GeoExchange for Office Buildings GeoExchange for Office Buildings(Published with the Permission of the Director of Communications, GeoExchange)
GeoExchange systems are the most economical and environmentally friendly way to heat and cool office buildings. They are already providing office-by-office savings and comfort across the United States and Canada.
GeoExchange systems have been known by various names, including geothermal heating and cooling, ground source heat pumps, and earth coupled heat pumps. GeoExchange is the new national brand name for the technology which heats and cools by taking heat from or returning heat to the earth.
Below the frost line, the temperature of the earth is relatively constant. GeoExchange heating and cooling systems take advantage of this constant temperature to provide efficient comfort conditioning. Since GeoExchange systems operate by moving heat from or to the earth, they burn no fossil fuels. This approach taps an inexhaustible source of renewable energy.
In most office buildings, each office or work area has its own geothermal heat pump. GeoExchange manufacturers package geothermal heat pumps in single cabinets that include the compressor, heat exchangers, fan, filter, and controls. These cabinets may be hung above the ceiling, installed in a closet (as at right), or used as self-contained consoles on the perimeter of the building. Common areas such as lobbies or meeting rooms can use larger heat pumps. This way, each office and each part of the common area can be individually controlled. Still other heat pumps can provide domestic hot water.
Generally, all of the heat pumps are attached to a loop of pipe inside the building. This building loop is, in turn, attached to a ground connection — either a series of buried pipes (closed loop) or water wells (open loop). The ground connection is often buried beneath parking lots or green areas such as court yards. Closed loop systems circulate water or an environmentally-safe antifreeze through these buried plastic pipes. The fluid absorbs heat from the ground during the winter and transfers it to the heat pumps inside the building. In the summer, the process is reversed with heat from the building returning to the ground. Open loop systems operate on the same principle, and can be installed wherever an adequate supply of water is available.
Unlike some central systems, GeoExchange can provide heating and cooling simultaneously. The heat pumps on the sunny side or core of the building may provide cooling while those on the shady side or perimeter are providing heat. Heat rejected from one zone or office can be used in another, or even to make hot water.
GeoExchange systems reduce energy and maintenance costs, reduce construction costs, provide quiet comfort and a healthy work environment, produce lasting savings, and enhance the safety and beauty of the property. GeoExchange is one of the few renewable technologies that can improve cash flow and boost return on investment.
Energy and Maintenance Costs
Because they use the Earth’s constant temperature, GeoExchange systems are inherently more efficient than systems that rely on outside air as a source of heat or for disposal of excess heat. GeoExchange also operates at lower cost than central systems using boilers and chillers. In office buildings, GeoExchange systems typically provide overall energy savings of 20 percent, and often more.
Maintenance costs are also reduced. Because they make ground loops from pipe guaranteed for up to 50 years, and since geothermal heat pumps are expected to be maintenance free for 20 years or more, GeoExchange systems rarely need service and are extremely reliable. A recent study shows maintenance costs at an extremely low 7 to 10 cents per sq. ft. per year.
Construction Costs
Using GeoExchange in large buildings eliminates the typical boiler room and chiller or external cooling tower. This saves space inside the building, and eliminates the need for additional structural support for rooftop equipment, potentially reducing construction costs. It also means that failure of a single piece of equipment, such as a chiller, will not impact the entire building.
For office buildings, developers often install the individual heat pumps only as tenant spaces are fitted-out. This reduces initial construction costs while providing the maximum in flexibility in the deign of interior spaces.
Quiet Comfort and Tenant Satisfaction.
Because GeoExchange systems use many relatively small geothermal heat pumps, each tenant has control of their offices and suites. These small units produce very low noise, leading to greater comfort and satisfaction.
Since rents are small when compared to the cost of employees, tenants also appreciate workplaces that keep their people healthier and more productive. Properly installed GeoExchange systems offer the highest indoor air quality available.
Flexibility
| "Geothermal allows you to do controls you wouldn't dare think about
if you were using gas or oil or other fossil fuels." Don Frederick |
Because GeoExchange systems use many smaller heat pumps, there are many control options from local thermostats and occupancy sensors to full energy management systems.
GeoExchange systems sometimes incorporate a fluid cooler to augment the ground connection. These "hybrid" systems provide the flexibility to maximize savings from utility time-of-use rates by using the ground for thermal storage. Hybrid systems can also reduce initial installed costs with little or no impact on operating costs.
Lasting Savings
Package terminal heat pumps and air conditioners start losing efficiency as soon as they are installed. A recent study shows that outdoor condensing coils lose a minimum of 3 percent in efficiency if properly maintained, and up to 27 percent if not cleaned regularly and meticulously. This cleaning often does not occur at all in busy properties. Since GeoExchange systems don’t have external air coils, their efficiency remains constant over their many years of useful service.
Safety and Aesthetics
GeoExchange systems have no combustion, and thus produce no indoor pollutants like carbon monoxide. And since the earth connection is buried, there is no outdoor or rooftop equipment to be vandalized or that may rust.
Compared to packaged terminal equipment, GeoExchange provides a much cleaner look. There are no exterior grills, and the outside of the property is just as quiet as the inside.
GeoExchange may or may not require an additional initial investment. In those cases where installation costs are higher than for other systems, GeoExchange systems consistently produce positive cash flows. The cost of financing is nearly always less than the energy savings.
The Geothermal Heat Pump Consortium, Inc. (GHPC) is ready to provide a wide variety of information to help you get started in applying GeoExchange. GHPC may also be able to provide design assistance for large or multi-site projects. Call us toll free at 1-888-ALL-4-GEO (1-888-255-4436). And visit our web site at http://www.geoexchange.org.
The most valuable information sources are other professionals with GeoExchange experience. The case studies developed by GHPC as well as those prepared by GeoExchange manufacturers and utilities can lead you to the architects and engineers responsible for actual GeoExchange installations.
Contact the electric utility in your area or in areas where you anticipate potential GeoExchange projects. They can tell you about other projects in the area — visit one or two, talk to owners, occupants, and facility maintenance staff. The utility will be happy to tell you about any incentive programs that apply in your area.
Many utilities offer technical assistance to support potential GeoExchange projects such as co-funding of feasibility studies or engineering design. Utility staff are often available to meet with clients interested in exploring potential projects.
The Geothermal Heat Pump Consortium is a non-profit organization with participation and support from the U.S. Department of Energy, the U.S. Environmental Protection Agency, and the Nation’s utilities. GHPC’s mission is to promote the use of GeoExchange — the most energy-efficient, environmentally-friendly heating and cooling systems available anywhere.
GeoExchange gives office building tenants quiet, comfortable, and environmentally friendly heating and cooling. And it gives building owners and managers the benefits of energy efficiency, reliability, and cost reduction.
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