New developments using geothermal pumps for AC

Not all heat rises. Some new air-conditioning units are using geothermal heat pumps to pump heat—absorbed by water—deep underground where the heat is dispersed in the chilly subterranean soil before returning to the surface. These pumps are more expensive to install, but can pay for themselves in a decade. They use about half the electricity of typical air-conditioners and emit less carbon. Buildings investing in the technology include a seven-story condo building at 180 East 93rd Street.