Electric Lighting + Health

I. Improved Visual Comfort

An article by Martin Luenendonk summarized existing literature related to the non-energy impacts on employees in the work environment. Until recently updates to office lighting were seen as an aesthetic improvement or even a reduction in energy consumption, but current research suggests that lighting has more profound – biological – impacts on those employees in the space. With this in mind it is vital that lighting is carefully considered within an office setting because the wrong choice can lead to headaches, eye strain, poor sleep quality, fatigue, and an overall reduction in productivity. In order to facilitate a healthy work environment, carefully consider the correlated color temperature (CCT) of the light source, the degree of personal control of the lighting system (i.e., can employees adjust the light output to match their needs), and when possible prioritize natural daylight.

In a study by van Bommel et. al., they found that “groups working in artificial light only tend to be more stressed than those working in a combination of natural and artificial light over the year.” Utilizing a lighting system that reacts to available daylight is a great way to boost the overall visual comfort of a space.

A study by Mills et. al. found that one way to enhance the visual comfort of an environment is to utilize luminaires with a high correlated color temperature (CCT). They found “improvements of 30% or more compared to baseline measures were observed in the areas of (i) concentration, (ii) light headedness, (iii) lethargy and (iv) sleepiness in the intervention group.” This significant finding offers strong evidence that a small change to just the color of the lighting can greatly improve the visual environment, employee satisfaction, and overall employee productivity.

II. Personal Control of Lighting System

Research by Newsham et. al. concluded that the ability to control lighting and flow rate of ventilation based on individual preferences led to greater satisfaction with the office environment. Not only did the controls lead to higher satisfaction, but they found that individual preferences actually led to an increase in energy savings. Over the course of a day, their study revealed two to three control actions from users, but in a long-term pilot study (several months) those actions reduced to just one control action per person per day. Lastly the study found that during load-shedding situations, those with personal control were less affected compared to the participants with no personal controls. As more advanced lighting control systems enter the market, especially luminaire-level control systems, personal control integration provided opportunities to increase employee satisfaction with their work environment, while also saving energy.

In a separate study, Robert Baron, Mark Rae, and Susan Daniels investigated the effects of indoor illuminance and spectral distribution on cognitive tasks and interpersonal behaviors. Their study found that gender played a role in preference (men preferred opposite conditions compared to women), which suggests individual control over spectral distribution (color) and illumination would allow users to create their ideal environments. When an employee is in control of their work environment they are less distracted by those overall conditions, allowing them to focus and be more productive. This higher level of productivity can lead to increased satisfaction.

A comprehensive report put together by Alison Williams, Barbara Atkinson, Karina Garbesi, and Francis Rubinstein of Berkeley National Lab synthesizes energy-savings data from 240 saving estimates found in over 88 papers and case studies. The collected data was categorized into daylighting strategies, occupancy strategies, personal tuning, and institutional tuning. In conclusion they were able to provide best estimates of average energy savings potential for occupancy, daylighting, personal tuning, institutional, and when multiple strategies are employed simultaneously. They found that energy savings attributed to personal tuning resulted in roughly 30%, which is a great indication of how personal tuning not only results in more satisfied individuals but energy-savings as well. Overall, they found that the highest energy savings potential occurred when utilizing more than one method to reduce the energy consumption of your lighting system.

In sum, as designers and building engineers implement energy saving control systems it’s critical to understand occupants’ preferences prior to installation in order to maximize savings and occupant satisfaction. A study by Sara Gilani and William O’Brien found that users in perimeter offices preferred some level of manual control over their lighting systems in order to maximize available daylight. With this information, they conducted a study in which vacancy sensors (manual-on / auto-off) were installed in place of existing occupancy sensors in these offices and found that lighting electricity use was reduced by a factor of seven. Not only did the manual-on feature of the vacancy sensor result in the luminaires staying off more often than being on, the employees were more satisfied because they could work under natural daylight when they wanted. This is another example of personal control leading to more satisfied employees.

III. Work Environment as Compensation

In the aforementioned article by Martin Luenendonk they mention “A study by the American Society of Interior Design shows that 68% of employees complain about the lighting situation in their offices. Because of poor lighting, people get headaches due to the strain it puts on their eyes.” If businesses wish to maintain a high employee retention and attract new talent, it is imperative to consider the impacts of your lighting system. As noted in other literature, a quality work environment with thoughtful lighting design can boost productivity, leading to more satisfied employees.

