Homes - Renovating

Geothermics: Right under your feet

With the rising prices of electricity and heating oil, more and more people are turning to alternative energy sources, including geothermics.

Geothermics not only offers the advantage of using an inexhaustible source of energy – the sun – but it doesn't burn fossil fuel and therefore doesn't produce greenhouse gases. The results speak for themselves: On the one hand, users can expect to save 60 to 70 percent on heating costs; on the other, the average size household can cut its carbon dioxide emissions by 2.5 to 5 tonnes per year, according to Natural Resources Canada.

An intelligent technology
Did you know that almost half of the sun's geothermal energy is captured and stored in the ground and in water? At a depth of approximately two metres, ground temperature is constant during winter and summer, varying between 5°C and 12°C, depending on the geographic location of your home. A geothermal system makes it possible to extract and harness a part of this energy, and it produces a more uniform heat than oil or electricity. However, if your home is poorly insulated to begin with, a geothermal heating system will not necessarily make it more comfortable.

Geothermal systems can be installed in new and old homes alike. The process involves the installation of underground pipes outside the house and a geothermal heat pump inside the house.

Two types of geothermal systems are currently offered: open-loop and closed-loop. The open-loop system uses energy stored in a lake or wellbore, a method seldom used owing to tougher policies on the protection of waterways. The closed-loop system taps into the energy stored in the ground. In both cases, the heat pump circulates a liquid through a series of pipes buried beneath the ground or water. As its name suggests, the heat transfer fluid carries the heat to the heat pump, which compresses it before pushing it through the home-ventilation conduits. Thanks to its coils, the geothermal system can also be used in homes heated with hot water. It works the same way for air conditioning but in the reverse direction: Hot air drawn from the home is sent back into the ground, and cool air is pumped into the conduits.

While a geothermal system will meet almost all of your home-heating needs, it is still equipped with a backup electrical system in the event that the heat pump breaks down or for especially cold days. And it has the added advantage that it can be attached to a “desuperheater,” which uses a part of the heat recovered by the heat pump to preheat the water used in the home.

To install the piping system, consumers can choose between drilling vertically or horizontally into the ground around the house. In the first case, the borehole will reach 30 to 122 metres (100 to 400 feet) in depth, depending on the amount of energy the home requires. This method uses a minimum amount of space but is more expensive than drilling horizontally – which requires that the pipes be installed only two to three metres below the ground. The two methods are equally effective, and the final choice will depend on the size of the property (a minimum of 3,700 square metres – 40,000 square feet – is needed for horizontal drilling) and the type of soil (such as sandy or peaty).

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