High energy reading: Glazing contributes to LEED certification of two Los Angeles libraries
In 2002, Los Angeles officials approved an ordinance requiring that all public buildings in excess of 7,500 square feet be certified for Leadership in Energy and Environmental Design by the U.S. Green Building Council of Washington, D.C. Among the first buildings to achieve those ratings were two concrete block-and-glass branch libraries completed in 2003. The libraries were the subjects of an American Institute of Architects’ tour June 7. Architect James Weiner of Collaborative Project Consulting in Los Angeles, the libraries’ principal designer and project manager, led the tour, and emphasized many ways glass contributes points to the LEED designations.
The $4.2 million Lake View Terrace Branch Library, for instance, a rare LEED platinum award—the top designation—features a long reading room with windows on both sides. On one end, a canopy and light shelves interrupt tall windows, effectively keeping sun off the glass. Windows at the top of the building foster natural ventilation, Weiner said. Electric lights and windows bear automatic controls. Photovoltaics and skylights also contribute to energy conservation.
In selecting the glass, “we looked carefully at the transmittance of the glass and distinguished between the function in the lower and upper glass,” he said during a Sept. 20 telephone interview. “The lower glass we selected for glare control and vision; for the upper portion of the building, we selected glass to let in more light. The visible light transmission was in the range of 65 percent-plus for daylighting and—in California—45 percent to 50 percent for vision glazing.
“To make the space functional at night, we have to be quite aware that the glass doesn’t have good reflectance for interior space with electric lights, so you do this kind of daylighting in concert with pull-down Mecho shades that also have a relatively high reflectance,” Weiner said.
Although both libraries feature low-emissivity glass, Weiner insists that if you keep the sun off the glass—via building orientation, light shelves and deep recesses—low-emissivity coatings aren’t always necessary. Also, California boasts such a forgiving climate that laminated single panes can often take the place of insulating glass units, he says. The Lake View library has IG units and the Sun Valley project has laminated glass.
Funded by a 1998 bond issue, the 10,700-square-foot Lake View Terrace Branch was a demonstration project to show how such public buildings could achieve energy efficiency. Its sustainable design strategies led to more than $500,000 in grants from the California Integrated Waste Management Board, Los Angeles Department of Water & Power and The Gas Co., all of Los Angeles.
The Lake View branch, a multi-use facility with a community room, an environmental display gallery and an exterior courtyard, has won numerous architecture awards. Judges cite it for innovative approaches to site planning and watershed management as well as daylighting.
According to city officials, “the building plan responds to the desire expressed by community members to have a library that reflects the rancho tradition of the region, with interior spaces organized around an open central courtyard. A spacious main reading room stretches along the east-west axis and enjoys dramatic views of the park to the south.”
The high curved ceiling in the reading room draws warm air up for improved ventilation and cooling; placed high up on the walls, automatic motorized windows then allow the warm air inside to escape and bring cool outside air into the building, reducing the use of air-conditioning and electricity. A passive cooling tower conditions air at the entry and in the exhibition space.
The public areas also receive ample daylight from large glass windows and skylights. Small skylights bring sunshine into the stacks.
The windows feature double glazing, Argon gas and a low-emissivity coating to improve insulation. Photo sensors automatically control the light, thereby also improving the energy efficiency. Light-shading shelves on the south façade reflect sunlight to the interior while screening direct afternoon sunlight, effectively reducing interior ultraviolet heat. Deep protective columns create recesses for the west windows, further reducing the direct afternoon sunlight.
Photovoltaic cells, installed on the roof, generate one-third of the building’s electricity. The design resulted in energy performance 40 percent higher than that required by the state’s Title 24 energy code.
Weiner remains particularly sensitive to the directional orientation of his buildings, striving to keep direct sunlight off glass nearly all the time with deep recesses for curtain walls, light shelves, a dramatic canopy at the entrance—soon to be draped in vines—and staggered windows flanking the reading room. “Guard the glass” in the California climate, he advised fellow architects during the AIA tour June 7.
“Does LEED cost more money [for construction]?” one architect asked Weiner during the tour. “It costs more at the time,” he replied. “But somewhere down the line, it creates efficiency,” both in building operation, and, in the case of public buildings, by serving as case studies for construction and operation of other such facilities. So it was with construction of Sun Valley Branch Library, which cost 30 percent less than the Lake View Library and achieved gold LEED status.
Sun Valley Branch
The gold-rated $3.2 million Sun Valley Branch Library sits on a small plot in a direction permitting reading room visitors to enjoy light from north and south facing windows and generous views to the outside. Solar cells generate 20 percent of the building’s regulated energy load. A scattering of tinted panes bring rainbow colors to the rooms. For example, the façade of the building consists of a dramatic curved brick wall scattered with tiny punched openings containing such multihued panels.
The facility attracted more than $200,000 in grant money from the Los Angeles Department of Water & Power and The Gas Co. for its sustainable design strategies.
According to a case study published by the city, an integrated design approach resulted in energy performance 35 percent higher than required by the state’s Title 24 energy code. Energy efficiency measures include high-efficiency lighting with daylight and occupancy sensor controls, an exterior and insulated mass wall system, a light-colored, or “cool,” roof, well-shaded windows and high-efficiency air-conditioning units.
For more information about either branch, write firstname.lastname@example.org.