From an article by Meredith Thorn in the Stevens Point Journal:

It looks like a large black box clinging to the side of the new airport hangar, but it is really a one-of-a-kind energy savings tool for the Stevens Point Municipal Airport.

The wall collects the sun’s heat and fills with warmth. The warmed air then is pulled into the hangar, said Joe Wheeler, the airport manager.

Because it’s so new, the actual energy savings have yet to be calculated. But, Wheeler said, in two months, savings have been “pretty significant.”

“Utilities on the hangar (are) going to be very cheap,” Wheeler said.

The hangar will be a “community” hangar, meaning pilots can rent an unspecified hangar space in the building, and airport employees will take care of the rest, Wheeler said. Rental rates have yet to be determined for the hangar, which can fit eight single-engine planes.

Wheeler didn’t say how much the project cost, but said the wall was completed by Sunny Solutions, a Berlin, Wis.-based company.

It’s the first solar transpired wall in Wisconsin, said Stevens Point Mayor Andrew Halverson.

“We want to be a leader in sustainability issues,” he said, and the project was a way for the city to put “its money where its mouth is” on energy-saving and environmentally friendly projects.