The PILCS Human Centric Lighting research project

The PILCS project aims to develop the first fully user-centred, dynamic, personalized and smart lighting control system based on vast scientific research.

Although "smart lighting" has been known for some time and is becoming increasingly sophisticated, existing control systems are not human-centred and the lighting is not really "personalized". The PILCS project aims to develop the first fully user-centred, dynamic, personalized and smart lighting control system based on the vast scientific research and knowhow in the field of chronobiology, psychology, Human Centric Lighting and Human Computer Interaction.

What is the latest on Human Centric Lighting research for offices?
Professor Yvonne de Kort is a lead researcher at the Human-Technology Interaction group at Eindhoven University of Technology (TUe) in the Netherlands. She and her colleagues represent one of the leading research environments for Human Centric Lighting in offices in Europe. For years they have studied the impact on natural and artificial light on office workers and they believe field studies are the best method to reveal the practical possibilities and limitations of tuneable white lighting systems.

The PILCS project
De Kort and her team (Dr. Karin Smolders and Renske de Bruijn) are now doing a study on the effect of tuneable white light on mood, sleepiness and alertness among office workers. The project is called PILCS – Personalized Intelligent Lighting Control Systems. The test is managed by the Danish light management system provider Lighten in collaboration with TU/e and lighting product developer Moto Muto and has received funding from Eurostars, an EU-backed valorization funding initiative. Glamox Luxo has provided the luminaires for the study.

Several cell and multi-user offices are fitted with a Glamox Luxo Linea freestanding luminaire. The office workers undergo a carefully designed, randomly selected lighting regime for 3 weeks, and then they are exposed to a second test regime. Either, the worker would receive standard office lighting, that is, 500 lux average illuminance on the desk with a neutral white light. Alternatively, he or she gets a dynamic light with varying colour temperature and intensity. This light has been customised to the test person’s age and chronotype, i.e. whether he or she is a morning lark or a night owl. The software that calculates the individual settings is developed by Lighten and Moto Muto. The result would sometimes be that workers in the same room would experience different light settings at the same time.

During the last week of the test period, the users are given full autonomy of the light. Then they can select the wanted intensity level, colour temperature and whether to have more light directed onto the eye or at the table. They can also choose between three pre-set scenes: Relaxation, concentration and energy boost. The researchers will carefully study the user behaviour as this has not yet been studied in the past.

Useful feedback
The feedback from the users so far has been very positive. They like the extra light and the quality of it as well.  A challenge remains as to define optimal light scenarios and how much light at specific times of the day that is needed for optimum effect. De Kort and her team will continue to research the trade-offs between visual and non-visual effects. Most of the research within this area has been performed at night or on non-visual effects of light, not taking visual comfort into account. The researchers also want to study the effect on the post-lunch dip. Most people experience a natural dip in concentration and alertness between 2 and 4 in the afternoon. Strangely, this down-period does not vary according to chronotypes, as you would expect night owls to experience later in the afternoon. But it has inter-personal and even intra-personal (from day to day) variations. The question is whether light boosts can mitigate the low-point or, on the contrary, have a negative effect. A second question is whether this effect should be there due to causes we yet do not understand.

Implementing Human Centric Lighting in offices
According to de Kort, implementation of Human Centric Lighting solutions is the next hurdle the lighting industry faces. Instead of a one-size fits all approach, the researchers at TUe believes that personalised lighting is the future, where a person’s chronotype, age and personal preference is taken into account. However, we still not know exactly what each person may need. One example is the simple question of which light to give at the end of the workday. A cool white light to make the worker ready to hit traffic and arrive at home more alerted, or a warm white light to allow him or her to wind down before the evening falls. To understand this, we need to perform more field studies, as their outputs are more ecologically valid compared to those from laboratory studies. Second, there is always the question whether or not these new lighting concepts will ever pay back.

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