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Chapter 1: Fire geometry and smoke movement in buildings
HVAC systems
Commercial heating, ventilating, and air conditioning
(HVAC) systems can usually be adapted for smoke
control use. In order to meet smoke control reliability and
tenability criteria established in NFPA 92A, an HVAC
system must be capable of supplying outside air to the
protected space, returning air from the protected space,
and exhausting air from a protected space to the
outside.
An HVAC system can be as simple as a fan in a housing
(such as a roof-mounted exhaust fan) or a complex
system with ductwork, supply air outlets, return air inlets,
fresh air intakes, humidifiers, filters, heating and cooling
coils, preheat coils, and dampers.
Individual floor units
Air handling units serve a single floor or area. Units can
have separate supply and exhaust fans. The smoke
control system designer must verify that the units are
capable of providing sufficient outside air and an exhaust
capability for the expected fire condition. See Figure 9.
Figure 9: Individual floor units
Fan
Fan
Fan
Fan
12
Induction units
Induction-type air handling units are usually used in
conjunction with a central HVAC system, which supplies
high-pressure air to the induction units. Induction units
are located around the outside of a building and are
used to condition the air for areas around the perimeter
of a building. Room air is then drawn into the induction
unit, mixed with the primary air from the central system,
and returned to the room. Induction units servicing a fire
area should be shut down or have the primary air from
the central system isolated. See Figure 10.
Figure 10: Induction units for central HVAC system
Fan
Fan
Ductwork
Ductwork is constructed of a variety of materials
including steel, aluminum, concrete, and masonry.
Ductwork usually connects the fans with the areas to be
served. Air travels from the supply fan through the
supply ducts into the building. Return air is often pulled
through the plenum space above the ceiling as shown in
Figure 11 on page 13.
VM-1 Smoke Management Application Guide
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