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A New VAV Pressure Control System Provides Energy
Savings Opportunity
Osman Ahmed, Ph.D.,
PE, Siemens Building Technologies, Inc.
This paper presents a method for dynamic pressure control of a
building fluid distribution system. This control method is currently
implemented in a cancer research center. The energy savings potential
using this control methodology is substantial. A year- long monitoring
and verification at the center has demonstrated an energy savings
opportunity between 20%-50% as compared to a traditional Variable
Air Volume (VAV) system that uses constant fan static pressure.
The novel fan control dynamically resets the fan static pressure
set point in response to the varying demand of airflow rate in a
VAV distribution system. The approach first identifies a static
pressure model for the distribution system. Then, in real time,
the fan controller obtains the flow set points from local controllers,
and uses the model in order to calculate the minimum static pressure
that the fan has to maintain. Unlike other methods, the proposed
control method does not require any additional sensors or hardware
beyond that required for conventional VAV control, and its implementation
is cost effective and simple. This control approach can also reduce
noise level and maintains desired control performance. The presentation
will cover the principle of new control system, its innovative implementation
and remote engineering methods, and the results obtained from the
cancer center project.
Findings:
- Laboratory VAV systems offer significant opportunity for energy
savings by implementing dynamic fan pressure control.
- On an average the fan static pressure can be reduced by as much
as 50%.
- Lowering fan pressure means reduction in noise and improvement
in controllability.
- Matured and reliable technology is available for easy and cost-effective
implementation.
- Design practices should call for dynamic pressure reset strategy
instead of a constant static pressure setpoint.
- The designers need to not choose an arbitrary location of a
static pressure sensor.
Labs21 Connection:
The proven control application reduces energy consumption and,
as an indirect benefit, also cuts down generation of pollutants.
It improves performance and environment quality. Finally, it simplifies
design practices. In short, it affects the following principles
of the Lab21 approach:
- Minimize overall environmental impacts.
- Employs energy strategy.
- Promote energy and water efficiency efforts.
- Expand beyond the laboratory building.
Biography:
Osman Ahmed, Ph.D., PE, is a Senior Principal Engineer
with the Systems applications/ Advanced technology Group at the
Siemens Building Technologies. He has a Ph.D. in Mechanical Engineering
from the University of Wisconsin—Madison and a registered PE
in the State of Illinois. He has about 20 years of experience in
the HVAC industry including 16 years with his current employer.
Osman Ahmed has published and presented close to 50 technical papers
and articles in the USA and abroad. He has about twenty patents
including several pending on global optimization, web based applications,
model based control, Micro-electro mechanical systems (MEMS) applications,
remote monitoring and solutions and laboratory HVAC systems. Osman
is an active member of ASHRAE technical committees, represented
ASHRAE to NIH project on laboratory fluid modeling project and was
a member ASHRAE 110 standard 1995 on fume hood testing. Osman is
currently focusing on technology and innovation management and is
developing value oriented innovative solutions. His expertise includes
HVAC and HVAC control systems, artificial intelligence, small systems,
remote services, soft computing, object modeling, energy and thermal
systems, modeling and simulation, optimization and computational
fluid dynamics.
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