upward away from the body in the
living space. The M-shaped louvers
reduce the velocity of the wind by
25 to 50 percent, with the larger
reductions occurring at higher wind
speeds. The velocity reductions are
equivalent or less than those of
other louver types (see Figure 36).
Devices. A roof overhang is the
simplest and most maintenance-free
exterior shading device. They are
most effective on the south side,
but can also be used on the
southeast and north facades. On
east- or west-facing walls,
must be very deep to be effective. The necessary depth may be achieved by the
use of an attached covered porch or carport, or by adequately wide exterior
balconies. See Figure 37.
Careful detailing of horizontal exterior shades will maintainthe
ventilation efficiency of the openings. Leave a gap between the shade and the
building to prevent airflow from attaching to the ceiling (see Figure 38).