A geothermal heat pump was first installed in a commercial building at Portland’s Commonwealth Building in 1948.
The system used the relatively stable temperature of groundwater as a heat source in winter and a heat sink in summer. A heat pump moves heat rather than creating it directly, allowing a building to be heated or cooled with electricity and underground thermal exchange.
The Commonwealth Building installation was designed by engineer J. Donald Kroeker. It demonstrated that geothermal heat pumps could serve a large commercial structure, rather than only a small residence.
Geothermal heat pumps differ from geothermal power plants. Power plants use high-temperature underground resources to generate electricity, while heat pumps generally use shallow ground or groundwater temperatures for building heating and cooling. They can operate in many climates, although drilling and installation costs vary.