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Energy Benchmarks. Goal: Identify Energy Efficiency Opportunities in Cleanrooms Through Comparison of Benchmark Data. Cleanroom Energy Benchmarking. In California many industries rely on Cleanrooms:. Why Benchmark High-tech Buildings?. From PG&E’s perspective:

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Energy benchmarks

Energy Benchmarks


Identify Energy Efficiency Opportunities in Cleanrooms Through Comparison of Benchmark Data

Cleanroom energy benchmarking

Cleanroom Energy Benchmarking

  • In California many industries rely on Cleanrooms:

Why benchmark high tech buildings

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

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 cleanrooms1

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

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

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



  • Ability to compare performance regardless of process

  • Focus on system efficiency rather than production efficiency

Cleanroom hvac metrics

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

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

Vision - an Energy BenchmarkData 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

Cleanroom Benchmarking

Some Results and observations to date

Energy benchmarks

Energy End Use

Energy end use

Energy End Use

Process related efficiency issues

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

Process Loads

Energy intensive systems

Energy Intensive systems

Recirculation of air in cleanrooms

Recirculation air comparison

Recirculation Air Comparison

Energy benchmarks

Recirculation Systems

Design vs. Measured

Energy benchmarks

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

Benchmarks as Design Criteria

Idea! As a building owner,

Why not specify a system efficiency?

Recirculation air comparison1

Recirculation Air Comparison

System Performance Target

What is the cost impact

What is the cost impact?

Fan filter standardized reporting

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

Energy benchmarks

Make-up Air Comparison

Make up air system considerations

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

Energy benchmarks

Make-up Air

Design vs. Measured

Why is make up air system efficiency lower

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

Energy benchmarks

Air-Change Rate Comparison

Air change and velocity observations

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

Energy benchmarks

Chilled Water Systems Comparison

Energy benchmarks

Chiller Comparison

Chilled water system observations

Chilled Water System Observations

  • Wide variation in overall efficiency

  • 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

Chilled water system resources

Chilled Water System Resources

Existing efficiency information for chilled water plants is under-utilized.

Chilled water system

Chilled Water System

  • PG&E’s CoolTools

Non energy benefits of benchmarking

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

New Construction or RetrofitEfficiency Opportunities

  • Air Change Rate Reduction

  • Temperature Set Point

  • Chilled Water System Pumping

  • Better Use of Cooling Towers

  • Chilled Water Temperature

More efficiency opportunities

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

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.


Benchmarking can be used to establish efficiency goals

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

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

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.

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