What’s in a Name?
Geo, geothermal, ground source, water source – what do they all mean?
These terms have become part of everyday language and Ground Source Heat Pump Technology is one of the fastest growing technologies today. A ground source heat pump uses the ground as a thermal energy source to heat a building, or as an energy sink to cool a building. A geothermal heat pump does the same thing, and the terms can be used interchangeably.
Geothermal heat pumps belong to a larger category called “water source” heat pumps. Water is pumped through them to provide or absorb heat to the refrigerant inside the heat pump. Bury the water piping in the ground and the equipment becomes a geothermal heat pump. Connect the water piping to a boiler and cooling tower instead, and the equipment becomes a water source heat pump, but is not geothermal. This brief focuses on Geothermal Heat Pumps.
How’s it Work?
Geothermal heat pumps transfer heat between the stable temperature of the earth and the building to maintain the building’s interior space conditions. The stable earth temperature provides a source for heat in the winter and a means to reject excess heat in the summer. Heat pumps make the collection and transfer of this heat to and from the building possible.
Who can Benefit?
Geothermal heat pump systems are used in existing and new buildings. Benefits are greatest in buildings with similarly sized annual heating and cooling loads. The systems can provide efficient heating and cooling of different zones simultaneously. Installations include single family homes, schools, hospitals, hotels and even 500,000 square-foot office buildings.
Office buildings and schools are particularly good applications for geothermal heat pumps. These facilities have high occupancy, fluctuating schedules, and widely varying heating and cooling requirements: a challenging task for conventional systems.
How About Industrial?
Industrial environments are heavy energy users, producing heat that usually has to be removed continually. When a heating requirement does come up, the industrial engineer usually has a source for that heat that can be recovered in a more direct way than running it through the refrigerant cycle of a heat pump. Using geothermal heat pumps in industrial plants would mean rejecting heat to the earth continually, and consequently the resulting increase in ground temperature would reduce system efficiency AND system capacity.
In an industrial environment the process takes precedence. Effort and capital go into efficiently making the product the highest priority. Production-area occupant comfort, space heating, cooling, and the efficiencies related to those functions can become less important.
When selecting a heating and cooling system, geothermal does fit for many applications. But just remember it isn’t the right fit for all situations. The right balance between first cost, energy usage priorities, occupant comfort and process needs can lead to other choices that are more appropriate. Identify and quantify your priorities and the right system for you will become apparent.