Cleanroom Energy Benchmarking Results

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(No Transcript)
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Background

• Prior study demonstrated practicality of
  controlling air flow by measuring particle counts
• Benchmarking quantified large savings during
  periods of airflow setback
• Increasing interest in reducing airflow during
  periods of inactivity
• Parallel research project in CA and
  implementation in NY
• Two Industrial partners ready for demonstrations

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Demand controlled filtration

• Definition A method of controlling
  cleanliness (particle counts) in a room by
  changing the recirculation flow rate based upon
  real-time measurements of particle concentrations.

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Air-change rates and air velocity
Not an exact science

• The Institute of Environmental Sciences and
  Technology (IEST), ASHRAE Applications Handbook,
  and other sources provide recommended
  recirculation air-change rates
• Many large companies set their own criteria
• Many owners and design firms use rules of thumb
• Studies have shown that more airflow is not
  necessarily better suggesting a sweet spot
  between too little and too much airflow

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Benchmarks of recirculation air-changes and
velocities
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Recirculation set-back

Good contamination control while achieving energy
savings was demonstrated in case studies
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Pilot study

• Air set-back when not occupied
• Particle counter detected 0.10 1.0 micron
  particles and separated them into six size bins
• Data was logged for 23 days (2004)
• Some correlation between fan speed and particle
  counts
• No attempt to optimize air change rates

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Changes in airflow and particle counts
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Changes over different time periods
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Pilot study conclusions

• Higher fan speeds dont necessarily result in
  lower particle counts. There may be an optimum
  airflow that is unique to each room
• Large energy savings may be possible with no
  adverse impact on contamination control
• Particle counter placement and particle sizes
  collected are key parameters
• Demonstrations in operating industrial cleanrooms
  should be pursued more study is needed

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University study

• Public interest energy research co-funding
• Installation of particle counters and control in
  17,000 sf cleanroom
• Simple payback expected - approximately three
  years

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University study details

• 25 particle counters updating counts every second
• Airflow increased if necessary for cooling
• Two particle size ranges monitored
• Calibration of single location counters by use of
  portable mobile counters
• Data only being collected in first year control
  provided after first year

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Case study - recirculation setback
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Conclusions

• Energy efficiency can be achieved in cleanrooms
  without affecting contamination control
• Different strategies can be used to control
  recirculation air flow
• Demand controlled filtration offers promise
• It may be possible to optimize cleanroom air flow
  for cleanliness and energy efficiency