This retrofit house is located in Brookline, MA (Cold Climate). It involved retrofitting the walls with two 2” layers of polyisocyanurate rigid insulation to the exterior of the existing wall sheathing. The existing cellulose insulation in the framing cavities was left in place. The windows were replaced with triple-glazed windows.
For complete details on this deep energy retrofit, go to
National Grid Deep Energy Retrofit Pilot Program–Three-Story Victorian Partial Retrofit