The Louisville Northeast Regional Library, the latest addition to Louisville’s library system, exemplifies cutting-edge sustainable design and cost efficiency. Faced with the challenge of exceeding the energy and cost performance of its predecessors, the project team implemented 53 Solatube SkyVault M74DS tubular daylighting devices (TDDs). By replacing traditional clerestories with these advanced daylighting solutions, the library achieved a dramatic reduction in electrical usage—from 1.02 to 0.65 watts per square foot—resulting in substantial energy savings and a $249,765 reduction in structural steel costs.