LED Lighting Design: Illumination Calculation & Fixture Selection
Pyrotech Technologies is an India-based LED lighting manufacturer providing application-oriented lighting solutions for EPC contractors, consultants, and project managers. The company offers LED lighting solutions for commercial, industrial, infrastructure, warehousing, power generation, and oil and gas projects. The lighting fixtures are created based on requirements of illuminance, energy conservation, mounting and the environment surrounding the project. With its combination of manufacturing proficiency and design knowledge for lighting, Pyrotech Technologies offers LED lighting that fits in with the project’s needs.
What is Lux in LED Lighting?
Lux is the SI unit for illuminance and is the quantity of visible light falling on a surface.
While lumens measure the amount of light emitted from the light source, lux measures the amount of light reaching the surface or work plane. So even if a lighting system has high lumens, it may not achieve the required lux level on the work plane.
Influencing factors on the illuminance produced by an LED lighting system include mounting height, beam angle, spacing of fixtures, room size, reflectance of surfaces, and photometric distribution.
Why Is Lux Calculation Important in Industrial Lighting?
Lux calculation helps determine whether a proposed lighting system can provide adequate illumination for a specific industrial area or task.
A proper lighting calculation helps designers:
Determine the required illuminance level
Estimate the number of LED fixtures required
Select appropriate lumen output
Improve lighting uniformity
Reduce unnecessary energy consumption
Minimise dark spots and over-illuminated areas
Select suitable fixture spacing and mounting arrangements
Verify whether the proposed lighting design meets project requirements
For industrial work, lighting design should consider the use as well as the standards involved and not solely rely on the wattage of light fittings.
How to Calculate Lux for LED Lighting?
Lux values can be calculated using the following equation:
Average LED Lux = Total LED Lumens Produced ÷ Areas
However, in actual practice, it should be taken into consideration that not all the light from a luminaire falls on the working plane. Therefore, the above parameters need to be taken into account.
Using the lumen method, the first approximation of the number of luminaires needed may be done with the following formula:
Where:
Required Lux is the desired illuminance for the particular case.
Area is the area of the working plane or illuminated surface.
Lumens per Luminaire is the luminous flux of one LED luminaire.
Utilisation Factor (UF) is the ratio of the emitted light that reaches the working plane. It varies according to luminaire distribution, room geometry, and surface reflectance.
Maintenance Factor (MF) is used to take into account the reduction in illuminance over time because of such factors as depreciation of light sources, luminaire dirt, etc.
Example of Lux Calculation
For example, an area of 200 m² requires 300 lux. Using a 15,000-lumen luminaire with a utilisation factor of 0.8 and maintenance factor of 0.8 gives approximately 6.25 fixtures, which should be rounded up to 7 fixtures. This lumen-method calculation provides a preliminary fixture estimate the final quantity, spacing, and uniformity should be verified using photometric data and lighting simulation.
Factors Affecting Industrial LED Lighting Design
The following parameters play an important role in defining the design of an industrial LED lighting system.
Mounting Height: - Mounting height affects the illuminance and light distribution of the luminaire across the working area. Higher mounting heights may require appropriate optics and higher-output luminaires.
Beam Angle: - The beam angle determines the light distribution throughout the workspace. The suitable beam angle will vary based on the mounting height, workspace design, and lighting distribution.
Floor Area and Ceiling Height: - Dimensions of the room, ceiling height, equipment arrangement, and any obstructions affect the placement and spacing of the luminaire.
Maintenance Factor: - Reductions in illuminance caused by dust accumulation, light-source depreciation, and luminaire depreciation are considered during lighting system design through the maintenance factor.
Operating Environment: - In industrial settings, there may be dusty, humid, hot, vibrating or hazardous conditions. Luminaires should be chosen based on the actual operating environment.
How to Select the Right Industrial LED Fixture
Once the lighting needs have been established, the appropriate LED luminaires should be selected based on several technical and application factors:
Photometric Distribution & Beam Angle: Ensure effective light distribution and uniformity.
Efficacy: Indicates how efficiently electrical power is converted into light.
Glare Control, CCT & CRI: Support visual comfort, colour appearance, and colour rendering.
IP Rating & Operating Temperature: To ensure the light is suitable for the particular operating environment.
Power Factor & Surge Protection: To ensure good electrical performance and protection from transient voltage spikes.
LED Driver Performance: For efficiency and performance of the LED lighting.
Application Requirements: To meet the application specifications.
Why Wattage Alone Is Not Enough for LED Fixture Selection
It is very often a misconception in industrial lighting projects that comparison of fixtures be made based on watts only.
For instance, two LED fixtures could have the same input energy but will differ in lumens output, beam angles, optics, etc.
So, the following points should be considered while selecting fixtures:
This approach provides a more reliable basis for industrial lighting design than wattage comparison alone.
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