for nearly half the year. Solar panels also are severely limited in the colder months by both the declination of the sun, which sinks ever lower into the southern horizon leading up to the winter solstice, and by weather, often cloudy and, on the coast, foggy. There also is snow, on average between 50 and 70 inches a year in the coastal zone (last winter, Port Clyde, on the midcoast at the intersection of the Gulf of Maine and Penobscot Bay, topped 131 inches, according to the Maine Tourism Association).
At press time, Pendleton had the outside of the building completed and was starting interior work. He plans to use the usual array of energy-efficient technology, including air-source heat pumps that can generate heat down to 15 degrees below zero backed up by electric baseboard heat, an LP-fired on-demand hot water system, Energy Star appliances and a solar power system, either 8K if roof mounted or 14K if he decides on a ground-mounted array. From the start, however, he knew that the building envelope was going to be the chief contributor to the efficiency necessary to achieve net-zero or anything close to it.
To that end, he designed and built the building to be completely encased in 2-inch extruded polystyrene blue board, glued between the exterior 1/2-inch Advantech sheathing and the balloon 2X6 framing, sealed at every junction. He installed 4 inches of blue board beneath the 4-inch concrete slab on which the building rests and continued the blue 2 feet out from the foundation walls and 16 inches above the top plate. To preserve the integrity of the insulation, he built the living spaces first, installed the blue board, then added the eaves and garages. The blue board runs continuously around the slab up the walls to the roof.
The second floor ceiling will be insulated with 16 inches of blown-in cellulose, and another 2 inches of spray foam will be added to the existing blue board throughout the structure, adding rigidity (along with hurricane straps) to the walls, which then will be further insulated with fiberglass. Pendleton says that will give the building an R-value of 65 at the roof and 37 at the walls. He also is using triple-pane, argon-filled low-E glass from Kohltech Windows and Entrance Systems in Canada, which also is providing the glass for the Therma-Tru doors. Most of the glass in the building faces south.
So far, with the interior work yet to be done, Pendleton says he has about $90,000 invested in the building, not including labor. He figures the finished product, which he hopes to complete next year, will cost around twice that. He’s not sure he’ll get to net-zero, but he’s determined to get as close as possible and then incorporate what he’s learned into the high-end oceanfront homes he builds, making this an experiment in Low-E R&D.