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8/3/2019 Cleanroom Air Design (2)
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Cleanroom Air Systems Design
William Tschudi
June 22, [email protected]
510-495-2417
8/3/2019 Cleanroom Air Design (2)
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Today’s session
Plan to focus on energy efficiency of cleanroom air systems.
Concepts rather than “how to”
What does this audience want to know? What is the audience background?
What industries/institutions are represented?
New construction or retrofit?
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Session outline
Background on LBNL’s work
Examples of air system designs
Cleanliness standards
Cleanroom programming guide
Savings by design cleanroom baseline criteria
Air systems benchmark results Air change rates
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session outline (continued)
Fan-filter selection
Case Study
Summary Multi-discipline issues – whole building approach “Best practices” from initial benchmarking
The big issues
Resources
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Prior cleanroom efficiency work
Market assessment in CA
Characterization of opportunity
Design Charrettes/case studies
Energy Benchmarking
Cleanroom Programming Guide
Research “Roadmap” for CA EnergyCommission
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Prior laboratory efficiency work
Invention and
development of highperformance fume hood
Laboratory design guide
Design Intent Tool Laboratories for the 21st
Century Energy benchmarking Design assistance
Training
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Current laboratory activities
Side-by-side testing of LBNL’s highperformance fume hood
CAL/OSHA approval
Industrial demonstrations Labs 21 participation including benchmarking
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Business case -
air system optimization
Business case for energy efficiency incleanroom air systems - saving energy puts$$ directly to bottom line
Optimizing airflow may improve: Production (yields)
Research results
Regulatory oversight
Maintenance frequency And may Lower capital cost
Some improvements are low or no cost
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Types of Cleanrooms
Each cleanroom is unique – but there arecommon efficiency opportunities
Many industries and institutions use
cleanrooms for a variety of processes Many different contamination control schemes
Many different air systems designs
8/3/2019 Cleanroom Air Design (2)
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Cleanroom Arrangements
82,4 m
Sta
Return Air
Cl. 100turbulent
Air Return Shafts
Process Vacuum LineMake-Up Air Process Supply SubmainsGas Cabinets
Main Process Supply Systems
Level 1Lower Subfab
Level 2
Level 3
Scrub
Air Recirculation Concepts
Building Concepts
Dr. Manfred Renz, Anto Filipovic, Stuttgart, Feb 2000
© M+W Zander
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Recirculation concept 1:
Recirculation units/ ducted HEPA’s
Smoke-PurgeFan
S S
SS
28.6 m
Waff le SlabCleanroomUt ility SubfabDuct ed Filters Ret urn Air Outer FacadeRaised Floor
Make-up AirHandling Unit
Make-up Air
SupplyRecirculating AirHandling Uni t
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Recirculation concept 2:
fan towers/ pressurized plenum
72,0m
20.6m
Cleanroom
SubmainsChemical
Supply Systems
Process
Supply Systems
Gas Cabinets
Basement
Waff le Slab
Pump
Fan Tower
Return Air
Silencer
Cooling CoilMake-Up Air
Pressurized Plenum
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Recirculation air concept 3:
fan-filter units
Stair Case
Exhaust Stacks
Return Air
Non-Pressurized Plenum
SubmainsProcess Supply SystemsMake-Up Air Gas Cabinets
Basement
Scrubber
18.90m
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Another fan-filter scheme
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Resources
ISO standards
IEST recommended practices
Cleanroom Design, second ed., W. Whyte
LBNL Cleanroom Programming Guide
Case Studies
Benchmark results Design Intent tool
Laboratory Design Guide
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Cleanliness standards
The Institute of Environmental Sciences and
Technology (IEST) is developing a series of ISO standards that among other thingsreplace Federal Standard 209E:
ISO 14644 (1 through 8) – Cleanrooms andControlled Environments
ISO 14698 (1 through 3) - Biocontamination
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The International Organization for
Standardization (ISO)
ISO Standard 14644:
Part 1: Classification of air cleanliness
Part 2: Specifications for testing and monitoring to provecontinued compliance with ISO 14644-1
Part 3: Metrology and test methods Part 4: Design, construction and start-up
Part 5: Operations
Part 6: Terms and definitions
Part 7: Separative devices
Part 8: Classification of airborne molecular contamination
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Biocontamination standards
ISO 14698-1 General principles and methods.
