Underneath our beautiful Stockton lawn is a large geothermal field which provides air conditioning for the sanctuary, as well as heating down to a fairly low outdoor temperature.  The system consists of 20 deep wells with 9 heat pumps which circulate fluid through the wells and the heat exchangers in the undercroft.  When it was installed in 2010, it was the first thermal heat pump system in a commercial or institutional building in Princeton. 

Every year, this system provides us with carbon-free energy and saves thousands of dollars in utility expenses.   Our Grounds committee makes sure that no trees are planted over the geothermal field, which avoids any interference with its operation.  Otherwise, it’s easy to forget that it’s there under the lawn!