The Lincoln Public School District, in Lincoln, Nebraska, recently installed vertical-bore geothermal heat pump systems in four new elementary schools. Because the district has consistent maintenance records and procedures, it was possible to study repair, service, and corrective maintenance requests for 20 schools in the district. Each school studied provides cooling to over 70% of its total floor area and uses one of the following heating and cooling systems: vertical-bore geothermal heat pumps (GHPs), air-cooled chiller with gas-fired hot water boiler (ACC/GHWB), water-cooled chiller with gas-fired hot water boiler (WCC/GHWB), or water-cooled chiller with gas-fired steam boiler (WCC/ GSB). Preventative maintenance and capital renewal activities were not included in the available database. GHP schools reported average total costs at 2.13 cents/ ft ² - yr, followed by ACC/GHWB schools at 2.884 cents/ ft ² - yr, WCC/GSB schools at 3.73 cents/ ft ² - yr, and WCC/GHWB schools at 6.07 cents/ ft ² - yr. Because of tax exemptions on material purchases, a reliance on in-house labor, and the absence of preventative maintenance records in the database, these costs are lower than those reported in previous studies. A strong relationship (R ² 50.52) was found between costs examined and cooling system age: the newer the cooling equipment, the less it costs to maintain.

Units: I-P