CLEANROOM ENERGY BENCHMARKING William Tschudi October 9, 2002 Acknowledgements: Pacific Gas and Electric Company, Rumsey Engineers

Energy Benchmarks Goal: Identify Energy Efficiency Opportunities in Cleanrooms Through Comparison of Benchmark Data

In California many industries rely on Cleanrooms: Cleanroom Energy Benchmarking

Why Benchmark High-tech Buildings? From PG&E’s perspective: PG&E saw that the market was large and growing. In California:  9400 GWH in 1997 (all high tech buildings)  4.2 million sq. ft. of operating cleanrooms  Semiconductor and Biotech exhibited high growth

Why Benchmark Cleanrooms? Owners perspective: Cleanroom owners and facility engineers saw an opportunity to determine their energy end use, compare their efficiency to others, and potentially find efficiency improvement opportunities or uncover operational problems.

Why Benchmark Cleanrooms? From a public goods perspective:  Under-served Market – Emphasis on product rather than cleanroom  Explore some Myths  Energy is not a controllable expense  We already considered efficiency  Of course its efficient, we just built it.  California would like to keep high-tech companies in the state  And the usual “save the planet” reasons

What we hope to accomplish  Identify energy efficiency opportunities  Integrate current best practices into operation and future design  Research new approaches and technologies  Reduce electrical demand to improve reliability and room for growth  Apply lessons learned in California cleanrooms in other regions and other building types

Benchmarking Process  General plan – informs participants  Enlist Benchmarking participants  Site specific plan developed  On-site measurement and data collection  Draft site report  Final participant report and anonymous version  Data and results entered in data base and summarized on web site

Metrics  Ability to compare performance regardless of process  Focus on system efficiency rather than production efficiency

Cleanroom HVAC metrics  Recirculation air system – cfm/kW  Make-up air system – cfm/kW  Exhaust system efficiency – cfm/kW  Cleanroom air changes – ACH/hr  Air velocity in cleanroom - ft/sec

Central Plant metrics  Chiller efficiency – kW/ton  Cooling tower efficiency – kW/ton  Condenser water pump efficiency – kW/ton  Chilled water pump efficiency – kW/ton

Vision - an Energy Benchmark Data Base  Anonymous reporting  Comparison of similar class systems  Comparison of components  Comparison of overall facility  No production metrics  Sufficient data to identify best practices

Cleanroom Benchmarking Some Results and observations to date

Energy End Use

Process Related Efficiency Issues  Energy intensity varies greatly depending upon the process in the room  Estimating process (heat) loads during design is a challenge so HVAC systems are often oversized  HVAC equipment sized and controlled appropriately operates more efficiently  Benchmark data can help determine realistic design loads to integrate into future projects for similar processes  It is difficult to compare process energy efficiency unless nearly identical processes are occurring

Process Loads

Energy Intensive systems Recirculation of air in cleanrooms

Recirculation Air Comparison

Recirculation Systems Design vs. Measured

Why are Design Efficiencies less than Measured Efficiencies? Design efficiency is generally understated because larger power consumption (kW) is generally assumed. (nameplate vs. actual)

Benchmarks as Design Criteria Idea! As a building owner, Why not specify a system efficiency?

Recirculation Air Comparison System Performance Target

What is the cost impact?

Fan-Filter Standardized Reporting  LBNL and the Industrial Technology Research Institute (ITRI) in Taiwan are advocating a standard test procedure for fan-filter units  The Air Movement and Control Association (AMCA) is organizing member companies to develop such a standard

Make-up Air Comparison

Make-up Air System Considerations Efficiency is influenced by:  Right sizing exhaust and pressurization  Resistance of make-up air path  Adjacency of air handler(s)  Air handler face velocity  Duct sizing and layout  Fan and motor efficiency  VFD controls

Make-up Air Design vs. Measured

Why is make-up air system efficiency lower?  Retrofitted systems with less than optimal configurations  High face velocity air handlers (due to space constraints or just inefficient design)  Older less efficient equipment (motors, fans)  Resistance due to heating and cooling coils, filters, etc.  Duct sizing and layout

Air-Change Rate Comparison

Air Change and Velocity Observations  Wide variation  All processes had acceptable yields (so why do some get by with less airflow?)  All cleanrooms were “certified”  Some velocities exceeded (and some were below) IEST recommended ranges  IEST provides recommendations based upon historical adequacy – not science based  Air velocity reduction and ceiling filter coverage are efficiency improvement opportunities

Chilled Water Systems Comparison

Chiller Comparison

Chilled Water System Observations  Surprise! Name plate chiller efficiency is different than measured  Pumping energy can be significant – over pumping sometimes occurs  Chiller performance dominates  Water Cooled chillers are more efficient  Wide variation in overall efficiency

Chilled Water System Resources Existing efficiency information for chilled water plants is under-utilized.

Chilled Water System  PG&E’s CoolTools

Non-energy benefits of Benchmarking  Operational problems revealed Controls Setpoints  Maintenance needs identified Leaks Motors, pumps, Fans Filters Chillers, boilers, etc.  Safety issues uncovered Hazardous air flow

New Construction or Retrofit Efficiency Opportunities  Air Change Rate Reduction  Temperature Set Point  Chilled Water System Pumping  Better Use of Cooling Towers  Chilled Water Temperature

More Efficiency Opportunities  Control Problems  Filter Coverage and Type of Filter  Removal of Pre-filters  Humidification  Minimize reheat  Lighting controls  Pressurization losses  Exhaust Reduction

Efficiency Considerations during Programming LBNL Cleanroom Programming Guide Provides a Way for Owners and Designers to Explore Efficient Options During the Early Stages of a Project. ProgrammingGuide-LBNL49223.pdf

Benchmarking Can Be Used to Establish Efficiency Goals  Energy Budget Total facility End use  Integrate Efficiency Targets as Design Requirements for Key Systems and Components Cfm/KW KW/ton System resistance – i.e. Pressure drop Face velocities

Benchmarking highlights some important issues  Designing and operating at higher cleanliness than is needed does not improve yield, but it does use more energy  Air change rates can be reduced in many cases  Chilled water pumping may be excessive  Flow resistance has a big effect on life cycle cost  Overcooling and reheating often represents opportunity

My Recommendation Designers (and constructors) will provide what their customers ask for. If you are an owner and want efficient systems, ask for them. If you are a designer, show owners the benefits of an efficient design – often lower first cost or early payback. Huge benefits over the life cycle.