The Historic Preservation through Technology project describes the upgrading of the HVAC system in a historic building while preserving and reusing its historic qualities. The existing HVAC systems in the U.S. Customhouse in Portland, ME, consisted of an oil-fired boiler and a chiller with an air-cooled condenser unit. Because the building occupied the entire site, the condenser was located in interior mechanical space vented to the outside. There was also a 6,000-gallon, single walled oil tank for the boiler that extended beyond the property line, posing an environmental risk. The interior condensing unit used considerable space. The unit, when idle, also allowed for infusion of vehicle emissions from the street. To address these problems the project team investigated alternative solutions and proposed a ground source heat pump (GSHP) system.
The team justified their solution with a life cycle cost analysis. Although initial costs were more than the replacement of the existing system, the project was authorized. After removing the interior condenser, the team installed a natural gas fired emergency generator to reduce the building electrical load during high usage periods, in addition to providing emergency power. The Customhouse, built in 1877, used a convection system for ventilation, consisting of 12 vent shafts. The shafts, which were sealed, have been reopened, ducted and are now used as the interior air distribution system, taking a feature from the past and reusing it in the present. The new systems’ life cycle cost savings is based primarily on energy use. The system is projected to save 30 percent over a conventional system. Current data indicates a savings in excess of 40 percent.
This is the second GSHP system installed in Maine, demonstrating that this technology works in the New England climate. The project is a prototype for a larger project, the new U.S. Courthouse in Springfield, MA, which will use a 23 well system.
For more information, contact Mr. James E. Devir at (617) 565-7902 or via e-mail at james.devir@gsa.gov
