Biomedical Engineering Reference
In-Depth Information
Background
Terrorism events have increased interest in the
vulnerability of U.S. workplaces, schools, and
other occupied buildings to CBR threats. Of
particular concern are the airflow patterns and
dynamics in buildings, specifically in the building
heating, ventilating, and air-conditioning (HVAC)
systems. These systems can become an entry point
and a distribution system for hazardous contam-
inants, particularly CBR agents. Building owners
need reliable information about how they can
(1) modify their buildings to decrease the likeli-
hood or effects of a CBR incident and (2) respond
quickly and appropriately should a CBR inci-
dent occur. Comprehensive guidance is needed in
several areas, including:
systems.
b
This step may require, or benefit from,
the assistance of qualified outside professionals.
Without this baseline knowledge, it is difficult to
accurately identify what impact a particular secu-
rity modification may have on building operation.
While it is important to understand how the existing
building systems function, the systems need not
operate per design before you implement security
measures. A
partial
list of items to consider during
your building walk-through includes:
•
What
is
the mechanical condition of
the
equipment?
•
What filtration systems are in place? What are
their efficiencies?
•
Is all equipment appropriately connected and
controlled? Are equipment access doors and
panels in place and appropriately sealed?
•
How to modify existing buildings for better air
protection and security.
•
Are all dampers (outdoor air, return air, bypass,
fire and smoke) functioning? Check to see how
well they seal when closed.
•
How to design new buildings to be more secure.
•
What plans building managers should prepare
in advance to help them make effective deci-
sions in the midst of a CBR incident.
•
How does the HVAC system respond to manual
fire alarm, fire detection, or fire-suppression
device activation?
Preparatory Recommendation—Know
Your Building
While more comprehensive guidance is being
developed, this document focuses on the shorter-
term goals of identifying those protective actions
that you can take immediately. But it recognizes
that some recommendations may not be feasible
for you or in all situations.
In initiating any plan to modify building system
design or operation, an important first step is to
understand these systems: How were they intended
to operate? How do they currently operate?
Getting to know your building may best be
handled by conducting a walk-through inspection of
the building and its systems, including the HVAC,
fire protection, and life-safety systems. During this
inspection, compare the most up-to-date design
drawings available to the operation of the current
•
Are all supply and return ducts completely
connected to their grilles and registers?
•
Are the variable air volume (VAV) boxes
functioning?
•
How is the HVAC system controlled? How
quickly does it respond?
•
How is the building zoned? Where are the air
handlers for each zone? Is the system designed
for smoke control?
•
How does air flow through the building? What
are the pressure relationships between zones?
Which building entryways are positively or neg-
atively pressurized? Is the building connected
to other buildings by tunnels or passageways?
•
Are utility chases and penetrations, elevator
shafts,
and fire
stairs
significant
airflow
pathways?
b
Note
: If sufficient questins or surprises arise from the building walk-through, an independent evaluation by a qualified HVAC
professional should be used to establish a useful baseline.
