Large Exhaust Fan Energy Savings at Several Laboratory Buildings at the Georgia Institute of Technology

Chet Wisner, Ambient Air Technologies, LLC
Stanton Stafford, Integral Group

Six laboratory buildings on the campus of the Georgia Institute of Technology in Atlanta were studied in the wind tunnel to determine how much the exhaust fans could be safely turned down in support of a SmartLabs project to reduce energy use. Most of the exhaust systems utilize large induced-air fans of a type which is known to provide compromised plume dispersion performance. Even though plume dispersion from these units was significantly less than specified, it was still found possible to safely turn down the exhaust fans enough to eliminate bypass air from the exhaust flows and to reduce the overall exhaust fan energy by approximately 9,200,000 kWh per year. Existing conditions were verified by field measurements and energy modeling was utilized to obtain realistic predictions of potential fan energy savings. This study demonstrates the large energy savings available through application of SmartLabs principles on laboratory buildings spanning a broad range of building ages on a complex research campus.

Learning Objectives

  • Identify opportunities early in new or renovation laboratory facility exhaust system design that considers both safety and energy. Waiting until late in the design process may prevent such opportunities.
  • Recognize how opportunities to solve difficult exhaust dispersion design can also promote energy savings through the use of advanced techniques such as wind-responsive controls.
  • Understand the tradeoffs between the beneficial large initial dilutions provided by induced-air fans with the corresponding energy penalty.
  • Have a better understanding of exhaust plumes and their trajectories.


Chet is the President of Ambient Air Technologies, a Colorado firm specializing in wind tunnel modeling of laboratory and healthcare facilities. In recent cutting-edge studies, AAT has produced data supporting energy reduction initiatives which are reaping significant energy savings for numerous clients. He has a BS from UC Berkeley in Eng Physics, an MS in Meteorology from the South Dakota School of Mines, and an MBA from UCLA. He is a frequent I2SL presenter and member of AWMA, and AMS.

Mr. Stafford brings over 15 years of mechanical engineering and sustainable design and operations experience. His career includes designing, modeling, commissioning and optimizing building systems for healthcare, science and technology, institutional and government projects across the U.S. with many LEED certifications. Has served on 3 ASHRAE technical committees, the Board of the Lifecycle Building Center of Greater Atlanta, the USGBC GA chapter, and the Univ of GA Mech Eng Dept.


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