Daylighting Offers Great Opportunities

Today, there is increasing evidence that daylight is essential for the health, well being and productivity of individuals. Although productivity is often difficult to quantify, clinical disorders, such as daylight deprivation and seasonal affective disorder (commonly called SAD), are directly linked to a person's lack of light. By carefully designing window specifications for either commercial or residential buildings, architects can contribute to the increased productivity and psychological health of building occupants.

Through the years, daylight has played an invaluable role in the lighting of buildings. Until the industrial revolution, workers generally spent a large amount of time outdoors or within close proximity to daylight. Not until this century, when electric lights became commonplace, has daylighting been neglected in most buildings.

A recent study indicates that typical people are exposed total daylight levels of greater than 2000 lux for only 90 minutes each day (Savides, 1986). Light exposure is important to the inner time keeping of humans. Through evolution, man has adapted to rhythms such as body temperature to provide him with explicit knowledge of external time (Terman, et al, 1987). The loss of this connection can contribute to fatigue, insomnia, and SAD. Another study of Russian and Czechoslovakian literature indicated that occupants of windowless factories were more subject to headaches, faintness and sickness that similar occupants of factories with windows (Plant, 1970). However, with today's advanced window technology, combined with efficient electric lighting, we can now design cost-effective, healthy buildings, that help to minimize these effects.

Daylight, a full-spectrum light source, most closely matches the visual response that, through evolution, humans have come to compare with all other light. Daylight provides continually changing values, brightness and contrasts to the workplace, allowing the human eye to constantly adjust. This adjustment reduces eye fatigue. The human eye is capable of adjusting to high levels of luminance without producing discomfort (AIA, 1993). However, reflections and brightness need to be controlled in relation to the task or design program.

Windows provide outside contact

Windows are the best means of providing points of contact with the outside environment. Short- and long-range views allow the eye to change focus, provide a connection to the natural world, and to assist in knowing time and weather and provide orientation. The lack of a physical connection is a major source of occupant dissatisfaction in offices. Studies show that many European countries now require that workers be within 27 feet of a window. Switzerland and the Scandinavian countries go a step further. They require that windows also be operable (Loftness, et al, 1993). To offset the problem of overburdening a mechanical system with open windows, automatic sensors are placed within the air diffusers in individual offices. These sense, through a change in air pressure, that a windows is open. They then cut off heat flow to the room so that the heating system is not working against an open window.

With reduced reports of headaches, fatigue and seasonal disorders through increased daylight, worker productivity is bound to increase. Wages and salaries can represent about 95 percent of all costs of a typical office building (Ternoey, et al, 1984). Reduced sickness and absenteeism and the increased performance would, therefore, more than offset any increased initial costs or life cycle costs (Robbins, 1986) associated with providing more workers visual access to windows.

The NMB Bank Headquarters in The Netherlands was designed by architect Ton Alberts of Alberts and Van Huut, to heavily rely on daylight. No desk may be more than 23 feet from a window. Window louvers bounce daylight deep into the space. Inside the bank, wood windows are used to bring the light from one area into another, thereby giving all workers access to daylight, even when they are located in interior spaces.

The bank has seen a significant drop in employee absenteeism, which is attributed to the attractive work environment (Browning, 1992). Each tower of NMB Bank is punctuated by a glass-roofed atrium, allowing a generous use of plants to help bring the outside in.

Enhanced spatial relationships, both within a building and to the outside, are also positive attributes of daylighting. Natural light is the best source of good color rendering, making people and colors look more realistic than they do in electric light. Daylight adds a dimension of expansiveness to spaces and can help to define shapes and tasks. This attribute of daylight is especially critical to the elderly. As the baby boomers age, sensory loss will become a significant issue which designers must face. Common eye problems associated with aging include slower adaptation to light level changes, increased difficulty with glare and requirements for higher illumination levels (Noell, 1992). Contrast between window openings and surrounding wall surfaces can be reduced by proper shading of windows, splaying of window jambs, and proper interior lighting.

When designing a daylit building, the designer must carefully consider the visual tasks to be performed in a space and the needs of the occupants. Glazing choices and the location and design of window openings then are carefully chosen and detailed. With the variety of window types available, fading, overheating and glare can be controlled. Generally, using glass that is clear in color and has a high visible transmittance is desirable. Shading coefficients will vary according to climate, orientation and the thermal needs of the building.

Way Station, a mental health facility in Frederick, Md., uses daylighting to create an aesthetically pleasing and healing environment that helps promote wellness of people with serious mental illness. "Members" and staff of the center comment that the building makes them feel great and that they love that daylight is available in almost every room. The Way Station uses light monitors, tracking daylight collectors, and finely-tuned window strategies to enhance the positive qualities of light. The daylighting techniques are part of an overall strategy that results in an energy cost savings of more than two thirds.

As architects and designers explore the inclusion of daylighting into their designs, the availability of high performance windows with diversity of characteristics to accommodate specific functions will be necessary. Jacob Liberman, Ph.D., states, "When we speak about health, balance and physiological regulation, we are referring to the function of the body's major health keepers; the nervous system and the endocrine system. These major control centers of the body are directly stimulated and regulated by light, to an extent far beyond what modern science, until recently, has been willing to accept."

A Body Of Lighting Knowledge

Included in this list are the sources referred to in the foregoing article as well as some additional reference sources. Within their pages, you will find additional information concerning the effects of daylighting on humans.