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Harrah’s – Atlantic City: Extensive use of LEDs creates the opportunity to cover the building in different patterns for different events.
(photo by Stone Mountain Lighting Group)

November - December 2007 Newsletter
(exclusive online content)

A recent DOE webinar reminds that "The 'cost of light' is not simply the up-front cost," but an analysis must include: energy costs, power consumption, labor costs, lamp costs, expected lifetime, and light output. The most important result is that those using a space are comfortable in that space, and the lighting is a crucially important factor in comfort.

Each light source has its own unique characteristics of efficiency, color temperature, and color rendering index, making some lamps more appropriate for certain applications than others. Color temperature (CT) is a measurement of the "warmth" or "coolness" produced by the lamp. Lower CT light sources give a yellowish, "warm" light often preferred for residences, while high CT sources produce a blueish, "cool" light often used in stores requiring high levels of illumination such as groceries or pharmacies. Neutral (around 3500K) are common for office and retail use. A Color Rendering Index (CRI) is often the only information available for compact fluorescents. A CRI closest to 100 is the best.

Avoid over-lighting a space. More light does not mean better light. The IESNA www.iesna.org provides good standards for determining light levels for specific needs. Considerations and choices include installation requirements, color qualities, fixture efficiency, lumen output, reflectance of surroundings, room size and shape, and availability of natural light.

The primary strategy in energy efficient lighting lies in a design that recognizes what will occur in the area to be lit and sizes the lighting to that task.
Task lighting can greatly reduce the need for stronger overall lighting. It has long been recognized that the counter area of a kitchen requires approximately twice the amount of light in the kitchen itself. But this same principle can be applied to many other situations both in residential and commercial applications. The amount of energy needed to produce the light is also greatly decreased if the lighting can be as close as possible to the activity – under the cabinet is much more efficient than ceiling for task lighting.

Very low wattage lighting can be used for areas needing only enough light to safely walk through or for activities requiring no direct lighting. Light reflected off the ceiling or walls is often used for this.

When in doubt about lighting requirements oo if they are apt to change over time, consider variable lighting which can quickly change from bright to dim. New automation techniques makes this increasingly practicable.

View print version of November-December 2007 newsletter