The institutional project
Photos by Tom Bonner Photography, Santa Monica, Calif. The design team for the Silver Lake Branch Library aimed at Gold certification from the U.S. Green Building Council's Leadership in Energy and Environmental Design program. In the end, they exceeded their expectations and achieved LEED Platinum, with 52 points.
Glass is the defining element of the new Silver Lake Branch Library in Los Angeles—and it is also the key green element, says Tom Michali, project architect and partner, M2A Milofsky Michali & Cox Architects, Los Angeles. The building features several diverse glazing types carefully integrated into the overall project design. "The glass was a critical design element from a formal and green point of view. It provides the daylighting prevalent throughout, as well as vision from all spaces," Michali says.
The library features four major glazing elements: a channel glass façade; a point-supported glass corner enclosure; clerestory window systems; and skylights with some integrated photovoltaics. The design team performed ample energy modeling—"We did a half a dozen energy models instead of one or two," Michali says—to develop the best performing design. "We could say, okay, that's not working. Let's tune the glass and add more translucent lites. Or, let's tune how much of this kind of glass is used," Michali says. The result is an innovative building design with minimal glass on the south and west elevations, which receive the most sun, and ample glazing, with varied sun controls on the north and east elevations.
Arguably the most prominent glazing feature is the channel glass façade. The building features 3,750 square feet of exterior, vertical, double-glazed Lambert's channel glass curtain wall from Bendheim Wall Systems, Passaic, N.J. The design team used modeling to determine the maximum thermal performance of the wall and chose to alternate between translucent and clear channel glass units. Bendheim supplied its P26/60/7 channel glass in 504 Rough Cast with Azur for the outer plank, a TIMax fiberglass insulating interlayer, and 504 Rough Cast with low-emissivity coating for the inner plank; and uncoated 504 Rough Cast and Clarissmo.
"The ability to tune the glass by adding blue and low-emissivity coatings, and the translucent insulation helped us maintain the energy goals by creating a high performance glass in shading and U-value while maintaining the good light transmittance," Michali says.
In one area of the building, the channel glass juts outward, like the front of ship, describes Mark Mischel, president of Harris Glass Co., the Bell, Calif., glazing contractor. "What made this job unique was that we weren't dealing with rectangles. There was just steel out in the air, and we filled it. One challenging element was a triangle projecting out from the building engineered to carry the weight of the glass. The shape required various sizes and a corner condition, both ways," Mischel says. "Due to time constraints, we weren't able to wait until the steel was installed to measure. The glass was ordered off of a combination of guaranteed openings, and we used mathematical equations to create the rest of it."
The library also features a stand-out point-supported glass corner dubbed the "living window." The Pilkington Planar system, supplied by W&W Glass, Nanuet, N.Y., features Pilkington Opti-float 19 millimeter glass combined with Evergreen 6 mm glass. "We used this system because of the openness—minimal support at the grid points—and clarity of the end product. Because of the mullion-free enclosure, the window is like a prow into the corner space of the patio and street," Michali says. "The aluminum trellis provides the shading for all but a few hours of low easterly summer sun."
The building also features a clerestory, a storefront system with insulating Guardian SN-68EO/Optifloat clear glass. The clerestory is deeply set, and the overhang is designed to block all but a few hours of morning and evening sun.
Lastly, the building features a skylight system of 6 mm clear float glass with silkscreen ceramic frit, a 12 mm air gap, and a top panel of laminated 6 mm low-emissivity and clear glass. Integrated solar cells cover 14 panels of the skylight, and 60 percent frit covers the remaining 40 skylight panels.
The combination of all four glazing types allows natural daylight to reach all areas of the library. "The clerestory provides all of the perimeter daylighting. The skylight and channel glass provide the interior daylighting, and the [point-support system] provides daylight and vision to the main reading 'living room' of the library," Michali says.
The design team was highly sensitive to the issue of glare and heat gain, versus natural daylighting, Michali says. The team used several tools to prevent unwanted heat gain and glare, including deep overhangs, a trellis and automatic shades to "block the few hours of low-angle sun along the clerestory," he says. "Since these angles are almost level, no amount of overhang will work all the time. We aim at 42-degree sun angle to get most of the heat and glare. We are also sensitive to placement of computer terminals in relation to open windows for background glare and over-the-shoulder glare."
The shades offer a high shading value to cut glare while allowing some visibility. "They are operated by sensors on each of the four sides, because in a public building, they would always be closed—the staff does not have time to operate them four times a day," he says.
The M2A team had high green goals for the Silver Lake Branch Library, aiming at Gold certification from the U.S. Green Building Council's Leadership in Energy and Environmental Design program. In the end, they surpassed their own green expectations and achieved LEED Platinum, thanks to the addition of integrated photovoltaics on the roof. "We were excited about the concept of using the solar cells integrated into the skylight as both a shading device and energy source. During design, we reversed the slant of the skylight to provide maximum orientation to south and west," Michali says. "Unfortunately we could only afford to cover 25 percent of the glass; therefore, we incorporated them into the entry to visibly showcase the future of energy production. There will be a display panel and monitor with a display of energy production of these cells, which provide 3.04 kilowatts, as well as the hidden roof top arrays which produce another 31 kilowatts." SolarCity, Foster City, Calif., provided the Suntech solar cells.
The $12 million, 13,600-square-foot library was completed in November 2009. Ford E.C. Inc., Los Angeles, served as the general contractor.