IV. Dynamic Lighting & Biological Cycles

Utilizing a controls-based lighting system is a great way to save energy, but the effects of good lighting on our biological processes extends much further than we typically think. Recent medical and biological research has consistently demonstrated that light entering the eye, apart from visual effects, also has non-visual impacts our biological processes. As a result, good lighting has a positive impact on our sleep quality, health, well-being, and alertness. In a paper by van Bommel et. al. they highlight the biological significance of using cool white light. They found that when using cool white light at moments that biologically active lighting is required can promote healthier work environments – boosting the well-being of employees. Their report stated “This novel photoreceptor cell type, an intrinsic photosensitive retinal ganglion cell (ipRGC), regulates many non-visual biological effects such as circadian timing, body temperature, heart rate, cortisol production, melatonin production and alertness.” Being able to use dynamic lighting controls that adapt the luminaire’s CCT to mimic natural lighting changes, is a great opportunity to enhance the visual environment and promote the health and general well-being of individuals.

An additional study by Mills et. al. also highlights the recent discovery of “non-visual” retinal receptors confirms the ability for light to impact biological processes in non-visual ways. This could be alertness, the ability to concentrate, sleepiness, work performance, overall fatigue, mental health, and even vitality. This study found that the use of high correlated color temperature could provide an improvement in overall worker well-being and performance. 

Keis et al. were also interested in the use of high-CCT luminaires. Their study explored the influence of exposure to blue-enriched white lighting in the morning on the performance of students. They found beneficial effects on performance for students working in classrooms with blue-enriched white lighting compared to those students working under typical classroom lighting. Students working under the blue-enriched white lighting showed faster cognitive performance and concentration.

Henri et. al explored the effects of workplace lighting changes on employee performance. They believe a change in workplace lighting can effect employee performance through the following mechanisms: visual performance, visual comfort, visual ambiance, interpersonal relationships, biological clock, stimulation, job satisfaction, problem solving, the halo effect, and the change process. Their thorough paper provides clear logic to understand a wide range of impacts caused by a lighting system.

As lighting technology continues to improve and integrate new features, Cupkove et. al looked forward into the future. They investigated how an intelligent lighting system can adapt to user’s emotions through facial recognition to deliver quality lighting that meets their needs. They found that the autonomous system is able to influence user moods, and propose looking into wearable devices that provide more thorough user data that the system can respond to. Their findings demonstrate how this application could be used in healthcare environments to deliver quality lighting aimed at improving the users’ well-being.

V. References

Primary Research

• Luenendonk, Martin. 2019. “How Lighting Affects Productivity And Mood”. Cleverism. https://www.cleverism.com/how-lighting-affects-productivity-and-mood/.
• Mills, Peter R, Susannah C Tomkins, and Luc JM Schlangen. 2007. “The Effect Of High Correlated Colour Temperature Office Lighting On Employee Wellbeing And Work Performance”. Journal Of Circadian Rhythms. https://www.jcircadianrhythms.com/article/10.1186/1740-3391-5-2/.
• van Bommel, Wout J.M. 2006. “Non-Visual Biological Effect of Lighting and the Practical Meaning for Lighting for Work.” Applied Ergonomics 37 (4). England: Elsevier Ltd: 461–66. doi:10.1016/j.apergo.2006.04.009.
• Newsham, Guy, Brand, Jay, Donnelly, Cara, Veitch, Jennifer, Aries, Myriam, and Charles, Kate. 2009. “Linking Indoor Environment Conditions to Job Satisfaction: a Field Study.” Building Research and Information : the International Journal of Research, Development and Demonstration 37 (2). Routledge: 129–47. doi:10.1080/09613210802710298.
• Gilani, Sara, and O’Brien, William. 2018. “A Preliminary Study of Occupants’ Use of Manual Lighting Controls in Private Offices: A Case Study.” Energy and Buildings 159. Elsevier B.V: 572–86. doi:10.1016/j.enbuild.2017.11.055.
• Juslén, Henri, and Tenner, Ariadne. 2005. “Mechanisms Involved in Enhancing Human Performance by Changing the Lighting in the Industrial Workplace.” International Journal of Industrial Ergonomics 35 (9). Elsevier B.V: 843–55. doi:10.1016/j.ergon.2005.03.002.
• Cupkova, Dominika, Kajati, Erik, Mocnej, Jozef, Papcun, Peter, Koziorek, Jiri, and Zolotova, Iveta. 2019. “Intelligent Human-Centric Lighting for Mental Wellbeing Improvement.” International Journal of Distributed Sensor Networks 15 (9). London, England: SAGE Publications: 155014771987587. doi:10.1177/1550147719875878.
• Keis, Oliver, Hannah Helbig, Judith Streb, and Katrin Hille. 2014. “Influence Of Blue-Enriched Classroom Lighting On Students’ Cognitive Performance”. Trends In Neuroscience And Education 3 (3-4): 86-92. doi:10.1016/j.tine.2014.09.001.