Interior Lighting for Designers

Direct sunshine from flat skylights or from
pitched skylights facing east, south, or west
must also be controlled. Interior louvers or
translucent shades will reduce glare and heat,
but exterior controls provide superior shading.
Exterior sun shades can be oriented to
shade light and heat from the sun during
warm weather yet allow penetration during
the cold seasons, or be designed to elimi-
nate direct sun from the interior all year long
(figure 5.16).

A difficulty with fixed overhangs and

awnings is that the amount of shading fol-

lows the solar seasons rather than the clima-

tic seasons. The middle of the summer for

the sun is June 21, but the hottest days

occur from the end of July to the middle of

August. The overhang designed for optimal

shading on September 21, when the

weather is still warm and solar heat gain is

unwelcome, causes the same shading on

March 21, when temperatures are lower and

solar heat gain is welcome (figure 5.17).

Vegetation, which follows the climatic

seasons, provides excellent shading year-

round. On March 21, many plants are with-

out leaves and do not obstruct the passage

of sunlight. On September 21, however, the

leaves are still full and provide good shading.

Deciduous trees or an overhanging trellis

with a climbing vine that sheds its leaves in

DAYLIGHT

Figure 5.15Vertical louvers.

Figure 5.14High sun and low sun angles at exterior
louvers.