Field Tests of High Performance Laboratory Fume Hoods: A Systems View

Craig Wray, Lawrence Berkeley National Laboratory

Laboratory ventilation involves exhausting air from rooms and enclosures such as fume hoods to contain, dilute, and remove hazardous gases (as well as to remove heat) generated by processes within the lab. Its objectives are to maintain acceptable air quality for occupants and to prevent related fires and explosions. Lab ventilation rates can be hood dominated, lab minimum ach (dilution) dominated, or thermally dominated by process heating or cooling needs. Together with reductions in the other two ventilation rate components, high-performance hoods can reduce the associated make-up air volume and save substantial amounts of energy. However, end-users are not currently adopting such hoods widely enough, because of uncertainty about returns on investment and concerns about increased maintenance effort and associated reduced reliability.

As a step to overcome these barriers, Berkeley Lab recently carried out a DOE-funded field demonstration project to test about 100 bench-top hoods as installed and operated at three U.S. chemical laboratories. One objective was to evaluate energy savings and economic benefit persistence relative to both design intent and to conventional hoods. Another objective was to assess relative differences, if any, regarding maintenance effort and associated reliability.

The project focused on three underutilized high performance hood technologies relative to two widely used conventional ones:

High performance hoods:

  • Low flow constant volume (60-80 fpm face velocity)
  • Low flow constant volume retrofit kits (60-80 fpm face velocity)
  • Variable air volume with two state (high/low flow) control based on occupancy sensing

Conventional hoods:

  • High-flow constant volume (100 fpm or greater face velocity)
  • Variable air volume with single state control

This presentation describes our test methods and provides both hood and related HVAC system performance results based on data that we collected during summer and winter operation. These results showcase the energy and cost savings that can be achieved by high performance fume hoods.

Learning Objectives

  • Understand how fume hoods interact with HVAC systems.
  • Be able to collect and analyze field data that characterize the energy performance of combined fume hood and HVAC systems.
  • Understand the bases and methodology for deriving hood-level, HVAC system-level, and related national-scale energy and cost savings estimates.

Biography:

Mr. Wray has 30 years of experience addressing building energy and ventilation issues. His work currently focuses on air-handling system experiments, modeling, and diagnostics. He is currently Vice Chair of ASHRAE MTG.EAS 'High Performance Air-Handling Systems for Buildings Except Low-Rise Residential Buildings' and is active on many related technical and standards committees. He has Bachelors and Master of Science degrees in mechanical engineering, and is a registered professional engineer.

 

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