As the sun’s rays shine down on the earth, solar energy is constantly being absorbed and stored by the earth’s surface as thermal energy. Several meters below the surface, the ground is no longer affected by seasonal variations and the temperature remains constant all year round. Simply put, nature has provided us with an efficient and reliable ‘bank’ from which we can deposit or withdraw thermal energy.
In recent years, major improvements in technology have provided a catalyst to vault geo-exchange from a relatively unknown technology to one of the fastest growing and greenest technologies available.
A geo-exchange system is made up of three parts, each of which plays a separate yet vital role. These components are:
Each component of the system is described in more detail below.
A ground heat exchanger is comprised of plastic pipe that is installed in the ground (either horizontally or vertically) and exchanges heat with the ground by way of a non toxic fluid that circulates within it. The ground heat exchanger then transfers that heat energy from the ground to the heat pump typically located within the home or building.
The amount of energy that can be transferred to and from a ground heat exchanger is dependent on the geological conditions of the site as well as the installation method. Different types of rock and soil conduct heat at different rates and hold different amounts of energy. This depends on density, moisture content as well as other factors. Generally, the more heat that is required, the more ground area that must be utilized.
During the heating cycle, the heat pump uses the incoming fluid from the ground heat exchanger to extract heat from the ground. As the system pulls heat from the loop it distributes it through the home or building through a conventional duct system as warm air.
In the cooling mode, the heating process is reversed - creating cool, conditioned air throughout the home. Instead of extracting heat from the ground, heat is extracted from the air in your home and either moved back into the earth loop, or used to preheat the water in your hot water tank.
The system can also provide an average of between 50-70% of the typical home’s hot water needs through the use of a desuperheater.
Geothermal systems work best with in-floor hydronic heating or forced air distribution systems.
In a hydronic system, hot water is circulated through radiators or a system of in-floor pipes to provide heat.
In a forced air system, a fan in the heat pump blows over a fan coil and the heated or cooled air is circulated throughout the house or building. Forced air systems are the most common as they tend to be the most economical and they also provide both heating and cooling functions.