ISO 14698-2 Evaluation and interpretation of biocontamination data (pending).
ISO 14698-3 Technical Report.
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Cleanliness classes
ISO 14644-1 cleanliness classes
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ISO 14644-1 formula for maximum
allowable particles
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Which class do I choose?
Cleanliness class must match the contamination
control problem Higher class than needed does not improve yield
Cleanliness class and cleanroom protocol work
together
Higher class means more energy use (airchanges/filtration/etc.)
Facility staff and process engineers must work together to define
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ISO 14644-4
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ISO 14644-4
(Its OK to save energy!)
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ISO 14644-4
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Cleanroom Programming Guide
Provides general guidance on topics often
decided during programming phase
Facilitates agreement between owner and
designer Reinforces that energy is an equally
important consideration
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Cleanroom Programming Guide
How does the guide relate to air systems design?
Minimize clean space Correct cleanliness level Optimal air change rate
Consider use of mini-environments Optimize ceiling coverage Consider cleanroom protocol and cleanliness class Minimize pressure drop (air flow resistance)
Location of large air handlers – close to end use Adequate sizing and minimize length of ductwork Provide adequate space for low pressure drop air flow Low face velocity
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Cleanroom Programming Guide
More concepts from the guide:
Use of variable speed fans Optimizing pressurization
Consider air flow reduction when unoccupied
Efficient components Face velocity
Fan design
Motor efficiency
HEPA filters ∆ P
Fan-filter efficiency
Electrical systems that power air systems
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Savings By Design
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
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Savings By Design
Cleanroom baseline criteria
Make-up air system Metric: Watts/cfm
Determine watts by measurement or from design BHP
W = BHPx7460.91
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 cfmwhere annual cfm = .7 x design cfm
Run redundant stand-by units in parallel
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Savings By Design
Cleanroom baseline criteria
Additional criteria for:
Chilled water system Hot water production
Compressed air
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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
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LBNL energy benchmark ing
Prior Benchmarking Studies available at:
http://ateam.lbl.gov/cleanroom/benchmarking/results.html
LBNL obtained energy benchmarks for fourteencleanrooms. Energy end-use was determined alongwith energy efficiency of key systems.
Energy efficiency recommendations were providedto each facility.
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Adding benchmarks
Additional energy benchmarks:
In the mid-ninety’s Sematech benchmarked
fourteen semiconductor cleanrooms aroundthe world. Similar metrics were obtainedalthough measurement techniques may have
differed.
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CA energy benchmarking
Currently:
Additional energy benchmarking is beingperformed in California with an emphasis onair systems .
Benchmarking sites are being sought –
4 to 6 cleanrooms.
Labs 21 is also collecting benchmarks.
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Benchmarking benefits
Establish Baseline to Track Performance
Over Time
Prioritize Where to Apply Energy Efficiency
Improvement Resources Identify Maintenance and Operational
Problems
Operational Cost Savings
Identify Best Practices
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Plus non-energy benefits
Reliability Improvement Controls
Setpoints
Maintenance identification Leaks
Motors, pumps, Fans
Filters
Chillers, boilers, etc.
Safety issues uncovered Hazardous air flow
Chilled Water Pump Power
60
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Chilled Water Pump Power
0
10
20
30
40
50
60
12:00
10/12
12:15
10/12
12:30
10/12
12:45
10/12
13:00
10/12
13:15
10/12
13:30
10/12
13:45
10/12
14:00
10/12
Time: Hour, Day; October 2000
P o w
e r ( k W )
0
10
20
30
40
50
60
12:0010/11
12:0010/12
12:0010/13
12:0010/14
12:0010/15
12:0010/16
12:0010/17
Time: Hour, Day; October 2000
P o w e r ( k W )
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System efficiency vs.
production efficiency
Metrics allow comparison of air systemefficiency regardless of process – e.g.cfm/kW or kW/cfm
Production metrics can mask inefficientsystems – e.g. kW/cm2 (of silicon) or
kW/lb of product
Process electrical load intensity
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Process electrical load intensity(heat load)
Process Load Intensity Comparison
0
10
20
30
40
50
60
W /
s f
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Energy end-use
Facility 3
Hot Water &
Steam
7%
Office
(Lights, Plugs)
9%
Process Utilities
17%
Cleanrooom
Lights
1%
Process
35%
Other Misc.
