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Room Pressurization Criteria, Effectiveness, and
Energy Conservation in Controlled Environments
Jim Coogan, Siemens Building
Technology
Pressurization is one of the most important considerations
in the design of a controlled or critical environment (CCE) such
as a general lab, biosafety lab, cleanroom, hospital isolation room,
or even a smoke control space. Pressurization technology utilized
in a CCE space normally is intended to direct desired flow patterns
and prevent airborne cross contamination.
Pressurization design has been traditionally based on intuitive
suggestion instead of well-validated guidelines. Due to unknown
room conditions during design phases, design engineers tend to over
design pressurization systems to prevent possible problems during
air balancing and commissioning. This mentality and practice could
cause adversary effects and significant energy wastes. Improper
pressurization/depressurization can cause undesired airflow strengths
and patterns, uncorrectable airflow directions during balancing
and commissioning, which can result in contaminated products, ineffective
protection for working environment, endangering operation personnel's
safety, as well as increased energy costs.
This presentation will provide a systematic analysis on pressurization
criteria, primary and secondary barriers, suite (multiple rooms)
and staged pressurizations, decontamination effectiveness, simulation
aid, automatic room air-tightness test, updated adaptive control
strategies, recommended practices on energy conservation, and quantification
between the reduction of pressure differential level and the possible
energy saving.
The presentation will further offer the recommended practices on
energy conservation of pressurization systems, such as reduction
of room enclosure leakage, utilization of barrier devices to lower
the required room pressure levels, utilization of VAV supply and
exhaust systems to lower total air consumption, lowering air volumes
during unoccupied modes while maintaining required pressurizations,
locating CCE spaces in interior zones to enhance the stability of
room environmental conditions and reduce cooling/heating loads,
utilization of network flow simulation to enhance and validate pressurization
effectiveness, low-pressure-drop design for ductwork, airflow control
devices and other components, and etc.
Labs21 Connection:
Energy conservation on room pressure control for laboratories is
an important issue but has not been particularly addressed by design
professionals. Due to complexity and many unknown factors during
pressurization design, design engineers tend to place low priority
on energy conservation and over design pressurization systems, which
could cause unnecessary energy wastes.
This presentation will discuss decontamination effectiveness and
simulation tools to emphasize on occupant safety, will quantify
possible energy saving on reduction of pressure differential level
to further analyze whole building efficiency on a life-cycle basis,
and will list the recommended practices to promote energy efficiency
efforts and employ a range of energy efficiency strategies by design
professionals. These are the key elements of Labs21's approaches.
Biography:
Jim Coogan, P.E., is a Senior Principal in product development
and applications for Siemens Building Technologies. He has 25 years
experience designing microprocessor-based controls for mechanical
systems, with 15 of those spent in the HVAC industry. Jim has served
as chairman of ASHRAE Technical Committee 1.4 Controls and has been
an active member of TC 9.8 Laboratory Systems. Publications include
technical papers on room pressurization and laboratory system commissioning.
He has participated in development of HVAC control products ranging
from simple room controllers to Internet-based operator interfaces.
Jim earned his S.B. in mechanical engineering at MIT in 1980.
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