High-Performance Custom Home: Transforming Old Into Net Zero

Architect Donald Powers wanted his 100-year-old cottage to be the epitome of energy efficiency. So he transformed it into a net-zero home.

Cottage with solar array on garage in high-performance, net zero house at Jamestown, R.I.

Placing the 6 kW solar array on the detached garage allowed architect and homeowner Donald Powers to calculate the ideal roof pitch for maximum effectiveness. | Photo: Anthony Tieuli / This Old House

December 23, 2020

Donald Powers’ firm, Union Studio Architecture & Community Design, has built a reputation for designing homes above and beyond what building codes require. Naturally, he wanted his own home—a 100-year-old cottage in the heart of Jamestown, R.I.—to represent the epitome of high performance, so he transformed it into a net zero home. 

Project: Jamestown Net Zero House, Jamestown, R.I. 
Architect: Union Studio Architecture & Community Design, Providence, R.I.
Builder: Sweenor Builders, Wakefield, R.I.
Size: 2,300 square feet   
Site: 0.23 acres
Photos: Anthony Tieuli/This Old House

Kitchen in high-performance, net zero house in Jamestown, RIBalancing the nooks and crannies that give the century-old house character with today’s preferred open floor plans, Powers stepped the living room addition down from the existing kitchen/dining area and used a column to support the large-span opening.


Making a house that meets net zero standards isn’t complicated, but Powers also doubled the size of the existing 1,000-square-foot structure, which, as he puts it, had been clad with whatever wood could be found at the time. Making the poorly built original house as well-insulated and energy efficient as the addition was a challenge.



“We had to find techniques that worked as well on the old part of the house as the new one,” Powers says. “For example, we used spray foam, which some don’t prefer, but it made sense with the wonky framing on the existing part, and we re-sheathed the entire house, so everything aligned.”

Bookcase doubles as stair railing in piano alcove in net zero house A built-in bookcase doubles as a guard rail for the stairs.


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