By Susan Martig
From the February 2021 Issue
Evaluating light levels in outdoor areas (i.e., parking lots and walkways) is one way that facility management teams can maintain safety on their properties. Before retrofitting your building’s exterior lighting system, here are five key considerations that will help to maintain safe light levels outside, meet new energy efficiency codes, and reduce long-term costs.
1. Design to IECC 2018, or beyond. Currently, the International Energy Conservation Code (IECC 2018) has been adopted by about half of the U.S. states. Compliance with IECC 2018 ensures energy and operational efficiency, and eventually all states will move toward adoption.
Pro Tip: Consider designing to IECC 2021 (published in October 2020), even if your state does not currently require it. An energy efficient design will save money in the long term and set you up for future upgrades compliant with IECC 2021 and beyond.
2. Know your exterior lighting power allowance. IECC 2018 reduces exterior lighting power allowances by about 30% on average.¹ Each component of an exterior space has a power allowance. Examples include parking areas/drives, stairways, landscaping areas, and entrances/exits. The power allowance for each is based on that building’s lighting zone, determined by geographical location.
The code specifies four main lighting zones: Zone 1, 2, 3, 4. Each zone increases in density, and allowance. The higher the density, the higher the allowance. For example, residential areas qualify as Zone 2, with allowance of .04 watts/sq.ft. for parking areas, while downtown urban centers like Chicago’s Magnificent Mile are rated Zone 4, with allowance up to .08 watts/sq.ft. for parking areas.
3. Choose LED lighting. A great way to meet a reduced lighting power allowance is by transitioning to LED lights. Lowering lighting power density reduces wattage per square foot while still maintaining the same light output. While not mandated by IECC 2021, the best way to do this is by employing LEDs.
When looking to transition to LEDs, start with flood lights, which generally require a lot of power. Replacing a 150-watt metal flood light bulb with 35-watt LEDs in a classic metal halide flood light, without altering controls, produces 80% cost savings. Other benefits compared to fluorescent or metal halides include more control over the light area, ability to refine or broaden it, and longer lifespan.
Pro Tip: Add color selectively. Color light does not give the same savings as white light due to multiple drivers required to create the color. Multiple drivers mean higher wattage.
4. Start with lumen output. Light used to be defined mainly by wattage. Today, consideration is on more than just power consumption, but light output as well. In fact, current best practice is to consider lumen output first. A big reason for this shift is LED technology, as it requires far less energy to give off the same amount of light. For example, if the required lumen output for your space is 36,000 lumens, both a 400-watt metal halide and a 160-watt LED fixture will provide this output.
5. Save energy with smart controls. Controls are a key way to reduce energy consumption and costs. The age of facility, the last time lighting was upgraded, and location all play a role in what can be installed. If you haven’t renovated in 10 to 15 years, the older infrastructure generally accommodates an on-off control, whereas new facilities or recent retrofits tend to support local dimming controls. The latest trend is using sensor control versus a timeclock for exterior lighting. Instead of lights going completely off at midnight, sensor controls allow for a greater balance of energy savings and safety, as the lights react to movement. This can increase safety by not turning the light off but dimming them to 50% or 30%.
Pro Tip: Try to use the same manufacturer for all remote exterior lighting upgrades so everything can work together wirelessly, easily. Running wires every 100 feet for each fixture increases costs and may not operate over long distances.
Ultimately, occupant safety is the most important factor when retrofitting exterior lighting systems. New codes such IECC 2021 support safe design with more control and greater cost savings through technologies including LEDs and sensors.
Martig is technical authority, lighting controls at Environmental Systems Design, Inc. in Chicago. Her expertise extends over multiple facility types and lighting control solutions.
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