How geoexchange works

Geoexchange systems use the solar heat stored in the Earth, just below the frost line or in a body of water, to heat or cool buildings.

 

In colder months, heat pumps draw heat from the ground to warm buildings, while in warmer months, the systems use the cooler ground as a “heat sink" to cool buildings. The size of geoexchange system is determined by the amount of energy required. A variety of system options can be included, such as:

Geoexchange systems can be used to supply energy to spaces of all sizes and types, from multi-family residential buildings to commercial and industrial buildings.

Heating and cooling energy for geoexchange can be extracted from the earth using a closed loop or open loop system.

 

In a closed loop system, piping in the ground or a body of water circulates a fluid through polyethylene piping to transfer energy. In these systems the fluid never leaves the pipes, so the heat is transferred but not the fluid. The heat extracted from the earth is a “low grade heat” and not substantial enough to provide full heating requirements. This heat is upgraded by a heat pump that collects the heat from the ground and transfers it to a either a hydronic or a forced-air distribution system.

 

To replenish the ground heat and provide cooling in the summer months, the system extracts heat from the building space as it passes over colder coils providing air conditioning. The heat taken from the space is released into the ground via the ground loop.

 

In an open loop system, water is extracted from nearby water wells or a body of water. Once this water passes through a heat exchanger and transfers heat to a heat pump, it is released back to its source.

For larger loads, the geoexchange system can also incorporate waste heat from a variety of close proximity sources including refrigeration (ice rinks, grocery stores), waste water effluent, and sewer exchange. In order to recover the heat, a series of pipes are placed around various heat sources which then transport the heat to the buildings requiring the energy.

The chief benefit of geoexchange is the high level of system efficiency, which is typically measured as a Coefficient of Performance (CoP). The CoP of a heat pump is the ratio of the output heat to the energy input. For a CoP of 3.5, it means that for every kilowatt of electricity needed to operate the system, the heat pump provides 3.5 kilowatts of heat energy. The CoP often ranges from 3.0 – 4.0, which translates to lower energy costs and low emissions when compared to conventional systems.

Terasen currently owns and operates geoexchange loop systems in several stand alone developments and has several other agreements in place for buildings under construction.