6%
Cleanroom Fans
11%
Total Chilled
Water
18%
Facility 1
Hot Water &
Steam
23%
Chilled Water
19%
Cleanroom Fans
16%
Other Misc.
8%
Process
13%
Cleanrooom
Lights
1%Compressed Air &
Process Vacuum
6%
Office
(Lights, Plugs)
9%
Facility 2
Hot Water, Steam
and Cafeteria
17%
Total Chilled
Water
20%
Cleanroom Fans
Other Misc.
10%
Process
9%
Cleanrooom
Lights
1%
Compressed Air
7%
Office
(Lights, Plugs)
9%
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What are the costs?
Utility bills from one case study:
Billing days Dollars
Elec 368 38,084,148 kWh $2,549,330
Gas 371 70,203 therms $43,715
approx 20,000 sq ft cleanroom in 68,000 sq ft buildingw/ $.065 ave. per kW!
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Energy intensive systemsair systems in cleanrooms
Process Tools
34%
Exhuast Fans
7%
Nitrogen Plant
7%
Recirculation and
Make-up Fans
19%
Chillers and Pumps21%
Support
3%Process Water
Pumping
4%
DI Water
5%
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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
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Recirculation air comparison
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
Fac. A
Class 10
Press.
Plen.
Fac. A
Class 100
Press.
Plen.
Fac. B.1
Class 100
Ducted
Fac. B.1
Class 100
FFU
Fac. B.2
Class 100
Ducted
Fac. B.2
Class 100
FFU
Fac. C
Class 100
Press.
Plen.
Fac. D
Class 10
Ducted
Fac. E
Class 100
FFU
Fac. E
Class 100
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10k
C F M
/ k W ( h i g h e r i s b e t t e r )
Averages (cfm / kW)FFU: 1664
Ducted: 1733
Press urized Plenum: 5152
Average 3440
Recirculation efficiency
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Recirculation efficiency –
Sematech study
Recirculation Efficiencies
0
500
1000
1500
2000
2500
3000
3500
4000
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Facility
C F M / k W
Average 1953 cfm/ kW
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Using benchmarks to set goals
Building Owners and Designers can use
benchmark data to set energy efficiencygoals.
8/3/2019 Cleanroom Air Design (2)
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Goal setting and benchmarking
Facility and End Use “Energy Budgets”
Efficiency Targets or Design Requirements forKey Systems and Components
Cfm/KW
KW/ton
System resistance – i.e. Pressure drop
Face velocities
Etc.
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Recirculation air comparison
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
Fac. A
Class 10
Press.
Plen.
Fac. A
Class
100
Press.Plen.
Fac. B.1
Class
100
Ducted
Fac. B.1
Class
100
FFU
Fac. B.2
Class
100
Ducted
Fac. B.2
Class
100
FFU
Fac. C
Class
100
Press.Plen.
Fac. D
Class 10
Ducted
Fac. E
Class
100 FFU
Fac. E
Class
100
Press.Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class
10k
C F M /
k W ( h
i g h e r i s b e t t e
r )
Averages (cfm / kW)FFU: 1664
Ducted: 1733
Pressurized Plenum: 5152
System
PerformanceTarget
Hypothetical operating
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yp p gcost comparison
Annual energy costs - recirculation fans
(Class 5, 20,000sf)
-
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
A n n u a l
k W h C o s t b a s e d o n $
0 . 1 0 / k W h , $
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0
200
400
600
800
1000
1200
1400
1600
1800
2000
Facility AClass 10
Facility AClass
100
FacilityB.1
Class
100
FacilityB.2
Class 10
FacilityB.2
Class
100
Facility CClass
100
Facility DClass 10
Fac.E.1.1
Class
100
Fac.E.1.2
Class
100
Fac. F.2Class 10
*
Fac. F.3Class 10
Fac. F.1Class 10
C F M / k W ( h i g
h e r i s b e t t e r )
Make-up system comparison
Average 972
k ff
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Make-up system efficiency
Sematech studyMake-up Air Energy Efficiency
0
500
1000
1500
2000
2500
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Facility
c f m / k W
Average 946
M k ffi i
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Make-up system efficiency
Adjacency of air handler(s) to cleanroom
Resistance of make-up air path
Pressurization/losses/exhaust
Air handler face velocity
Coil Pressure Drop
Duct/plenum sizing and layout
Fan and motor efficiency
Variable Speed Fans
R i l t d i t
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Recirculated air system
Air changes per hour
0
100
200
300
400
500
600
700
Fac. A
Class 10
Press.
