Daylight control is a control technique in which artificial lighting is automatically adjusted based on the amount of available daylight. A sensor continuously measures the illuminance in the room or area, and adjusts the LED fixtures accordingly: more daylight means less artificial light, less daylight means more. This makes daylight control an effective method for reducing energy consumption without compromising the required working conditions. The sections below will delve deeper into how this works, which sensors are used, and when daylight control is suitable or unsuitable for industrial applications.

How does daylight control work in practice?

The principle is actually quite elegant: a daylight sensor measures the current illuminance at a reference point, compares that value with a set target value (the so-called setpoint), and adjusts the luminaires via a dimmer or switch until the desired lighting level is reached. This process repeats continuously, so the lighting is always optimally adapted to the circumstances—without anyone having to do anything.

In practice, there are two basic principles of daylight-dependent lighting:

• Closed loop: The sensor measures the total light level on site, including both daylight and artificial light. The control system adjusts accordingly based on the combined result. This is more accurate and is most commonly used in industrial environments.
• Open loop: The sensor only measures the incident daylight, for example through a skylight or facade, and calculates based on that how much artificial light is needed. This is simpler but less accurate.

The control itself is done via DALI, 0-10V, or wireless protocols. In larger industrial installations, daylight control is often integrated into a Building Management System (BMS), allowing multiple zones to be managed centrally. Lighting expertise for complex environments is the correct choice of control technology as important as the fixture itself.

What types of daylight sensors are used in industrial lighting?

Not every sensor is suitable for every environment. In industrial LED lighting, three main types are used: photoelectronic sensors for switching control, dimmable photoelectronic sensors for continuous dimming, and multifunctional sensors that combine daylight detection with presence detection. The choice depends on the desired accuracy, environmental conditions, and complexity of the installation.

In harsh industrial environments, sensors demand high robustness. Consider dust resistance (high IP rating), vibration resistance, and resistance to temperature fluctuations. A sensor that functions perfectly in an office environment may quickly fail in a production facility or an outdoor location. Read more about the relevance of protection classes on the page about IP and IK ratings.

In addition to the type of sensor, its placement is also a key factor. A sensor mounted too close to a skylight will provide a distorted picture of the actual lighting conditions on the factory floor. Proper positioning and calibration are therefore essential for reliable lighting control in industrial settings.

What is the difference between daylight control and occupancy detection?

Two technologies, two different approaches. Daylight control adjusts the illuminance based on available light. Occupancy detection turns the lights on or off or dims them based on the presence of people. They complement each other, but are not interchangeable.

The key differences at a glance:

1. Daylight Control reacts to the amount of ambient light and ensures that the illuminance at the workplace remains constant, regardless of the time of day or weather.
2. Presence Detection reacts to motion or body heat from people and turns lighting on or off based on whether someone is present.
3. Combined systems Both techniques are used simultaneously: the presence detector determines whether the lighting should be active, the daylight sensor determines at what level.

In industrial environments with continuous occupancy—such as production facilities or port areas that operate 24/7—occupancy detection offers less added value. Daylight control is the more relevant technology in such cases, because the space is always occupied but the amount of daylight entering the space varies. In environments with varying occupancy, such as warehouses or outdoor areas, the combination of both technologies yields the greatest energy savings.

How much energy does daylight control save in an industrial environment?

The figures are promising: in real-world situations with sufficient natural light, a 20 to 40 percent reduction in lighting consumption is realistic. The actual savings depend heavily on the specific situation—there is no one-size-fits-all answer.

Factors that determine the savings include:

• The quantity and quality of daylight openings (skylights, domes, facades)
• The geographical location and orientation of the building or site
• The number of operating hours during the day versus at night
• The dimming capabilities of the installed LED fixtures
• The accuracy of the sensor setting and calibration

For outdoor lighting, such as industrial site outdoor lighting, is daylight control a standard measure: the lighting automatically switches on at dusk and off when there is sufficient daylight. This prevents fixtures from burning unnecessarily and extends the lifespan of the installation. In combination with other energy-saving measures, daylight control can also contribute to the criteria for the Energy investment allowance (EIA)..

