A good design
will provide ample
quality daylight,
saving energy
and money.
Text and photos by
or lighting, as for many other sensory inputs, quality is more important than quantity. Just as music
is judged for its quality and not its
loudness as long as the music is loud
enough to be properly heard, so too with lighting. above a certain minimum requirement, the
quality of lighting is paramount.
For high-quality lighting, glare and excessive brightness ratios in the field of view
should be minimized. The designer should
also avoid strong shadows from too much
directional light. The best lighting for most
visual tasks is a diffused light from overhead.
For these reasons, electric lighting is almost
always achieved by either direct lighting from
the ceiling or lighting reflected off the ceiling.
When this general illumination is less than the
minimum required, task lights such as desk
lamps should supplement it.
daylighting not only can save energy, thereby saving money and reducing the environmental consequences, but it can also increase
productivity and performance. For example,
research by the Heschong Mahone Group has
shown that children in daylit schools perform
better than children in schools that are only
electrically lit. However, daylighting will only
provide these benefits if properly designed.
Thus, a good daylighting design will provide
ample quality daylight to allow many electrical lights to be turned off much of the time.
Though Difficult, Side Lighting
Can Be Done
daylighting comes in two types: top lighting
from skylights or clerestories, and side lighting
from windows. Top lighting is best because the
lighting will come from the most effective angle,
f
light shelves work best on south windows and are not needed on north windows. They divide windows
into two parts: the upper daylight glazing and the lower view glazing.
daylighting is especially relevant to office, institutional and industrial buildings.
solartoday.org SOLAR TODA Y June 2012 33
but unfortunately it is only possible for one-story buildings and the top floor of multi-story
buildings. Skylights are best in mostly cloudy
climates, while clerestories should be used in
mostly sunny climates (see figure 1, page 34).
When winter heating is required, which is the
case for small buildings in most of the United
States, the clerestories should face south. When
winter heating is not required, as in Florida
