Human-centric office lighting ‘boosts productivity’

THE INSTALLATION of 'human-centric' lighting at the office of the property company CBRE has boosted productivity by 18 per cent, results of an experiment show.

Additionally, work accuracy improved by 12 per cent, 76 per cent of employees reported feeling happier and half felt healthier.

The 124 employees at the CBRE headquarters in Amsterdam were then surveyed over seven months, with more than 100,000 data records analysed. 

The findings – by scientists from the Twente University, The Free University Amsterdam – will be seized on by the lighting industry as long-awaited hard evidence that investment in dynamic lighting gives a tangible return.

The time-controlled lighting system features a ‘circadian-friendly’ lighting sequence, which varies the colour temperature and intensity during the course of the day. Employees are stimulated during the morning and early afternoon with high illuminance levels and cool indirect white light. At midday and late afternoon, the light levels fall and become warmer.

The general lighting pendants feature direct light with a colour temperature of 4000K and ulta-cool indirect monochrome light of 6500K. The latter component is distributed across the ceiling during the course of the day via the separately controllable direct and indirect components.

Additionally, light sources were aligned onto the walls to create high vertical illuminance levels. Luminaires suspended from the ceiling in the open office area generate a pleasant indirect light component and avoid glare. In total, the luminous intensity was almost doubled.

The Arktika-P Biolux tunable white system from Osram was used for the general lighting of the office.

The 124 employees at the CBRE headquarters in Amsterdam were then surveyed over seven months, with more than 100,000 data records analysed. The survey included questionnaires, experiments, biological data, daily movement evaluations and interviews.

The Healthy Offices project, as the survey was dubbed, measured the effects of changes in work surroundings and health over a period of seven months. The team of researchers specified five modifications to the work environment that could theoretically have the most impact on health and employee potential – on the one hand health aspects such as healthy nutrition, mental balance and physical movement and on the other, environmental factors such as the natural interior design and suitable lighting. In this case the influence of circadian lighting adapted to the sequence of daylight was analysed.

Reseachers recorded an accuracy improvement of 12 per cent in an objective experiment. Additionally, the participants working in the office with the human-centric lighting found their total work performance to be 18 per cent better, 71 per cent found they had more energy, 76 per cent thought they were happier and 50 per cent healthier.


  • A CBRE representative will speak about office lighting at LuxLive 2017. The presentation, entitled ’How IoT lights can help offices get more from less’, will explore how location-tracking technology embedded in luminaires is giving building owners insights into how their space is used. The presentation will be followede by a panel discussion. One of a series of presentations on office lighting at the event, it takes place at 2.35pm on Wednesday 15 November at the LuxLive 2017 exhibition and conference at ExCeL London. The show itself runs on both Wednesday 15 November and Thursday 16 November 2017.  Entry is free if you pre-register. See the full programme and register HERE.




Comments 6

I appreciate that this research as an important step forward, to encourage design of healthy office spaces. As a next step for future research, please modify each control treatment, so that the control appears to be an experimental treatment in its own right. A plausible placebo is essential, to isolate the specific effect of each experimental treatment, from the general effect that peoples’ performance improves when it’s expected to improve. For example, in order to accurately assess the positive effect of an experimental treatment such as circadian lighting, the researchers should do something randomly unhelpful to the lighting for the control group, so the participants do not realize that they are only the control. Perhaps change the color temperature a few times throughout the day, without providing enough vertical illuminance to stimulate the circadian system. As a second example, to check the effect of plants, add some new abstract art or new furniture for the control group, so both groups think that they might be the actual beneficiaries of the study. Further, in order to create a double-blind study, hire naïve survey administrators who don’t actually know which group is the control. This data is suggestive, and I personally believe that some of the positive outcomes can probably be attributed to the experimental treatments. However, it’s difficult to assess the positive effect attributable to each experimental treatment, vs. the placebo effect related to special attention and high expectations from fancy new lights, fancy new plants, a smoothie that looks and tastes “good for you”, etc.

