Homeowners who understand the need for change.

The owners of this home are long time Boston residents who understand the need for big changes in energy use in Boston and beyond. When it became clear their old wood singles needed replacement, the anticipated paint job became a much bigger and exciting endeavor. Upon learning about the about the National Grid DER pilot program, they were eager to become the first three-family Deep Energy Retrofit in Boston and a case study for other homeowners and landlords.

Boston Three Family Retrofit

  • Boston three family before
  • Boston three family overhang framing
  • Boston three family siding installation
  • Boston three family window detail

Byggmeister's Solution

The super-insulated enclosure, made possible through financial and technical support from National Grid and Building Science Corporation, includes an exterior insulation wall build-out. Challenged by a slate roof, we opted to insulate the roof from the inside with interior cellulose and foam to meet the program's high insulation requirements while leaving the slate intact. Separate heat recovery ventilators in each unit decrease energy use, improve indoor air quality, and eliminate cross-contamination between units.

We insulated the roof with a combination of cellulose, rigid foam and spray foam. Existing walls were filled with dense-packed cellulose to which we added 4" of polyisocyanurate foam insulation to the exterior. The basement walls were insulated with closed-cell spray foam as an air barrier and water management layer, after which we blew in mineral wool for additional R-value. The basement floor was also insulated with closed-cell foam with a new concrete slab poured on top.

Ventilation needs are met with heat recovery ventilators in each of the three units. Heating is provided by the existing FreeWatt system (hot water delivered via cast iron radiators). Cooling is provided by window units as needed.

Project Location

Boston, MA