Electric Lighting + Performance

I. Personal Control of Lighting System

Sara Gilani and William O’Brien believe that 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. This study 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 with vacancy sensors (manual-on / auto-off) installed in these offices and found that lighting electricity use was reduced by a factor of seven.

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.

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.

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.

II. High Quality Visual Environment

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 Henri Juslen and Ariadne Tenner’s report exploring the effects of workplace lighting changes on employee performance, they found that 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. For example, as the visual environment improves due to the improved quality of lighting, individuals are able to see their task more clearly and with less eye strain, which results in improved performance. With regards to job satisfaction, an improvement in the quality of lighting signals that their work is significant, which boosts satisfaction and overall job performance.

III. Thoughtful Lighting Design

Juslén et. al. investigated the effect of illuminance on the speed and quality of workers assembling electronics in a factory setting. The two lighting scenarios, 1200 lux and 800 lux, were studied during both the summer and winter months to account for seasonal daylighting differences. The study found that under higher illuminance (1200 lux), there was a increase in production speed during both the summer and winter months. 

Viola et al. conducted a robust, real-world experiment to determine the impact of blue-enriched bright white light on office workers. Their study found that users exposed to blue-enriched bright white light during work hours showed an increase in alertness, positive mood, performance, and concentration. It also showed a reduction in evening fatigue, irritability, and eye discomfort, which lead to an overall increase in worker productivity.

A similar study by Keis et. al. 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.

An additional experiment by Mott et al. investigated the impact of focused lighting on student’s oral reading fluency scores (ORF). They found that students who studied under high-intensity, glare free lighting (focused lighting) over the course of the year improved their ORF scores at a greater rate than students who studied under normal lighting conditions. This suggests the key role artificial lighting plays in creating productive learning environments

Lastly, thinking about the technological advancements, Cupkova et al. 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 precise user data that the system can respond to. Their findings demonstrate how this application could be used in healthcare, workplace, and educational environments to deliver quality lighting aimed at improving the users’ well-being.

IV. References

Primary Research

• Antoine U Viola, Lynette M James, Luc JM Schlangen, and Derk-Jan Dijk. 2008. “Blue-Enriched White Light in the Workplace Improves Self-Reported Alertness, Performance and Sleep Quality.” Scandinavian Journal of Work, Environment & Health 34 (4). Helsinki: Scandinavian Journal of Work, Environment ＆ Health: 297–306. doi:10.5271/sjweh.1268.
• Baron, R. A, Rea, M. S, and Daniels, S. G. 1992. “Effects of Indoor Lighting (illuminance and Spectral Distribution) on the Performance of Cognitive Tasks and Interpersonal Behaviors : the Potential Mediating Role of Positive Affect.” Motivation and Emotion 16 (1). Heidelberg: Springer: 1–33. doi:10.1007/BF00996485.
• 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.
• 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.
• Juslén, H. T, Wouters, M. C. H. M, and Tenner, A. D. 2007. “Lighting Level and Productivity: a Field Study in the Electronics Industry.” Ergonomics 50 (4). ABINGDON: Taylor & Francis: 615–24. doi:10.1080/00140130601155001.
• 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.
• Newsham, Guy, Mancini, Sandra, Veitch, Jennifer, Marchand, Roger, Lei, William, Charles, Kate, and Arsenault, Chantal. 2009. “Control Strategies for Lighting and Ventilation in Offices: Effects on Energy and Occupants.” Intelligent Buildings International (London) 1 (2). Taylor & Francis Group: 101–21. doi:10.3763/inbi.2009.0004.
• Williams, Alison, Barbara Atkinson, Karina Garbesi, and Francis Rubinstein. 2011. “A Meta-Analysis Of Energy Savings From Lighting Controls In Commercial Buildings”. Ernest Orlando Lawrence Berkeley National Laboratory. https://eta.lbl.gov/sites/default/files/publications/a_meta-analysis_of_energy_savings_from_lighting_controls_in_commercial_buildings_lbnl-5095e.pdf.
• Mott, Michael S, Robinson, Daniel H, Williams-Black, Thea H, and McClelland, Susan S. 2014. “The Supporting Effects of High Luminous Conditions on Grade 3 Oral Reading Fluency Scores.” SpringerPlus 3 (1). Cham: Springer International Publishing: 1–5. doi:10.1186/2193-1801-3-53.
• 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.
• Luenendonk, Martin. 2019. “How Lighting Affects Productivity And Mood”. Cleverism. https://www.cleverism.com/how-lighting-affects-productivity-and-mood/.