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Groundsource Heat
Overview
What's Happening in BC?
What Does it Cost?
Environmental Matters
Technical Matters
Social, Economic and Political Matters
Can I Do It at Home?
Links
Overview
A ground-source 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.
Ground source 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 that’s 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?
Ground-source 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 ground-source 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.
Environmental Matters
The US Department of Energy and Environmental Protection
Agency (EPA) have both endorsed ground source 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.
Ground source heat systems work without creating any pollution
by simply utilizing the sun’s 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.
Technical Matters
Ground-source 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 ground-source
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 ground source 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 ground source systems, requiring their
installation wherever geological and space considerations
make them feasible.
- Banks and credit unions should factor the cost of a ground
source 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 ground
source 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 ground source 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 ground source
heat system.
- The BC government should waive the PST on ground source
heat systems, and create a 100% tax-credit for their installation,
to encourage their use.
- The federal government should waive the GST on ground
source 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 ground-source 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.
Links
Credits
Written by Nitya Harris, for the BC Sustainable Energy Association
Text updated April 13, 2004
Links updated September 7, 2007
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