ROCKLAND — Black Bros. Builders, of Rockland, are the only net zero builders in Maine. Net zero translates into energy efficiency. What does that mean? Black Bros. Builders President Dennis Black explains: “Net zero means it’s an energy efficient, green house that costs very little if nothing for heat, electricity, lights and water.”

Founded 15 years ago, Black Bros. Builders represents brothers Brenan Black and Bryce Black, as well as their father, Dennis. A family-owned company, Dennis credits the two brothers with taking Black Bros. Builders from a traditional company to a forward looking company with a bright future. The Black Bros. Builders rebuild of the Knox Street apartments in Thomaston, now the Sail Lofts — the first and only large scale multi-family net zero in Maine, and one of only 5-6 nationwide — will be open for tours Oct. 5 during the annual Northeast Sustainable Energy Association (NESEA) open house. The Sail Lofts has a 65 panel array to provide heat and electricity for all nine units.

What is involved with building a net-zero building?

“It’s a little complex,” said Dennis. “We build a double wall system. Traditionally, most carpenters and construction companies would build one solid wall all the way around the outside of the house. We build two walls and they’re parallel to each other. The studs do not touch each other; they’re 12 inches apart, so it presents a true thermal break. The electrical and plumbing can go between the two walls, after which a blower air test is conducted to find leaks and seal them off.”

Note: A blower door is a tool that depressurizes a house. This depressurization exaggerates the home’s air leaks, making the leaks easier to measure and locate. Blower-door testing is useful for both new construction and existing homes. By testing a new home, a builder can determine whether a certain air-tightness target has been met, and can document aitightness levels needed to qualify for certain home labeling programs.

“After the blower test we use a dense packed cellulose insulation that’s at least an R-60 between the two walls and sometimes a R-120 in the ceilings, so it’s very, very tight,” he said. “We have to make sure the air is exchanged and we use whisper fans and vents to do that. And to heat a net-zero house we use solar panels and heat pumps. The windows are double-paned and in some cases triple-glazed.”

Does energy efficiency translate to a little more in construction costs?

“It is more and of course it depends on the house and what you have in it for finish work ,such as cabinets and flooring and appliances,” said Dennis. “Generally, the pay-back period for net zero houses is three years, and after three years there should be no energy costs at all for the rest of the life of the house.”

Are Black Bros. Builders are the only ones who do this type of housing at this time?

“We are the only ones in this area that do it without geothermal,” said Dennis. “We use solar panels and heat pumps; we’re not tapping into the energy source of the ground. We think our way is less costly. There are competitors in Portland, but we are the only ones doing what we’re doing in the area. We have homes going up now in Jackson, N.H., and in Freeport. We’re doing a timber frame house on Lake St. George in Liberty. And there will be a net zero envelope around the outside of the building. The owners can see the timber frame on the inside and it will be a complete net zero envelope on the outside. We’re pretty busy and we are fortunate.”

As net zero catches, on do you see this type of construction as the wave of the future?

“I absolutely do. We have five homes under contract for 2014 and we’re adding two more this year as soon as the plans come from the architect. Most all of our contacts have come from the Internet, or local people who have decided they want to go either green, or energy efficient. People are just tried I think of paying excessive fuel and heat bills. We haven’t had too many recent inquiries to build a standard house.”

Are there tax breaks and incentives associated with this type of construction?

“There certainly are. If someone goes to SOLAR MAINE INC. you can get a quick demonstration on how a heat pump works and see what tax breaks are available. From time to time depending on what the legislature does, it could be considerable.”

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