Lighting is more than lamps


Industrial lighting and LED technology

André Kerremans

A properly lit work environment is important. Well-balanced lighting increases employee productivity and safety. Poor lighting makes for tired workers and reduces their motivation and hence their productivity. Therefore industrial lighting is not only about energy costs, but also about creating lighting comfort. Each location in the building should be properly illuminated, but only to the extent needed.

Think first of all of natural light entering through windows and skylights. Natural light is free. In central and eastern Europe for example, the rules for natural lighting are defined as a percentage of the roof surface. For warehouses, this means that 2 percent of the roof surface must consist of skylights. This is 12.5 percent for production halls.

Each location in the building should be properly illuminated, but only to the extent needed.

However, there’s no daylight at night. Daylight is not constant throughout the day. And one day is darker than the other, for example in winter. Artificial lighting imitates extended periods of daylight, and provides additional lighting where and when needed.

For an industrial building, you want continuous proper lighting at each workplace. Each activity has its own lighting needs and requirements. And these depend on the use of the building and the type of activity that takes place at a particular location in a building. When a given activity by 1 person takes longer than 4 hours, production standards for lighting are applied, even in a warehouse.

Each activity has its own lighting needs and requirements.

When speaking of light, use often is made of lumens. The lumen (lm) is a unit of luminous flux, the total amount of visible light emitted in all directions by a light source. Thus the number of lumens of a lamp tells us nothing about the light that actually falls on the workplace. Which is what counts in a company. The luminous flux after all can be blocked by an object. Or a layer of dust on the lamp or fixture can significantly restrict light output.

Lighting requirements are expressed in lux (lx), the unit of illuminance. Lux represents the amount of light that is measured per unit of surface area (square meter, for example), independent of the number of light sources being used. These are expressed as minimum amounts in the regulations. The legal requirement for a storage facility is 200 lux. For a production environment, this is 300 lux. But if seeing details is important, 500 lux is better. 500 lux is also required for office environments. In stairwells, corridors and for surveillance work outside, much less is required: 5 lux.

In addition to illuminance, luminance also plays a role. Luminance is the illuminance per unit of surface area at right angles to the viewing direction. Luminance that is too high will be a hindrance. You notice this immediately when you look at a light source at a right angle. Your eyes will also tire quickly if you need to see in locations that alternate between a luminance that is too high and one that is too low, i.e. too light and too dark. The light reflected off a surface can also hinder.

The proper placement and balancing of lighting thus is equally as important. If there is no shelving in a large warehouse, the light fixtures will reinforce one another and the lighting can be freely suspended. But if there are high shelves in the warehouse, each fixture must hang precisely above the aisles and independently provide sufficient illuminance. In addition, the lighting must extend downward and shadows must be avoided.

The right decision on which lighting goes where can yield significant savings: on energy costs, but also on maintenance costs. Concern for our environment has meant greater attention in general to sustainable solutions. The same applies to contemporary lighting: ‘greener’ solutions are the aim. Old mercury lamps and filament lamps are all out. Modern fluorescent lights use ± 70 percent less energy than traditional incandescent bulbs and last a lot longer. One down side of the fluorescent light is the fact that it takes a while to reach full brightness and cannot be dimmed. Fluorescent lights also contain mercury, which is bad for our health and environment.

‘Greener’ solutions are also the aim when lighting modern facilities.

Thus we see more and more industrial projects making use of LED lighting, a technology whose price has fallen sharply in just a few years.  LEDs convert electricity much more efficiently than even the most modern fluorescent lamps. And the potential saving compared to old incandescent lighting is many times greater.

Energy consumption is measured in watts (W). For incandescent bulbs, watts also gave us an idea of the brightness, but this is not the case with LEDs. For example, a LED bulb with a brightness comparable to a 150-W incandescent bulb consumes only 27 watts, and compared to a 60-W incandescent bulb, the LED counterpart consumes only 8 to 12 watts. In a 5000-m2, 10-metre high industrial hall, you would need a lighting system that generates approximately 800 lm/m2 to achieve an illuminance of 200 lux 1,5 m above the work floor. Using incandescent bulbs, this would require 5000 60-W lamps. With LEDs, you can achieve the same result with 5000 lamps of 10 W each. Thus electricity consumption would be reduced by no less than 250,000 W.

Lumens incandescent LED
2 600 lm 150 W 27 W
1 600 lm 100 W 18 W
1 100 lm 75 W 11 W
800 lm 60 W 10 W
450 lm 40 W 8 W


LEDs are not only kinder to your energy bill, they are also more durable and require less maintenance. An additional advantage of LEDs as a light source is that their pump wavelength is around 470nm (+/-20nm) and therefore does not contain harmful UVA, UVB or UVC wavelengths. On the other hand, LEDs do not take heat well. And they can be very blinding. Their comfort is largely determined by the optical system installed around the lamp.

Comparative table      
Incandescent CFL LED
Relative cost € 1 € 2 € 6
Average lifespan 1 200 hours 8 000 hours 25 000 hours
Watts consumed 60 W 14 W 10 W
No. of bulbs needed for 25 000 hours of use 21 3 1
Total purchase price of bulbs for 25 000 hours € 21 € 6 € 6
Total cost of electricity consumed (25 000 hours at € 0.17 per kWh) € 255 € 60 € 43
Total operational cost over 25 000 hours € 276 66 49
24/7 operation with a need for lighting 16 hours/day 4.28 years



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