The former Des Moines Public library, now designated as the Hall of Laureates, is undergoing energy efficiency upgrades in order to become LEED certified, Des Moines Register reports. There are many upgrades planned for the building, such as replacement windows, solar panels, geothermal wells, and an irrigation system. Century-old LEED certified buildings are a rarity, and the Hall of Laureates is the only building in Iowa to hold both characteristics.

"Sometimes the team had to choose between green priorities and historic ones. The new tinted windows, for example, conserve energy but don’t look like the untreated ones that would have been there in 1903."

Although the building's replacement windows do not appear as the original windows from over a century ago, the energy savings will rectify the slight loss of historic character. LEED recognizes Energy Star replacement windows as the highest energy efficient replacement windows on the market; they are available for both residential and commercial buildings.