Spring 2007, Volume 10 Newsletter:
Harvard Becomes a Leader in Ground Source Heat Pump Technology
The well head of one of Blackstone's geothermal wells.
Ground source heat pumps are an exciting renewable energy technology that Harvard has enthusiastically adopted! Ground source heat pumps (GSHPs) can be used to heat and cool buildings and to generate domestic hot water. These systems have a long history as a residential technology, but in recent years large institutions have been adopting them. With five existing GSHP systems and 3 in planning, Harvard is fast becoming a leader in GSHP installation, operation, and maintenance.
HGCI and Harvard University Operations Service have undertaken a data-collection process to produce a “lessons-learned” presentation on Harvard’s experience with GSHPs. We have discovered several surprising design, installation, and maintenance issues that, if not properly addressed, may reduce the efficiency of a GSHP system. To prevent this, we’ve taken our presentation on the road to building operators, project managers, and to students and professors so that our shared knowledge base continues to grow and benefit future GSHP projects at Harvard.
Buildings with GSHP systems include the 2 Arrow Street ART theater; the 1 Francis Avenue Nieman Foundation House; 46 Blackstone Street, home to the HGCI and UOS; 90 Mt Auburn Street, home to Harvard’s Special Collections Library Department; the Radcliffe Gym; and the Quadrangle Recreation and Athletic Center. Byerly Hall and the Weld Hill Arboretum Lab Complex are planned to include GSHP systems. The HGCI team leader is Emily Martin. UOS partners include Tony Ragucci, Sean Reagan, and Jeff Smith.
What is a Ground Source Heat Pump?
Closed-loop, residential systems, from earthenergysystems.com
Ground source heat pumps (GSHPs) are a technology that use the constant temperature of the Earth to heat and cool buildings. A GSHP system consists of a heat pump within the building and one or more geothermal wells in the ground outside. In the well, a fluid that has passed through the heat pump, either ground water or an antifreeze solution, is heated or cooled to the Earth’s native temperature. In winter, the ground is warmer than the air, so the fluid transfers heat to the building. In the summer, the ground is cooler and heat is transferred from the building to the ground. Wells can be open- or closed-loop, in a vertical or horizontal configuration. All of Harvard’s existing wells are standing column wells. This design is almost identical to a drinking water well, and is the most appropriate design for New England. Groundwater is taken from the Earth, passed through a heat pump, and returned to the well in a cycle. GSHPs are more efficient that traditional heating and cooling systems because they use no fossil fuel (except that used to create electricity that runs the pumps) and because they take advantage of the constant temperature of the earth to reject heat in a more efficient manner than traditional cooling towers or window-unit air conditioners.