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A Not So Simple Building

How to solve the difficult task of integrating a full glass curtain wall without compromising energy efficiency at Yale University's new transparent sculpture building.

November 01, 2007 |

Yale University's new $52.6 million sculpture building and gallery has been described by its architect, Stephen Kieran, as a “very simple” building. But Kieran, a partner at Philadelphia-based KieranTimberlake Associates, had to navigate the complexities of designing a virtually transparent building without compromising energy efficiency. His ambitious program to combine competing project objectives—complete transparency, super energy efficiency—has helped put the 51,000-sf building in New Haven, Conn., on the cusp of earning LEED Platinum certification. And he makes it all look so simple.

The new sculpture complex occupies an entire city block within Yale's bustling arts district, on a site formerly used for surface parking (all site paving has been made permeable, to gain LEED points). The complex consists of a 2,500-sf single-story gallery, mainly for exhibiting graduate students' work; a 288-car parking garage; 11,000 sf of ground-floor retail; and a four-story studio building with flexible, open spaces reminiscent of Parisian high-ceiling artist lofts. With natural light so important to the visual arts, the interior of the studio building had to be flooded with daylight, so its four-story façade is clad almost entirely in glass. “There's tremendous daylight penetration into the core of the building,” says Kieran.

The university was unwilling to sacrifice either light or energy efficiency, so designing such a transparent building in the four-season weather extremes of New England meant that energy efficiency might take a hit. It was therefore incumbent upon the Building Team, which included mechanical/electrical engineer BVH Integrated Services, Farmington, Conn., and Shawmut Design and Construction, Boston, as contractor, to devise an energy-efficiency strategy for the big glass box—and fast. The project was fast-tracked to accommodate architecture students displaced from Paul Rudolph's famous Art & Architecture Building while it is being renovated over a 15- month period beginning this past September.

The energy strategy the Building Team devised includes a high-performance curtain wall that works in conjunction with a super-efficient, low-velocity air diffusion system. The HVAC set-up introduces large volumes of air at the building's core at higher than usual temperatures and at a relatively low height (rather than at 14-foot-high studio ceiling levels) so the air permeates occupied space. Air is then drawn across the studio spaces via natural convection to the building's sun-splashed perimeter walls. Thanks to the high-performance curtain wall, the interior air is carried by convection up and along the glazing rather than leaching out, and then moves back across the ceiling into a return air system. “It saves considerable energy by dramatically reducing fan energy required to move air,” says Kieran.

Getting the curtain wall components right was as important as setting HVAC specifics, and involves an innovative combination of triple-glazed low-e glass and light-diffusing translucent panels. “Energy modeling showed that in order for us to get reasonable energy performance on the building, we couldn't use clear glazing everywhere,” says Kieran.

Most of the studio building is clad in transparent glass panels, some of which open for natural ventilation (another LEED consideration). A solar shading system runs along the entire south façade and portions of the east façade, reducing solar heat gain by about 30%. Special aerogel-filled translucent Kalwall panels are strategically placed within the curtain wall to filter light in zones where direct light isn't required, such as spandrel panels between floors and between the floor and sill—an area against which work benches might be pushed. The Kalwall Nanogel panels are filled with a fibrous material that's about 99% air, and the insulation value (approximately R-20) is a by-product of the trapped air. “It's not reliant on an insulating gas that can escape, so there's no problem with it losing its R-value,” says Kieran. “The panels should last as long as the wall—about 60 years.”

Kieran admits to having taken additional precautions to make sure the life of the curtain wall is maximized. The Nanogel panel manufacturer was worried about heat buildup in cavities where transparent glazing overlapped translucent glazing. The overlap is only a matter of inches, but they are a crucial few inches necessary to create a uniform façade. The Building Team conducted its own tests, concluding that heat gain would not reach the danger point at which panels would degrade.

The curtain wall system provides additional energy efficiency by cutting down on the need for artificial light within the complex, reducing both energy use and unwanted heat produced by light fixtures. Now that's a pretty simple idea.

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