Saskatchewan's Green Directory Helping Saskatchewan choose a better environment

The word geothermal has come to be used for two different things.

True geothermal energy is energy extracted from hot rocks at depth; the means to do this is not within reach of the typical Saskatchewan householder.

In common terms, however, it has also (not strictly accurately) come to mean a heating system based on ground-source heat pumps (GSHPs). In such a system most of the heat is pumped from a lower to a higher temperature (from the ground to the house), but the laws of thermodynamics require that in order to do this a certain amount of "high grade" energy - typically in the form of electricity - is required.

This means in practice that a GSHP system will generally result in lower greenhouse gas emissions than oil-fired or electrical resistance heating. But if you buy your electricity from SaskPower it is unlikely that a GSHP will be more climate-friendly than an efficient gas-fired system (though there are some possible exceptions to this general rule). The current rules for government subsidies (see below) are framed to recognise this reality.

• Please read THIS DISCUSSION to help you decide if a ground source heat pump is the best option for your situation.

What to look for

Consider the following when selecting a GSHP:

Proper Sizing

Make sure the heating capacity of the heat pump is not too high for your home. You can get an estimate of the capacity you need in a number of ways. If you have had an EnerGuide for Houses or ecoENERGY evaluation carried out on your house, it is possible to calculate the heating capacity you require from the annual heating and hot water estimate. Or if you have reliable fuel consumption data for a full year you can run a similar calculation. Or hire an energy consultant / HVAC engineer / building physicist to estimate your heating requirement.

Standard "efficiency" rating

How much heat can a given model provide per unit of electricity used? This is measured by the heating coefficient of performance, or COP_h: this is the principal criterion on which we have created the list of approved units.

Local "efficiency"

The actual COP_h of a heat pump depends on the temperatures across which it is operated. Warmer ground gives a better COP than cooler ground. Given that Saskatchewan underground winter temperatures are somewhat colder than the standard test conditions, it is worth asking your supplier: what is the seasonal average coefficient of performance of the unit in typical Saskatchewan conditions? Ask for actual results of monitoring surveys.

Heating only, or also summer cooling?:

GSHPs can be used in both modes. If you intend to use it as an air conditioner, you should consider the EER or COP_c rating for the unit (which will generally be superior to that for a conventional air-source heat exhanger).

What working fluid is used?

(see the discussion of working fluids in the section on air conditioners) Most currently-used working fluids are potent greenhouse gases, so proper provision needs to be made to capture them before there is a serious risk of large-scale leakage. One alternative working fluid which is not a greenhouse gas is propane (also known as R290 when used in heat pumps or refrigeration equipment).

Your supplier/installer

Designers and installers of heat pump systems should be able to demonstrate accreditation through a credible institution. At present we are aware of two such training and accreditation schemes: The Canadian GeoExchange Coalition is a Canadian industry-driven initiative: http://www.geo-exchange.ca/ The International Ground Source Heat Pump Association , based at the University of Oklahoma, is an independent US non-profit organisation with international outreach: http://www.igshpa.okstate.edu

EnergyStar

Does the unit have EnergyStar certification?

Government Grants

Grants are available for GSHPs meeting the terms and conditions of EnerGuide for Houses (Saskatchewan) and ecoEnergy Retrofit (federal). Before committing to purchase, read the terms and conditions of these grants carefully.

Gas or electric?

Until recently, all of the heat pumps available for the domestic market in North America were compression cycle models, which require electricity. Domestic-size absorption heat pumps, which run on natural gas, are now also available. By sucking heat out of the ground, these can reduce your gas bill by about 1/3 compared to an efficient furnace or boiler. We are not at present aware of a local dealer stocking or installing these; neither does the provincial subsidy system mention them yet, but watch this space.

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