By Craig DiLouie
Lighting can play a significant role in LEED (Leadership in Energy & Environmental Design) certification - directly and, in the case of energy optimization, indirectly - and is related to earning five to 14 points. To optimize LEED points with lighting, the architect must ensure that the lighting achieves maximum efficiency and has automatic shut-off controls; there are daylight and outside views for occupants where possible; that users can control their own lighting; that nighttime light pollution is minimized; and that lighting controls are commissioned.
Many of LEED's lighting-related provisions encourage lighting quality, as in the case of daylighting, reduced light pollution, and individual user control of lighting. When minimizing energy consumption, however, architects should be careful to ensure that the lighting renders the built environment properly and provides desired light levels and lighting quality that users need to perform tasks within the space safely, efficiently, and with satisfaction. It's important to save energy but not at the expense of lighting quality.
Here are the major areas where lighting and LEED intersect:
LEED-NC v.2.2, Sustainable Sites, Credit 8: Light Pollution Reduction (one LEED point): Light pollution is a broad term encompassing skyglow, light trespass, and glare, which are negative potential by-products of electric nighttime lighting. To earn this LEED point, minimize skyglow and light trespass while optimizing the efficiency of outdoor lighting systems.
LEED-NC v.2.2, Indoor Environmental Quality, Credit 6.1: Controllability of Systems: Lighting (one LEED point): Providing users with control over their light levels has been shown to save energy and increase satisfaction. To earn this LEED point, provide individual lighting control to occupants and shared multioccupant spaces through dimming controls, task lighting, or bilevel or multilevel switching.
LEED-NC v.2.2, Indoor Environmental Quality, Credit 8.1: Daylight 75 Percent of Spaces (one LEED point): Daylighting is the use of daylight as a primary source of general illumination in a space. Daylight has been shown to have positive impacts on user satisfaction while providing opportunities for energy savings via daylight harvesting controls such as dimming or switching systems operating with photosensors. To earn this LEED point, provide daylight in at least 75 percent of regularly occupied building areas.
LEED-NC v.2.2, Indoor Environmental Quality, Credit 8.2: Views for 90 Percent of Spaces (one LEED point): Research suggests that users are more satisfied when they have a view of the outdoors and prefer spaces where view windows constitute at least 20 to 25 percent of the perimeter walls. To earn this LEED point, provide views of the outdoors in at least 90 percent of regularly occupied building areas.
LEED-NC v.2.2, Energy & Atmosphere, EA Prerequisite 2: Minimum Energy Performance (required): This LEED prerequisite requires compliance with ASHRAE/IESNA Standard 90.1-2004's lighting requirements, which encourage high-efficiency lamps and ballasts and LED exit signs while requiring automatic lighting shut-off controls.
LEED-NC v.2.2, Energy & Atmosphere, EA Credit 1: Optimize Energy Performance (one to 10 LEED points): Exceed the minimum requirements of Standard 90.1-2004 using one of three methods valued at various potential LEED points, with the maximum being 10. (To earn as many as 10 points, other building systems would become involved in addition to lighting.) These methods contain several commonalities regarding lighting, including encouragement of daylighting, daylight dimming around daylight apertures such as windows and skylights, automatic shut-off controls and bilevel switching, LED exit signs, high-efficiency lamps and ballasts, lighting controls commissioning, and ambient task lighting using direct/indirect fixtures and task lighting.
Additional lighting opportunities include:
Innovation in Design (Innovation & Design Process, Credits 1.1, 1.2, 1.3, 1.4): Projects can earn one to four points for exceptional performance above the requirements of LEED-NC or innovative performance in a sustainability category not covered by LEED-NC.
Enhanced Commissioning (Energy & Atmosphere, Credit 3): After meeting the prerequisite commissioning requirements, projects can earn one LEED point by extending commissioning activities to include ensuring proper training of owner staff, providing a systems manual to staff, making an on-site inspection within 10 months of project completion, and other activities.
Craig DiLouie, a journalist, analyst, and consultant, is principal at ZING Communication Inc. (www.zinginc.com).