Perception of the Impact of Day Lighting on Workplace Satisfaction Mason Couvillion Clemson University Psych 310

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Abstract Students are less willing to work in an office where there is no daylight. It is believed that our circadian rhythms are affected by the exposure and intensity of light in our workspaces. It is important to understand if typical college students realize the impact of lighting on their work satisfaction and productivity. This study investigates whether college students perceive daylight in their work place to influence their work satisfaction and productivity. The participants were given a survey with one of two images of possible offices. Participants were then asked a series of questions that are designed to assess the perception of job satisfaction if they were to work in the office that they are shown. The participants’ scores from the survey were converted into a percentage where 100% is the highest level of satisfaction and 10% is the lowest possible score. The students who viewed the image of an office that was day lit were significantly more likely to perceive the space to have a positive influence on their satisfaction and productivity (mean=78.8%) then the participants who are shown the office without day lighting (mean=29.5%)(p<. 01)

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The Importance of Day Lighting to the Future Workforce Day lighting has been known for years to have positive effects on the workplace (Sullivan, 1990). It is important for designers as well as employers to understand how important lighting is to the workforce. Day lighting is a design option for using day light to light the interiors of buildings. Day lighting can create spaces that are dependent on the outside world, which gives the inhabitants an increased awareness of the weather and time outside of their walls. Day lighting can also decrease the amount of energy a building uses by requiring less artificial lighting and also creating warmth that decreases the need for additional heating (Leslie, 2002). For years buildings were built to take advantage of daylight and other passive strategies out of necessity because electricity was either not available or not economical. However in the early 20th century electricity became inexpensive and interior lighting and air conditioning became a standard for most new construction. These technologies led to larger buildings and factories with little to no daylight. By the mid 1980’s there was a clear degradation productivity and health in the workers who worked in these spaces. This became known as sick building syndrome. Much of the issues associated with sick building syndrome stem from inadequate lighting. Symptoms such as tiredness, dry and gritty eyes, and headaches can be caused by glare, flicker lack of contrast, inadequate illumination or unsuitable spot lighting. There is a now more evidence that lightings impact can go deeper than just relating to the visual experience (Boyce, Rea, 2001). There is increasing data that shows possible impact of lighting on our biological systems. These studies show that a person’s overall satisfaction and productivity may be linked to exposure to daylight (Rea, Bullough, Figueiro 2002). It is important for us to be able to quantify day lighting’s impact on people and on enhancing our building designs and technologies to respond better to human preferences and needs. By understanding how people perceive the importance of day lighting we can create spaces that maximize its benefits and create invigorating workspaces (Boyce & Rea, 2001). In 2004 after evaluating the past indoor

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lighting research determined that visual performance and visual discomfort have been the twin foci of lighting research in interiors for many years. Where we are not so well endowed with knowledge is in the effect of lighting conditions through the ‘message’ elements of the perceptual system, and in the effects that operate through the circadian system. That the visual environment can change the mood of people and that peoples’ moods can change the judgments they make and how they behave are not in doubt. What is in doubt is how potent lighting can be and how persistent are its effects relative to all The other factors that can change mood and motivation. This preference for a day lit office may stem from biological factors. In our bodies melatonin (a sleep inducing hormone) is suppressed with high energy in the shorter wavelengths. This happens to be precisely where daylight falls. There for it is possible that daylight provides the right type of light at the right intensity to trigger our circadian systems (Rea, Bullough, Figueiro 2002). It is believed that our circadian rhythms are synchronized by regular and consistent exposure to daylight. A disruption in the quality of light or time of exposure could lead to fatigue and/or mood shifts that could negatively affect productivity and job satisfaction. The researchers believe that by the time students are in college they are aware of things effects either consciously or subconsciously and will seek out spaces that allow them to be exposed to light in ways the confirms their wake/sleep cycles. The experimenters believe that college aged individuals will feel as though they would be more productive and have a higher job satisfaction when working in an office with natural lighting as opposed to an office without natural light. During the experiment students at Clemson University were given a hypothetical job description. With that description was either one of two pictures. The image shown to the first group was a rendering of an office with daylight entering the office from 2 of the four walls. The other group was shown a rendered image where there was no natural light. The two images include exactly the same furniture and floor plan so the only difference is the lighting. Those

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who answer the survey with the office that is flooded with natural light will respond more positively to the job offer and the workspace then those who are given the image of the office lit only by artificial light.

Method Participants 38 Clemson students between the ages of 18-41 (mean= 22.21, stdv=3.184) were conveniently selected from graduate and undergraduate classes at Clemson University. Participants received an email asking if they would be willing to participate in study for a classmate by completing a survey. The participants were directed to follow a link to a webpage where they would read the letter of intent before receiving one of the two surveys. The surveys were randomly assigned to each class. Where half of the class received a link to survey 1 and half of the class received the link to survey 2. Materials Hypothetical job description The Survey included a hypothetical job description from a hypothetical employer. The job description was the same across both variables and described a job that would require long hours in the office and a moderate level of immediate responsibility. Hypothetical office images Immediately following the job description the participants were shown one of the two images above. The two images were produced digitally using Revit Architecture 2010 to simulate offices with identical floor plans, furniture and layout. The only difference in the images is the amount of daylight entering the space. The image in survey 1 featured two walls that were glass from the floor to the ceiling. The image is rendered to allow natural light into the office mimicking a day lit office. The image in the second survey had brick walls with no windows. This image was meant to mimic an office that has no natural lighting. -

