Deep Heating

Green energy doesn’t always lend itself easily to the urban environment. In the city the skyscraper across the street can compromise the solar installation of your dreams. Nearby neighbours cringe when you mention your backyard wind-farm idea. Now geothermal heat pumps may offer the solution you need.

Geothermal heat pumps (also called ground-source heat pumps, geoexchange systems, and earth energy systems) are green energy solutions that easily fit into the energy-conscious urban homeowner’s circumstances. The temperature of the earth below the frost line is stable, staying warmer than the air around us in winter and cooler in summer. Geothermal heat pumps make use of this year-round stability, heating and cooling your home by harnessing the ambient temperature of the earth.

What’s Underground

Every geothermal system has three main components. The ground loop is the underground system of pipes that run either vertically or horizontally around your home, depending on the available space. A solution of water and antifreeze circulates through the loop, absorbing or releasing heat to match the temperature of surrounding earth. In the winter, the fluid is cold when it leaves the house and warm when it returns from the ground loop. Reverse the system in the summer and cool air is delivered to your home, courtesy of Mother Earth.

The second step in the system is the heat pump itself, and this is where magic really happens. A refrigerant is circulated through a second, smaller loop of piping inside the home, absorbing heat from the ground loop. This solution becomes a gas, gets compressed, and through the mysteries of physics, amplifies the heat. The distribution system blows this heat through your home. The now-cool refrigerant returns to the ground loop to pick up more heat, and the cycle of free home heating begins again.

Energy Savings

The big news about geothermal heat pumps is their energy-saving capabilities. Using the earth to temper your indoor climate will save 35 to 70 percent on your heating bills. With this rate of payback, the additional cost of installing a residential geothermal system–installations often run between $10,000 and $20,000–will be recovered in four to seven years. As an added bonus, two to five tons of carbon dioxide are eliminated annually by installing a geothermal system in a 2,500-square-foot home.

So why isn’t everyone using a heat pump? Although there are over 500,000 geothermal installations in North America, this energy alternative has yet to make a name for itself in the mainstream market. While the cost is recovered over the long-term, the initial cost outlay is about double the cost of a conventional heating solution. Other considerations, including soil characteristics, upgrades to existing electrical and duct systems, and add-ons like water heaters can push the cost even higher.

More Reasons to Change

If you are still on the fence, there are other compelling reasons to choose a geothermal system. Conventional furnaces can heat the air in your home to 60 C, many degrees warmer than the desired air temperature, creating hot spots and cold pockets in the same room. Heat pumps emit heat more consistently at a lower temperature, about 35 C, creating a more comfortable living environment. Geothermal systems will both heat and cool your indoor climate, and as all components are sheltered from the elements, minimal maintenance is required over the long life of the system.

For further information about geothermal heating, download the comprehensive Earth Energy guide from the Canadian Renewable Energy Network (canren.gc.ca). Check with your local utility or visit the Canadian GeoExchange Coalition website (geo-exchange.ca) to find out more about this remarkable green energy option for the urban environment.