“Geothermal” is the commonly used term for sourcing heat from the ground. “Geoexchange” is an application which uses the earth to provide both heating and cooling in homes and buildings. The geoexchange process makes use of specialized heat pumps which take advantage of the fact that the temperature in the ground beneath the frost line remains relatively constant throughout the year, whereas temperatures on the earth’s surface fluctuate greatly across the seasons.
Pipes are installed in the ground in a loop connected to the heat pump, circulating a liquid to exchange energy with the earth. In the colder months, the liquid extracts heat from the ground, which is transmitted to the building. In the warmer months the system is reversed, sending heat into the cool ground more efficiently than can be done with conventional air conditioning systems which have to be exposed to hot ambient outdoor air.
As a consequence, users can displace traditional energy sources by using a renewable alternative while cutting global greenhouse gas emissions. The underlying reason this technology is so attractive is that for every unit of energy used to operate the heat pumps, the systems extract 3 to 4 times the equivalent in free and clean energy from the earth.
Types of Ground Loops
Depending on the area where the building is situated, a horizontal or vertical ground loop will be installed. In more congested areas such as Downtown Toronto, a vertical ground loop would be installed due to the space constriction. A horizontal ground loop can be installed, for example, underneath of a parking lot of a large office building. On sites that have a suitable nearby body of water such as a lake or pond, the system economics and efficiencies can be further enhanced by installing the loop in the water as an alternative to drilling a vertical loop or excavating a horizontal loop.
What types of buildings can geoexchange be installed in?
Whether it is offices, recreational facilities, schools, grocery stores, hotels, condos, warehouses or other commercial buildings, building owners and occupants are looking for renewable energy alternatives. The benefits of geoexchange in commercial buildings include operating cost savings, greater comfort, lower greenhouse gas emissions, lower maintenance and equipment life cycle costs, and individual zone control. Geoexchange is an excellent option for the majority of buildings, whether building new or retrofitting an existing building.
Challenges & Misconceptions
1. Higher upfront capital costs in comparison to a traditional HVAC system
Although the initial capital cost is higher than a traditional HVAC system, the incremental capital cost is recovered through reduced energy/ fossil fuel and maintenance costs. Once the incremental capital has been recovered through savings, all the savings are a pure cost reduction
2. Most engineers, architects and mechanical contractors “go with what they know” so it difficult to change HVAC technologies
- It is up to the building owners and tenants to drive change for the better
- Geoexchange has many advantages over a traditional HVAC system including lower operating costs and it is environmentally friendly
- They are open to change if they have time to adapt
3. The misconception that geoexchange is not suited for many types of buildings
- Although geoexchange may not be suited for every building, it is suited for most buildings that have a seasonally balanced heating and cooling load and can use low-grade heat for space heating
- Geoexchange can be installed in schools, office buildings, condos, warehouses, recreational facilities, hotels, grocery stores
- Geoexchange can be easily incorporated with new buildings while retrofit projects require a more thorough evaluation, but most will work with geoexchange
4. Sometimes a lack of understanding of the technology causes concern
- Education of geoexchange is paramount. There are many projects that you hear about that haven’t been properly designed or installed. With thorough engineering, design and installation, a geoexchange system will work for decades
By Megan Macadam, Business Analyst, Corporate Development, Alter NRG Corp.
Tags: alternative energy, Clean Energy, CleanEnergy, commercial geoexchange systems, commercial geothermal systems, energy efficiency, geoexchange, geothermal, geothermal heating and cooling, hvac systems