What is a geoexchange system, anyway?
You may have heard the term ‘geoexchange’ before and wondered what it is exactly – in short, a geoexchange heating system has 3 basic components:
- Water- (or water and refrigerant-) filled plastic pipes which run through underground trenches in the earth just outside the house. In winter, the Earth’s temperature is significantly warmer that the air and the opposite holds true for summer. A geoexchange system makes use of this renewable energy.
- A heat pump or heat exchange unit into which the water from the pipes (as above) run and which extracts heat, discharging it for use in heating the home (this same unit can be operated the opposite way, where cooling for the house is required). The heat exchange unit works just the same way as a refrigerator or an air conditioner.
- Some method of distributing the heat throughout the house: forced-air is a common distribution method, but the most comfortable and efficient means of heating a home is using radiant-floor heating, where a system of tubes filled with heated liquid keep the home at the desired temperature. This method integrates very well with a geoexchange system.
A truly excellent Flash presentation has been developed by Geoexchange.org: www.geoexchange.org/animation/flash-56k.html
OK then, what is a geothermal system?
Geoexchange systems are frequently and erroneously referred to as geothermal systems.
As described above, the geoexchange system employs a heat pump (otherwise known as a heat exchange unit) to either heat or cool the home. The key word here is ‘exchange’ – the home is exchanging its coolness for heat, or vice versa, by means of a device similar to an air conditioner or a refrigerator.
A true geothermal system uses natural hot springs such as those commonly found in Iceland, for example, to heat homes. This system is relatively rare, as it depends on this gift from nature. In Iceland most homes are heated in this way, which is very lucky for them; however most home owners in North America are limited to using the less dramatic geoexchange system. It doesn’t matter where on Earth your home is: you can depend on this significant heat source.
So many people refer to geoexchange systems as geothermal systems, that the misnomer is quite commonly accepted; in fact, many geoexchange companies and contractors refer to themselves as geothermal companies, just for the sake of being understood.
How does a geoexchange (‘geothermal’) system save money in heating my home?
Once the system is installed, the only energy it requires is enough electricity to run the heat exchange unit. This is usually very inexpensive, but the bottom line will depend on what your local utility company is charging you per kWh. Often, if you live in a cold climate, a backup system may be desired where, in case the geoexchange system is not supplying enough heat, then electrical or oil-heating may be employed to ‘top-up’ the geoexchange system. This is most convenient in a retro-fit where the existing/former heating system is there anyway. Generally a 100% geoexchange system works fine for most people.
With oil, gas, and electricity prices skyrocketing with no end in sight, geoexchange systems are expected to grow in popularity. The payback period on such a system varies based on several factors, mainly oil, gas, and electricity prices in your area and how cold or hot your climate is. If you are considering installing a geoexchange system, you can ask your contractor to show you a cost/payback analysis.
Do many people have geoexchange (‘geothermal’) systems?
Although only a tiny percentage of existing homes in North America currently employ geoexchange systems, that percentage is on the increase – by an estimated 20% a year. According to one study, over 95% of geoexchange system owners would recommend such a system, a satisfaction level higher than with conventional heating systems.
Can I have a geoexchange (‘geothermal’) system installed on my old house?
Absolutely. Of course, as with anything, a new installation on a new home is the easiest, but depending on certain factors, your existing home may be easy and inexpensive to retrofit with a geoexchange system.
How much does a geoexchange (‘geothermal’) system cost and how do I get it?
Your cost will depend on many factors:
- The size of the system you want (how big is your house?)
- what will be involved in drilling or digging for the loops – if you have a pond in your back yard it may save a lot of money on the system, as the loops may be laid in a pond or other body of water without any digging
- Is your house already built or in the planning stage?
- Your contractor – do some shopping around, bearing in mind that the cheapest is not always the right choice
- Realistically, you will need to find a reputable geoexchange contractor or company in your area to design and install your system. There is a lot of do-it-yourself (DIY) information out there about geoexchange systems, but the fact is that the success of your system is going to depend very largely on the experience and expertise of the designer/installer. If you are adamant about doing it yourself, at least have some consultation with a professional – it’s money well-spent
- Make SURE your contractor is IGSHPA-certified. This is extremely important. Any reputable geoexchange contractor will have this certification.
- Beware of companies who list geoexchange systems as one of their services. With the recent explosion of interest in geoexchange systems, there are many companies who have dabbled with geoexchange projects who are perfectly comfortable proclaiming themselves experts.
- Check references, past projects. In the final analysis, a reputable contractor has a number of successful installs and a list of satisfied customers. Never hire a contractor until you have established that you are dealing with someone who has plenty of experience and a proven track-record.
- When searching for contractors to work on your geoexchange system, you will usually find plenty of entries in the yellow pages. You will do best to search for both geoexchange and geothermal, as the words are used quite interchangeably.
Hopefully this online directory is some help in locating the right contractor – again, DO NOT FORGET: check that they are IGSHPA-certified and definitely check their references! Good luck with your geo-projects!!!