Geothermal System Overview
Stockton College is a public, undergraduate college of arts and sciences located the Pine Lands of Southern New Jersey.
The main academic building complex consists of 14 wings connected by an enclosed gallery containing approximately 440,000 square feet of floor space. The original buildings were designed and built prior to the energy shortages of the 1970s and thus were not as energy efficient as they might be. By 1990, the Heating, Ventilating and Air Conditioning (HVAC) units were reaching the end of their useful life, and a feasibility study was undertaken.
The proposed geothermal system consisted of replacement rooftop water source heat pump units coupled to a closed loop system of 400 wells (see illustration) each 425 feet deep located under a 4 acre parking lot. In the original buildings, 61 heat pump units provide 1,470 tons of cooling and in the new building (1996), 57 units provide 242 tons of cooling capacity.
The feasibility study compared the costs and projected energy savings of both a direct replacement of the existing units and a replacement with ground-coupled water-source heat pumps. The projections showed that a geothermal system would cost about $1.2 million more to install, but that it would be expected to save $330,000 annually in energy costs. Thus, the simple pay back of the extra costs of the geothermal system would be about 3.5 years.
Furthermore, because the reduced peak electrical demand would reduce the need for Atlantic Electric Company to install new generators, the utility offered an $800/Ton rebate for installing the geothermal system. On the 1600 ton system, this rebate just covered the incremental initial costs of the geothermal system. With additional funding from the State of New Jersey obtained in 1992, a contract was awarded for the retrofit and the geothermal system was installed in 1993. The new heat pumps were lifted to the rooftops and the old units removed in a day and a half by helicopter during the 1993 Christmas break and in mid-January 1994 when classes began, the new geothermal system was turned on.
The Arts & Sciences building with about 40,000 square feet of additional space was added to the system in 1996.