Daylighting Challenges
Challenges of Daylighting
The use of daylighting in new construction and renovation projects is gaining momentum. As more owners seek to capitalize on the energy efficiency and occupant satisfaction characteristics inherent in day lit buildings, designers must come to terms with several challenges in order to provide an optimum daylighting application. Bad daylighting design can result in increased energy use and emissions, and a poor occupancy experience. Seasonal and climatic changes must be accommodated as well as the hour to hour fluctuation of natural light. Solar heat gain must be managed while properly utilizing the harvested indirect light. Exterior conditions must be no more than 10 – 20 times greater than the interior to control glare. Finally, to reap complete energy savings, lighting controls are a necessity. Bringing together a design team that can meet these challenges is the first step towards a successful project.
An integral part of this team, lighting design is critical when contemplating a daylighting application. Fortunately there are programs available to aid this process. One solution, AGi32 is a flexible software tool which predicts photometric performance. A CAD-like program, AGi32 offers two methods of calculation. The first, Direct Only does not measure reflective light and is used primarily for exterior lighting applications. Conversely, Full Radiosity takes into account the interaction of light with reflective surfaces. For use with LEED specification to determine useable daylight penetration, AGi32 is also capable of calculating Daylight Factor, the ratio of outside luminance over inside luminance. AGi32 is WYSIWYG (what you see is what you get). Exports are available in .DXF or .DWG, renderings in .JPG, BMP, or animated in .AVI format.
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Daylighting design must be supported by fixtures and controls. Photocells, occupancy sensors, and dimmable fixtures are examples of features required to successfully augment harvested natural light. Utilizing proper control of lighting and lighting systems insures the right amount of light exists where it’s needed and is diminished where it isn’t required. Control enhancements that automatically dim or turn off electric lighting when daylight levels reach adequate levels are central to garnering LEED points. Keeping in mind that 40% of a commercial building’s electrical consumption comes from electrical lighting*, proper control is critical to a successful daylighting strategy.Providing increased energy efficiency, reduced emissions, and improved occupant satisfaction, daylighting has emerged as an important design strategy. Visa Lighting is committed to daylighting and assists designers with products and services designed to meet the challenges of daylighting applications. Located in the AGi32 database, the Visa Lighting product line is available for calculations. Dimming is engineered in over 90% of the Visa catalog as a standard option. Versed in photometrics and product variations the Visa Application Team assists designers with light levels and product solutions. Support is available by contacting your Regional Sales Manager or the Application Team. For more information on daylighting, visit www.daylighting.org.
See Visa Lighting on AGi32
*Zack Rogers, Architectural Energy Corp, Light Louver LLC, Velux 2nd Daylight Symposium, March 7, 2007 Bilbao, Spain
Posted on: May 20 2008, 10:54 AM
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