Implementing Wind Responsive VAV Exhaust Systems at NREL's ESIF Building: A Four-Year Follow-Up

Otto Van Geet, National Renewable Energy Laboratory
Brad Cochran, CPP, Inc.

The Energy Systems Integration Facility (ESIF) is the first building on NREL's Golden campus to integrate a wind responsive variable air volume exhaust systems into its laboratory HVAC control design.

The wind responsive system is designed to minimize the volume flow rate necessary out of the laboratory exhaust stacks, while minimizing the risk of re-entertainment of the exhaust.

It establishes a minimum volume flow rate as a function of the local wind speed and wind direction, as measured by a roof top anemometer.

The ESIF facility has been up and operating for about 4 years. This presentation will report the current status of the system. It will address such question as: Is it providing the predicted energy savings? Is the system still operating as designed, or does it need to be tweaked to adjust to current building ventilation requirements?

Learning Objectives

  • Just because a building went through a thorough commissioning process before occupancy doesn't necessarily mean that it is operating properly post-occupancy, particularly after several years of operation.
  • Thing change over time; equipment is added/moved and controls are fiddled with. A thorough investigation into the current HVAC operation is warranted to ensure safe and efficient operation.
  • When properly employed, a wind responsive VAV exhaust system can provide significant energy savings while maintaining a safe working environment.
  • What to look for when evaluating the current operation of a VAV laboratory exhaust system to determine whether or not it is functioning properly.


Otto is a Principal Engineer at NREL with over 30 years of experience. Otto has been involved in the design, and operation of energy efficient research facilities such as labs and data centers, general use facilities, and low energy use campus and community design. Otto was one of the founding members of the Labs21 program and provides technical guidance for the program. Otto is a Registered PE, a Certified Energy Manager, a LEED Accredited Professional, and a Project Management Professional.

Brad is a Registered P.E. with over 25 years of experience in dispersion modeling of laboratory extract systems. Brad has helped define new design techniques to minimize the energy requirements for laboratory exhaust stacks by utilizing VAV technologies. He has successfully designed and employed VAV exhaust systems for over 50 laboratories throughout the US, Canada, and the United Kingdom. He has authored and presented several papers on laboratory exhaust design.


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