Exterior Lighting: Making LED Upgrades Worktest

By Thomas A. Westerkamp

June 2017

Making upgrades work

The following are recommended practices to deliver the best results and meet the upgrade goals:
• Follow manufacturer installation instructions, including references to base position for replacement lamps — base-up, base-down, or horizontal.
• Pair LED lamps and luminaires with manufacturer-recommended dimmers and other controls.
• Observe manufacturer recommendations on operating temperature in order to prevent heat-related performance degradation.
• Follow-up the installation with an assessment by a lighting engineer to ensure the footcandles emitted are appropriate for the application, as specified by the Illuminating Engineering Society
• Use reflectance of lighter colors from ceilings, walls, and floors in order to optimize energy use.

The system upgrade will deliver the desired improvements related to safety, efficacy, life, and cost if the specifier understands the capabilities of the lamp-fixture-control combination and pairs them with the environmental conditions under which the lighting system and controls will operate,

It also is worthwhile to get a specification sheet from the manufacturer, including the performance section. For luminaires, the performance section has a photometric diagram showing in chart form the light pattern over the dimensioned area covered, according to the mounting height and shape of the luminaire.

The maximum to minimum footcandles will radiate in rings from directly below the luminaire to the farthest distance light will reflect on the ground, and lumen output, electric load, and projected lumen maintenance are given. Projected lumen maintenance shows the percentage of original lumens that will be emitted at various stages of the fixture’s life.

For example, 0.90 lumen maintenance at 50,000 hours indicates that tests show the source still will emit an average of 90 percent of its lumen value at 50,000 hours’ life. The specification sheet also will show other facts, including lumen output, watts, efficacy, color accuracy, and certified color temperature, a measure of the color emitted on a color spectrum chart.

Many case studies show benefits versus costs as a guide to developing an outdoor lighting upgrade. One example of a university case study states that as a part of its Smart Lighting Initiative in 2014, the University of California at Davis undertook a campuswide exterior lighting retrofit that involved installing more than 1,500 network-controlled LED street lights, area lights, post-tops, and wall packs. The upgraded lighting system has reduced the campus's exterior lighting energy use by 86 percent — 1.2 million kilowatt hours annually — saving at least $120,900 in annual energy and maintenance costs.

Thomas Westerkamp is a maintenance and engineering management consultant and president of the work management division of Westerkamp Group LLC, www.westerkampgroup.com.