Daylighting and Productivity: A study of the effects of the indoor environment on human function

As the pace of technological innovation intensifies and human beings are daily asked to process more information and perform increasingly complex tasks, it becomes exceedingly important that architectural design respond to human needs. Building design is a critical tool in the promotion of societal health and well being, yet there remains a radical disconnect between the physical expectations placed on modern workers and the architectural response to such demands. A thoughtfully designed space can increase productivity, foster a sense of community, and minimize environmental impact.

The design firm of Kaplan McLaughlin Diaz (KMD) is highly committed to promoting sustainability, energy efficiency and workplace productivity. The firm’s unique approach to design is predicated on a rapidly expanding body of research that confirms the value of bringing natural light and views not just to the executives who occupy coveted corner offices, but to as much of the workforce as possible. Recent investigations into the effect of the indoor environment on human function suggest that basic design choices—dynamic fenestration and ventilation, in particular—can dramatically affect the performance of a building, and by extension its end users. Several of KMD’s current projects, including Brentwood City Hall in Brentwood, California, the new County Government Center in San Luis Obispo, California and the Jie Fang office tower in Shanghai, China, translate this research into innovative design strategies that increase worker satisfaction and productivity while slashing energy costs. Such outcomes promise impressive savings for KMD’s clients over the course of a building’s life cycle.

Our lifestyles have become increasingly sedentary and cloistered over the past few decades, with the rise of the digital age. As a species, we now pass the vast majority of our time indoors, and more than half of the adult workforce spends a considerable portion of that time interfacing with a computer terminal.1 Though we as humans possess a remarkable ability to adapt to changes in our environment, this extreme shift from agrarian to information society has placed an enormous strain on our bodies and spirits. Over the course of thousands of years of evolution, human beings have developed a range of instinctive behaviors and survival skills that once aided us in our primal roles as hunters and gatherers. We crave change, favoring an environment that sharpens our mental acuity by presenting us with shifting stimuli and signals; the static office setting may be anathema to this need for challenge. We prefer to see the effects of our actions on the world around us, and are stymied both by our alienation from the fruits of our labor and by our inability to control our immediate surroundings. We seek a territory to call our own, an instinctual preference too often trumped by limitations in space. And finally, we relish contact with the outside world, even if only through a windowpane.2

Clearly, our environment greatly impacts our sense of well being, our productivity and satisfaction. As we spend more time confined to our desks, focused on the artificial glow of the computer screen, it becomes imperative that we mitigate the negative effects of this artificial setting through some form of contact with the natural world. Yet building design has been slow to meet the challenges of the present paradigm. With a focus on functional efficiency, our office buildings, schools, and hospitals have placed too little emphasis on these basic human needs. The steady increase in prevalence of chronic work-related illness, including repetitive stress injuries, asthma, and cardiovascular disease, suggests that the stressors in our artificial environments are exceeding the flexibility of our biological systems.3

A significant body of recent research has positively correlated building conditions with productivity. Two recent Dutch studies, for instance, revealed that a significant percentage of sick leave can be linked to complaints about the quality of the workplace. A healthy indoor climate, by contrast, was shown to lead to a 2.5% drop in absenteeism.4 Though such a decrease may seem inconsequential, it is instructive to note that over a thirty-year period, the corresponding increase in productivity implied by such improved attendance would more than match the initial outlay for a building’s design and construction. With increasingly sophisticated methods, researchers are striving to isolate those environmental conditions that most strongly impact productivity, in order to provide designers and building owners with reliable data that will enable them to maximize the work done within a building while minimizing costs.

Perhaps the most powerful and conclusive finding has concerned the importance of windows. Beginning in the late 1960s, a design trend emerged toward buildings that admitted little or no daylight. Windowless schools and office buildings, illuminated solely by fluorescent lights, were believed to minimize distractions, prevent eyestrain, and create greater efficiency in heating and cooling.5 New research reverses these assumptions, however, asserting that windows that admit daylight and provide an ample and pleasant view can dramatically affect mental alertness, productivity, and psychological well being.6

Environmental biologists theorize that regular contact with daylight promotes circadian stimulation, regulating physical and mental function through our natural responses to the rhythms of light. Circadian dysfunction has been associated with cardiovascular problems, immune dysfunction, cognitive and functional deterioration, and depression.7 Several studies have shown that the disturbances in sleep and circadian rhythm often associated with old age are ameliorated by sufficient exposure to bright light.8 Furthermore, exposure to full spectrum sunlight enables us to synthesize vitamin D, which promotes strong nerve and muscle functioning as well as cell growth regulation, and without which our bones and tissue cannot efficiently absorb calcium.9 Adequate exposure to daylight is particularly important for older adults—as the eye ages, less light reaches the retina, so that aging adults receive only a third of the light exposure experienced by younger people under similar conditions.10

