A groundsource heat system can provide heating and cooling for a building by taking heat from the earth in the winter and returning it in the summer for cooling.
The technology started in the 1940s, and has become so efficient that for many homes it is the most effective way to save energy and reduce CO2 emissions.
Groundsource heat pumps can be categorized as having either closed or open loops. The, loops can be installed in three ways: underground horizontally, underground vertically, or in a pond or lake. The type you choose will depend on the area of land thats available, and on the soil or rock type at the installation site. These factors will help you to determine the most economical choice for installation the loop.
For closed loop systems, a water or antifreeze solution is circulated through plastic pipes buried beneath the earth's surface. During winter, the fluid collects heat from the earth and carries it through the system and into the building, into a heat exchanger. During summer, the system reverses itself to cool the building by pulling heat out of the building, carrying it through the system and dumping it in the ground. This process creates free hot water in the summer, and delivers substantial hot water savings in the winter.
Open loop systems operate on the same principle as closed loop systems, and can be installed wherever an adequate supply of suitable water is available, and open discharge is feasible. Similar benefits to the closed loop system can be obtained.
What's Happening in BC?
Groundsource heating systems have been installed all over BC, for residential use, for institutions such as schools, for pools, for commercial projects and for the aquaculture industry.
What Does it Cost?
A groundsource heat system for an average 2000 sq. ft house may require a 2.5 ton system (30,000 Btus), and cost $6,250 for a ground system (less for a lake system; more if the house has no ducts). Heating costs can be reduced by 50 to 70% in winter, and cooling costs can be reduced by 20 to 40% by reversing the system in summer. With the reduced heating and cooling bills, the payback on your investment will take 5 to 12 years. In colder parts of Canada, a 4 ton system costing $10,000 may be needed.
The US Department of Energy and Environmental Protection Agency (EPA) have both endorsed groundsource heat pump systems as being among the most energy efficient and environmentally friendly heating, cooling, and water heating systems available.
In a 1993 report, the EPA concluded that geothermal technologies represent a major opportunity for reducing national energy use and pollution, while delivering comfort, reliability and savings to homeowners.
Groundsource heat systems work without creating any pollution by simply utilizing the suns stored energy. If a home presently emits 7 tons of CO2 from its heating and cooling, a ground-source system will reduce this by 50% to 3.5 tons.
Groundsource heat pumps require very little maintenance or attention, compared to the normal furnace/air conditioning systems. Not being exposed to the elements, dirt, leaves or vandalism, and with less moving parts, makes them highly dependable. The underground components, when properly installed, are virtually worry free, with warranties up to 50 years. A properly installed system offers the highest indoor air quality available today. A study by the EPA found that high efficiency groundsource systems are on average 48% more efficient than the best gas furnace, and more than 75% more efficient than an oil furnace. The best system will outperform the best gas heat pumps by an average of 36% in the heating mode, and 43% in the cooling mode, less gas costs.(Thanks to Lockhart Industries for this data).
Social, Economic and Political Matters
Given that groundsource heat systems are such an efficient, sustainable system of heating, it makes sense that we should seek ways to encourage their use. Here are some suggested policy changes that would accelerate their use:
- The BC Building Code should be amended to include specific encouragement for groundsource systems, requiring their installation wherever geological and space considerations make them feasible.
- Banks and credit unions should factor the cost of a groundsource heat system into their mortgages, and take the reduced heating costs into account when calculating their monthly payments.
- BC Hydro should advance low interest loans for groundsource heat systems, since the reduced demand will free up kilowatts that can be sold elsewhere, while offsetting the need for new power generation.
- City planning and building departments should require all new development proposals to include groundsource heat, except where geological or space considerations make it unfeasible.
- City building departments should conduct aerial surveys of all existing buildings, to indicate where there is sufficient lawn or other open space to retrofit with a groundsource heat system.
- The BC government should waive the PST on groundsource heat systems, and create a 100% tax-credit for their installation, to encourage their use.
- The federal government should waive the GST on groundsource heat systems, in order to reduce greenhouse gas emissions, improve air quality, and encourage affordable heating systems.
Can I Do It at Home?
Yes. A groundsource heat system can be installed in a residential house of any size, anywhere, whether single or multi-family. It can be installed on almost any sized lot: under lawns, under landscaped areas, under driveways, or even under the house itself. An existing house can be retrofitted with a system using the ductwork that is already in place. If a house has no existing ductwork, however, the cost of creating the ductwork to spread the heat around will generally cost too much to make it a feasible option.
- GeoExchange BC
- Lockhart Industries Ltd
- Earth Energy Society of Canada
- International Groundsource Heat Pump Association
Written by Nitya Harris, for the BC Sustainable Energy Association, 2007.