Environmental Engineering Reference
In-Depth Information
accepted as being valid. It is reasonable to expect that there may be others,
perhaps subtle, perhaps not, that are yet to be accepted.
While the organic mechanisms are not fully understood, it is well known that
light plays a significant role in psychological health. One very familiar example
is the psychological phenomenon that occurs with reduced winter lighting
conditions. It is widely appreciated that, during winter months, inhabitants of
northern latitudes are often affected by a condition known as ''seasonal affect
disorder'' or SAD, which can manifest as a severe depression in extreme cases.
Whether the quality of light is important in this regard, or merely the quantity
of light received, the ability of light to play a profound role in one's general
sense of well-being is appreciated.
These and other potential mechanisms by which lighting can affect health,
happiness, and performance can be explored in depth elsewhere but the sum of
these discussions lays the groundwork for some credible mechanisms that may
explain some of the positive attributes that have been attributed to natural
lighting. Among these benefits, there are claims that workers feel better, have
fewer health complaints, and higher productivity when exposed to natural
lighting. Similarly, there is evidence that students remain healthier and perform
better academically in environments where natural lighting is prevalent. In both
work and school environments, the absenteeism rates (which are easily quanti-
fied) have been shown to decrease with natural lighting [7].
From a cultural standpoint there are obvious financial and social advantages
to having workers and students that are productive, present, healthy, and
happy. Factors that have even a small influence over these characteristics can,
over time, have dramatic economic and societal impact. From the standpoint of
pure economics, some retailers have discovered benefits that daylight can have
on the retail environment. Retailers are starting to use daylighting in their stores
specifically to enhance their store environment, increase sales, create a more
pleasant shopping environment, attract customers, and improve color render-
ing. Using daylighting also has aesthetic benefits that encourage customers to
enter the store [7].
If even a portion of the claimed biological and cultural benefits associated
with the natural solar spectrum are true, the positive societal influence of
increased use of daylighting could vastly outweigh the benefits in energy sav-
ings. In the near term, however, the economic justification for the use of day-
lighting to offset energy usage will predominantly determine the extent to which
daylighting is implemented.
5.5 Energy and Environmental Benefits of Daylighting
In industrialized nations, the majority of the inhabitants leave their homes at
some point during the daytime to spend time in non-residential buildings. Non-
residential buildings remain lighted (mostly by electric lighting) throughout the
