In 2008, when my business partner and I decided to form a design/build firm, we agreed to build to the highest standard of sustainability and to do so cost-effectively. With all our projects, we hoped to achieve a synergy between designing for human comfort, building in response to the site, and achieving long-term durability. We quickly agreed that the Passive House standard, which was just being introduced to the United States, would be the most comprehensive and clear measure of our success. To demonstrate that we had the ability to reach the standard, we built our first prototype, a house we called the GO Home. To reach the Passive House standard in Maine’s cold climate, we developed a new way to design and build homes collaboratively. The GO Home, completed in 2009, was Passive House certified, achieved LEED platinum, and was named the U.S. Green Building Council’s residential project of the year.

Since building the GO Home, we’ve refined our design-and-build approach in completing several other high-performance projects. This house in Bath, Maine, is based on one of our design-plan packages that delivers (depending on the site) a house that could meet the Passive House standard, that’s comfortable and attractive, and that has a modest base cost—roughly $160 per sq. ft. Here is how we achieve such grand results on such a low budget.

Design it to be compact

Wendy and Bill came to us because they were interested in building the smallest and most sustainable home they could for their retirement. Of the plans we offer, they chose to work with our 1000-sq.-ft plan, which includes one bedroom; two bathrooms; an open kitchen, dining, and living space; and a small study.

The shape of the house was influenced by…