The Bullitt Center, located in the heart of the hill towns of the Pioneer Valley, has undergone a complete renovation to meet the net-zero carbon goal of the client, The Trustees of Reservations, and the occupant, the Hilltown Land Trust. The historic farmhouse was stripped of the existing skin, revealing its historic timber frame and sheathing, and then wrapped with a new super-insulated exterior.

MEASURES IMPLEMENTED

The exterior walls were coveredwith polyisocyanurate rigid foam, while the roof received new structural insulatedpanels (SIPs). In addition to providing thermal bridge-free continuous insulation, the SIPs' rigidity and span worked very well with a roof that had succumbed to structural sag over time. The interior building cavities and the foundation walls were sprayed with closed cell foam insulation.

Two air source heat pumps provide heating and cooling for the building, while a 95% sensible efficiency heat recovery ventilator maintains a constant supply of fresh air.

With extensive air sealing and attention to detail the building achieved a leakage rate of only .6ACH@50Pa, matching requirements of the Passive House Standard.

THE RESULT

The result of this deep energy retrofit is an overall energy use reduction of 90% when compared to a typical office building of similar size.

After a year of energy consumption measurement, The Bullitt Center used less than 6,200 kWh total, yielding only 8.4 kWh/sf/yr (24% less source energy than that required by the Passive House Standard). 5kW of solar electric would be enough to offset the building's total energy consumption, making it net zero energy.

TEAM

ZeroEnergy Design provided energy consulting and limited HVAC design, Quigley Builders provided construction, and James Younger AIA of the Trustees of Reservations provided architecture. Photos by Mary Quigley and Norm Eggert.