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Survey The survey that followed the images served as the tool for measuring the participants’ perception of the workspace on their satisfaction and productivity. Each survey consisted of a series of 8 questions that ask the participants to imagine if they were to work in the particular office they were shown. All the questions were answered on a continuous scale from 1-10 where 1 was completely disagree and 10 was completely agree. The data from the survey was then coded and analyzed by the experimenters. Satisfaction scores were measured as the percentage of the possible points selected in the survey. Satisfaction will be quantified as a percentage of the total score (80 points) possible. For instance someone who answered 5 for every question would have a satisfaction score of 50 (5x8/80). Results Day Lighting Condition The 19 participants reported high levels of perceived satisfaction and productivity (M=78.62, SD=6.95) when given the image that included day lighting and agreed that: (a) The image of the office made them feel positively about the company offering them the job (M=8.1, SD=1.329); and (b) they would be very productive working in the office (M=7.632, SD=1.606) Non-Day lighting Condition The 19 participants reported low levels of perceived satisfaction and productivity (M=29.53, SD=5.39) when shown the image that did not incorporated any day lighting and disagreed that: (a) The image of the office made them feel positively about the company offering the job (M=2.368, SD=.955); and (b) they would be very productive working in the office (M=3.579, SD=1.895) Outcome Analysis As can be seen in Figure A, a two way ANOVA revealed that participants who were shown the image with day lighting scored significantly higher on the satisfaction scale (M=78.8, SD=6.946) then participants who were shown the image without daylight (M=29.5, SD=5.39).

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However there was not a main effect of age on satisfaction scores. There were no other significant results.

Discussion The main goal of this research is to change the emphasis of indoor lighting studies from the direct effects of the visual system and the discomfort that is associated with it to investigating the effects of lighting on the through the circadian system and the perceptual system (Boyce, 2004). When this study is looked at in the body of other lighting research it reinforces the benefits of designing with day lighting in mind. It is well documented that day lighting can help to offset energy costs for a building. Those benefits may be negligible however because as this study uncovers day lighting’s most powerful impact is on the building’s occupants. Buildings are constructed for people. One hour of salary is equivalent to the cost of 1 year of lighting energy for that worker. Therefore, the strongest economic argument for day lighting may be the worker’s improved productivity, increased job satisfaction, or reduced absenteeism, each of which can easily off set an initial investment in daylight systems (Leslie, 2003). It is important for this research to not only be understood by psychologists but to be understood and implemented by designers and owners. How to Daylight There must be collaboration between researchers and architects. The two groups need to be able to work together to not only determine the ways in which lighting influences the people who interact with it, but to also determine the best possible design strategies to exploit the benefits that the research points to. Based on the above study it is important for all interior workspaces to have access to daylight. This can be accomplished by; (a) keeping buildings narrow along the east-west access and creating a service core as to allow all public spaces to be reserved for the perimeter; (b) Utilizing sky lights to allow sunlight to penetrate into the buildings core in building where a narrow footprint is not an option or undesired. Skylights

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however are limited in the depth that light can penetrate and there for are not the best solution for multistory structures; or incorporating courtyards/atriums. This option is most applicable in a multistory building where a narrow footprint is not possible. The spaces also have the benefit of being central gathering areas for those who inhabit the building.

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Appendix

Figure A – Office with Day lighting

Figure B – Office without Day lighting

Hypothetical Job Description After only a couple of phone interviews you have been hired by a large company in your field. The pay will be reasonable but not great. For the first few years you won’t be allowed any vacation time except for 2 days of sick leave per year. Most people in the company work about 50-60 hours per week. Many of the current employees are in the office on weekends in order to meet their deadlines. The CEO of the company has told you that he would want to start as soon as possible because he needs your skill set to move forward on his newest pet project. He originally wanted you to work in a cubicle but you have pleaded with him and he has agreed to give you your own office. The image below is a picture of your office if you choose to accept the job.

Survey 2 Complete the following statements based on the above scenario. * Required I would be willing to accept the job based on the description? * 1

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This office would be an invigorating place to work? * 1

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The image above makes me feel positively about the company, which offered me the job? * 1

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Working in this office would make me feel energetic * 1

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I would NOT enjoy working in the office above. * 1

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I would be very productive when working in the office shown above. * 1

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I would not want to spend any extra time in the office * 1

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I would NOT enjoy going into work * 1

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9 10 Definitely Agree

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Figure C – Satisfaction % vs Condition

Figure E – Satisfaction % vs Condition

Figure D – Satisfaction % vs Age

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References Rea MS, Bullough JD, Figueiro MG. Circadian photobiology: a new framework for lighting practice, Lighting Research and Technology, in press 2002 Rea MS, editor. IESNA lighting handbook: reference & application, 9th ed. New York: Illuminating Engineering Society of North America, 2000. Boyce P, Rea MS. Lighting and human performance II: beyond visibility models toward a uni1ed human factors approach to performance, EPRI, Palo Alto, CA, National Electrical Manufacturers Association, VA, and U.S. Environmental Protection Agency OKce of Air and Radiation, DC: 2001 R.P. Leslie, Capturing the daylight dividend in buildings: why and how?, Building and Environment 38 (2003), pp. 381–385 Boyce P, Beckstead JW, Gutkowski JM, Fan J, Strobel RW. Brightness enhancing glazing: perception, performance, and energy. Troy, NY: Rensselaer Polytechnic Institute Lighting Research Center, 1992 Sullivan, C. (1990). Employee comfort, satisfaction and productivity: Recent efforts at Aetna. In P. Souter, G.H. Darnoff, & J.B. Smith (Eds), Promoting health and productivity in the computerized office. London: Taylor and Francis. Boyce P, Kennaway D. Effects of light on melatonin production. Biological Psychiatry [serial online]. April 1987;22(4):473-478. Available from: PsycINFO, Ipswich, MA. Accessed April 11, 201