Facility:

Dubuque County Courthouse – Dubuque, Iowa

38,000-square-foot, five-story, 105-year-old structure listed on the National Register of Historic Places

Geothermal heat pump system:

• 106-ton Mammoth brand.

• 100 console-type water source heat pumps sized from ¾ to four tons each.

• COPs of 3.88 and EERs ranging from 17.7 to 22.6.

Geothermal loop system:

• Open loop well at 94 feet deep.

• 350 gallon-per-minute capacity.

• Variable speed drive on well pump.

Annual energy costs:

First-year savings to taxpayers was $6,000 in natural gas, $3,000 in water and $2,000 in electricity.

At a glance:

• Former boiler and cooling tower heap pump system provided existing piping to each console, minimizing disruption of building and occupants.

• Building now has increased comfort with simultaneous heating and cooling – critical in Iowa’s volatile spring and fall weather.

• New system uses only 10 percent of the old, gaining valuable floor space in a historic building.

• Maintenance needs were reduced considerably, allowing staff spread time at other county facilities.

System performance report:

GeoExchange System Monitored Performance: Dubuque County Courthouse – Final Report by CDH Energy
[PDF format – 20 pages, 393KB]

Design:

Steven Ulstad Architects – Dubuque, Iowa

Engineering:

Gilmor & Doyle, Ltd. – Waterloo, Iowa

Contracting:

Giesler Brothers – Dubuque, Iowa

View more photos

Alfa-Laval plate heat exchanger

Mammoth console unit