Designed by SOM and completed in 1974, the Edith Green-Wendell Wyatt Federal Building in Portland, Oregon, was typical of office towers of its era. The 18-story structure featured a pre-cast concrete facade filled in with tinted single pane windows. By the beginning of the 21st century, this envelope system had reached the end of its lifecycle. The sealant joints were failing and the wall, which was not very well insulated to begin with, was leaking like a sieve. In spite of Portland’s mild climate, the building had become one of the worst energy hogs in the General Services Administration’s (GSA) portfolio.
With funds from the American Recovery and Reinvestment Act of 2009, the GSA set out to improve this state of affairs. The agency hired Bainbridge Island, Washington-based Cutler Anderson Architects and local firm SERA to renovate the building and bring it into compliance with the efficiency standards set by the Energy Independence and Security Act of 2007. The team’s strategy involved a total over- haul of the facility, stripping it all the way down to its steel structure and building it back up again with a new high performance glass curtain wall. When completed later this year, the project, which is in the running for a LEED Platinum rating, will use 55 percent to 60 percent less energy than the typical office building.
The design of the new facade was driven by changes that the team made to the facility’s mechanical system. The architects discarded the old variable air volume HVAC in favor of more efficient radiant heating and cooling. The slim profile of the new distribution system, which is made up of hydronic pipes behind metal ceiling panels, allowed the team to raise ceiling heights from 8 feet 6 inches to 9 feet 6 inches, allowing more daylight into the interior. It also meant that sun loading on the building envelope would have to be mitigated. “The wrinkle is that the radiant system has a limit on its capacity,” said Jim Riley, associate project architect at SERA. “We might get a fair amount of rain in Portland, but we get enough sun to make it uncomfortable if you don’t have a strategy.”
To cut down on sun loads, the team employed exterior aluminum shading systems on the building’s east, south, and west faces. On the east and south, the architects designed an egg-crate-style system of vertical shades with horizontal light shelves that bounce daylight as much as 30 to 35 feet into the interior. On the west, which receives the most low-angled sunlight, the architects applied 50 percent shading with a system of vertical aluminum “reeds.” The envelope itself is a Benson-designed panelized system. Typical panels are 5 feet wide by 12 feet 6 inches high. Half of each panel is a vision window made up of a 1⁄4-inch-thick, argon-filled Viracon IGU with a low-e coating. The spandrel is the same, except it features a green ceramic frit flood coat on the #6 surface, 4 inches of insulation integral to the panel, plus 4 inches of insulation on the interior, making for a highly insulated building envelope.
The green spandrel along with the natural green-cast of the vision panels gives the newly-reclad federal building an overall green appearance, a design nod to the structure’s environmental friendliness.