by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.
As winter approaches, and the amount of daylight decreases, it’s important to realize the positive effects of natural daylight. The lack of daylight has been documented to cause Seasonal Affective Disorder (SAD), maladjustment of our body clocks (circadian rhythms) and consistent periods of reduced productivity and enthusiasm. One solution is providing a well-lit space, with as much natural light as possible. Daylighting provides superior quality, full-spectrum, flicker-free light that positively impacts behavior. In study after study, daylighting is correlated to dramatic improvements in human performance in retail, workplace, educational and health care facilities.
Daylight is a full spectrum source of visible light. That is, it imparts the same spectral distribution as sunlight. Unlike electric lights, which sometimes provide a limited spectral range that is concentrated in the blue/green or yellow/green range, daylight is best suited to human vision. Daylight can also provide various illumination levels through proper design. These inherent characteristics of daylight contribute to improved lighting quality by enhancing color discrimination and rendering. Working by daylight is believed to result in less stress and discomfort.
Daylighting saves dollars by using controls to automatically turn off the electric lights when interior daylight levels are sufficient for the task. This reduces both lighting and cooling costs, since reduced electric lighting cuts cooling loads. Daylight is inherently more efficient than electric light, contributing substantially less heat to a space for the same amount of light.
Electric lighting comprises 515,000,000 MWh or 20 percent of the nation’s electricity consumption. Of this total, approximately 10-15 percent is used to light a building’s perimeter zone where daylight is already present. For daytime-occupied commercial buildings, research projections show that total electricity and peak demand savings of 20-40 percent in lighting and its associated cooling energy can be achieved with the proper use of dimmable daylighting controls throughout the United States. Daylighting a building properly is like adding an alternative energy power plant that produces zero carbon emissions.
Daylighting strategies and architectural design strategies are inseparable. Daylight not only replaces artificial lighting, reducing lighting energy use, but also influences both heating and cooling loads. Planning for daylight therefore involves integrating the perspectives and requirements of various specialties and professionals. Daylighting design starts with the selection of a building site and continues as long as the building is occupied.
Watch for part two and three on daylighting in December and January and in “Architect’s Guide to Glass and Metal.”
Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.