Recently rededicated following almost two years in construction, the 95-year old Wayne S. Aspinall Federal Building and Courthouse in Grand Junction, Colorado has seen the last of its transformations by the U.S. General Services Administration. Building systems performance will be measured and verified against energy targets by project architect, Westlake Reed Leskosky (WRL), for one year, beginning in April 2013, in hopes of achieving LEED Platinum status and becoming the National Register of Historic Places’ first net-zero-energy building.

The Aspinall is a 41,562-square-foot, four-story Neoclassical building that has been used continuously since it was first built in 1918, with an addition built in the 1930s. Having undergone sustainable renovation using federal stimulus funds while still occupied, its plumbing and mechanical systems were overhauled and careful consideration was given to character-defining features.

“The federal government has a goal to be carbon neutral by 2030,” said Roger Chang, Assoc. AIA, director of sustainability for WRL, in an interview with EcoBuilding Pulse. “One of our major selling points was that we could show that we figured out how to make an existing building net zero, 17 years ahead of schedule.” Net-zero energy features include a rooftop canopy that houses a large photovoltaic solar array, which underwent scrutiny from preservationist who were concerned about its visibility from the main entrance.

“If we had to scale back the canopy, we would have had less PV to generate power for the building,” said Jason Sielcken, regional project manager for the U.S. General Services Administration’s (GSA) Rocky Mountain Region. “So we had to offset that by driving down the building’s energy use.” The solution was a 123-kilowatt array the minimizes the canopy’s appearance, along with the addition of closed-cell, spray-foam insulation with pre- and post-consumer recycled content along perimeter walls, solar-control film on interior storm windows, maximization of natural daylight from existing windows, and a 32-well geothermal exchange system. Surplus energy is exported into the city power grid.

With metering and monitoring of energy usage playing a key role in net-zero energy goals, data from lighting, receptacle use, HVAC equipment loads, and carbon dioxide levels is displayed in the lobby so that adjustments can be made on-the-fly and lights can be automatically turned off when occupancy sensors determine that an area is not being used.