Cleanroom Energy Benchmarking Results

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Energy benchmarking

• Continuous process improvement is aided by
  observing actual energy use in operating
  cleanrooms. By studying the better performing
  systems, an engineer can debunk old myths and
  find innovative new solutions.

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Energy benchmarking

• Building owners can compare performance
  against similar systems without regard to the
  process in the room.

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Goal setting and benchmarking

• Facility and End Use Energy Budgets
• Efficiency Targets or Design Requirements for Key
  Systems and Components
• Cfm/KW
• KW/ton
• System resistance i.e. Pressure drop
• Face velocities
• Etc.

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System efficiency metrics vs. production metrics

• Compare HVAC systems regardless of process
• Focus on HVAC systems efficiency
• Production metrics can
• mask inefficient systems

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Cleanroom HVAC metrics

• Air systems cfm/kW cfm/ft2
• Recirculation
• Make-up
• Exhaust
• Cleanroom air changes ACH/hr
• Re-circulated, filtered air
• Outside air (Make-up and Exhaust)

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Cleanroom HVAC metrics

• Chilled water efficiency kW/ton
• Chiller
• Tower
• condenser pump
• chilled water pump
• total chilled water plant

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Recirculation air change rates and average
velocities
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Comparison of ISO Class 5 Cleanrooms
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Recommended Air Change Rates Various Sources
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Improvement over ISO recommendations
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Recirculation air change rates

• Studies confirm that air-change rates are often
  higher than is needed
• Benchmark data confirms that many achieve
  contamination control with lower air changes
• Since fan power is roughly proportional to the
  cube of the airflow, small reductions yield large
  energy savings
• Use of benchmark data and other studies can be
  used to set energy efficient air change rates
• Right Sizing Air Change Rates can result in lower
  construction costs and lower energy costs

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Recirculation systems
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Recirculation systems

• Benchmark data reveals large variations in
  efficiency
• All energy in recirculation path (air movement
  and conditioning) needs to be included
• System pressure drop is key concern
• Air flow setback may achieve additional savings
• Efficient fans and motors can make a difference

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Pressure drop is key
Benchmark data illustrated that ducted HEPA
filters (high pressure drops) were the worst
performers
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Make-up Air Opportunities
Opportunities when higher than average CFM/kW
is observed

• Low face velocity/low pressure drop air handler
• Low pressure drop filtration strategy
• Run multiple makeup units in parallel
• Optimize exhaust air flow

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Chilled Water Systems
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Chilled water systems
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Design Load vs Measured Load
Design - Med Temp 39
Annual Average - Med. Temp 66
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Swing Chiller Concept
Dual Temperature Chilled Water Plant
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Chilled water systems

• Potential efficiency measures
• High-efficiency variable-speed drive chillers
• Low pumping energy schemes such as primary
  only variable speed pumping
• Efficient cooling towers with low approach
  temperature
• Optimized setpoints
• Free cooling Optimized setpoints
• Dual Temperature Chillers

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Chilled water system choices

• Free Cooling
• Chiller Efficiency
• Variable Speed Chiller
• System Pressure drop
• Primary only or
• primary/secondary
• System controls
• Efficient Pumping
• Water vs. Air Cooled

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DI water opportunity

• Variable speed drive RO pump
• Lower pressure drop RO membranes
• Variable speed drives on DI water recirculation
  pumps

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Benefits of benchmarking

• Establish Baseline to Track Performance Over Time
• Prioritize Where to Apply Energy Efficiency
  Improvement Resources
• Identify Best Practices
• Identify Maintenance and Operational Problems
• Operational Cost Savings

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Non-energy benefits of benchmarking

• Reliability Improvement
• Controls
• Setpoints
• Maintenance needs identified
• Leaks
• Motors, pumps, Fans
• Filters
• Chillers, boilers, etc.
• Safety issues uncovered
• Hazardous air flow

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Conclusion

• Benchmarking Is Useful to Building Owners,
  Operators, and Designers
• Benchmark results can be used set performance
  targets and point to efficiency opportunities
• More Robust Data is Needed To Identify and
  Advance Best Practices
• You Cant Control What You dont Measure
• If You Have Benchmark Data Share It!