Electricity + Control April 2018

LIGHTING

Small improvements in efficacy can result in significant operating cost savings over the lifetime of a lighting solution.

charges into account may significantly improve the cost-effectiveness of more efficient technologies.

• The light distribution of the existing solution does not suit the uses of the space (e.g., if there have been changes in the design, com- ponents, furnishings, or conditions in the space) • The desired illumination or distribution cannot be achieved with the available retrofit options

Maintenance Costs Industrial users should understand the mainte- nance costs associated with a lighting solution. Having a plan in place for routinely replacing lamps and cleaning surfaces can reduce the total amount of labour needed for maintenance. Maintaining the appearance and uniformity of the lighting can also help with workplace safety and productivity. The performance of any lighting solution will deteriorate over time through the failure of lamps, ballasts, or drivers; gradual lumen depreciation and colour shift; or the accumulation of dust and dirt on lenses and reflector surfaces. The deterioration rate can be determined by the system’s operating pro- file, the system’s technical characteristics, and the conditions of the operating environment. To plan effectively, it is important to attempt to predict the lifetime of a given technology and understand how and when the lighting system will likely deteriorate. LED technology is treated differently from non- LED technology in this regard. LED chips degrade slowly over time, producing less light and shifting their colour characteristics. The metric used to define the lifetime of LEDs is L70 lumen mainte- nance. This refers to the amount of time the LED will operate while maintaining at least 70% of initial output. Some LEDs will take longer to get down to 70%. Non-LED technologies have electri- cal components or filaments that fail completely at some point; the rated lifetime for those products is defined as the number of hours of operation at which 50% of the units in a sample fail. Non- LED technologies also experience depreciation in lumen values over time, with some technologies depreciating more quickly than others.

Proper illumination for workstations can be a cost-effec- tive, long-term solution to increasing ergonomics and productivity. Operational Costs Small improvements in efficacy can result in sig- nificant operating cost savings over the lifetime of a lighting solution. Achieving appropriate levels of light for work areas by using focused task lighting can also save on operating costs. Lighting controls that dim or turn off lights when they are not need- ed is another way to reduce operating costs. Efficacy ratings vary significantly among differ- ent technologies and applications, from less than 15 lumens per watt (lm/W) for standard 60 W in- candescent lamps, to nearly 150 lm/W for the lat- est LED area lighting. Generally, lights with higher lumen outputs have higher efficacy ratings. LEDs often have better efficacy than other technologies, but highly efficient fluorescent and HID options can provide better or similar efficacies for some applications. Reducing the lighting system’s pow- er will also save on demand charges. When commercial or industrial customers sig- nificantly reduce their power draw, they should review their utility rates schedules to determine which schedule is most economically attractive. Large customers that face 'ratchet' charges may benefit by shifting to a different schedule if de- mand reductions are significant. Taking ratchet

Table 1: Range of rated lifetimes and lamp lumen depreciation (LLD) values at the end of the rated life for selected technologies [1].

LightingTechnology Rated Lifetime (Hours) Lamp Lumen Depreciation (LLD) At end of rated life Halogen Incandescent 3 000 – 5 000 5% Linear Fluorescent 15 000 – 45 000 10% High Pressure Sodium 15 000 – 40 000 30% LED 20 000 – 50 000+ N/A

Electricity + Control

APRIL 2018

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