Technology Spotlight: New lighting technologies may make canopy retrofit a winner

Exterior lighting attracts customers to retail locations, enhances safety conditions and improves the perception of safety in spaces where pedestrian and vehicle traffic mix, such as convenience stores with gas pumps. TSsidebar1

Gas station canopy lighting operates for long hours in all weather conditions to light the fuel pumping area. Metal halide (MH) lighting has long dominated this application, but LED and induction lighting offer an alternative. These products save energy, reduce maintenance, provide higher-quality light and offer more control options. The biggest unknown is if the technologies can deliver the promised long lamp life in real-world conditions. High-quality fixtures are the key to achieving that longevity.

Better, not more, lighting
While energy codes reduce power allowances and regulate light pollution, businesses still want to look brighter than their neighbors to attract more customers. New technologies can provide more light with less energy, and a good retrofit can put the right amount of light where you need it without producing excess light.

Some utility programs promote canopy lighting retrofits with incentives and the promise of energy savings. LEDs can often deliver more useful light for less than half the energy MH lamps use, but there are no standard rules about how many LEDs are needed to replace MHs.

According to the Illuminating Engineering SocietyRedirecting to a non-government site (IES), measured and perceived light levels are not directly related. An articleRedirecting to a non-government site by the National Lighting Product Information Program explains that the perceived brightness of a space is affected by the average light level, contrast and distribution, and amount of light produced. For example, a recent retrofit projectRedirecting to a non-government site replaced 56 320-watt MH fixtures with 30 142-watt LED luminaires, reducing energy use by 80 percent.

Different luminaires, different needs
A recent survey of canopy retrofits found very high light levels under canopies but not enough area lighting beyond the structures. This high contrast can impair vision. People also feel safer when they can see and respond to what is going on beyond their immediate space.

Many gas pump islands exceed the light level recommendations for these retail spaces in the horizontal plane (see sidebar), while vertical light levels are often much lower. These levels should be the same because vertical light is needed to make people and objects more visible.  TSsidebar2

A qualified lighting designer can maximize lighting effectiveness and energy savings by using different types of luminaires on different parts of a property. The IES classifies luminaires according to the amount of light that they distribute upward. Full-cutoff fixtures direct all their light down, while semi-cutoff fixtures emit some light sideways. Non-cutoff fixtures may be omnidirectional and contribute to light pollution. Using a variety of luminaires in different locations ensures that there is enough light to meet customers’ needs and it does not create glare or other safety issues.

Realistic energy savings expectations
Understanding how much of the total energy bill canopy lighting represents helps in managing savings expectations. Exterior lighting at convenience stores can consume 20 percent of the total energy useRedirecting to a non-government site. Convenience stores and truck stops have many other significant energy loads, such as refrigeration and heating and cooling. If those systems are upgraded at the same time, or if electricity rates change, energy savings from a lighting retrofit may be obscured.

Many facilities still rely on manual controls, even though photocells and timer controls are available. MH is most efficient when left on for at least 10 hours; in contrast, LEDs and induction lamps can be switched frequently without affecting their lamp life or light quality. Bi-level operation—lamps that come up to full power when customers arrive and drop to a lower light level when customers leave—might offer additional savings at less busy stations.

More savings from maintenance?
MH lamps have a relatively short lifespan (10,000 to 20,000 hours) compared to LED and induction lamps (50,000 to 100,000-plus hours), and experience much higher depreciation of lighting quality over time. To compensate for these drawbacks and to avoid frequent expensive replacements, facilities using MH lamps often over-light. LEDs and induction lamps, with their long lamp life and more durable quality, can reduce the need for maintenance and over-lighting. Maintenance savings may accumulate faster than energy savings, improving the payback in spite of high first costs.

As LED performance improves and costs decline, this technology has become competitive in many markets, especially when factoring in total cost of ownership rather than energy savings alone. Induction lighting may also be worth considering.

Call Western’s Energy Experts hotline, 800-769-3756, for more guidance on customer lighting projects.

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