Luminous intensity is the amount of light that a fixture or light source emits in a specific direction, expressed in candela (cd). In industrial environments, luminous intensity determines whether a workplace is safely and effectively illuminated: too little light increases the risk of errors and accidents, while too much unfocused light causes glare and energy waste. In this article, we answer the most frequently asked questions about luminous intensity—from basic principles to practical application in heavy industry.
How does luminous intensity differ from lumens and lux?
Three concepts that are often used interchangeably, but each measure something different. Luminosity (candela) indicates how much light a source emits in one specific direction. Lumen describes the total amount of light a fixture emits in all directions combined. Lux measure how much of that light actually falls on a surface, at a certain distance.
A useful example: a fixture with many lumens does not automatically have high illuminance. If the light is widely dispersed, the beam is less intense in any given direction. A spotlight with the same lumens but a narrow beam has a much higher illuminance in that single direction. For industrial applications, this distinction is crucial — high illuminance ensures that light reaches far and is directed, which is essential for high masts, large halls, or outdoor locations.
The relationship between the three quantities in a row:
- Candela (cd): Luminous intensity in a specific direction
- Lumen (lm): total luminous flux emitted by a luminaire
- Lux (lx): illuminance on a surface (lumens per square meter)
More background on the relationship between lumens and luminous flux can be found on the page about Luminous flux and what you need to know.
Why is light intensity critical in industrial environments?
On a factory floor, a construction site, or a haven terminal work with heavy machinery, dangerous materials, and complex installations. Insufficient targeted lighting directly leads to reduced visibility and an increased safety risk — and that's precisely where the importance of light intensity comes in.
Industrial fixtures are often hung at great heights, sometimes twenty meters or more above the work floor. At that distance, the illuminance decreases rapidly if the fixture's luminous intensity is too low. A fixture with high luminous intensity in the correct beam shape ensures that light reaches the workspace with sufficient intensity, even at a great distance.
In addition, environmental factors play a role. Dust, vapor, heat, and corrosion can further reduce light output. In such conditions, a generous light intensity margin is not a luxury, but a necessity to guarantee reliable lighting throughout the entire lifespan of the installation.
What illuminance level is required for different industrial applications?
The required illuminance varies greatly depending on the application and is determined by the mounting height, the area to be illuminated, the nature of the work, and applicable standards. For industrial workplaces in the Netherlands and Europe, guidelines apply based on the EN 12464-1 standard for indoor lighting and EN 12464-2 for outdoor locations.
Global guiding values per application:
- Hallways and storage rooms: at least 100 lux at work surface height, low illuminance is sufficient at short distances
- Production halls and workshops: 300 to 500 lux, high-bay fixtures require high luminous intensity
- Precision work and quality control: 750 lux or more, with emphasis on even distribution
- Outdoor areas and port locations: 50 to 200 lux depending on activity, high brightness needed due to large lighting distances
- Crane operations and working at height Specific high-brightness bundles aimed at the work area
For complex environments where large areas and varying working heights converge, a professional lighting design is essential to determine the correct illuminance per zone.
How do you measure the light intensity in an industrial space?
Luminance itself is measured with a goniophotometer, a specialized laboratory device that records the light intensity of a fixture in all directions. In practice, however, on the workplace, you measure illuminance (lux), not luminous intensity (candela) directly—for this, you use a lux meter.
A workplace measurement proceeds as follows: position the light meter at working surface height (standard 0.85 meters above the floor) at multiple measurement points distributed across the room. By comparing the measured lux values with the required standards and analyzing the differences between them, you assess whether the lighting installation provides sufficient and uniform illumination.
Modern lighting software allows for simulations to determine the required light output per fixture to achieve desired lux levels on the work floor. This prevents installations from failing to meet requirements after the fact, which can avoid costly adjustments on large industrial projects.
The consequences of incorrect light intensity in the workplace are: * **Eye strain and fatigue:** Too little or too much light can cause discomfort, dryness, headaches, and blurred vision. * **Reduced productivity and performance:** Poor lighting can make it difficult to see details, increasing errors and slowing down work. * **Increased risk of accidents:** Insufficient lighting can lead to tripping hazards and difficulty navigating the workspace. * **Sleep disturbances:** Exposure to incorrect light, especially blue light at the wrong times, can disrupt the body's natural sleep-wake cycle. * **Mood and well-being:** Inadequate or harsh lighting can contribute to feelings of stress, irritability, and general discomfort. * **Damage to vision over time:** Chronic exposure to improper lighting can potentially contribute to long-term vision problems.