I would expect that any well designed lighting arrangement would enhance productivity, if it indeed was well designed and provided optimal illumination for the tasks at hand. So while the particular installation was successful that does not imply that it was the ultimate in all the variables. Being "Very good" is not the same as being the best possible. So while this is the happy tale of a success, it is not a description of the ultimate best, since there is no chance at direct comparisons with other good designs.

It’s important that stakeholders close to property owners and developers, and with the depth and breadth of CBRE’s property portfolio, recognize the impact of human factors and interior environmental quality on building occupants and the bottom line. Certainly, CBRE’s contribution to the conversation raises awareness and elevates the role and the value of design in the building process. Unfortunately, efforts to make the science “consumable” and relevant via attractive marketing publications and common language can place the credibility of the research in question, or worst, steer the design and/or premise of the experiment to begin with. Not to diminish CBRE’s efforts to elevate considerations for workplace wellness, I feel some clarification may be in order relative to the related CBRE e-paper entitled "The Snowball Effect of Healthy Offices" and its implications for workplace lighting. First, to state that “the most important aspect of good lighting is timing” fails to acknowledge the complex and multi-dimensional task of lighting interior spaces. While the statement may have been directed only to the non-visual effects of light on human well-being, the word choice is unfortunate and leads the reader to a diminished perspective of the many other critical lighting related concerns. Secondly, suggesting that the study employed “circadian lighting” as a “right lighting” attribute may be a misnomer. A system of lights that change from “a yellow tint in the morning to a blue tint in the afternoon, returning to a softer yellow tint toward the end of the day” leaves much to the imagination and is only superficially “circadian.” In actuality, while the color temperature of daylight and sunlight vary noticeably at sunrise and sunset, they vary little over the course of the typical workday. Furthermore, research suggests that circadian entrainment relates more to the spectral content of light as opposed to its color appearance and is best supported by increased exposure early in the day. Thus, the reported lighting related impacts on occupant performance and mood may speak more to the alertness affect of “strong bright light in the afternoon” than to a circadian effect. Thirdly, the publication is confusing and lacking in its description of the implemented lighting systems, leaving the reader with little to go on. Graphically, it associates a personal task light with the lighting aspects of the study; however, no task lights are mentioned or visible in the photos. Two types of pendant luminaires are shown, and it is said that “in some areas [the lights were] lowered from the ceiling to allow the light to shine on the right part of the face and avoid glare.” What is “the right part of the face” and how is this assessed? At the same time, it is said that light sources were mainly directed at a wall. Hopefully, CBRE will reveal additional project details that clarify and provide designers with some direction. Finally, the publication acknowledges recent findings by Nelson, Noordzij and Verhagen which reinforce the notion that “empowering an individual will, by definition, make them feel more in control and less stressed, [leading] to higher levels of commitment to…the workplace.” In a recent study, we found that office workers demonstrate a wide range of preference for lighting intensity and color temperature, and that personal control of these aspects results in elevated levels of worker satisfaction. There may be related performance benefits associated with personal control of lighting as well. Yet, empowerment related to personal control of lighting was not explored in the CBRE study. As the industry continues to explore various aspects of workplace well-being, we would encourage CBRE and others to also consider personal control of lighting as a key “right lighting” feature of a “healthy office.”

Diana…As I recall, the Lutron/New York Times building project was directed toward building automation and energy conservation. While they did deploy high luminance VDTs to reduce luminance contrast and maintain visual comfort in conjunction with perimeter windows (thus elevating the luminance threshold for shading to maximize daylight harvesting), I do not believe the project assessed occupant performance and health benefits.

It's great to see some numbers on this. Will the full study be published by the university or by Osram?

This is not new . Lutron did it at the New York Times offices 5/6 years ago . The question should be why does it take so long for the lighting industry to catch up . We still see bad lighting everywhere ?

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