Daylighting is an aspect of green building design that should be ubiquitous;
without adequate daylighting, people will not perform well and will
not be healthy. For building plans, this implies a design that is no more
than 66 feet wide, front to back, or about 33 feet to a window from any
workstation. This is a standard design requirement in many places in Europe,
where people’s health is placed before economic e‹ciency. Looked at
another way, a building should be oriented so that the long axis is eastwest;
this allows for maximum daylighting, from both south- and northfacing
windows.
Daylighting’s beneŠts are immediately apparent; people see better and
feel better whenever there is natural light for reading and working. Good
daylighting design can employ skylights, north-facing windows on the
roof, a central atrium, light shelves to bounce light into a space while shading
windows from the summer sun, and other techniques. Good daylighting is always indirect, without glare.Daylighting is usually combined with
electric lighting, so that there is a constant lighting level, typically 30 footcandles
at the desktop, or there is task lighting provided for each workstation.
According to a report from Carnegie Mellon University analyzing
daylighting research,“Eleven case studies have shown that innovative daylighting
systems can pay for themselves in less than one year due to energy
and productivity beneŠts…the ROI [return on investment] for daylighting
is over 185%.”38
A California study of the impact of daylighting examined 73 stores of
a chain retailer, of which 24 had daylighting. The results:
The value of the energy savings from daylighting is far overshadowed
by the value of the predicted increase in sales due to daylighting.
The proŠt from increased sales associated with daylight
is worth at least 19 times the energy savings.
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