NEWRY — To all outward appearances, a two-story cape being built off Sunday River Road is a conventional house with many south-facing windows.

It’s the future home of Ken Hotopp, a conservation biologist, and his wife Robin Gorrell, a veterinarian at the Bethel Animal Hospital.

Closer examination reveals thick doors and triple-pane windows that Hotopp said were made in and shipped from Lithuania.

Inside, the Passivhaus solar home is being buttoned up tight by Danish native Jesper Kruse of Greenwood and his Maine Passive House crew.

So tight and super insulated that when finished, the “green” energy-efficient house will use less than a third of a cord of wood for heat annually, Kruse said standing in the front entryway on Wednesday.

“If you want to be green, for me, it really starts with the energy,” he said.

“If you want to reduce your carbon footprint, it’s got to really come down to how much oil are you burning? How much electricity are you using?” Kruse said. “I mean, you can buy a bamboo floor, but it’s not going to increase your comfort.”

Hotopp said the house “is an evolution in building.”

“Virtually all the techniques you see here, you can find in other houses in the area,” he said.

“Some of them are 10 years old; some of them are 20 years old. There’s nothing here that’s really rocket science, I mean there’s no new materials or something that isn’t fairly straightforward,” Hotopp said. “It’s putting it all together in a well-designed way that gives you really high energy savings.”

That’s why it’s called a Passivhaus building and is only the third such in Maine, Kruse said.

Passivhaus is the German energy standard for such structures. That means they are certified to meet stringent standards, like the amount of energy used to heat the building, the amount of energy used overall by the house and its air tightness, he said.

“With this, you know that your house is going to be built to a certain standard and you’ll know exactly how much energy you’ll use for heating, cooling and overall, which is about 85 to 90 percent savings over a traditionally built house,” Kruse said.

And that means being very meticulous while building it, including taping all seams and joints, Gorrell said.

“Jesper does wonderful work at Maine Passive House,” she said.

“They really are meticulous. Every detail they make sure is correct, because if they don’t get something right now, then the house won’t function right. It’s got to be airtight and sealed in.”

That’s why there are wireless temperature and humidity sensors in the walls and rooms to ensure energy efficiency by checking the data with a computer throughout construction and when completed.

Additionally, on Monday, Kruse said an infrared camera and blower door will be used to ensure there are no air leaks prior to Sheetrock installation.

A blower door is a powerful fan that is placed in an exterior door frame. It sucks air out of the house, lowering the air pressure inside, while allowing higher outside air pressure to seep in through any unsealed openings.

Kruse said the building has an inside wall and an outside one that are much thicker than conventional house walls. They’re 15 inches thick. The attic will also have 3 feet of insulation.

“Basically, the whole house is a continual envelope of insulation,” Hotopp said. “The outside wall rests on a poured foundation; the inside wall is on this slab, but the space between them has 14 inches of foam.

“Part of the idea of it being passive, is it means it will just sit here and work without any power,” he said. “Basically, the moving parts are the air exchange system and even that’s fairly simple.”

The house was designed by Ben Southworth, who owns Garland Mill Timberframes in Lancaster, N.H.

“It’s been fun to watch it go from a two-dimensional plan to a 3-D house,” Gorrell said.

Ninety percent of the building’s heat will come from the sun, including powering a solar water heater. A mix of small, wall-mounted electric heaters and a small wood stove will provide the other 10 percent.

“I like to think of it as a nuclear-powered house, because it relies on the giant, huge reactor in the sky,” Hotopp said.

tkarkos@sunjournal.com

Copy the Story Link