Steele County Strives for Energy-Efficiency

Precasting methods provide an unusual amount of design flexibility for such a small facility.

New government buildings are increasingly being built to consume fewer resources and save energy. Cost restrictions and security concerns can make it difficult for jail planners to fully participate in the trend, but jails are not being left out in the cold.

One jail striving for energy efficiency is the $12.75 million Steele County Detention Center, the first jail in Minnesota to incorporate extensive daylighting. Steele County’s jail is also among a growing number of rural lockups turning to geothermal energy as a source for heating and cooling.

More than 11 miles of vertical piping runs through a geo-wellfield with 330 bore holes, each 90 feet deep. From the water comes energy. Geothermal energy systems rely on ground wells to heat exchangers located throughout the jail to take advantage of the Earth’s natural heat to turn water into free energy.

Renae Torborg, a mechanical engineer at Ericksen Ellison & Associates, which provides engineering services for geothermal systems, says water at only 40 F is required to make the system effective. “Even though 40 degrees seems cold to us, there’s energy in that water.”

Although geothermal systems have a much greater start-up cost, the system could pay for itself in just seven years, after which the facility’s energy will essentially be free. In addition, Torborg says that because the building’s many heat pumps are located throughout the building, there is greater flexibility in heating different areas at varying temperatures.

According to Randy Lindemann of KKE Architects, the project’s lead designer, the high start-up costs of geo-exchange systems make them best suited for new projects, not upgrades. Unfortunately, the systems also require a lot of space-in Steele County’s case, almost three acres of the 19-acre site is occupied by wells. It was safe to pave a parking lot over the wellfield, but the ground is not stable enough to support a facility-a setup that may suggest only rural jails with ample acreage are candidates for geothermal, but Torborg says that any available retention ponds or lakes can also serve as heat sinks.

With geothermal systems, water running through groud wells is heated naturally by the earth to provide heating and cooling with minimal operational cost.

Steele County also happens to be the first jail in Minnesota to use extensive daylighting, eliminating the need for cell windows. The idea of bringing natural light through large windows into the recreation areas was a tough sell to the Minnesota Department of Corrections, which regulates jail design in the state, Lindemann says.

“To date, the interpretation of the Minnesota DOC’s daylighting code is that a cell should have a window,” says Lindemann. “Due to mental [health] issues [among the inmates], the DOC officials were extremely concerned we were going to create these cave-like environments.”

To convince them that KKE’s daylighting plan would not just meet codes, but exceed the required amount of natural light, DOC and Steele County officials were shown models in design charettes at the firm’s daylighted offices in Minneapolis, to further illustrated their argument.

“Our DOC 2911 code required 140 square feet of glass. By implementing borrowed light, we actually provided 765 square feet of glazing, four times the requirement, and it was less expensive,” Lindemann says. Thus, Minnesota became the latest state to embrace the borrowed light concept.

Freed from the constraints of having windows on the building’s exterior, KKE was also able to exploit this flexibility to create better precast concrete solutions. Lindemann says that building an entire facility out of precast panels can become problematic in small jails of between 100 and 200 beds, but his firm was able to meet the challenge.

“We strive to design cells that are appropriate for each security level,” he says. “But the way you achieve efficiency is by repetition, or economy of scale. We have nine different cell types in a facility of only 160 beds, and with nine different precast molds, the precast advantage disappears pretty quickly because of the expensive mold charges.”

Instead of calling for nine different cell molds covering the range of security levels and ADA requirements, KKE designed the mezzanine level and roof as the precast frame, as opposed to a typical two-story design, in which the cells support the mezzanine. Using the building shell instead, the project team was able to build the facility out of simple concrete blocks to deliver a variation of cell types for the small facility. “Instead of the walls holding up the building, the building is a kit of parts,” Lindemann explains.

In addition to cost-saving construction methods and energy systems, the Steele County Detention Center also responds to two important developments in Minnesota because the facility is expandable. A recently-passed felony DUI law tightening drunk-driving penalties was already expected to swell inmate rosters. Then, Minnesota corrections officials announced that jails would be responsible for housing more state inmates, making expandability critical.

Opened in early October, the 58,500-square-foot facility also includes a video-arraignment courtroom that will help the jail earn an anticipated $3.2 million in boarding revenue by making Steele County more attractive to client counties, cutting down on their transportation costs for court appearances.