Better light for better quality of life

People today tend to stay indoors with artificial lighting, and many work shifts or in windowless buildings. Therefore daylight light levels and how they change, as well as the darkness of night, lose their effects on people, who move ever further away from their natural rhythm.

This has consequences: too little daylight can lead to people’s body clocks going off track, or their sleeping and waking phases becoming less well differentiated. Both these factors have a negative effect on biorhythms, and can affect health.

Circadian lighting is aligned with the natural day-night rhythm (circa = around, dies = day), with one cycle lasting 24 hours. Biologically effective lighting should be tuned to the user’s circadian rhythm, and must intelligently support both naturally active times and periods of rest in the course of the day. PureColour occupancy detectors use the control of non-visual effects of light to bring the dynamics of daylight indoors. They can gently and unobtrusively support users’ performance and wellbeing.

Essential concepts:

  • Human Centric Lighting (HCL): the science of biologically effective light, which is adjusted to people’s wellbeing through artificial lighting that is similar to daylight.
  • Circadian Rhythm: this is aligned with the biological day-night rhythm (circa = around, dies = day), and is intended to stabilise a person’s day-night rhythm.
  • Tunable White: a function in advanced lighting which allows the light source white tone to be smoothly tuned to the required colour for the time of day.
  • PureColour: Innovative B.E.G. DALI Compact occupancy detector with tunable white function, as an option also available as a function in the scalable DALI-SYS.
  • Biological effects of light: in 2002, scientists identified a third kind of light receptor in the retina, alongside the familiar cones (for colour vision) and rods (for low light vision). These special ganglion cells are light-sensitive, but do not contribute to vision. They only register the local light level; when light falls on them, they regulate biological processes in the body, such as the pupil reflex or hormone production.
  • Melanopic effect of light: non-visual effect of light. The light is received through special photoreceptors in the eye by the light-sensitive compound melanopsin. This regulates the hormones cortisol (stress hormone) and melatonin (sleep hormone), and the process leads to us feeling alert or tired.

WORLD FIRST – DALI occupancy detector with HCL function for biodynamic light

We are the first manufacturer to have developed an occupancy detector with “Tunable White Function”. The detector regulates the colour temperature of the white tone in the room to provide the most beneficial influence on people’s biorhythms.

The PD4-M-HCL2 is the new DALI occupancy detector with “Tunable White” function for Human Centric Lighting (HCL). Like other DALI occupancy detectors, this detector regulates different lighting groups according to daylight and occupancy, to increase convenience and energy efficiency. A new feature is that the detector can also control the colour temperature in the room if DALI lights with “Tunable White Function” (Device Type 8) are connected.


Preset application profiles can be selected according to the room’s current usage. These profiles control the colour temperature and light level in the room as the day progresses. The change in the colour temperature from warm white to cool white and the change in light level conform to human biorhythms. This takes place very slowly, and is hardly apparent to the user. This kind of biodynamic light is proven to increase wellbeing and has positive effects on health. There are numerous applications for biodynamic lighting control in offices and industry.

The introduction of this technology into schools and healthcare institutions also achieves positive effects. Biodynamic light is especially good in retirement homes, where it can help regulate the human body clock and significantly improve the quality of sleep.

While other HCL controllers often require a complicated building-wide control system, the B.E.G. detector works completely independently thanks to its integrated real-time clock and DALI controller. This means each room can be individually configured. The detector supports up to 4 DALI lighting groups and 3 pushbutton inputs. The DALI lights are quickly and easily grouped using the bidirectional B.E.G. smartphone app. The PD4-M-HCL2 is thus ideal for retrofitting or refurbishment work in buildings where there is no bus system. Thanks to a large detection area of 24m, it can be installed effortlessly in areas with up to 64 DALI lights.

To the product

Advantages of PD4-M-HCL2

The complete solution for HCL in one device
Controller, push-button interface and occupancy detector are integrated into one device. Using the pre-programmed factory setting and the convenient B.E.G. smartphone app, the sensor is ready to use immediately, and can be configured in no time at all. The mechanical switches in the installation can be used via the three pushbutton inputs.

An economical solution for the DALI standard
Thanks to a large detection area and support for up to 64 DALI electronic ballasts, the detector is also suitable for large rooms, and is therefore a very economical solution for HCL with DALI lights which support “Tunable White” (Device Type 8) – see compatibility list.

A fully-featured occupancy detector

The occupancy detector provides occupancy-dependent daylight integration for energy saving and can control up to 4 DALI lighting groups e.g. training rooms, conference rooms or open plan offices. Its offset constant light regulation provides uniform lighting levels in rooms where the daylight falls from one side, thereby contributing to energy savings.

Flexible relay included

The built-in relay can be used to control non-DALI lighting for example. Alternatively, the
occupancy information can be forwarded to a BMS. Or, the relay can be used for a “cut-off” function, through which the DALI electronic ballasts are powered down when not being used. Depending on manufacturer, this saves between 0.2 and 1 watt per electronic ballast in standby losses.

Real-time biodynamic colour profiling
Different application profiles can be selected, e.g. for retirement homes, healthcare institutions and circadian lighting. The system runs autonomously thanks to its built-in real-time clock. But HCL can also be deactivated or pre-configured with a customer-specific profile.

World first – Pure Colour
Instead of simulating changes in daylight through the day, an optional external daylight sensor detects the actual daylight colour temperature and uses this information to control
the HCL. This has the advantage of exactly replicating actual daylight colour temperature.

Orientation light
The “orientation light” function can be activated, and operates after the follow-up time previously
configured. It limits the maximum output level of connected lights to an adjustable value. This means that areas with a safety requirement are not completely dark, but energy is still saved compared to full illumination.

Simple to extend
Up to 4 additional slave units can easily be connected via the DALI bus, enabling economical extension of the detection area.




Local advice

Our office is always at your side for advice and action. For questions on ordering, products, technology or planning, just contact us:

Telefon: +49 2266 90 121 0
E-Mail: info(@)beg(.)de
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