In 2004, McLean County District Unit No. 5 in central Illinois replaced the HVAC systems at six of its oldest elementary schools with GSHPs.
“Installation costs were under $20 per square foot, and our overall energy costs have been reduced by over 40 percent,” Jeff Monahan, district construction coordinator, said. “Maintenance requirements have also been reduced to only standard PM work. Our students and staff are very pleased with the new ground-source systems, with better classroom control and an overall reduction in noise level.”
Kirk Mescher, PE, of Columbia, Mo.-based CM Engineering Inc. is largely responsible for the success of the district's GSHP designs. He was able to reduce installation, energy, and maintenance costs with a novel and simple combination of features, including:
A vertical ground loop designed to maintain loop temperatures between 45°F and 85°F.
A one-pipe interior water-distribution loop.
Packaged low-noise water-to-air heat pumps with low-head circulation pumps.
Zone thermostats.
Energy use is monitored closely as part of the Energy Ed program. Bruce Boswell, manager of the program, noted that all GSHP schools in the district have achieved an Energy Star rating above 83 without lighting or envelope upgrades.
In Austin, Texas, ground-loop contractor Lonnie Ball of Ball Drilling Co. maintains a list of more than 100 GSHP systems with 17,423 vertical bores that he and others have installed in the area since 1985. As in McLean County, the early installations were retrofits, and the unitary heat pumps, as shown in Photo B, worked well. Although other engineers installed a few central systems, loops in newer schools in surrounding districts are almost exclusively unitary.
“I talk to the people in our office and encourage them to design systems that keep in mind what our local work force is capable of doing,” Mike Green of MEP Engineering Inc. in Austin said. “The number of quality people is going down. They are still out there, but there is a greater chance that the contractor that is low bid on the project is not going to have people with a high level of skill. So we need to ‘keep it simple.’”