An earlier paper showed that commercial ground-source heat pump systems have significantly lower service and maintenance costs than alternative HVAC systems. This paper expands on those results by adding 13 more buildings to the original 25 sites and by comparing the results to the latest ASHRAE survey of HVAC maintenance costs. Data from the 38 sites are presented here including total (scheduled and unscheduled) maintenance costs in cents per square foot per year for base cost, in-house, and contractor-provided maintenance. Because some of the new sites had maintenance costs that were much higher than the industry norm, the resulting data are not normally distributed. Analysis (O'Hara Hines 1998) indicated that a log-normal distribution is a better fit; thus, the data are analyzed and presented here as log-normal. The log-mean annual total maintenance costs for the most recent year of the survey ranged from 6.07 cents per square foot to 8.37 cents per square foot for base cost and contractor-provided maintenance, respectively.

Units: I-P