This retrofit house is located in Belmont, MA (Cold Climate). It involved adding three layers of 2” foil-faced polyisocyanurate rigid insulation above the roof deck and netted cellulose insulation in the rafter cavities. The walls were retrofitted to add two 2” layers of foil-faced polyisocyanurate rigid insulation to the exterior of the existing wall sheathing and cellulose insulation in the framing cavities. The windows were replaced with triple-glazed windows. Closed-cell spray foam insulation was added to the interior of the mud sill and foundation wall along with the addition of metal stud walls with rockwool insulation. A new sub-slab perimeter drain was added by replacing a portion of the existing slab and the slab was left uninsulated.
For complete details on this deep energy retrofit project, go to
National Grid Deep Energy Retrofit Pilot Program–Two-Family Belmont Residence