We interviewed RTM Principal Doug Brewer to talk about geothermal systems and the trends in efficient heating and cooling systems.
Q: How do geothermal systems work?
A: Geothermal systems are a major energy saver in that they utilize consistent ground temperatures to assist in the heating and cooling of a building. The moderate ground temperatures boost equipment efficiency and reduce operational costs of the environmental systems.
Q: If geothermal systems save on energy costs, why don’t more companies use them?
A: While geothermal systems save on energy costs, the up-front expense often dissuades clients from selecting and installing them.
These systems quite often require bores of up to 500 feet underground. These bores/drills can get very expensive. When we talk to clients about system options, we discuss the difference in efficiencies, the up-front installation costs and the operating costs. Clients typically are not against spending a bit more for the systems if they will get a quick return on their investment in the way of energy savings. It is common to target a three- to five-year return on investment. For geothermal systems, a common return on investment can be 40 to70 years.
Q: Given the length of time needed to achieve ROI, when would geothermal actually make sense?
A: Good question! Geothermal can be a great fit for colleges and hospitals—really any building that will be utilized in the same way for about 50 years. These types of buildings also can qualify for state and federal funding, which can reduce the client’s up-front cost and make the investment in geothermal more attractive. Unfortunately, these significant incentives are not available to the public sector, in general.
Q: Are there any other challenges to be aware of with geothermal systems?
A: Another challenge to be aware of is the space needed for the geothermal field. A 2,500-square-foot house with a three-ton air conditioning unit would require a single well with a pair of three-inch pipes down 500 feet. A larger building with a cooling load of 300 to 400 tons will require a hundred such wells. Since the wells need to be spaced about 15 to 20 feet apart, the field needs to be rather large.
Q: What are other options that are still efficient?
A: The truth is, traditional refrigeration equipment is constantly getting more efficient, but it will never be as efficient as when coupled with a geothermal field. The most efficient, non-geothermal system is called variable refrigerant flow (VRF). These systems, if set-up properly, can share heating and cooling loads between the different zones in a building and allow for simultaneous heating and cooling. These systems are becoming much more commonplace, particularly in the residential sector.