Darien’s new library has won a top design award from the Connecticut Green Building Council.

Among its winning features were the geothermal wells that both heat and cool the building and its location on the recovered brownfield site of a former gas station.

But the whole design approach also was praised, according to a Darien Times report. For the start it was planned under the premise that the initial construction costs should take a back seat to the building’s long term “lifecycle” costs.

The library took the top award in the institutional/public building category. The runner up was the Amistad Building at the Yale Medical Center.

The Connecticut Green Building Council is a chapter of the U.S. Green Building Council that promotes environmentally sound building standards.

The citation said the library was the first in New England to meet the LEED Gold standard. It noted the building blended traditional New England architecture and with “excellent sustainable attributes” and that during construction 50 percent of waste was recycled.

According to an article in the Library Journal, the library trustees originally planned an expansion of the existing building. But when costs escalated, they chose to proceed with a new 54,000 sq. ft. stand-alone building that was to cost about $28 million, including land acquisition and remediation costs.

It was designed to last a century, with steel columns and concrete block walls, brick and aluminum-clad windows, and a slate roof.