Boston launches a sustainable housing initiative with net-zero energy townhomes.As anyone who has come into contact with Red Sox Nation knows, Bostonians tend not to believe in half measures. A case in point is the city's E+ Green Building Program, a joint initiative of the Office of Environment & Energy Services, the Department of Neighborhood Development, and the Boston Redevelopment Authority. Designed to demonstrate the feasibility of building net-zero energy, multi-unit housing in an urban context, the program made its built debut in 2013 with 226-232 Highland Street, a development consisting of four three-bedroom townhomes in Boston's Roxbury neighborhood. The building achieved substantial energy savings on a tight budget in part through a highly insulated facade constructed from conventional materials. "The envelope is key," explained Interface Studio Architects (ISA) principal Brian Phillips. "We design many super high performance projects and we believe strongly in the quality of the envelope as the starting point." ISA became involved in the project at the invitation of developer Urbanica, who had seen their 100K Houses, a high performance housing prototype designed to be constructed at less than $100 per square foot. One of three winners of the E+ Green Building Program's developer design competition, the Urbanica-ISA team crafted the townhomes with a dual awareness of the project's immediate surroundings and efficiency goals. "We're always interested in observing and measuring the context in order to create our design approach," said Phillips. "The materials and shapes of the Roxbury neighborhood inspired our design—as well as the requirements of creating a super high performance building." For instance, he describes the facade's most distinctive feature, a recessed vertical stack of windows, as "a riff on the prevailing bay window typology." The architects' material choices "were motivated by aesthetics, affordability, and recycled content," said Phillips. The primary facade material, prefinished fiber cement lap siding, is common to the neighborhood's existing residential fabric. Each attached house features an interlocking pattern of grey-blue and cedar-textured siding, for contrast, while the reverse bay windows are wrapped in dark grey metal panels. Double-stud walls, blown in insulation, and super tight doors and windows reduce thermal gain to a bare minimum. Thanks to its high performance envelope, energy-generating rooftop photovoltaic panels, and integrated user-feedback system, 226-232 Highland met the E+ Green Building Program's concrete goals, earning LEED Platinum for Homes certification and HERS Index scores between -11 and -15. Even during the unusually cold winter of 2013-2014, the Boston Redevelopment Authority reported, the project recorded energy positive days. But the townhomes also fulfilled the less tangible component of the city's mission, as a demonstration that sustainable housing can be built simply and for a reasonable price. "Green development is no longer just the big high-rises and large projects downtown," said Boston Redevelopment Authority deputy director Prataap Patrose at an event celebrating the building's LEED Platinum certification. "It's happening here. It's happening in our neighborhoods."