Geothermal heat pumps achieve high efficiency by extracting or rejecting heat to the ground surrounding a building
through either horizontal or vertical heat exchangers. Their operation is not adversely affected by weather changes
as electric heat pumps are on very cold winter days or heat pumps and air conditioners are on hot summer days. Projects
were undertaken to develop new or improve existing computer models for simulating ground coil performance, to demonstrate
and monitor ground coil installations, to develop and test water source heat pumps, and to document ground-water
resources in the U.S. for ground-water heat pumps.