NORTHAMPTON — When Brien Baker was teaching English in Japan during the 1980s, he heard a story about a colleague that witnessed a student buy an 8-ounce can of soda from a vending machine, even though a 12-ounce soda cost the same price. When the colleague, puzzled, asked why he wouldn’t want to get 50% more for his money, the student replied, “well, I’m not that thirsty.”

Now an architect with the Amherst firm Simple City Studio, Baker has taken that same philosophical approach helping design the construction of three new Habitat for Humanity affordable homes at 781 Burts Pit Road, all of which contain an innovative new water heating system that only around a thousand other homes across the country possess.

“It’s this idea of, how thirsty are we? How much space do we really need? How much energy do we really need to heat us?” Baker said. “That’s where this all started.”

Habitat for Humanity, in partnership with sustainability group Local Energy Advocates of Western Mass, recently held an open house at one of the homes to showcase the homes’ solar-powered heat pump system for providing hot water. The all-electric homes range from 800 to 1,000 square feet in size, are single story and do not have a basement, making a more conventional electric water heater impractical.

“Hot water heaters are noisy, and for high-efficiency net-zero homes or homes without a basement or cooling space, they can be extremely detrimental,” said Bruce Dike, owner of New England Solar Hot Water, which provided the heat pumps. “I’m certainly not here to denigrate that technology or say that it is a panacea that replaces everything, everywhere. But it does here.”

According to Dike’s company website, the solar-assisted heat pumps work in a manner similar to refrigerators. But while a refrigerator uses a circulation panel to keep things cold, the heat pumps instead use one to extract heat and maintain warmth. The panels are also placed outside the home to absorb sunlight, meaning they take up less space inside the home.

The houses at 781 Burts Pit Road were the result of Northampton’s “Just Big Enough” contest in 2018, where the city challenged architect teams to design housing that was both affordable and sustainable in how they consume energy, a contest that was won by Simple City Studio. The homes broke ground in 2021 and construction finished this fall.

Originally, the homes were going to use the more standard electric water heaters. But the Local Energy Advocates group felt there had to be a better way, and after doing some research proposed the solar heat pumps.

“We formed this organization about two years ago, and our goal is to help our municipalities reduce our greenhouse gas emissions,” said Adele Franks, who serves as treasurer of the group and spoke at the open house meeting. “We had some really big ideas, and we still do, but we decided that we would start out with some smaller projects. And this is one of them.”

The homes are just one example of efforts across Northampton to create more sustainable living environments as the city looks to achieve net-zero carbon emissions. In September, the City Council became the first in western Massachusetts to approve a new specialized building code, advocated by the state, with more stringent sustainability requirements for future building development.

Habitat for Humanity has found residents for the three homes who are expected to move in before the end of November, according to executive director Megan McDonough. The organization is also building three additional homes just down the street at 278 Burts Pit Road that are expected to be completed next spring or summer.

These houses, larger in size, will use more conventional water heaters, McDonough said, but she added the organization may use the solar heat pump system for future projects.

“We’ll see how the homeowners like them,” she said.

Alexander MacDougall can be reached at amacdougall@gazettenet.com.