THE EXPERIENCE OF DAYLIGHT by Judith Heerwagen
Prior to the advent of buildings, humans lived immersed in nature. Daily activities were aided or constrained by the presence or absence of daylight and by qualities of light that signalled time and weather. Our physiological systems – especially our sleep-wake cycles – were in synch with the diurnal rhythms of daylight, as were our emotional responses to light and darkness. The strong, consistent preference for daylight in our built-up environments today suggests that evolutionary pressures are likely to be influencing our responses.
Although all our sensory systems acting together were important to survival, the visual system is our primary mode of gathering information. Thus, light must have played a powerful role in information processing and survival. In ancestral habitats, light was likely to have had several key functions that are relevant to the design and operation of built-up environments.
Light provides information for orientation, safety and surveillance, interpretation of social signals, identification of resources and awareness of hazards. Whether it is the changing colour of light associated with sunset or storms, the movement of fire or lightning, the brightness in the distance that aids planning and movement, or the sparkle of light off water – all these aspects of light have played a role in helping our ancestors make decisions about where to go, how to move through the environment, what to eat, and how to avoid dangers. The life-like and life-supporting qualities of daylight strongly suggest that daylight is a basic human need, not a resource to be used or eliminated at the whim of the building owner or designer. The presence of daylight and sunlight in buildings clearly affects our psychological and physiological experience of place. Its absence creates lifeless, bland, indifferent spaces that disconnect us from our biological heritage.
Judith Heerwagen, PhD, is an environmental psychologist in Seattle, Washington. She is an affiliate faculty member in the Department of Architecture at the University of Washington where she has co-taught seminars on bio-inspired design and sustainability. She has written and lectured widely on the human factors of sustainable design, including health, psychological impacts and productivity. She is co-editor of Biophilic Design: The Theory, Science and Practice of Bringing Buildings to Life (Wiley, 2008).