Montana Library (Quietly) Takes the LEED® in Daylighting
There are two thousand people in Bozeman, Montana, who know that it takes a library book 20 minutes to travel five blocks. They know this because on a cool and breezy day in October 2006, they lined the streets and passed 3,000 books hand to hand, bucket brigade style, from the city's old library to a new one more than twice as large and state-of-the-art in every way. Library workers in orange safety vests patrolled the route on bicycles to prevent snags, the high school drum line marched from end to end and back again, and traffic was detoured from the area for over an hour.
That's how seriously the people of Bozeman take their library. In fact, patrons here check out more materials per capita than those of any other major library in Montana. Reference questions are up 38% in the past ten years. Meeting rooms must be booked months in advance. When the new Bozeman Public Library opened, any lingering nostalgia for the old, cramped facility, overstuffed with 113,000 books and materials, was quickly swept away by its successor's innovations, improved design and comforting environment of daylight. Much of the design was based upon input from library experts, employees and the customers themselves.
To begin with, the library's welcome desk stands at the front door, living up to its name. The children's section keeps to the first floor. A coffee shop, bookstore and ongoing used book sale provide a steady revenue stream back to the library. There are rooms dedicated to quiet study, a Teen Corner, a Montana Room bigger than its predecessor, and 25 new computer stations. The library, at 52,300 square feet, is not only more than twice as large as the old one, it also expands public meeting space with a conference room and a bigger, baby grand piano-equipped Community Room.
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The new library is innovative in more than just function. From day one, the Library Board knew it wanted a design that was green in every way, starting with the building site itself. A polluted, weed-grown patch, fenced off and unused for at least a generation, was reclaimed, part of a rehabilitation of the city's east side and a gateway of sorts to the historic Main Street district. The building abuts park land on two sides; a number of trails traverse or terminate on the grounds. Inside, high ceilings and wood beams create an environment almost as open and airy as the second-floor view of the Bridger Mountains.
The environment-friendly theme continues, of course, into the structure's more practical, less aesthetic aspects, such as the photovoltaic system on the roof. Some of the toilets operate without the need for water, and the ventilation system is designed to eliminate any lingering tobacco odors. A Montana-based, wind-to-energy company even donated the library's energy needs for its first two years.
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And interestingly, even though the new facility was more than twice the size, the total cost of that energy plus all other utilities was just a bit more than it had been at the old library. The energy savings were achieved in large part with daylighting by Kalwall, specifically, the Kalwall+ Nanogel daylight diffusing system. Nanogel translucent aerogel is a silica aerogel and the world's lightest and best-insulating solid material. Incorporated within Kalwall's standard daylighting system, the product provides as much energy savings as a solid roof or wall. In addition, the translucent material allows natural, even daylight to be transmitted into interior areas. With an achievable U-value of 0.28 W/m²K (.05 btu/ft²/°F), the system provides insulation that is four times better than insulating glass units or any other light-transmitting system.
In fact, early in the design process, Mark Headley, head of project architecture firm StudioFORMA, had briefly considered, then rejected triple-glazed glass; compared with Kalwall, the R-value gain was too small and the 30-year cost payback too long. Headley also felt that Kalwall gave him more aesthetic options. Except for some carefully placed, insulated glass for clear views to the library grounds and the mountains beyond, all 8,700 square feet of the library's fenestration, and another 2,300 square feet of skylights is Kalwall+ Nanogel!
As a result, whether cloudy or clear, the library uses almost no artificial lighting during the day. Kalwall showers the building's interior with shadow-free, controlled, natural daylight, and an automated lighting system constantly monitors overall light levels, turning the energy-efficient lighting units on or off as needed. (As with all Kalwall systems, that lighting generates a welcoming glow through the translucent panels when viewed from outside after dark.) Additionally, because the panels filter out the sun's harmful ultraviolet rays, the library's furnishings and especially older books and materials are protected from fading and becoming brittle. And with all those computer screens, Kalwall cuts glare and the resulting eye strain. The thermally-broken panels' superior insulating properties also control unnecessary heat gain or loss, thereby lowering HVAC system expenses. The library's design exceeds ASHRAE 90.1 by 29%, and LEED credits in the areas of daylighting and views, energy reduction, and renewable energy sources contributed more than a third of those needed for Silver certification. In fact, the Bozeman Public Library is just the fourth Montana project – and the state's first municipal building – to be LEED-certified.
The new Bozeman Public Library was a long time coming, but is now a center of civic pride for the community. And Kalwall is proud, too, of further advancing the cause of green building in the public sector.
Bozeman Public Library
Architects: Overland Partners and StudioFORMA
Photos by Michael Blevin, George Baskin
Kalwall Specifications:
Wall Panel U-Value: .05 BTU/(hr/ft²/°F) = .30 W/m²K
Skylight Panel U-Value: .23 BTU/(hr/ft²/°F) = 1.30 W/m²K
NFRC System Wall U-Value: .10 BTU/(hr/ft²/°F) = .57 W/m²K
NFRC System Skylight U-Value: .29 BTU/(hr/ft²/°F) = 1.65 W/m²K
Light Transmission: 15%/20%
Solar Heat Gain Coefficient: 0.12 Walls, 0.20 Skylights
For more information, contact:
Bruce Keller
Kalwall Corporation 603-627-3861 (800-258-9777 N. America)
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