Upgrading a lighting system can reduce energy consumption in two ways. Since Energy = Power x Time, we can either reduce the lighting system's input wattage (W or kWh) or reduce its hours of operation. As the kW and the kWh are the basic products for which an electric utility charges, significant operating cost savings can result that can pay for the investment and then reduce a desirable return on that investment (see Retrofit Economics ).
It is beyond the scope of this article to discuss in detail every possible retrofit strategy. Readers are encouraged to see Lighting Upgrades by Damon Wood (The Fairmont Press, Inc.). For lighting retrofit fundamentals and retrofit management, the reader may be interested in seeing The Lighting Management Handbook (The Fairmont Press, Inc.) by the author. In this article, we will review general approaches to retrofitting.
Common Upgrade Strategies:
Upgrade with reduction in light levels
In some applications, ambient light levels can be reduced, particularly in spaces where ambient light is needed only for the task of orientation, in spaces where planned lighting maintenance is resulting in a light level higher than originally planned for, and in spaces where IES light level recommendations have been revised (that is, reduced).
Approaches include dimming, lamp/ballast removal, specular reflectors, reduced-output (lower-wattage lamps) and current limiters.
Increase light levels
This entails increasing light levels via planned lighting maintenance, specular reflectors, higher room surface reflectances or higher-output lamps and other approaches; after light levels are increased, we are then afforded the options to then reduce light level and save energy as shown under "upgrade with reduction in light levels."
Maintain light levels
In these spaces, we need to maintain current light levels but can do so by retrofitting with lighting equipment, such as more-efficient lamps and ballasts, to provide comparable light output at a reduced wattage.
Focus light levels
In some applications, the overhead ambient lighting system is doing most of the work in the space, providing illumination for both ambient and task lighting. In many of these applications, by providing portable, adjustable task fixtures at the task locations, we can upgrade to reduce light levels in the ambient system, since its primary function will be retasked for orientation only. An example of this approach is an indirect lighting scheme for ambient illumination, with task fixtures.
Reduce hours of use
Controls such as energy management systems, occupancy sensors and daylight-dimming ballasts can be installed to control the hours the lighting system is used, eliminating waste and reducing energy usage.
Here are some useful guidelines to remember when attempting a lighting upgrade:
Typical Fluorescent Fixture Upgrades
Compact Lighting Upgrades
High-Intensity Discharge (HID) Lighting Upgrades
Typical Exit Sign Upgrades
Typical Control Upgrades
See also: Retrofit Economics
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