CLEANROOM ENERGY BENCHMARKING William Tschudi October 9, 2002
Acknowledgements: Pacific Gas and Electric Company, Rumsey
Engineers [email protected] Slide 2 Energy Benchmarks Goal:
Identify Energy Efficiency Opportunities in Cleanrooms Through
Comparison of Benchmark Data Slide 3 In California many industries
rely on Cleanrooms: Cleanroom Energy Benchmarking Slide 4 Why
Benchmark High-tech Buildings? From PG&Es 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 Slide 5
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. Slide 6 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 Slide 7 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 Slide 8
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 Slide 9 Metrics Ability to compare
performance regardless of process Focus on system efficiency rather
than production efficiency Slide 10 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 Slide 11 Central Plant metrics Chiller
efficiency kW/ton Cooling tower efficiency kW/ton Condenser water
pump efficiency kW/ton Chilled water pump efficiency kW/ton Slide
12 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 Slide 13 Cleanroom Benchmarking
Some Results and observations to date Slide 14 Energy End Use Slide
15 Slide 16 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 Slide 17
Process Loads Slide 18 Energy Intensive systems Recirculation of
air in cleanrooms Slide 19 Recirculation Air Comparison Slide 20
Recirculation Systems Design vs. Measured Slide 21 Why are Design
Efficiencies less than Measured Efficiencies? Design efficiency is
generally understated because larger power consumption (kW) is
generally assumed. (nameplate vs. actual) Slide 22 Benchmarks as
Design Criteria Idea! As a building owner, Why not specify a system
efficiency? Slide 23 Recirculation Air Comparison System
Performance Target Slide 24 What is the cost impact? Slide 25
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 Slide 26 Make-up Air Comparison Slide 27
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 Slide 28
Make-up Air Design vs. Measured Slide 29 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 Slide 30 Air-Change
Rate Comparison Slide 31 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 Slide 32 Chilled Water
Systems Comparison Slide 33 Chiller Comparison Slide 34 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
Slide 35 Chilled Water System Resources Existing efficiency
information for chilled water plants is under-utilized. Slide 36
Chilled Water System PG&Es CoolTools
http://www.hvacexchange.com/cooltools/ Slide 37 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
Slide 38 Slide 39 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 Slide 40 More Efficiency Opportunities Control
Problems Filter Coverage and Type of Filter Removal of Pre-filters
Humidification Minimize reheat Lighting controls Pressurization
losses Exhaust Reduction Slide 41 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. http://ateam.lbl.gov/cleanroom/guide/
ProgrammingGuide-LBNL49223.pdf Slide 42 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 Slide 43 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 Slide 44 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.
