Light of knowledge

Dieter Lang, LEDVANCE, lighting, human centric, LED, HCL, schools
Dieter Lang

Dieter Lang explains how human centric lighting, a lighting concept that simulates the course of natural daylight, holds great potential for education

In the course of evolution, the biological rhythm of all living beings has adapted to the natural course of day and night, with the internal clock and therefore sleep-wake cycles being controlled significantly by daylight. If people mainly spend their time outdoors, the changes in natural daylight will give them the exact light their bodies need: bright, cold white light with a high blue component in the morning and during the day, and less bright, warm white yellow-reddish light without blue components in the evening.

The problem is that in our modern industrial and service-based society most people spend about 90% of their day in enclosed spaces under artificial light. This already applies to young people who throughout their entire education – from school and vocational training to university – spend a lot of time during the day in mostly poorly lit teaching and seminar rooms or auditoriums.

How much the changes in light between day and night influence what is known as the circadian rhythm, which is actually fully geared toward outdoor life, people notice not only after a long-haul flight but quite clearly twice a year – when the clocks change between summer and standard time and many feel uncomfortable, experiencing effects similar to a mini jet lag. A survey in the European Union on whether the time change should be scrapped therefore created a clear majority in 2018 for a uniform time throughout the year.

A human-oriented lighting concept for buildings – known as human centric lighting (HCL) – uses smart controllable LED lighting systems to simulate the characteristics of natural daylight. One key approach of HCL is to use natural daylight as much as possible, complementing it with artificial light that simulates the changes in natural daylight at times and in places where it is lacking.

However, architectural measures alone are usually not enough to provide good lighting in schools, universities and other educational institutions in line with the principles of HCL. After all, too much direct sunlight often causes thermal problems. Eliminating them is expensive and energy-consuming. And as far as the lighting is concerned, there are glare effects which are very annoying when working with a computer in particular. So a good HCL solution will always try to strike the best possible balance between natural and artificial light, taking into account the biological lighting effect.

To achieve that, a smart HCL solution using artificial light needs to automatically adapt to the changes in natural daylight in terms of light colour, brightness, and spatial distribution. Here, large lights from above have the greatest biologically activating effect, imitating the sunlit blue sky. It is important to note that people are especially receptive to the biological effects of light in the first two hours after getting up and at least two hours before bedtime. Therefore, at the start of the day until lunch time and after the lunch break, bright, cold white light with a high blue component should be used – in other words approximately 6,500 kelvin at an illuminance of 300 lux at the eye. Indirect light which includes both ceilings and walls is ideal for this. Towards the evening the lighting should be switched to direct warm white light without blue components to help our bodies to relax and prepare for the night.

The education sector is very well suited for the use of HCL because lessons in most educational institutions start at similar times in the morning. The room layout, the incidence of light, the arrangement of the furniture and the students’ and teachers’ lines of vision are usually also very similar – which makes conditions virtually ideal for a wide-ranging use of HCL.

SSL-erate – a research project on the effect of light funded by the European Union involving several renowned universities – divides the different effects of light and benefits of HCL in educational environments in three dimensions.

Positive effects on attention and concentration can be measured directly in appropriate lighting conditions. A field study carried out as part of SSL-erate showed that oral reading fluency of elementary school pupils improved by almost 35 percent in activating bright light with a high blue component. In another study, concentration and sustained attention improved by about 30 percent. Similar results have been confirmed in numerous other studies.

Dieter Lang, LEDVANCE, lighting, human centric, LED, HCL, schools

Experts see the better sleep-wake rhythm of the pupils as an effect that is not directly measurable but long-term. Since the brain processes impressions of the day and newly learned things during sleep, a well-balanced sleep-wake rhythm plays a key role for the learning process. At the beginning of puberty this rhythm significantly changes in many teenagers.

In the evenings they go to sleep later, while in the mornings they are not fit and therefore less receptive. Only years later, often only on entering their working lives, this pattern changes again in most of them. Scientists talk about the “owl” type which is at a disadvantage compared to the “lark” type who is active early in the morning. A study involving students between the ages of 20 and 22, for example, showed a clear positive correlation between the early chronotype and their academic performance. “Owls” in particular therefore need daylight and bright light in the morning during lessons. Here, HCL can actively support the effect of daylight.

In connection with the EU-wide plans to scrap the time change, it is therefore advisable to permanently switch to standard time instead of summertime. If the dark phase was extended by one hour in the morning through the introduction of a continuous summertime, it would significantly reinforce the previously described effect in the “owl” chronotypes during the winter in particular.

Referring to “third order effects”, SSL-erate describes them as positive group-dynamic effects that an HCL concept has in the classroom. Thanks to increased mental attention, pupils can follow lessons easier and a focused learning environment is created. This reduces general restlessness and promotes a productive learning environment, from which teachers will benefit too.

When designing HCL lighting, it is also important to take into account their position in the room and their line of vision.

The different types of joint learning including the large variety of different “formats” for a typical, modern learning environment also need to be taken into consideration. These range from classic frontal teaching – where it is about minimum distraction and maximum concentration – to creative design such as in art and music classes, and interactive project work in groups and presentations. For each form of learning and teaching an HCL system should make it possible to adapt the lighting to the individual situation.

Operating an HCL solution using LED technology is now no more expensive than a conventional, modern LED lighting system. After all, it is a smart system which provides light only where it is actually needed. The greatest advantages of HCL are shown in other areas, however. A study published in 2015 by renowned management consultants A.T. Kearney identified the key economical reasons for the use of HCL to be an increase in cognitive performance in pupils by up to 15 percent and a significant reduction in mental strain such as stress and burnout and therefore fewer sick days among teachers.

In view of the great overall economic and social importance of education in a competitive, digitalized world, these reasons alone are sufficient to introduce HCL in education as quickly and comprehensively as possible.

Dieter Lang is R&D expert in Human Centric Lighting with LEDVANCE

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