Continuing our coverage of the 2014 AIA COTE Top Ten green projects, this article is part of a series of 10 pieces that examine a specific, defining design challenge or innovation of each of this year's winners.
It was an unprecedented challenge: convert Portland, Ore.’s Edith Green–Wendell Wyatt (EGWW) Federal Building—a 40-year-old, 18-story energy hog—into a showcase that could rival today’s most energy-efficient new office towers. Led by Portland-based SERA Architects and Cutler Anderson Architects in Bainbridge Island, Wash., the team succeeded, in large part due to the radical decision to re-skin the entire building. The process involved removing the precast concrete façade and installing a high-performance glass curtainwall. The building’s fresh new face reduces solar heat gain, tightens the building’s seal, and radiates sustainability.
The team knew early in the process that the uninsulated, precast concrete panels had to go.
“You could pop off a ceiling tile and see daylight through the joints between the panels,” says SERA project architect Jim Riley, AIA. Demolition crews removed the first panel by reusing the precast pickup points, but due to cracking they resorted to a safer but more labor-intensive strap-and-tackle rigging technique for the rest of the panels. In the end, all 3,337 tons of concrete were crushed and reused for an on-site road bed.
The building’s performance requirements, to a large degree, dictated the design for the new façade. To meet the General Services Administration’s (GSA) aggressive energy-use-intensity (EUI) target—35,000 Btu per square foot per year—the architects replaced the building’s inefficient variable-air-volume system with a radiant-ceiling heating-and-cooling system built by Steel Ceilings, with Barcol-Air USA doing the activation. But because of the inherent output limits of radiant-ceiling systems, the new façade would have to meet certain minimum performance standards to allow the new climate-control system to do its job.
To determine how the new façade would meet those standards, SERA oversaw three months of site-specific climate and solar analysis. The firm studied orientation and seasonal changes, taking into account free shading from surrounding buildings. Complex parametric analysis specified 40 percent vision glazing and 50 percent shading during peak loads during summer. Armed with those guidelines, GSA Design Excellence architect Jim Cutler, FAIA, principal of Cutler Anderson Architects, led the design of the new skin: a wraparound aluminum glazing system fine-tuned through the use of elevation-specific shading and reflective elements.
The designers added 34-inch slab extensions on all floors to allow for the curtainwall anchor system, consisting of Halfen cast-in channels. Portland-based Benson Industries designed and built the curtainwall system, which features blast-resistant, triple-laminated glass made by Viracon, headquartered in Owatonna, Minn. Vertical arrays of aluminum “reeds” project out from the northwest façade, shading harsh afternoon sun in summer. On the southwest and southeast façades, where the sun isn’t as strong, an egg-carton grid of horizontal aluminum plates and more subtle vertical reeds follow the curtainwall frame. Plates at the top of each window (their undersides painted green) block sunlight, while reflective plates (green below, silver above) at the 42-inch sill height bounce natural light up to 16 feet into the interior spaces. The north façade requires no shading.
The EGWW Federal Building’s new façade is paying off in many different ways. Between Benson’s lock-tight curtainwall system, triple-laminated glass and 8 inches of thermofiber insulation (R-17) below the sill, the skin is tight, helping reduce annual energy usage by 60 percent and annual operating costs by up to $400,000. That tight envelope enables the use of the radiant ceiling climate control and a separate ventilation system that delivers 100 percent fresh air (as opposed to the majority recycled air of a typical VAV system). And removing the 3,337 tons of precast concrete reduced enough weight that no costly seismic upgrades were needed during the renovation, even despite today’s more stringent seismic codes.
The new façade also makes a bold statement. The glass is tinted green. The vertical “reeds” have an organic look and are designed to hold climbing vines on the lower floors. “A lot of eco-friendly buildings look like rocket ships,” Riley says. “We wanted to make this a building that any kid visiting Portland on a field trip would immediately recognize as environmentally sensitive.”