Both too low and too high light levels in the wrong place cause problems that go beyond discomfort. The consequences directly affect the safety, productivity, and health of employees.
By too low brightness Employees see details less clearly, react more slowly to dangerous situations, and make more mistakes. This is particularly risky with machine operations, crane operation, or working at heights. Fatigue and headaches are common complaints with structurally insufficient lighting.
By excessive brightness or incorrectly aimed beams This causes glare. Direct or reflected glare disrupts vision and can lead to serious workplace accidents. This risk is particularly high in environments with shiny surfaces, water, or metal.
Additionally, an incorrect lighting installation has economic consequences: luminaires that provide too little light are replaced or supplemented, leading to higher costs. Over-dimensioned luminaires unnecessarily consume energy. A good lighting design based on the correct illuminance prevents both pitfalls.
Which factors influence the effective luminous intensity of an LED luminaire?
The specifications on a datasheet don't tell the whole story. Various technical and environmental factors determine how much light actually reaches the workplace.
The main factors are:
- Optics and beam shape: The lens or reflector determines how the light is bundled. A narrow beam provides high intensity over a small angle; a wide beam spreads light over a larger surface with lower intensity per point.
- Temperature: LED chips perform less well at high ambient temperatures. In hot industrial environments, light output can significantly decrease if the luminaire is not thermally well-designed.
- Pollution and light transmittance: Dust, grease, and condensation on the fixture cover reduce effective light transmission. Fixtures with a high IP rating maintain their performance better in dirty or humid environments. More about IP ratings can be found on the page about IP and IK ratings.
- Light depreciation over time LED lighting gradually loses light output as it ages. Quality fixtures retain a higher percentage of their initial brightness over a longer period (expressed as an L80 or L90 value).
- Mounting height and angle: The higher the fixture is mounted, the more light intensity is needed to achieve the same lux value on the floor. The mounting angle also determines where the peak of the light beam lands.
For applications in extreme environments, such as high temperatures or aggressive chemical exposure, choosing a fixture specifically developed for those conditions is crucial for long-term performance.
Examples from practice: DFDS Terminal Lighting
A concrete example of how light intensity plays out in practice is the project at DFDS — a large ferry and logistics terminal where lighting must meet strict operational requirements. The challenges at this type of location are multifaceted: large open areas, varying working heights, intensive truck and trailer traffic, and the constant presence of salt and moisture due to the proximity of the water.
The central question in this project was how to achieve uniform and sufficient illumination across the entire site with a limited number of fixtures. The solution lay in carefully matching the beam shape to the mounting height and the terrain's geometry. Fixtures with a focused, asymmetric light beam ensured efficient light distribution without glare for drivers or terminal staff.
An important lesson from this project: the illuminance of a fixture must always be assessed in conjunction with the on-site environmental factors. Salt, moisture, and temperature fluctuations accelerate the degradation of fixtures not specifically designed for these types of environments—resulting in a faster drop in effective illuminance than would be expected on paper. Therefore, ease of maintenance and robustness are just as important as the initial illuminance. More projects in similar environments can be viewed at the DFDS Seaways Vlaardingen Project Page.
How JEL Products Helps with Light Intensity in Industrial Environments
Choosing the right light intensity for an industrial environment is not a one-size-fits-all solution. It requires an understanding of the specific work environment, mounting heights, activities on the shop floor, and applicable standards. JEL Products supports technical decision-makers and project managers at every stage of this process:
- Professional lighting design based on your specific situation and standards
- Selection of luminaires with the correct beam shape and light intensity for the application
- Calculations and simulations that provide advance insight into the expected lux values
- Fittings designed for extreme conditions, from high temperatures to corrosive environments
- Guidance from engineering to installation and commissioning
Whether it's a production hall, a port terminal, or an outdoor location with harsh conditions — there's always a solution that meets your organization's technical and operational requirements. Feel free to contact us for a no-obligation consultation via contact page.