What is a GeoExchange System and why do I want one?
It all starts with Geothermal Energy:
Geothermal Energy is heat (thermal) derived from the earth (geo).
The sun has always heated our earth, and that's a good thing!
It's energy warms the earth directly, but also indirectly. It's heat evaporates water from the lakes, oceans and streams, which eventually falls back to earth and filters into the ground. A few metres of surface soil insulate the earth and ground water below. The warm earth and the water below the surface provide a free, renewable source of energy for as long as the sun continues to shine.
Almost everywhere in North America the earth under an average residential lot can easily provide enough free energy to heat and cool the home built on it.
Add a Geothermal loop and Heat-pump
The free energy has only to be moved from the ground into your home. This is done either by pumping water from a well (open loop) or by pumping a heat transfer fluid through a horizontal or vertical circuit of underground piping (closed loop). The fluid, absorbs the heat in the ground water or soil and transfers it to the heat pump. The heat absorbed by the fluid from the solar-heated ground is extracted from it by the heat pump, and the now-chilled fluid is circulated through a heat exchanger over and over again to extract more heat from the earth.
Burying a loop in the ground around your home is like owning your own oil well, but instead of pumping oil from an underground pool and burning it to create heat (and greenhouse gases), you tap into clean energy that will be there for as long as there is a sun.
If your home is located near a suitable pond or lake or even the ocean, you can use a Geo- Exchange System to draw on this excellent source of free energy.
GeoExchange System (GXS)
The heat energy taken from the ground by is considered low-grade heat. In other words, it is not warm enough to heat your home without being concentrated or upgraded somehow. However, there is plenty of it – the average temperature of the ground just a few metres below the surface is similar to (or even higher than) the average annual outdoor air temperature. For example, in Toronto, the average annual air temperature is about 8.9°C, but the average ground temperature is 10.1°C. It is important to note that this ground temperature is 10.1°C on the hottest day of summer as well as on the coldest day of winter. That is also why a GeoExchange System works so efficiently – it uses a constant, relatively warm source (ground or water) from which to draw energy.
Generally speaking, a GeoExchange System is made up of three main parts: the ground heat exchanger (a loop), the heatpump (ground source heat pump) and the distribution system.
In the winter, the heat pump removes heat from the heat exchanger and pumps it into the delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to heat water, providing a free source of hot water.
After the GeoExchange System has taken the heat energy from the ground loop and upgraded it to a temperature usable in your home, it delivers the heat evenly to all parts of the building through a distribution system. It can use either air or water to move the heat from the heat pump into the home. Forced air is the most common distribution system in most parts of Canada, although a hot-water or hydronic system can also be used.
Why you want one: a GeoExchange System is a smart choice for you, your wallet and the planet:
Year-Round Comfort
People living in homes with a GeoExchange System often say, “This home is the most comfortable we’ve ever lived in.”
There are several reasons for this.The air temperature produced by a Forced Air GeoExchange System is typically about 35°C. The air produced by a fossil fuel furnace or electric furnace is often heated to 50–60°C – much warmer than room temperature. This can create hot spots in a room. Moving around the room, you can often feel temperature differences of 3–4°C.
Most manufacturers make multi-speed units that match the heating and cooling loads of your home virtually year round. In spring and fall, when you do not need the full capacity of the system, the compressor and fan will operate at low speed, providing only as much heating and air conditioning as you need. As the days get colder in winter, or during very hot summer days, the system will operate at high speed.
GeoExchange Systems are installed with electronic thermostats that offer more precise temperature control and switch from heating to air conditioning automatically. You will find that, on days in the spring and fall when you need heat in the morning and cooling in the afternoon, you are more comfortable.
Good for the environment
More than two thirds of the energy delivered to your home by a GeoExchange System is renewable solar energy stored in the ground. This is great for your wallet because it is free energy. It is also good for the environment because there are virtually no toxic emissions. Each kilowatthour (kWh) of electricity used to operate a GXS draws more than 3 kWh of free, renewable energy from the ground.
A large part of the cost of energy supplied to your home is the expense of getting it there. Gas lines and oil pipelines are costly to build and require extensive rights-of-way. Oil is shipped in tankers halfway around the world so you can heat your home. Trucks delivering fuel to your home need fuel and maintenance. Shipping energy to your home entails real costs. They include not only direct expenses, like building pipelines, but also indirect costs, like dealing with emergencies. The infrastructure needed to transport energy is large and expensive – for you and the environment.
With a GXS, most of the energy you need is moved less than a few hundred metres into your home. The cost of transporting earth energy into your home is the cost of running a circulating pump.
Measuring the energy your GeoExchange System produces, and dividing it by the energy you put into it (and pay for) gives you the Coefficient of Performance (COP). Depending on the system you can expect a COP between 2.5 and 4. That means your GeoExchange System could be up to 400% Energy Efficient. And let's not forget that for most of us in BC that is all Green Hydropower Electricity!
The Costs of Owing a GeoExchange System
As said, more than two thirds of the energy produced by a GeoExchange System is free energy drawn from the ground. It is easy to see why the operating costs can be much lower with a GXS than with any other fuel, including natural gas. Also, earth-based system maintenance costs are generally lower than those for a conventional heating and air-conditioning system.
However, a major difference in purchasing cost between a GXS and a conventional heating and air conditioning system is the cost of the loop. This can vary significantly from one location to another.
The total cost of ownership is a complex calculation specific to each system, but a cash-flow analysis will show you that the difference in annual energy costs more than makes up the difference of the higher initial cost of installing the GeoExchange System.
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