Achieving net-zero energy usage is laudable in any building, but to do it in a nearly century-old building—and one listed on the National Register of Historic Places at that—is exceptional. In Grand Junction, Colo., the U.S. General Services Administration (GSA) and a design/build partnership between Westlake Reed Leskosky and The Beck Group aim to do just that.
Named for a longtime Colorado congressman, the Wayne N. Aspinall Federal Building and U.S. Courthouse is a three-story, 42,000-square-foot neoclassical structure that has been in continuous use since its construction. The building was first built as a post office and courthouse, and then was expanded in 1939. In the decades since, however, the building had become cramped and outdated, with some alterations such as dropped ceilings obscuring historic features.
Because the building is listed on the National Register, the project underwent a federally mandated review of its impacts on the building’s historic features, as required under Section 106 of the National Historic Preservation Act. The design team assigned a series of “preservation zones” to the building that helped determine which elements should be retained and which could be disturbed. The most public areas, such as the exterior and lobby, were afforded the most protection. The areas that had the least important historic fabric, such as a nonpublic area in the basement, were given more leeway.
New interventions included a roof-canopy-mounted, 123-kilowatt photovoltaic array (which generates enough electricity on site to power 15 average homes); the addition of spray foam and rigid insulation to the building shell; the installation of storm windows with solar control film inside the historic windows, in order to preserve the exterior appearance; a 32-well geothermal exchange system for heating and cooling; fluorescent and LED lighting upgrades; and post-occupancy monitoring capabilities. Because the original fenestration needed to be retained, the design team increased daylighting through other means, two examples being a skylight that was installed over a tenant space on the first floor and perimeter ceiling zones that were kept free of building services on the second and third floors.
In some cases, inefficient features, such as the building's original and outdated plumbing fixtures, were replaced. Previously, the building had toilets that used more than 3.5 gallons of water with each flush. The design team researched methods to retain the existing fixtures with new flush valves, but ultimately decided that the best option would be to install low-flow fixtures such as toilets that used only 1.28 gallons per flush.
Finally, one of the most important features of the newly remodeled building may be those that support "passive survivability" in case of a power outage or major emergency—a concept that has emerged in recent years in response to the threat of terror attacks or natural disasters like Superstorm Sandy. These features include natural daylight in the most regularly occupied spaces, a high level of thermal mass and new wall insulation to stabilize internal temperatures, and the ability to use the basement as a shelter in a crisis.
"This project demonstrated the high value of investment in fairly 'low-tech' measures such as envelope upgrades to dramatically increase energy efficiency," says Paul Westlake Jr., FAIA, managing principal and lead architectural designer for Westlake Reed Leskosky. By choosing durable and efficient materials and fixtures, and respecting the existing structure, the design team has ensured that the Aspinall building could still be around well into another century.
Click here to see all of the 2014 AIA COTE Top Ten Green Projects. Scroll down for more images, along with performance data and project team and materials information. Stay tuned for profiles of this year's winning firms on Ecobuildingpulse.com, along with additional coverage of this year's Top Ten in the Spring issue of ECOBUILDING Review.
BY THE NUMBERS
Project completion date: February 2013
Building gross floor area: 41,562 square feet
Estimated percent of occupants using public transit, cycling, or walking: 20
Daylighting at levels that allow lights to be off during daylight hours: 50
Lighting power density (watts per square foot): 0.33
Percent of views to the outdoors: 92
Percent of spaces within 15 feet of an operable window: 0
Percent reduction of regulated potable water: 40
Potable water used for irrigation: No
Total EUI (kBtu per square foot per year): 14
Net EUI (kBtu per square foot per year): 0
Percent reduction from national median EUI for building type: 78
Third-party rating: LEED Platinum
Total project cost as time of completion (land excluded): $15 million