Daylight control is not suitable for industrial lighting when:

Daylight control is not a solution for every situation. When there is little or no daylight available, when lighting levels must be strictly controlled, or when the environment is so extreme that sensors cannot function reliably, daylight control does not result in savings—and can actually cause malfunctions or unsafe situations.

Specific situations in which daylight control is not recommended:

• Fully underground spaces or bunkers without any daylight
• Climate chambers and testing facilities where lighting conditions must be strictly controlled
• Environments with heavy dust, splashing water, or extreme temperatures where sensors are quickly damaged
• Processes in which even the slightest difference in light levels affects quality control or safety
• Equipment in steel mills or smelting furnaces that emits intense infrared radiation, which interferes with sensor measurements

In such environments, it is better to opt for fixed lighting levels with optional manual or time-controlled switching capabilities. For environments with extreme temperatures or unusual conditions, specialized high-temperature lighting more certainty than a complex system of rules.

What standards apply to daylight control in industrial facilities?

Anyone installing a daylight control system will encounter several important reference standards. The most relevant are EN 15193 (Energy performance of lighting in buildings), EN 12464-1 (Lighting requirements for indoor workplaces), and EN 12464-2 (Lighting requirements for outdoor workplaces). These standards set requirements for minimum illuminance levels, uniformity, and the manner in which control systems may be deployed without compromising working conditions.

In addition, there are installation requirements set forth in NEN 1010 (low-voltage installations) and, for potentially explosive atmospheres, the ATEX directives. Sensors and control equipment used in ATEX zones must meet additional certification requirements.

Practically speaking, this means that a daylight harvesting system should never result in lighting levels below the norm's required minimum values. The setpoint of the daylight sensor must always be set at or above the minimum illuminance applicable to the workspace. A lighting design that takes these standards into account forms the basis for a correct and safe installation.

Case Study: DFDS Terminal Lighting

A good example of how daylight control works in practice is the project for DFDS, a major terminal operator in the port. The challenge in this project was multifaceted: the terminal operates 24/7, meaning the lighting must meet strict requirements both during the day and at night. During the day, the amount of daylight varies considerably, depending on cloud cover, season, and the position of the fixtures relative to the quay and buildings. A fixed lighting setting would either lead to unnecessary energy waste in clear weather or insufficient lighting in cloudy conditions.

The chosen solution combined robust LED fixtures with a closed-loop daylight control system. The sensors had to withstand salty sea air, temperature fluctuations, and mechanical vibrations from passing vehicles and ships—a direct requirement for the IP and IK rating of the sensor housings. Calibration proved to be a critical point: sensors placed too close to the edge of the frame gave distorted measurements due to reflections from the water surface. After repositioning and recalibration, the system functioned stably.

From those who deliver this project for daylight control in general: the environment-specific factors—reflection, vibration, salt load—are at least as important as the technical specifications of the sensor itself. Placement and calibration are not trivial matters, but an essential part of the design. More practical examples can be found on the JEL Products's Projects Page.

How JEL Products Helps with Daylight Control and Lighting Control

JEL Products not only supplies high-quality LED fixtures for industrial environments, but also works with you to determine the right lighting control solution for your specific situation. Whether it’s a large outdoor area, a production facility, or an environment with extreme conditions, choosing the right control strategy makes the difference between an installation that wastes energy and one that performs optimally.

What JEL Products offers in this regard:

• Lighting design that incorporates daylight control from the outset
• Advice on the most suitable sensor technology and control method for your environment
• Light fixtures that are fully dimmable and compatible with common control systems
• Guidance on meeting relevant standards and utilizing available subsidies
• Full support from engineering to commissioning

Do you want to know if daylight control is suitable for your installation and what concrete benefits it can offer you? Please contact JEL Products for a no-obligation consultation.

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