Back to school with Human Centric Lighting!
The new Kongsgårdmoen School by Kongsberg in Norway opened in 2015. Here some 230 primary school pupils have excellent conditions for work and play. Among many modern features they will benefit from particularly good lighting conditions, since the school building is equipped with Human Centric Lighting.
The school has installed luminaires with adjustable colour temperature, so-called ”tuneable white” luminaires with LED light sources that can be tuned from cool white to warm white light. All classrooms are equipped with this solution, making this the most comprehensive Human Centric Lighting LED installation to date.
Light affects our circadian rhythms
When the children arrive in the morning, they are greeted by a cool white and intensive energy light for the first class. The cool white light regulates the production of stress and sleep hormones in the children’s (and the teacher’s) bodies. The light therefore shifts their daily rhythms forward, making them more active during the day and tired when the night falls. This also has a positive impact on the children’s sleep patterns.
Later in the day, the teacher may activate a focus light when it’s time for concentration tasks such as math tests or writing exercises. A shower of cool white and intensive light increases short term concentration and alertness. When the pupils gather in the front of the class room to listen to the teacher telling a story, a warm white light creates a nice and relaxing atmosphere. These adjustments are made by the teacher himself. The solution also has a standard setting, which is a neutral white, good working light.
The luminaires used are modular LED luminaires with diodes that shift the colour according to pre-defined or manual settings. The colour rendering of the light is very high (Ra >90), much higher than the minimum requirements for school lighting. That makes colouring, reading and writing easier and more pleasant. Colour tuning is made easy for the teacher through a wall mounted user panel.
Focus on user experience
Lars-Fredrik Forberg is Concept Manager at Glamox Luxo Lighting, and our leading expert on Human Centric Lighting. He played a key role in the development of the lighting solution at Kongsgårdmoen School, in close cooperation with the participating electrical consultants, programmers and installers. Here he elaborates on some of the considerations that were made when planning and installing the solution:
“The lighting industry now has a fairly good understanding of the benefits of Human Centric Lighting. A lot of research remains to be done, but by now we know for example how different wavelengths affect the hormone production in the body. Also, we know a great deal about which kind of light sources to use to achieve the wanted biological effects, and we know a little about which intensities to use and the timing of the various lighting scenarios. For example, studies show that cool white light exposure in the early morning is more effective than later in the day.
Furthermore, other studies show that the melatonin suppression is saturated at about 1000 lux at eye level. Planning for the right light levels is therefore a challenge. Providing a 1000 lux at eye level means at least the double amount of lux on the work plane. That is simply too much light, causing glare problems and using too much electricity. The solution is to adapt the light to levels that are biologically efficient, yet pleasant to work in. The resulting exposure time is therefore a little longer.
Morning larks and night owls
What makes timing and intensity tricky is that people are different in the way they perceive light and react to it. Morning larks have different daily rhythms than night owls and they therefore need a different lighting sequence. To design a lighting solution with tuneable white light that fits all users is therefore challenging. The compromise often caters to the needs of the night owls, to make sure that they are not disturbed by too early light exposure.
In the Nordic countries, people tend to favour warm white colours, as opposed to people in the south of Europe. To northern Europeans the cool white light setting may seem alien and too crisp. Colour perception is greatly influenced by the light setting the user experienced prior to the new one. That is, rapid shifts in intensity and colour temperature is often noted and perceived as disturbing. But smooth shifts may be imperceptible. The eye is an ingenious mechanism in that it adjusts rapidly to the new lighting situation.
At Kongsgårdsmoen School, our initial observation is that the teachers find both the warm white and cool white settings pleasant to work in. After switching from one setting to the other, it takes only a few seconds for the visual system to “adapt ” to the new setting and for the users to “forget” about the light. Such an “invisible” lighting solution is the best, because it doesn’t distract or cause discomfort to the users. What the lighting industry knows little of is how users actually will use Human Centric Lighting installations. Since we want to ensure that the circadian adjusting effect is achieved, part of the lighting cycle needs to be automatic. The energy light has to switch on in the morning and cannot be overruled by the users. At the same time, we know that users rate work environments as more pleasant if they have individual control over the light. Therefore, we have equipped the classrooms with an intuitive user panel that contains a few predefined settings.
After the first class (when the energy light is always on), the teacher may choose between three lighting scenarios. The standard light is a neutral white (3500 K) work light that ensures good working conditions. The minimum average illuminance requirement in the classroom is 300 lux at the pupils’ desks. During tests and concentration tasks, the teacher pushes a “focus light” switch on the user panel and a cool white light (6500 K) is turned on. Now, we do not want this light to be on for too long, otherwise the pupils may get too excited or worn out after a full day in cool white light. Therefore, the light is automatically tuned back to the standard light setting after 30 minutes. The tuning takes 10 minutes to make the transition unnoticeable. The same goes for the relaxation light. The cozy warm light is excellent for storytelling and relaxation, but not for sustained concentration work. Therefore this light also switches back to standard light after a while. We believe that the users will play with and adjust the installation according to their personal preferences as much as the learned biological effect. “
It will be exciting to see how the teachers and pupils will use this installation. We will continue our cooperation with the school in the years to come, and look forward to learn as much as they do on the opportunities and pitfalls of Human Centric Lighting. This is back to school for us as well!