Super-Insulated, Energy-Efficient Modular 

The Treats 2,400-square-foot house was built at the Keiser Homes factory in Oxford, Maine. As promised, says Treat, "The house arrived in four boxes on flatbed trucks. It was done all the way to the plaster on the walls. The electric was in, and the plumbing was roughed in."

"We use double stud wall assembly with a three-inch thermal bridge and dense-pack cellulose insulation," explains Meyer. "The windows are triple-pane. The doors are high-performance and insulated. Because the home is modular, it requires a four-inch crawl space or basement that's fully insulated and integrated with the thermal envelope of the house."

The air-tight construction resulted in R-40 walls, an R-60 roof, the slab at R-20, and the foundation walls at R-10. While assembling the home, the construction team sited the house for maximum solar gain - an 8.83 kW system by SunBug Solar powers the all-electric home. The project payback was projected at four to five years, with savings of $82,364 over 30 years, while producing 104% of electricity needs a year.

"We got our payback in a little more than four years," Treat says. She also wrote a blog on the family's energy use. In 2016, she wrote, "The total for our home energy use? $433.74! For a year! That's heating, cooling, hot water, cooking, appliances, even plugging in our Chevy Volt each night. Wow."

The Treats looked at electric options for heating and cooling that would work in conjunction with the home's rooftop solar array. Natalie was set on electric heat pumps, given her work with Northeast Energy Efficiency Partnerships, as the works on market strategies to advance energy efficiency. They decided electric heat pumps would provide more efficiency at less cost than a ground-source heat pump.

While the construction team was setting up the house, then, they installed a ductless system for the Hyper-Heating INVERTERTM (H2i®) system by Mitsubishi. Quiet and unobtrusive, the system keeps the home comfortable no matter the temperature. When they're out of the town, the couple, using a wireless system, can also turn the heat up or down, so the house is the right temperature when they return home. 

Heat-recovery ventilators (HRVs) provide fresh air to the living spaces, remove stale air from kitchens and bathrooms, and pre-condition the incoming air. The heat pump hot water heater uses one-third of the energy of an efficient resistance hot-water heater. It also doubles as a basement dehumidifier. Electric floor mats under the tile provide supplemental heat for the upstairs bathrooms.

The home also includes Energy Star electric appliances; low or no-VOC paints, finishes, adhesives, and sealants; and minimal or no flame retardant in upholstered furnishings. Dual-flush toilets and low-flow fixtures ensure water efficiency.  

Rewards and Challenges 

Being early adopters says Treat, came with challenges. Treat advises that if a homeowner is considering modular, that they "fully understand the project management arrangement between the architect, builder, and factory. In our situation, we were among the early customers going through the process with BrightBuilt. With our feedback, they changed the arrangement so that only their pre-selected partners will work with them, and the customer has a contract directly with BrightBuilt."

The adage "measure twice, cut once" is also pertinent when going with modular. "Building modular requires a lot of good planning and communication. Measure twice, cut once to avoid electrical outlets in places that don't make sense and other snafus," Treat says.