PWGC Designs Extensive Geothermal System for St. Patrick’s Cathedral Restoration
One of PWGC’s recent projects is making headlines: the design of a state-of-the-art geothermal heating and cooling system for St. Patrick’s Cathedral in New York City, the largest Gothic Catholic cathedral in the country.
Engineered as part of the $177 million restoration project of this 138-year-old landmark, the system replaces a more conventional HVAC system that dated to the 1980s. The geothermal plant will reduce the building’s energy consumption by more than 30 percent and reduce CO2 emissions by approximately 94,000 kilograms!
Early feasibility studies that were performed as part of the renovation determined that installing a conventional system would have posed many challenges for preserving the integrity of this historic building, requiring substantial excavation and rock removal and impacting the building’s architecture. The geothermal system, however, is ecologically sound, takes up just 40% of the space of a conventional HVAC system, and uses the building’s existing structure.
It took about nine months to drill the 10 wells that extend between 600 and 2,200 feet below the surface of the cathedral, each of which is used to harness clean, renewable power. The wells contain water, which remains around 55° F throughout the year and is used to heat or cool the cathedral’s air as needed. In the winter, heat is absorbed from the water and delivered into the building, and in the summer, the heat from the building is absorbed and delivered back underground.
“They were drilled deeper than anywhere else in the city and together the 10 wells provide by far more heating and cooling capacity than any other (city) system,” said John Rhyner, vice president of geothermal services at PWGC. “Aside from being the largest city-based geothermal installation to date, the plant at St. Pat’s is unlike many others of its kind because it is designed to be able to use cooling and warming simultaneously in different areas.”
The St. Pat’s project highlights the tremendous utility of geothermal systems for restoration projects—aside from the long-term financial and environmental gains, the systems are able to be built out of sight, without interfering with visual aesthetics that are crucial to preservation projects.