Human Centric Lighting

Offices with little or no daylight, dark meeting rooms or artificial light deep into the night: modern society is causing us to move further and further away from natural habits. Daylight, in particular, is one of the most important sources for stimulating our natural biological rhythm. And its deficiency can seriously disrupt our day-night rhythm and lead to listlessness during the day. Human Centric Lighting – or HCL for short – is a modern concept in lighting, which centers around people and positively impacts general well-being and health. In this article, we answer the most important questions surrounding the topic of HCL.

Why is light so important for people?
Light is a mood enhancer in the truest sense of the word. Depending on the quantity of light absorbed, we either feel energized or listless. Lighting intensity is stated in lux. Outdoors, at the height of the summer, our bodies can absorb up to 100,000 lux, and even at 3,500 lux on average in the winter months, the amount is still quite high. Besides that, we spend up to 90 percent of our lives indoors in artificial light.

How can HCL be used?
HCL focuses on daylight aspects and uses integral lighting design to deliver the benefits of the natural light to users. Not only should optimum light quality be available to perform visual tasks, but also to maintain our natural rhythm and activity to the greatest possible extent. The concept of Human Centric Lighting differentiates between four applications:

  • Stabilization of the circadian rhythm: By considering the melanopic effect of light (melanopic = stimulating the photopigment melanopsin, thus acting on the non-visual system via the eyes), lighting whose intensity and light color varies in accordance with the natural daylight is used in a focused way to support the sleep-waking rhythm and positively impact the maintenance and stabilization of well-being and health.
  • Activating and stimulating: Performance can be enhanced significantly with the right light, not to mention improved concentration and attention. Cold light colors have an activating effect.
  • Recovery and relaxation in the evening, but also during break periods during the day, is aided by warm light.
  • Awakening emotions: Light can also support positive feelings. Well designed lighting creates different ambiances, which can trigger feelings of enthusiasm or satisfaction for example.

What are the requirements for HCL and biologically effective light?
To create the right effect with HCL, the concept has to fulfill a number of special requirements.

  • Lighting varies in its intensity and light color and automatically simulates the natural course of daylight. It thus positively impacts the stability of the body's internal clock.
  • Activation by bright light with a high melanopic effect should only be used during the day, so as not to negatively impact the circadian rhythm at the same time.
  • It should be possible for users to adapt the lighting to their own needs within certain limits, in contrast to predefined dynamic processes and lighting scenes. It is also important in this regard that changes made by the user do not conflict with the points mentioned above.
  • The light sources should be distributed appropriately throughout the room so that physiological requirements in terms of good quality of vision are fulfilled, but more light hits the light sensitive receptors of the biological system in the eye at the same time. This means using higher indirect light portions over brightening up walls and ceilings.

A HCL concept in general must be discussed and designed together with the user.

How is Human Centric Lighting implemented technically?
For a HCL system to function effectively, the components used have to fulfill a number of specific requirements. For example, the lighting installation must be able to generate light in a way that it can be adjusted continuously in terms of its intensity and color temperature. Additional control technology (e.g. light management systems and sensors) is available for this purpose, which automatically adjusts the luminaire settings. As regards complex lighting installations, dynamic light sequences or comprehensive lighting scenes have to be programmed and put into operation for entire floors or parts of buildings or different functional areas.

Pre-configured systems are also available for smaller systems, such as manageably sized offices or meeting rooms, which already have preprogrammed light dynamics tailored to the course of daylight and which can be put into operation quickly and easily. Users must be informed about how the lighting system works and how to operate it. Ensuring regular maintenance and inspection of the lighting system during its useful life is an aspect that is sometimes disregarded. Because HCL is based on the right light at the right time, proper functioning of the lighting system does not simply mean that you can still turn on the light. Even if users can detect when something is amiss with the lighting, essential functions should be checked regularly.