The factor Light in warehouse and logistics

The illumination of distribution centers is a rather rarely addressed aspect of warehousing. The lighting factor is not directly related to intralogistics processes and is therefore often taken for granted. Nevertheless, it can be considered an important basic requirement for the processes in a warehouse. Particularly in warehouses that operate multiple shifts to ensure 24/7 flexibility and reliable delivery, good lighting is even more important. This is because lighting makes a significant contribution to the effective and energy-efficient operation.

Warehouse lighting has three main aspects that it can influence:

  • The work quality aspect, which requires comprehensive standard-compliant illumination of warehouse areas and transport routes to optimally support employees and systems in their work at all times of the day and night. Standard-compliant lighting also enhances well-being at the workplace and safeguards those responsible in the event of damage (insurance protection).
  • the economic aspect, which demands highly energy-efficient operation to contribute to an overall positive company result. For example, switching from fluorescent tubes to LED lighting can save between 60% and 75% in electricity costs – depending on the quality of the LED luminaire, system, and lighting design.
  • The climate protection aspect, i.e. the obligation of companies to design their energy processes in such a way that they meet the national and international climate protection requirements responsibly, which means reducing unnecessary energy consumption and thus CO2 emissions to a maximum. Accordingly, conversions to LED as well as new buildings are subsidized by various support programs.

Criteria of light and lighting

The lighting of warehouses and logistics halls is subject to the standards of DIN EN 12464-1, which sets the following criteria:

  • Adequate illuminance to optimally support the different visual tasks or areas of activity.
  • Uniformity of lighting, achieved by high luminance and large beam angles of the luminaires, so that even the spaces between shelves are optimally illuminated.
  • Low-beam optics extending from the hall ceiling to the hall floor contribute to the safety of employees.
  • Best possible freedom from glare, i.e. avoidance of direct or reflected glare, as well as veil reflections.
  • Suitable light color and good color rendering for better recognition of the condition of the stored goods, labeling, coding.
  • More safety by avoiding flickering and stroboscopic effects, especially in connection with retrofit luminaires (see below)
  • Inclusion of daylight qualities
  • Convenient lighting management, i.e. flexible adjustment of illuminance to specific work and visual requirements. In combination with the presence detectors (sensor technology), additional electricity and energy costs can be saved in areas that are not heavily frequented.
  • Emergency lighting capability of the luminaires, either integrated into the central control system or for decentralized emergency lighting operation with built-in rechargeable batteries.
  • The long service life and freedom from maintenance of high-bay luminaires are very important in this respect. After all, trouble-free operation increases efficiency, while defective luminaires disrupt or interrupt operations and cause exceptionally high costs for repairs or replacement.

The Benchmark for the service life of hall spotlights and luminaires is 80,000 – 120,000 operating hours, L80/B10, at an ambient temperature in the standard range of -30 to +60°C.

Lighting design parameters

A comprehensive and well-founded light planning refers to essential parameters:

 

  • Room dimensions and measurements including special structural features, e.g. indoor or outdoor storage, required inspection opening, fire protection, struts and load cranes, light point height(s), roof construction, additional requirements for refurbishment in existing buildings, ceiling structure:
    • low ceilings – wide-beam (damp-proof) luminaires
    • high ceilings up to 25 m – high bay luminaires
    • High-bay warehouses with mounting heights up to and above 50 m require dedicated high-bay luminaires with low- or wide-beam characteristics, depending on the spatial hall structure.

The flexible mounting method and correct positioning of the luminaires also contribute to an optimal overall solution.

  • Operating conditions: Operating times, burning duration, shift operation, required illuminance and lighting control, ambient temperatures.
  • A professional lighting design compares the size and height of the assessment areas and identifies the following points:
    • Height of the luminaire plane (illuminance decreases in square with the height of the hall!)
    • Maintenance factor
    • Total luminous flux
    • Average illuminance (Em)
    • Uniformity (U0 or g1)
    • Number and power of luminaires for standard-compliant lighting
    • Energy costs and profitability of the new warehouse lighting (compared to the previous one)

Identifying qualities of LED luminaires for warehouses and logistics

To judge the quality of LED luminaires, the following properties can be compared:

 

  • Absolute tightness of the luminaire is important so that neither dust, dirt, moisture, or other emissions can penetrate because this drastically reduces the service life.
  • A robust dimensionally stable profile, e.g. made of aluminum, ensures this. Also, pay attention to the nature of the luminaire cover – stable, for example, is a cover made of high-quality plastic (PMMA), which is not glued but screwed with corrosion-resistant materials.
  • The suspensions of the luminaires should be resistant to embrittlement so that they remain firmly suspended over the entire service life.
  • The more durable the LED modules, the more sophisticated the thermal management.
  • Degradation of luminaires: The service life of luminaire products is indicated by so-called L and B values. The L value indicates the light output to which the luminaires may have dropped after the specified time in operating hours (e.g. L80 = 80%). The B-value indicates what percentage of the luminaires may undershoot this value (e.g. B10 = 10%. No indication of the B-value means B50; ergo that 50% of the luminaires have a luminous flux below the L-value. In practice, this means that substitute measures must be taken ahead of time to ensure that lighting continues to comply with the standard.

Evaluating qualities of luminaire manufacturers/sources

For long-term use of lighting, manufacturers (sources of supply) should be checked in advance for warranty and availability of spare parts. To avoid an inhomogeneous, irritating light pattern in the case of remodeling or expansion of the hall, it is also important to ensure continuity of light colors when reordering.

Even if it may be a bit more expensive – recyclable materials, e.g. luminaire profiles made of recycled aluminum not only ensure the quality and longevity of the lighting but also protect the environment. Plastic luminaires from Far East production burden the eco-balance in terms of transport and residual material recycling.

Consequences with installed retrofit luminaires

Anyone who wants to install retrofit luminaires, i.e. LED luminaires in fluorescent tube housings, warehouses, and logistics halls should be aware of the insurance-related consequences. By converting the luminaire with retrofit / LED tubes, technical safety is no longer guaranteed, because the CE/TÜV certification expires, and possibly also the insurance coverage (see also VBG; ZVEI/VDE LA-T 2014-42). According to a study by the University of Darmstadt (Department of Lighting Technology, Prof. Quoc Khanh; not freely available), there is a risk of stroboscopic effects due to the low frequency of retrofit luminaires; fatigue and headaches can occur, and epileptic seizures can also be triggered.

Accordingly, common subsidies for retrofitting to LED are generally not eligible for retrofits in existing or new construction. This can make a crucial difference, start funding programs such as the BEG funding of non-residential buildings at 20%.

 

Image source: Pexels, License: Creative Commons Zero (CC0)

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