This retrofit house is located in Millbury, MA (Cold Climate). It involved adding two layers of 2” foil-faced polyisocyanurate rigid insulation above the roof deck and open-cell spray foam insulation below the roof deck. The walls were retrofitted to add two 2” layers of foil-faced polyisocyanurate rigid insulation to the exterior of the existing wall sheathing. The existing fiberglass batt insulation in the framing cavities was left in place. The windows were replaced with new triple-glazed windows and closed-cell spray foam insulation was added to the interior of the rim joist. Two 1 ½” layers of polyisocyanurate rigid insulation were added to the interior of the foundation wall, and a drainage mat with rigid insulation were added over the existing slab.
Enclosure Design
For complete details on this deep energy retrofit project, go to
National Grid Deep Energy Retrofit Pilot Project–Millbury Cape