Converting the campus to a district scale hot water system maximizes energy efficiency and supports the University's sustainability action plan. Princeton's campus conversion is achieved by drilling over 1,000 geo-exchange bores, installed 600 – 850 feet below ground, installing over 13 miles of distribution piping and upgrading our central plants and building systems. The geo-exchange bores form a closed-loop system which acts as a thermal “piggybank” below the ground. Heat-pumps are used to retrieve this thermal energy, heat or cool it and pump it out to our campus. Converting our campus to geo-exchange technology is a major component of becoming Net Zero by 2046.