As seen in College Planning & Management, April 2009
Let There Be Light
Glazing and Framing Options Enhance Daylighting Designs
By Jeff Razwick
Professors may wish for indoor exposure to daylight in capturing the attention of their sleep-deprived students. As they attempt to teach students who juggle work, exams, and late-night social events, most educators would recognize firsthand the benefits of building designs that incorporate natural light (known as “daylighting”).
Traditional windows and skylights have long been staples of daylighting. Now, new glazing and window framing materials enable college designers to capture sunlight and create bold looks, while solving key challenges inherent in daylighting.
Daylighting Benefits
Research shows that well-designed daylighting has a strong positive influence on student wellbeing and performance. According to a report on the benefits of daylight through windows by the Lighting Research Center, Rensselaer Polytechnic Institute, natural daylight is an effective stimulant to the human circadian system, which “influences the performance of all tasks, not just visual tasks.” The circadian system regulates the occurrence of the sleep/wake cycle and hormones, helping to stabilize erratic sleep and mood behaviors. Natural light also stimulates pituitary gland hormones for calm behavior and attentiveness.
A study by the Heschong-Mahone Group found that daylighting substantially improves memory capacity. Individuals who were placed near open, unobstructed windows had a ten to sixteen percent improvement on cognitive memory tasks over those who were not placed near a window.
With rising energy costs, daylighting can also help college and university administrators better manage energy usage. Natural light reduces energy needed for artificial lighting. And, as the U.S. Dept. of Energy reports, for the same amount of light, daylighting produces less waste heat than electric lights. Daylighting can thus reduce energy costs for both lighting and cooling.
Design Challenges
The central challenge of effective daylighting design is allowing natural light to penetrate deep into interior spaces, while eliminating glare and heat gain or loss. Designers can solve these problems through building orientation and treatments, automated lighting and shading controls, and selection of construction materials.
Joel Loveland, director of the Seattle Daylighting Lab at the University of Washington, emphasizes using diffuse daylight as the primary source of illumination. Such light provides bright, full-spectrum illumination, while avoiding the drawbacks of harsh direct sunlight.
In addition to placement of shades and incorporating design features like light shelves, the glazing material itself can play a key role in diffusing sunlight.
Glazing for Diffuse Light
Designers have traditionally used coatings, films or tints on window glass to diffuse sunlight. However, translucent glazing – such as glass block and channel glass – is increasingly popular. European design professionals have used channel glass for several decades, and the systems are now specified in many North American building projects, including colleges.
For instance, Evergreen State College’s Seminar II Building, Olympia, WA, incorporates floor-to-ceiling channel glass that takes advantage of borrowed daylight to reduce the need for artificial light.
Channel glass systems consist of self-supporting, “U”-shaped, cast-glass channels mounted in a perimeter frame. The glass is available in a variety of colors and textures with varying translucency, providing warm, diffuse light for interior spaces, without glare. Channel glass, such as Pilkington Profilit, come in lengths up to 23 feet, and can be installed vertically or horizontally. Vertical applications typically do not require intermediate mullions, so designers can create large, uninterrupted areas of glazing to help maximize daylighting.
In addition to reducing glare, channel glass helps address heat gain and loss. The glass channels overlap one another to create an insulating air-filled space. Thermally broken frames are also available to reduce heat bridging, and insulating aerogel can be placed in the enclosed space between the channels for further energy savings.
The Role of Framing
In addition to the glazing, the framing plays an important, but often overlooked role in daylighting. Framing choice affects the amount of uninterrupted glass possible, as well as the dimensions of the framing sightlines.
Most college design professionals are familiar with aluminum window, door and curtain wall framing, but may wish to consider advanced steel framing for daylighting projects with higher performance needs.
With its high strength, modern steel framing allows greater expanses of exposed glass and narrower frame profiles than traditional aluminum assemblies. Because it is about three times stiffer than aluminum, steel framing requires fewer horizontal and vertical framing members. It can also support longer spans without sagging or bowing under the weight of the glass or under wind loads.
For a given frame profile, steel framing, such as SteelBuilt Curtainwall Systems, can support glass panes approximately three times larger than is possible with aluminum framing. Or, for the same window design specifications, steel frames can be much narrower. In either case, the result is more glass and less framing to interfere with bringing natural light indoors.
The daylighting design possibilities for colleges are nearly endless. Today’s design professionals have a wide range of technical resources and building materials to help them effectively incorporate natural light into their projects.
Jeff Razwick is the vice president of business development for Technical Glass Products (TGP), a supplier of specialty architectural glazing products and fire-rated glass and framing systems. He writes frequently about the design and specification of glazing systems for institutional and commercial buildings. www.tgpamerica.com, 800-426-0279
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