1. Cleanrooms: Can They Be Energy Efficient? William Tschudi – LBNL Peter Rumsey – Rumsey Engineers November 4, 2004

2. Overview 9:30-9:45Introduction and research overview 9:45-10:30Energy benchmarking findings Savings-by-design cleanroom efficiency baselines 10:30-10:45Break 10:45-11:30Group discussion of successful efficiency projects and barriers 11:30-12:00Top ten air system opportunities 12:00-1:00Lunch 1:00-1:30Demand controlled filtration and Standardized testing and reporting of fan-filter unit performance 1:30-2:15Low hanging fruit – opportunities in cleanrooms 2:15-2:30Q&A, Wrap-up, Discussion What is the audience background? What industries/institutions are represented?

3. 3 Cleanrooms Healthcare Data Centers Laboratories Energy intensive high-tech buildings

4. Wide breadth of activities

5. Prior cleanroom research  Roadmap for California Energy Commission  Cleanroom Programming Guide  Benchmarking 14 cleanrooms  Case study reports  California market assessment  Laboratory Design Guide

6.  Benchmarking and Best Practices  Fan-filter unit test procedure  Demand-controlled filtration  Minienvironment efficiency Cleanroom Measured Electricity End-use Current cleanroom activities

7. Energy Benchmarking  Improves business performance - saving energy puts $$ directly to the bottom line  Optimizing facility systems may improve:  Safety  Reliability  Production (yields) or Research results  Maintenance and operation  Energy performance  And may Lower capital cost  Some improvements are low or no cost

8. Benchmarking benefits  Establish baseline to track performance over time  Enable comparisons to others  Prioritize where to apply resources  Best practices become apparent  Efficiency techniques can be applied to future projects

9. Benchmarking- additional benefits  Reliability Improvement Controls Setpoints  Maintenance Leaks Motors, pumps, Fans Filters Chillers, boilers, etc.  Safety Hazardous air flow

10. What are the stakes? Utility bills from one case study: Billing daysConsumptionDollars Elec 36838,084,148 kWh $2,549,330 Gas 37170,203 therms $43,715 approx 20,000 sq ft cleanroom in 68,000 sq ft building w/ $.065 ave. per kW

11. LBNL energy benchmarking  Energy end-use was determined along with energy efficiency of key systems.  Energy efficiency recommendations were provided to each facility. These are being used to identify “best practices”  Prior benchmarking results available at: http://ateam.lbl.gov/cleanroom/benchmarking/ results.html

12. Energy end-use

13. Energy intensive systems We examine energy intensive systems Representative end-use

14. System efficiency vs. production efficiency  Metrics allow comparison of air system efficiency regardless of process – e.g. cfm/kW or kW/cfm  Production metrics can mask inefficient systems – e.g. kW/cm 2 (of silicon) or kW/lb of product

15. Cleanroom air system metrics  Air systems – cfm/kW Recirculation Make-up Exhaust  Cleanroom air-changes – ACH/hr Recirculated, filtered air Outside air (make-up and exhaust)  Average room air velocity- ft/sec

16. 16 Recirculation systems Average 3440 Average 1953 LBNL Data Sematech Data

17. Recirculation system hypothetical operating cost comparison

18. 18 Make-up air systems Average 972 Average 946 LBNL Data Sematech Data

19. Factors affecting make-up system efficiency  Resistance of make-up air path  Air handler/coil face velocity  Coil Pressure Drop  Duct/plenum sizing and layout  Adjacency of air handler(s) to cleanroom  Filters  Fans  Fan and motor efficiency  Variable Speed Fans  Pressurization, losses, and exhaust

20. Air-change rates and air velocity  The Institute of Environmental Sciences and Technology (IEST), and others, provide recommended recirculation air-change rates  Many large companies set their own criteria  Studies have shown that more airflow is not necessarily better  Philosophy of ceiling filter coverage varies  Pressurization/losses can have a large impact  Air changes and cleanroom protocol are both important Not an exact science…

21. Recirculation air-change rates and average velocities

22. Ceiling filter coverage – achieving the same cleanliness level

23. Chilled water systems efficiencies

24. 24 Standby generation loss  Several load sources  Heaters  Battery chargers  Transfer switches  Fuel management systems  Heaters alone (many operating hours) use more electricity than ever produced by the generator (few operating hours) Opportunity may be to reduce or eliminate heating, batteries, and chargers

25. Component efficiencies also vary 2800 cfm/kW Source: Industrial Technology Research Institute, Taiwan Fan-Filter Units

26. Measured UPS efficiency

27. Case study Good news/Bad news Recirculation setback at night and on weekends was successfully utilized and dramatically saved energy Unfortunately air-change rates were higher than they needed to be and the system had a high pressure drop (resistance to airflow)

28. Ducting to HEPA filters creates large pressure drop

29. Case study – recirculation setback  Setback based solely on time clock, 8:00 PM-6:00 AM  No reported process problems or concerns from process engineers  60% – 70% power reduction on turndown

30. Recirculation setback – energy savings  Annual fan savings from daily and weekend setback: 1,250,000 kWh approximately $138,000  Cooling load reduction when setback: 234 kW 65 tons

31. Case study - recommendation Air-change rates exceeded IEST recommendations during daylight operation and were well above recommended minimums during setback. Further large reductions in energy use are possible by reducing air change rates and should not affect the process within the room.

32. ISO 14644-4 (international standard for design and construction of cleanrooms) (Its OK to save energy!)

33. What are we learning from cleanroom benchmarking?  Systems are often oversized  Contamination control can be achieved with reduced air change rates  Cleanliness ratings are often higher than needed  Rule of thumb criteria should be examined (e.g.: 90ft/min, air changes, filter coverage etc.)  Overcooling and subsequent reheat can be excessive  Chilled water pumping is often an opportunity  Chilled water temperature often is lower than needed

34. Using benchmarks to set goals Building owners and designers can use benchmark data to set energy efficiency goals. Cfm/KW KW/ton System resistance – i.e. pressure drop Air handler face velocities Others

35. Recirculation system performance System Performance Target

36. Statewide Savings-By-Design baselines Cleanroom baseline criteria Recirculation system Metric: Watts/cfm Determine watts by measurement or from design BHP W = BHPx746 0.91 Determine flow from balance report or design documents Baseline value is 0.43 W/cfm (2,325 cfm/kW) Annual savings=(Baseline - Efficiency metric) x Annual cfm

37. Savings-By-Design baselines Cleanroom baseline criteria Make-up air system Metric: Watts/cfm Determine watts by measurement or from design BHP W = BHPx746 0.91 Determine flow from balance report or design documents Baseline value is 1.04 W/cfm (961 cfm/kW) Annual savings=(Baseline - Efficiency metric) x Annual cfm where annual cfm =.7 x design cfm

38. Savings-By-Design baselines Additional cleanroom baseline criteria  Chilled water system  Hot water production  Compressed air

39. Savings-By-Design Five largest energy savings opportunities:  Low face velocity in air handlers  Variable speed chillers  Free cooling for process loads  Dual temperature cooling loops  Recirculation air setback

40. Best practices/conclusions  Clean space should be minimized  Better load determination is needed - actual load (not nameplate) and efficient strategies for load growth  Cleanliness classification needs to match contamination control problem (cleaner is not necessarily better)  Air-change rates can be optimized and save energy  Low pressure drop systems (low flow resistance) are much more efficient  Optimizing exhaust is an opportunity  There is no silver bullet – many strategies combined will provide best performance The answer is yes – cleanrooms can be more energy efficient!

41. Questions? Thank you! http://hightech.lbl.gov