Wavelengths of light have also been shown to influence the production of the hormone melatonin, which controls the cycle of sleep and mental alertness.11 In a 2003 study of office worker performance conducted by the California Energy Commission (CEC), exposure to daylight was consistently linked with a higher level of concentration and better short-term memory recall.12 A 1999 study by the CEC found that students in classrooms with the highest levels of daylight performed 7% to 18% higher on standardized tests than those with the lowest.13 In San Juan Capistrano, California, students with the most daylighting in their classrooms were found to progress 20% faster on math tests and 26% faster on reading tests over the course of a year than those in classrooms with the least light.14

Optimizing the use of daylight also has enormous potential to provide energy savings. Electric lights can be turned off when sufficient daylight is available, cutting lighting and cooling costs dramatically. The CEC estimated that incorporating skylights with automatic daylight sensors into all new educational buildings would save the state of California up to $7 million dollars in energy costs each year, after a decade of such construction.15 Daylit buildings are clearly advantageous in terms of minimizing environmental impact, as well—particularly in locales where energy resources are scarce.

KMD’s recent designs for government buildings in Brentwood and San Luis Obispo take advantage of the region’s central Californian climate, often characterized by blistering days and chilly nights. Both buildings employ a thermal mass concept to reduce energy consumption: a raised platform allows cool air to accumulate under the concrete floors at night and filter through the space all day, thereby reducing the need for air conditioning during working hours. In Brentwood’s City Hall, offices are massed around a spacious sky-lit central atrium, ensuring that most workers have access to daylight and views from the building’s operable full-length windows. The Council Chamber is outfitted with a 14 ft. diameter skylight, designed to open automatically and vent the space when an excess of heat collects at the ceiling level, as well as solar panels that harvest the sun’s energy during the day and convert it into electricity for nighttime council meetings.

Direct sun penetration into classrooms and office spaces has sometimes been associated with negative performance, due in part to glare and thermal discomfort.16 For this reason, daylighting with skylights has become a popular alternative. In a 1999 study by the Pacific Gas and Electric Company (PG & E) that linked skylighting to retail sales, skylights were lauded as a way to isolate daylight as an illumination source, while avoiding the negative qualities sometimes associated with daylighting from windows. This study, which gathered data from a chain of 108 stores (where two thirds of the stores had skylighting and one third did not), found that those with skylights boasted 40% higher sales than those without.17 Shoppers reported finding the skylit stores to be cleaner, more spacious, and more open; researchers postulated that the skylights relaxed customers, improved product visibility, made products appear more attractive, and boosted employee morale.18The skylights featured in KMD’s Brentwood City Hall are equipped with diffusers to reduce the glare of direct sunlight, while the building’s sweeping windows are outfitted with deep sills that provide shade and act as reflectors, bouncing light upward to illuminate the interior ceilings.

Interestingly, recent research suggests that the view from a window may be even more important than the daylight it admits. The CEC’s 2003 study of workers in the Sacramento Municipal Utility District’s customer service call center found that having a better view out of a window was consistently associated with better overall worker performance: workers were found to process calls 7% to 12% faster when they had the best possible view, versus those with no view. Those workers with better views additionally reported better health conditions and sense of well being, while reports of increased fatigue were most strongly associated with those who lacked a view.19 Another recent study showed that computer programmers with views spent 15% more time on their primary task, while equivalent workers without views spent 15% more time talking on the phone or to one another.20

Though educational researchers have in the past theorized that views out of windows cause unnecessary distractions for children in the classroom, recent research by educational psychologists actively stresses the importance of a stimulating visual environment to the learning process. The CEC’s 2003 study of the Fresno school district conclusively found that a varied view out of a window, including vegetation or human activity and objects in the far distance, supported better student learning results.21

These findings are consistent with earlier research, such as a 1984 hospital study that concluded that post-operative patients with a view of vegetation took far fewer painkillers and recovered more rapidly than those patients who looked out on a concrete wall.22 Health care facilities are notoriously stressful environments, for both patients and staff; incorporating natural views into the design of such buildings can help optimize patient outcomes and improve morale, allowing the hospital to function at peak efficiency.

Though it is difficult to isolate the precise physiological mechanisms affected by views of nature, it is theorized that natural elements rapidly trigger positive emotions that help reduce mental and physical stress.23 Ophthalmologists further speculate that a window view positively contributes to eye health—frequent changes in focal distance relax the eye muscles, helping to prevent the eyestrain so often associated with prolonged computer use.24 Views of nature are also believed to improve attention span, and some researchers hypothesize that natural views have the potential to refocus the directed attention capabilities of the brain after extended cognitive activity has drained a person’s ability to concentrate.25

In urban settings, introducing natural views can pose a serious challenge. KMD’s design for the award-winning Jie Fang News and Media Building in Shanghai addresses this problem by incorporating plentiful atriums and communal gathering spaces, alive with trees and plants, which can be viewed from many of the building’s offices. Jie Fang’s curvaceous glass façade draws sun into a full-length atrium on the south side, from whence warm air rises and disperses throughout the building, naturally ventilating its core.

