By Dan Linehan
MANKATO — Harvesting free energy beneath the Earth, using motion-triggered lights and employing an array of water-saving measures, Blue Earth County’s nearly completed justice center may save a quarter-million gallons of water and 16,250 tons of carbon dioxide every year.
The toilets have two-way flushers — pull up for liquids, push down for solids — designed to save water. There’s preferred parking for carpools and hybrids. The wood doors, paneling and millwork come from forests certified by the Forest Stewardship Council, which hires third parties to study the management practices of timber companies.
About three years ago, the county announced its pursuit of certification by the U.S. Green Building Council’s Leadership in Energy and Environmental Design (commonly called LEED) program. LEED, which started in 1998 provides a set of objective standards for environmentally friendly building design.
Now, the justice center is on track to be the first LEED-certified building in south-central Minnesota.
Multiple Dumpsters are used for the recycling of construction materials (on most sites everything is thrown in a landfill). The carpet, ceramic tiles, plastic toilet compartments, walls and other materials contain various percentages of recycled materials. Temperatures are kept constant via computer-controlled thermostats.
If LEED certification comes later this year as planned, the justice center — a consolidation of courts, county corrections, jail, prosecution, probate and law enforcement functions — may be one of the first jails nationwide to get the recognition.
Earth power
The building’s use of geothermal power is perhaps its most impressive energy-saving device, replacing at once energy-gobbling air conditioners and a boiler.
In their place is 48 miles of tubing beneath the ground and pumps to circulate the water and heated air.
In the winter, the water absorbs heat from the ground and takes it to heat pumps, where it is converted into air heat using pumps. In some cases, the heated water runs through pipes beneath the floor to provide so-called “radiant heating.”
In the summer, the heat is carried away from the building and dissipates in the ground.
The system runs on electricity, most of which is generated through the burning of fossil fuels, but the justice center is planned to be between 24 percent and 31.5 percent more efficient than if it were built to industry standards.
The Environmental Protection Agency calls geothermal heating “the most energy-efficient, environmentally clean and cost-effective space conditioning system available.”
Form meets function
Building a jail implies trade-offs between LEED standards and an effective jail.
Designers were unable to meet LEED standards for the number of watts used to light a single square foot because jail security required more lighting, said Kevin Flynn, a St. Paul architect who is consulting for the county on LEED matters.
Another trade-off: Toilets inside the jail cells needed to have narrower drains to prevent contraband from being flushed down, County Administrator Dennis McCoy said. Smaller drains mean more water pressure, which means more water use.
The other major competing value with the environment is cost.
Computer modeling was used to determine how long it would take for efficiency savings to pay back the initial cost. About 90 percent of a building’s overall cost comes from its operation, while the other tenth comes during its construction, McCoy said.
If the payback time exceeds 40 years, the more-expensive route was not taken, he said.
Overall, the entire efficiency package is slated to pay for itself in about 7.1 years.
A so-called “green roof,” which involves live plants on the roof, may have saved cooling costs. But it was also envisioned to be a “maintenance nightmare” whose payback time greatly exceeded any sort of optimistic projections about the justice center’s life span.
Why LEED?
Flynn, the St. Paul consultant, said labels like “green” and “sustainable” are popular, and LEED certification is one way to verify claims like these.
“It’s very easy to say you’re going to do something and harder to do it,” Flynn said.
The U.S. Green Building Council, the agency behind LEED, won’t send a representative to Mankato, but its professionals will review building plans submitted by Flynn and the project team. It awards points based on objective benchmarks such as using 10 percent recycled content and the creation of on-site renewable energy.
The justice center is aiming for LEED’s “silver” rating, which means it must earn between 33 and 38 out of a total of 69 points. The “silver” rating is better than the simple “certified” but lower than “gold” or “platinum.”
County officials also hope the pursuit of LEED would lead other local builders to adopt it as well.
Bryan Paulsen, whose Mankato architectural firm helped design the justice center, said three other local projects in the works are seeking the environmental accreditation.
They are the new elementary school planned for Mankato, an animal shelter and the National Guard’s field maintenance shop.
