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Daylighting, daylight simulation and public health: low-energy lighting for optimal vision/visual acuity and health/wellbeing
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|Title: ||Daylighting, daylight simulation and public health: low-energy lighting for optimal vision/visual acuity and health/wellbeing|
|Authors: ||Ellis, Eugenia Victoria|
McEachron, Donald L.
|Issue Date: ||3-Jun-2010 |
|Abstract: ||Recent research indicates that lighting has become a public health issue (Pauley, 2004). Studies have shown that people working in natural sunlight are more productive, more effective, and happier than people who work under traditional artificial light. Natural changes in daylight balance a body’s circadian rhythm, which determines sleeping and eating patterns, brain wave activity and hormone production. Disturbing the circadian rhythm can lead to jetlag, seasonal affective disorder (SAD), delayed sleep phase syndrome (DSPS), and may lead to more serious conditions such as cancer (Roberts, 2001). In industrialized nations it is estimated that up to 20% of the workforce are involved in some kind of shift work (Webb, 2006). Studies indirectly link exposures of shift workers to light at night (LAN) and higher incidences of breast cancer and colorectal cancers (Pauley, 2004).
Buildings consume 39% of the primary energy in the United States, out of which, on average 18% is from the lighting system (DOE, 2006). Furthermore, heat produced by the lighting system yields 24% of the total
building cooling load (Leslie, 2003). Therefore, proper lighting utilization through low-energy systems that generate little heat could result in significant cooling energy savings for buildings, which would further result in less environmental pollution during the energy production process. Moreover, studies (Leslie, 2003 and
Fay, 2002) have shown a connection between lighting levels and higher productivity and better performance from building occupants. Daylight brings enough light to meet lighting requirements of 50 to
70% of the occupancy period in the temperate zone of the earth, and even more around the equator (Fontoynont, 2002). Energy savings by using daylighting can be up to 50% of the gross full yearly use of light for interior conditions (Ne’eman, 1982). For proper health and energy savings it is important to use or mimic the full spectrum of natural lighting. Ocular light, or light reaching the eye, serves two functions: vision and control of circadian rhythm (Roberts,
2008). Studies have shown that daylighting provides the quality light necessary for maximum vision and visual acuity (Bliss, 1946) and provides the full spectrum of light needed for health and wellbeing (Roberts,2001). It is well established that the circadian rhythm is regulated by changes in visible light from the sun
throughout the day, and visible light can also be responsible for modifying the circadian rhythm (Aschoff,1965). The full spectrum of light includes UVA, UVB and visible light: at noon there is high intensity in the blue light region [400-500 nm], in the late afternoon blue light is preferentially scattered out of (removed
from) incoming sunlight so that the late afternoon sun provides red and orange light [600-700 nm], and when the sun sets it becomes dark. Circadian Rhythm is controlled daily by blue visible light [460-500
nm] together with darkness in the environment (Roberts, 2008). Daylighting strategies and composite solar luminaires will be installed and tested by student residents living at the Drexel Smart House, a Drexel Engineering Cities Research Initiative (DECI).|
|Appears in Collections:||Faculty Projects and Publications (COMAD)|
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