Discover the geoexchange difference?
Even though a Geoexchange system can deliver comfort in the same way as a conventional heat pump via ducting, hydronic heating, pool heating or hot water the difference is that instead of extracting heat (when heating) or rejecting heat (when cooling) to the outside air a Geoexchange heat pump uses the stored thermal energy of the ground or water.
Due to the temperature below the ground staying pretty constant all year round we can gain good stable efficiencies even when conventional heat pumps start to have to work harder and use more energy.
We can also move energy around with a Geoexchange system so if you are cooling a home or building we can move that normally thrown away heat to a pool or hot water.
Nature's Stored Thermal Energy Accessible with Geoexchange
Why havent I heard of Geoexchange?
Good question. Even though 100’s of Geoexchange heat pumps have been in use in Australia since the early 1990’s with some of the first installations being in South Australia the number of installations dropped during the early 2000’s as the cost of energy dropped and other options like gas heating became the norm. In recent years with rising price of electricity and gas and a growing request for more sustainable and efficient solutions interest in Geoexchange systems in Australia and globally has grown. These days it doesn’t take much to find a positive story on the great work a Geoexchange system is doing, we are now at a point where big Global companies like Google are realising that using the stored renewable energy in the earth is a smart move to help reduce their emissions and save on operational costs.
How does it work?
A few meters beneath the surface is a vast amount of stored renewable energy that we can utilise with Geoexchange. The earth’s temperature remains fairly constant and is constantly being recharged by the sun.
It is the use of this stored renewable energy that we can use to your advantage to provide extremely efficient heating and cooling.
In winter, a water solution circulating through pipes buried in the ground absorbs heat from the earth and carries it into the home. Inside the home a heat pump is utilised to concentrate the earth’s thermal energy and then to transfer it to either water for a hydronic underfloor, a hydronic radiator system or to air circulated through ductwork to heat the home.
In the summer, the process is reversed. The heat inside the home is extracted from the air and transferred through the heat pump to the ground loop piping. The water solution in the ground loop then carries the excess heat back to the earth.
Accessing Nature's renewable Thermal Energy ~ Heat exchange options
The true beauty of a Geoexchange system is that is is not just restricted to using the ground as a heat exchange. Below is an overview of some of the options are also available and work well.
Used where adequate land is available, horizontal loops involve one or more trenches that are dug using an excavator. High density polyethylene pipes are inserted, and the trenches are backfilled.
Vertical loops are used when space is limited. Holes are bored using a drill rig, and a pair of pipes with a special u-bend fitting on the end is inserted into the holes. The area around the loop is then grouted with a special concrete mix.
Pond, Dam or River loop
If an adequately sized body of water is close to your home or building a pond loop can be installed. A series of coiled, closed loops are sunk into the bottom of the body of water. The body of water will need to be over 1.8 meters deep.
An open loop is used where there is an abundant supply of bore water. The water that is used for the system can be re-injected into the ground, rejected to a dam or body of water or used for irrigation.
We can utilise the stored thermal energy of the ground surrounding a building by installing pipework in the building piles or piers before they are installed in situ.
As well as the above options for a heat exchange we can also utilise many other forms of thermal energy like that held in waste water, irrigation systems.
PlThe video on the right gives a simple overview of how a Geoexchange System Works