Controlling Light

Sept. 1, 2004
Incorporating Building Controls to Manage Electric Light and Daylight
Today’s innovative buildings are designed to be sustainable, flexible, and energy efficient. The integrated control of both electric light and daylight is a powerful new tool for design professionals, helping them to construct buildings that enhance sustainability. Lighting control designs that address both electric light and daylight improve building performance by saving energy and reducing maintenance costs.According to a study by The Light Right Consortium (, the lighting levels in a building also impact the performance, comfort, and productivity of its occupants, particularly when using fluorescent dimming and personal lighting control in the workplace. Personal control provides enhanced employee comfort by reducing glare and eye strain caused by harsh overhead light, while at the same time, saving energy. Because different people prefer various lighting levels while performing the same task, personal control of light is an important consideration for all employees.Building designers and facility management teams have numerous options for controlling electric light. There are personal control options available, as well as total building controls. In addition to addressing the concerns brought forth by The Light Right Consortium, these systems can also control daylight through integration with automated shade and drapery systems.Many of these control systems have been designed to incorporate lighting control strategies important to sustainable design, such as astronomical time clock scheduling, real-time monitoring and verification of lighting system performance, and integration of building management systems. These systems also offer advanced hardware capabilities and customizable user interfaces for the flexible and seamless integration of dimming, switching, and window shading systems for daylighting. They streamline building operations with simple (yet comprehensive) energy monitoring and management features, plus convenient integration with building automation systems.Computer simulations recently examined and quantified energy savings under varying conditions of cooling (specifically, air-conditioning) and window-shading fabric selection (no fabric shade vs. products with dual-sided basket weaves). During this simulation, a building using the dual-sided basket weave fabric shade instead of no shade at all realized a 59-percent energy savings.Integrated control is particularly beneficial to projects seeking LEED (Leadership in Energy and Environmental Design) Green Building Rating System™ certification from the U.S. Green Building Council (USGBC). Lighting controls may contribute to obtaining up to 22 points in five of six LEED credit categories in the LEED for New Construction (LEED-NC) Green Building Rating System.Strategies for obtaining LEED points include:Dimming and switching systems (including fluorescent dimming).Personal control of light.Daylight harvesting.Integration of controllable window treatments.Occupant-based sensing.“Tune to task” management of high-end light levels.These strategies are an important component in today’s designs. It is critical for building owners and designers to understand building controls and familiarize themselves with the capabilities of the integrated control of electric and daylight. The integrated control of electric light and daylight provides the ability for employees to not only choose, but also to maintain, a personal and optimal level of light on their workspace throughout the day. David Bennett is manager of commercial marketing for Lutron Electronics Co. Inc. (, based in Coopersburg, PA.

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