Cleanrooms: Two promising research areas William Tschudi – LBNL Peter Rumsey – Rumsey Engineers November 4, 2004

Two promising research areas  Demand controlled filtration  Fan-filter unit energy performance

Demand controlled filtration The goal: Match airflow to cleanliness. Through real-time monitoring of cleanliness in the cleanroom, allow lower airflow unless excessive numbers of particles are detected. If particle counters record increased particulates, airflow is automatically increased through variable speed drives on recirculation fans.

Demand controlled filtration – pilot study  Pilot study in LBNL cleanroom confirmed feasibility  Particle sizes of concern were studied  Fan speed controlled by particle counts  Optimum airflow is not too high or too low  Location and numbers of particle counters need additional study

Demand controlled filtration – demonstrations  LBNL is planning a demonstration to use the concept in an operating industrial cleanroom  Cornell University will be demonstrating the concept in its new Duffield Hall cleanroom

Demand controlled filtration – other options  Turndown of airflow can be achieved through simple controls: Manual Timers Occupancy sensors Combinations of these  An informal survey of the ASHRAE TC 9.11 committee (cleanspaces) found a that number of cleanrooms are currently turning down airflow

Fan-filter units The Need: A standard method of testing and reporting performance so that owners and designers can select units based upon performance – not hype. Performance can include: energy use, noise, vibration, filtration effectiveness, etc.

The players  Industrial Technology Research Institute (ITRI)  Institute of Environmental Sciences and Technology (IEST)  Air Movement and Control Association International (AMCA)  SEMATECH International  FFU manufacturers and end users  CA Energy Commission and public utility companies

FFU’s are popular  Fan-filter units are increasingly specified in cleanrooms in various industries  Fan-filter units are used in mini- environments  Many manufacturers produce fan-filter units for use in cleanrooms

Why the need for standardized reporting?  Benchmarking and testing in Taiwan has shown wide variations in performance  Fan-Filter manufacturers report performance in different ways  Cleanroom Owners and Designers need a standard comparison  Incentive programs need a baseline and standard comparison  Serious cost and energy efficiency implications

11 Recirculation systems Average 3440 Average 1953 LBNL Data Sematech Data

Comparing fan-Filter units  If fan-filters are desired, how can their energy efficiency be determined?  Confusing claims and catalogue information: Watts/fpm Noise distance) for single unit vs. many External static Flow area

FFU energy efficiency Source: Rumsey Engineers

Taiwan test data

Test procedure development  LBNL has developed a draft test procedure addressing energy performance  Draft procedure available on LBNL website – comments welcome

Test procedure considerations  Available total pressure  Air flow  Quantity/Variable flow  Uniformity  Sensible cooling (if provided)  Total power consumption  Noise and vibration levels  Filter area  Size of FFU (2’ x 4’, 4’ x 4’, etc.)

Test arrangements Similar to testing large fans

Establishing a baseline  PG&E is sponsoring a test of the test procedure at their test facility  CA Energy Commission Public Interest Energy Research (PIER) is sponsoring testing to establish baseline  If you can loan units for testing let us know

Expected outcomes  An IEST recommended practice will be issued  CA public utilities will establish baseline and include in incentive programs  Owners and designers will have a standard way to compare performance  Owners can evaluate first cost vs operating cost  Improvement in performance will follow

Energy-efficient Fan-filter Units Design Considerations Contour of inlet airflow path Baffles to direct flow and deaden sound Motor efficiency – AC or DC Fan efficiency Clearances Filter media Depth of box Filter area Controls More efficient units have considered all of this

Questions? Thank you!