MIL-HDBK-1011/2
4.5.3
Wingwalls. Wingwalls or exterior vertical fins can increase a
building's ventilative potential by catching and deflecting winds into the
interior. Properly designed wingwalls may also provide solar shading by
acting as vertical fins on east and west elevations. Refer to para. 4.5.6,
Solar Control--Shading Devices.
4.5.3.1
Ventilative Considerations. Wingwalls can increase interior
ventilation rates when the wind incidence angle is perpendicular to the
building face. Placement of wingwalls to the side, or parapets on top of the
building increases the area of the windward facade creating higher positive
pressures and resulting in higher interior velocities, (see Figure 23).
Wingwalls can also be used to intercept and increase the admittance
of oblique breezes into the building. Wingwalls placed perpendicular to the
building facade can create air dams that "trap" and redirect air into the
building (see Figure 25).
Improving Cross Ventilation. One of the most useful effects of
4.5.3.2
wingwalls is the creation of cross-ventilation in rooms with windows on one
wall only or in rooms without positive pressure inlets and negative pressure
outlets. Proper placement of wingwalls can create positive and negative
pressure which drive ventilation in otherwise stagnant rooms (see Figure 26).
Wingwalls can improve ventilation in rooms with openings only on
the windward side, but are effective only if they create positive and negative
pressure zones. They cannot improve ventilation in rooms with openings on the
leeward side only.
For ventilation with openings in one wall only, up to 100 percent
improvement of the interior airflow and air change rate may been achieved.
Wingwalls do not significantly enhance ventilation in cross-ventilated rooms
with openings on opposite walls unless the wind incidence angle is oblique.
For oblique wind angles (40 to 60 degrees), wingwalls can increase average
interior velocity by up to 15 percent.
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