The implications of the body of research explored here are considerable. An initial investment in energy-efficient design strategies may not only save energy but also dramatically impact worker productivity, stimulate retail sales, hasten recovery rates or improve student performance—ultimately spelling long-term savings for building owners. Mindful of the overwhelming body of evidence that supports the integration of nature into building design, KMD’s design teams strive to create interior spaces that foster a greater level of interconnection with and permeability of natural elements. Good building design is relatively inexpensive and is certain to reap rewards throughout the lifespan of a building, cutting energy costs and influencing the performance of thousands of students, employees or patients for many years to come.


  1. Tove Fjeld and Charite Bonnevie. “The Effect of Plants and Artificial Daylight on the Well-Being and Health of Office Workers, School Children and Health Care Personnel,” Floriade, Norway, 2002, p. 7.
  2. John Bergs. “The Effect of Healthy Workplaces on the Well-Being and Productivity of Office Workers,” Amersfoort, The Netherlands, p. 3.
  3. Fjeld and Bonnevie, p. 7.
  4. Bergs, p. 7.
  5. Heschong Mahone Group. “Windows and Classrooms: a Study of Student Performance and the Indoor Environment (Technical Report),” for the California Energy Commission, 2003, pp. 2-4.
  6. Ibid, p. 109.
  7. “Lighting and Circadian Rhythms and Sleep in Older Adults: Technical Memorandum,” EPRI, Palo Alto, CA; IESNA, New York, NY and Venture Lighting International, Solon, OH, 2003, p. 1-1.
  8. Ibid, p. 6-1.
  9. Dr. Sonia Anconi-Israel, Dr. Daniel Kripke and Philip Mead AIA. “Light Matters: the Medical Benefits of Light,” AIA Convention, San Diego, CA, 2003, p. 2.
  10. Eunice Noell Waggoner, LC, IES. “Let There Be Light, or Face the Consequences: A National Concern for our Aging Population,” Center of Design for an Aging Society, Portland, OR, 2002, p. 5.
  11. Heschong Mahone Group. “Windows and Classrooms: a Study of Student Performance and the Indoor Environment (Technical Report),” for the California Energy Commission, 2003, p. 3.
  12. Heschong Mahone Group. “Windows and Offices: a Study of Worker Performance and the Indoor Environment (Technical Report),” for the California Energy Commission, 2003, pp. 2-4.
  13. Heschong Mahone Group. “Daylighting in Schools: An Investigation into theÖ,” for the Pacific Gas and Electric Company, Fair Oaks, CA, p. 4.
  14. Ibid, pp. 3-4.
  15. Heschong Mahone Group, op. cit., p. 108.
  16. Heschong Mahone Group, op. cit., p. 121.
  17. Heschong Mahone Group. “Skylighting and Retail Sales: An Investigation into the Relationship Between Daylighting and Human Performance,” for the Pacific Gas and Electric Company, 1999, p. 2.
  18. Ibid, p. 9.
  19. Heschong Mahone Group, op. cit., p. 138.
  20. Ibid, p. 10.
  21. Heschong Mahone Group, op. cit., p. 109.
  22. Ulrich RS. “View Through a Window May Influence Recovery from Surgery,” Science 224, pp. 420-421.
  23. Heschong Mahone Group, op. cit., p. 5.
  24. Heschong Mahone Group, op. cit., p. 8.
  25. Ibid, pp. 9-10.

About the Author
As a Principal at KMD and Director of their public sector and commercial building projects, David Hobstetter provides overall project leadership for the firm. Under his direction, the firm has developed an International reputation for building design excellence.
In his 27 years at KMD, there has been a consistency in his approach and a philosophy of working that emphasizes three critical factors: the design process, the appropriateness of the design with its urban context and natural environment, and the symbolic expression of building function in the architectural form.
David is a nationally recognized architect in planning and design of major urban facilities. As part of a nationally recognized panel of architects and planners that provided design input to the selected design team, David was invited to participate in a GSA-sponsored design charrette for the Murrah Federal Building replacement facility in Oklahoma City. He was also appointed to the GSA National Register of Peer Professionals. In the two-year term (1998-2000), he was part of a nationwide GSA peer review panel to review prominent Federal projects and design competitions.
David is a frequent speaker at conferences, including International Design-Build Conference in Toronto, Canada and San Diego, California, the AIA National Convention in Dallas, Texas, CTC6 Courts Technology Conference in Los Angeles, California, , and AIA, New York Chapter, of the AIA. He was a speaker at a National Endowment for the Arts—sponsored conference on workplace productivity that featured the Oakland Federal Building as a case study.
David has been a visiting critic at area universities, participated in professional reviews and planning commissions. He has been widely published, including articles in the Wall Street Journal, Architectural Record, Progressive Architecture, Architecture, Building Design & Construction, @ Issue, Court Manager, and Court Review. His research covers subjects such as: Daylighting and Productivity—The Modern Workplace, The Modern Courthouse, and Historic Architecture of Ohio.

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