Jeff Morrow, owner of Solar Heat Exchange Manufacturing, works on installing solar panels Tuesday outside the Douglas County Jail. The panels will be used to heat water at the jail.

Inmates soon will be washing their hands, cleaning their dishes and cleansing their bodies using water warmed by a new set of solar panels at the Douglas County Jail.

The system — using five solar panels installed out back — is powering a push for sustainability in the county’s public buildings and, by extension, among county residents, organizations and businesses.

“This is the first in what I hope will be many projects where the county will lead the way in managing its resources sustainably,” said Nancy Thellman, chairwoman of the Douglas County Commission. “It’s also a way of leading by example. Our hope is, little by little, it will inspire our citizens to make even little changes in their homes, because this is the way of the future.”

The current incarnation of the future angles up toward the southern sky: glass-encased water pipes made of copper and attached to thin strips of metal coated with thinner — even microscopic — strands of metallic paint.

Together, the system cycles 120 gallons of room-temperature water through each of the panels until it reaches temperatures of up to 180 degrees. The water then is pumped back into the jail, into a heat exchanger where another 120 gallons is warmed by the passing fluid.

The system is designed to produce 500 gallons of 120-degree water each day during the summer — enough to meet the building’s needs through May, June and July and still enough to cut into natural gas bills during colder weather.

Expected savings: $18,000 during the next 15 years, enough to pay off the system within a decade.

“It’s basically free heat,” said Eileen Horn, city-county sustainability coordinator.

The system is one of two being installed this week by Solar Heat Exchange Manufacturing, a Perry-based company founded three years ago. The other will serve the Douglas County Youth Services building in North Lawrence.

The combined $19,996 contract is the county’s first major move at Horn’s suggestion. On Wednesday, commissioners will consider buying a new boiler for the Douglas County Courthouse, one efficient enough to cover the unit’s $50,000 cost within nine years.

County buildings soon will be getting fluorescent light tubes that are thin enough to use 50 percent less energy, and the Judicial and Law Enforcement Center is awaiting adjustments to its air-handling units to boost efficiency.

Even chandeliers in the County Commission meeting room will be getting compact fluorescent bulbs to save energy.

“We’re pursuing all measures that have the shortest payback period first,” Horn said. “We’re getting more efficient.”