Occupancy sensor controlled LED lighting — if done correctly — can enhance savings from an already efficient lighting system as much as an additional 76 percent, after those gained by the initial conversion to LED, according to a U.S. Department of Energy report.
The DOE Gateway Solid-State Lighting Technology Demonstration Program, which evaluates LED products in real-world applications, reviewed motion detection systems at two parking structures and two parking lots. It found a broad range of outcomes (see table) and several issues that affected savings, including product design deficiencies. In some cases, these problems stemmed from inexperience deploying occupancy sensors; in one case the products weren’t designed to sustain exposure to the environment, DOE reports.
Using technology that is not adapted to an individual site can also bring additional energy savings down to virtually nothing, according to the study. Problems here include inadequate or incorrect sensor coverage.
Additionally, widely varying time delay settings between sensors at a single site, and low power settings producing more light than needed during periods of non-activity made occupancy sensor systems less efficient. Overlapping controls over the same lighting system also cut savings.
In one of the report’s case studies, DOE reviewed an underground parking garage in Washington, DC. The project replaced 19 ceiling-mounted 100 W (129.5 W including ballast) HPS fixtures with LED lighting.
The parking garage, located under an office building, is lighted 24 hours per day, 365 days per year; it sees little traffic at nights, weekends and holiday. Most of the spaces are assigned, which means drivers don’t spend much time searching for parking. DOE says the parking garage’s consistent schedule makes is an ideal facility to use motion detectors.
The study found energy savings relative to the original HPS baseline was 74 percent when the sensors’ time delay was set at 10 minutes. It increase to 88 percent at the 2.5-minute setting. DOE says is the initial 10-minute LED setting is used as the baseline (instead of the HPS, yielding a projected 134 kWh/yr per fixture at 2.5 minutes versus 293 kWh/yr per fixture at 10 minutes), the increase in savings from adjusting the occupancy sensor delay is 54 percent.
Brookshire Brothers expects to reduce its annual operating costs more than $235,000 after installing energy-efficient lighting at its retail supermarkets in Texas and Louisiana, according to the companies.
The company launched a facility-wide lighting update at its 72 stores including in-store, parking lot, exterior signage and refrigerated case fixtures. Using several new linear fluorescent lighting (LFL) and LED technologies, Brookshire Brothers expects to cut its annual electricity use by 2.4 million kWhs, and eliminate more than 3.8 million pounds per year of CO2 emissions, the companies say.Brookshire Brothers has completed re-lamping of linear fluorescent lighting (LFL) fixtures at 69 locations, replacing its older 32-watt bulbs with more energy-efficient 28-watt T8 in some 450 four-lamp fixtures per 30,000-square-foot supermarket.
This saves the company more than $220,000 annually based on a $0.09 kWh electricity rate and 12 hours use per day.
Additionally, five supermarket parking lots including company headquarters have been retrofit with LED area lights. These 210-watt lights replaced 400-watt high-intensity discharge (HID) fixtures in two lots; the other three lots used 270-watt area lights to replace 1,000-watt HIDs. Brookshire Brothers says this retrofit will save more than $14,000 annually in electricity costs.
The supermarket chain installed LED lighting in refrigerated display cases in four Brookshire Brothers locations, which house 100 frozen food doors on average. these lights eliminate glare, reduce energy use by 60 percent and are rated for 50,000-hours life, which is four times longer than the fluorescent lights they replaced.
Additionally, wine displays in two stores have been lit with energy smart LED replacement lamps. 10-watt PAR30 LED floodlights (500 lumens) replaced 45 75-watt halogen lamps (940 lumens) in each store. This will save Brookshire Brothers $3,200 in combined annual energy and maintenance savings; the wine display lighting will pay for itself in 13 months.
In late November, Sheetz retail gasoline/convenience stores installed LED lighting at some 130 locations, which is delivering a 45 percent reduction in energy costs for interior lighting and a 50-55 percent reduction in exterior lighting compared to the lighting it replaced.
More than 130 locations of Sheetz retail gasoline/convenience stores now feature LED lighting.
The energy-efficient lighting at Sheetz store locations is delivering a 45 percent reduction in energy costs for interior lighting and a 50-55 percent reduction in exterior lighting compared to the lighting it replaced.
LED area and flood luminaires and 227 Series canopy luminaires replaced the exterior metal halide lighting fixtures. Additionally, 46 of the 131 upgraded Sheetz stores are illuminated with CR14 linear luminaires and CR6 downlights, updating the original fluorescent and compact fluorescent lights.
According to Sheetz, LED lighting makes its stores appear brighter and safer. Also, LED lighting provides 50,000 hours of longevity, and Sheetz expects a reduction in maintenance costs and a considerably lower amount of kilowatt-hours of electricity used annually.
Sheetz is planning to open new locations in its six-state footprint and to use LED lighting at those new facilities.