Maintenance Cost Data For Commercial Buildings
(published with the Permission of the Director of Communications, GeoExchange)
Geothermal systems in commercial applications show very low operating and maintenace costs compared with alternative systems, according to data. Documentation of low maintenance and energy costs of geothermal systems increases their attactiveness to designers, developers, and owners. Because owners understand that maintenance costs vary as much as energy costs, they want assurances of low and predictable maintenance costs. Low maintenance costs also indicate a system is reliable and requires little management attention. Current data shows that maintenance of geothermal systems costs less than 1/2 as much as equivalent alternative systems. This conclusion is based on three sources:
The 1995 ASHRAE Handbook (p. 33.5) offers a standard method for calculating costs for commercial-size HVAC systems, but does not explicitly include geothermal systems. ASHRAE includes water loop heat pump systems, which use similar (ARI-320) heat pumps, supported by a cooling tower and boiler instead of a geothermal loop. Because of the boiler and cooling tower, these systems are expected to cost more than "pure" geothermal systems to operate, but they should be comparable to "hybrid" geothermal systems. Calculating by the ASHRAE method, geothermal systems can cost in the range of $0.11-$0.22/ft< per year in 1996 dollars, vs. $0.38 (medium) to $0.50/ft< per year (mean) for the "average" commercial heating and cooling system. (Conversion from ASHRAE Handbook 1983 dollars to 1996 dollars)
The article, "Operating and Maintenace Experience with Commercial/Institutional Ground Source Heat Pump Systems," by R. Mancini, H.W. Heiss, and J.B. Singh, analyzed data from commercial systems in Southern Ontario. The one building with maintenance data shows annual maintenance costs of $0.03/ft< per year, with a long-run cost projection of $0.10/ft< per year ($US).
Lew Pratsch of the Department of Energy notes that the 4000-ton Galt House East Hotel, Louisville, KY, an indirect open loop system with distributed heat pumps, has a cost of $0.12/ft< per year. At Fort Polk, LA 4,000 housing unit project is budgeted at $0.18/ft< per year.
Thus, geothermal heating and cooling systems that are designed and installed well will have much lower maintenance costs than alternative systems. The best planning numbers now are in the range of $0.10 - $0.22/ft per year. Coupled with the low energy costs of geothermal systems, this is another reason why geothermal has such low life cycle costs.
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