Polk County Courthouse Exterior Renovation

Des Moines, Iowa

150,000 GSF

The Polk County Historic Courthouse underwent significant restoration to brilliantly display its original glory.

The $2.5 million renovation of the historic courthouse involved cleaning, repairing, and sealing the building’s limestone directed by OPN Architects. In addition to the exterior makeover, Alvine Engineering was tasked to design new exterior lighting for the façade of the downtown historical landmark. The challenge included undertaking a high profile design and required a high attention to detail and team collaboration to protect the intricate details of the historic façade against alteration.

Early in the design process, Alvine Engineering leveraged our close relationship with the University of Nebraska at Omaha to provide few graduate students a chance to assist the team with a luminance study of the downtown area. The result was a win for the project, the University, and Downtown Des Moines.

High Dynamic Range images (HDR) were taken of the courthouse and the surrounding downtown area. A luminance meter was used to determine the building’s surface reflectance as well as provide values used to transfer the HDR images into false color images with scaled luminance values. The false color images were used by the design team to compare the perceived brightness of the visual observer to the computer simulated renderings and calculations created during the design process.


  • 93 LED luminaires were installed that utilized ground-mounted flood lights, building-mounted flood lights, and in-grade mounted luminaires.
  • The design proved to be 61% better than the local energy code baseline and uses 43% less energy than an equivalent metal halide system.
  • High-efficiency light-emitting diode spotlights were installed on the roof and on the ground to illuminate the historic landmark.
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