Ultra efficient curtain wall system marries transparency and sustainability.
For some institutions, building “sustainably” means doing the bare minimum—checking the boxes of government or in-house requirements and then moving on.
Such was not the case at Colorado State University, where campus officials aspired to a higher standard for the new Suzanne and Walter Scott, Jr. Bioengineering Building. Though mandated by state law to achieve LEED Gold on new construction, the dean urged the architects—design architect RATIO Architects and architect of record Hord Coplan Macht (previously SLATERPAULL)—to aim for Platinum. At the same time, school authorities placed an extra emphasis on a tight envelope, having had difficulty maintaining pressurization in another recently-constructed facility. Thanks to a combination of an ultra-efficient curtain wall system, spray foam insulation, and exterior and interior sunshades, the designers exceeded the client’s performance expectations without sacrificing the program’s focus on visibility and connectivity.
The ultimate goal of achieving LEED Platinum directly shaped the facade of the classroom and office building. “[The dean] wanted to get to Platinum,” recalled Hord Coplan Macht’s Jennifer Cordes. “We knew the only way to get there was if we had a significant building envelope designed to add photovoltaics.” The PV panels themselves would have to wait, due to budget constraints. In the meantime, Hord Coplan Macht focused on two other challenges: the desire to prevent any loss of pressurization; and the need to rectify the design architect’s vision of a glass box with the reality of the Colorado climate. “When we added these issues together, we had to get creative with the building envelope,” said Cordes, who also acknowledged the role local municipal rebates played in incentivizing a high-performance design.
The design concept for the Suzanne and Walter Scott, Jr. Building, said Cordes, “was to create the space in between. The space between the research laboratories and the student classrooms was really where the students were going to learn from the researchers.” The architects arranged the labs along the north side of the building; faculty offices and teaching spaces line the south elevation. The programmatic separation allowed them to sequester the two components’ mechanical systems—a boon to efficiency—and to carve the center of the building into a naturally-ventilated three-story atrium that is a perfect space for casual interactions among students, faculty, and staff.
Elsewhere, the focus on connecting students with faculty and researchers is materialized in large expanses of glass. Hord Coplan Macht’s principal challenge was to rectify the emphasis on transparency with the mandate to minimize thermal gain. “We started to look at the window to wall ratio,” recalled Cordes. “Our first [number] was outrageous. [So we looked] at how we could insulate a curtain wall system and get an R-value of 20 even within that.” The solution, which the architects developed in concert with Kawneer, involved back-panning, adding polyiso behind all the spandrel glass to effectively decrease the window to wall ratio. They then added a sheet metal back-panning system inside the curtain wall frame for vapor barrier, plus insulation and GWB. Large panes of stone backed with spray foam insulation provided additional energy savings. “Spray foam insulation is very cost-effective, and you get a high R-value per inch,” explained Cordes. “It allowed us to get some significant walls into our system.”
On the vulnerable south facade, the architects deployed both external and internal sunshades. On the exterior, an integrated sunscreen helps cut back on solar gain. On the interior, the designers sloped the ceilings to help bounce light into the space. The internal light louvers they used, which Cordes compares to “good-looking mini blinds,” are “pretty impressive and work really well,” she said. The interior shading system “managed the glare and also increased the daylighting, pushing light deeper into the space.” All of the exterior glass carries a low-e coating, but the architects chose a higher visibility glass for use on the south facade, to further enhance daylighting.
Installing the thermally broken Kawneer 1600 curtain wall system proved trickier than Hord Coplan Macht had anticipated, said Cordes, in part because the contractors—working during the winter—installed the back panning from the inside out, rather than the reverse. But the extra coordination was well worth it, as the project’s LEED scores and post-occupancy energy and water use data have demonstrated. “With the caveat that the building is being used a little more than was projected in the model, it’s performing better” than expected, said Hord Coplan Macht’s Ara Massey. “Per the facilities manager, it’s one of the best performing buildings on campus.” For Cordes, no reward could be greater. “I think the one [thing] we’re most proud of is that it’s performing so well,” she said.