Building owners interested in entertaining a lighting upgrade proposal often are interested in an energy-saving retrofit, but they may actually need a redesign that saves energy and improves lighting quality.
In its Guidelines for Upgrading Lighting Systems in Commercial and Institutional Spaces, the Illuminating Engineering Society of North America (IESNA) defines a retrofit as “modifying a lighting system so as to lower the operating costs or improve the performance of that system while not changing the original intent of the lighting design.” Examples include lamp and ballast change-outs and direct replacement of lighting fixtures.
The guidelines define a redesign as “modifying a lighting system so as to intentionally modify the goals of the existing lighting design.” This basically entails starting fresh, formulating an original design intent and installing a new lighting system.
The first question is whether there is an opportunity to make changes to the lighting system to save energy. Does the existing lighting system feature older technology, such as incandescent lamps, probe-start metal halide systems, and/or fluorescent T12 lamps and magnetic ballasts? Are local utility costs (energy and demand charges) very high? Is the lighting uncontrolled and, therefore, operating longer than it is used each day? Was the building built before 1980 with lighting producing higher light levels than needed?
The more “yes” answers there are, the more likely a retrofit or redesign project will be an economical investment in energy savings. Newer buildings and recent renovations with short hours of operation are less likely to be cost-effective.
The second question is whether there is an opportunity to make changes to the lighting system to improve quality, keeping in mind that lighting quality is more than just producing minimum recommended light levels. Have the building’s primary spaces been retasked to new purposes for which the existing lighting system produces insufficient lighting conditions? Is uniformity poor, with uneven light levels and high contrasts between bright and dark areas—with one possible cause being the fixtures are spaced too far apart? Do the primary spaces have poor lighting on walls and ceilings, making the spaces appear cavelike?
“Yes” answers to these questions for each building space make these spaces candidates for a redesign.
Usually, the lighting audit, based on a building walk-through, will reveal the answers to questions related to both energy savings and lighting quality. Retrofits and redesigns are strongly related; a retrofit basically is a lighting design with the lighting fixtures already in place, while a redesign is a design with free choice of fixture selection and placement. Many electrical contractors have gotten good at thinking like electrical engineers when they look at numbers and, moreover, they may benefit if they become trained to think a little like lighting designers when they look at spaces. This means understanding what goes into a lighting system, what comes out of it and what is its relationship to people.
Lighting is for people, not buildings. While light is a commodity the owner wants to acquire each day for the lowest operating cost, lighting is a business asset that has a proven relationship with worker satisfaction and productivity as well as student learning rates and retail sales. If electrical contractors understand this, they will be able to sweeten the deal by offering value-adds to retrofits and producing the right results with a good redesign. An owner that gets this will be more amenable to investments in saving energy and improving lighting quality.
Acceptable lighting quality, according to the guidelines, accounts for a number of factors that can be explored during a walk-through, including visual comfort, glare, uniformity, color rendering, lighting on walls and ceilings, and harsh patterns, shadows and flicker. These factors are important to thoroughly understand if the project is retrofit or redesign and if the goal is to improve lighting quality or simply maintain it.
If the space is a workplace (and nonretail), is the lighting generally uniform? Are the lighting fixtures spaced too far apart based on their manufacturers’ spacing criteria? Does the space have some light distribution on walls and ceilings? Are there any sources of glare in the space? Do the lamps have a color rendering index rating of 80 or higher? Are there any sources of extreme contrast between bright and dark in the space, such as where task lighting is used?
The answers to these questions, properly evaluated, can help guide a lighting upgrade project’s lighting quality decisions and, ultimately, help determine whether a redesign proposal should be offered in addition to or instead of a retrofit proposal. In using this process, piloted by a contractor who is knowledgeable about lighting best practices, lighting quality and occupant satisfaction will help drive decision-making, and it will not just be the numbers.
DILOUIE, a lighting industry journalist, analyst and marketing consultant, is principal of ZING Communications. He can be reached at www.zinginc.com.