Lighting & Productivity

The Importance of Daylighting
Daylighting is a technique in which direct, diffused or reflected daylight is used to provide general or supplemental lighting. Its benefits include greater satisfaction with the interior environment for building occupants and lower ongoing energy costs for the owner.

From humanity's origins to the 20th century, the sun was the primary source of illumination. People desire access to the sun during the day to connect with nature and a sense of time. Jay Appleton, in The Experience of Landscape (1975), theorized that humans evolved a preference for environments that are safe locations from which they can view and survey the surrounding environment (the prospect-refuge theory). The human eye was also designed by nature to work best with sunlight. Connecting with the great outdoors is so important in Europe that in some countries, building codes require that all occupants have access to daylight, greatly impacting the architectural landscape with longer, thinner buildings. A study in Great Britain, published in The Responsible Workplace (F. Duffy, A. Laing and V. Crisp, editors), revealed that windows are the leading factor in occupant satisfaction with their environment. In another study (Butler & Biner, 1989), 80 percent of respondents desired windows in their office because it gave them information about the time and the weather--which we can interpret as a sense of "place."

With our very human love of the sun, it's no wonder that architect Mies van der Rohe said, "The history of architecture is the history of man's struggle for light--the history of the window." The psychological benefits of daylighting include:

• Sensory variability
• Visual pleasantness
• Modeling (light from side)
• Connection to nature
• Potential reduction in SAD (near windows)
• Time/Weather information
• Perceived as healthier than electric light
• Spectral quality ("full spectrum" lighting, and with higher color temperature increasing visual clarity and brightness perception at lower light levels, according to some research)
• Indirect component of light producing wall- and ceiling-washing effects, which can provide a more comfortable visual luminous environment

Many of these benefits boil down to simple mental stimulation due to moderate changes in the environment, so long as these changes are meaningful and patterned, which research repeatedly shows is beneficial to workers in monotonous, uniform office environments. In windowless offices, workers tend to experience stress and feelings of being cooped up. But people tend to prefer daylight inside the building as well as a connection to the outdoors.

One study (E. Ne'eman, 1974) revealed that daylight was desired (in interior spaces) by 73 percent of interviewed office workers, 91 percent of hospital patients and 93 percent of households. In another study (Heerwagen and Heerwagen, 1986), 49 percent of respondents wanted daylight and posters in windowless spaces. In a survey (T.A. Marcus, 1967), 86 percent of respondents interviewed indicated a preference for daylight in office spaces, while in a dual study conducted in 1983 (K. Cuttle), some 86 percent of London and 83 percent of New Zealand office workers reported that they preferred daylight. And in yet another survey (E. Sundstrom, 1986), 96 percent of office workers indicated a preference for daylight during working hours.

Introduction

Lighting & Health

Productivity vs. Energy Savings

Sustainable Case Studies

The Importance of Daylighting

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