The General Theological Seminary of the Episcopal Church, New York, is converting its present heating-cooling system, which uses fossil fuel, to an energy-efficient geothermal system. Drilling for a series of standing column wells, integral to the new system, will begin this fall. Years in the planning stages, construction on the project begins in the wake of the Episcopal Church's General Convention, which passed significant "green" legislation encouraging the church at every level to reduce "energy use through conservation and increased efficiency, and by replacing consumption of fossil fuels with energy from renewable resources" toward the reduction of global warming.
Thanks to the new system, the seminary will reduce its carbon dioxide emissions by more than 1,400 tons a year. Any need for roof-level cooling towers will be permanently eliminated, helping to preserve the architectural integrity of the campus - an entire city block of landmarked Gothic Revival buildings and serene, gardenlike open space set in the heart of the bustling Chelsea neighborhood.
"As stewards of both our Chelsea Square campus and of the glorious but fragile Earth we all share, we are investing in this geothermal system to benefit the seminary, our neighbors and our world for generations to come," comments the Very Rev. Ward Ewing, dean and president. "This project ensures that a campus built for the ages will continue to serve through the ages. And it reminds us that we must work as hard to preserve the environment as we do to save our seminary's historic buildings."
Geothermal heat pump systems make use of the constant temperature of the earth below the surface level. During the winter months, when the subsurface is warmer than the air above ground, the system transfers heat upward. During summer months, when the air is warmer than the subsurface, the heat is transferred down. Geothermal systems are inexpensive to operate and maintain, require no exposed outdoor equipment, and make a minimal impact on the environment. Because of the savings afforded by the new system, construction costs will be offset in just nine years. From the 10th year forward, the Seminary will enjoy a net savings in its operating budget.
Project architect Yetsuh Frank, RA, LEED AP, of Beyer Blinder Belle Architects & Planners LLP, explains that the seminary is planning to build a field of 22 standing column wells, installed beneath the sidewalks surrounding the campus. These wells will take advantage of Manhattan's geology by tapping the ground water that flows through the seams and fractures of the island's bedrock. A steel casing runs from the surface down to the bedrock. From there, an unlined borehole - 8 inches in diameter - is drilled to a depth of 1,500 feet. (Incidentally, the height of the Empire State Building, to the top of its lightning rod, is 1,453 feet.) Ground water is pumped out of the borehole into a cellar mechanical room, where a heat-pump system either transfers heat to it during the warm months or pulls heat from it in cold weather. The water then is returned to the standing wells, where it loses any acquired heat to the ground water and to the boreholes.
The Seminary's system will provide 850 tons of cooling to 260,000 square feet of buildings. Beyer Blinder Belle estimates it will create the single largest geothermal well field in the New York City area.