Plen.
Fac. A
Class
100
Press.
Plen.
Fac. B.1
Class
100
Ducted
Fac. B.1
Class
100
FFU
Fac. B.2
Class
100
Ducted
Fac. B.2
Class
100
FFU
Fac. C
Class
100
Press.
Plen.
Fac. D
Class 10
Ducted
Fac. E
Class
100 FFU
Fac. E
Class
100
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class 10
Press.
Plen.
Fac. F
Class
10k
A i r C h a n
g e s p e r H o u r
Cleanroom benchmarking
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Cleanroom benchmarking
highlights some important issues Contamination control can often be achieved with
reduced air change rates Cleanliness ratings are often higher than needed
Criteria based upon rules of thumb should be
examined (90ft/min, air changes, etc.)
Overcooling and subsequent reheat can be excessive
Many owners don’t know how they compare
Ai h d l it h i
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Air-change and velocity choices
Not an exact science…
IEST provides recommended recirculationair-change rates
Variable speed fans (start low with ability to
increase)
Ceiling coverage
Pressurization/losses
Cleanroom protocol
Recirculated air change rates
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Recirculated air change rates
ISO class 5LBNL Cleanroom Benchmark Data
ISO Class 5 (Class 100) Cleanrooms
0
100
200
300
400
500
600
Facility A Facility B Facility C Facility D Facility E Facility F Facility G Facility H
M e a s u r e d
A i r C h a n g e R a t e ( A
C / h o u r )
TYPICAL RECOMMENDED DESIGN RANGE
Recommended ranges from Cleanroom Design, second ed., W. Whyte
Make up/ exhaust air change rates
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Make-up/ exhaust air-change rates
Make-up and exhaust air-change rates were not
benchmarked Typically driven by code and process requirements
and so are industry/process specific
Process exhaust optimization (and resultingdecrease in conditioned make-up air) is anopportunity in many cleanrooms
Personnel safety is no. 1 but there is room tooptimize
Ceiling filter coverage
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Ceiling filter coverage
Also not an exact science…
ISO class 1-4 100%
ISO class 5 75-100%ISO class 6 30-50%
ISO class 7 15-20%
ISO class 8 5-10%
Within the system
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Within the system…
Efficiency choices can be made in many areas
System pressure drop – face velocity,duct velocity, chases, plenums,adjacency, layout
Air change rates
Ceiling coverage
Equipment – fans, motors, controls,filters, floor systems
Flow visualization
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Flow visualization
CFD Models and other
visualizationtechniques can helpsolve problems
Fan filter unit selection
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Fan-filter unit selection
How does one select an energy efficient
fan-filter unit?
A. Rely on sales representative recommendation
B. Use published manufacturers data
C. Recommendation from peers
D. Use your company’s standard
E. None of the above
Fan filter unit selection
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Fan-filter unit selection
None of the above Manufacturers report performance in various ways for
various operating conditions – no apples to applescomparison
A standard method of testing and reporting is being
developed through LBNL and IEST
For now, either specify that performance should bedocumented in accordance with the draft procedure, or
specify your conditions and request bid information in aconsistent manner.
Utilities are interested in developing incentive baselines.
Fan-filter unit selection
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Fan-filter unit selection
Standardized testing will allow
apples to apples comparison
Energy performance index
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Energy performance index
(for a given airflow rate)
0
5
10
15
20
25
30
0% 20% 40% 60% 80% 100%
Percentile
F F
U P o w e r I n t e n s i t y ( W p
e r m
3 / m i n )
Pressure vs airflow speed
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Pressure vs. airflow speed
Airflow Speed at FFU Exit (m/s)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
F F U P r e s s ur eR
i s e ( P a )
0
100
200
300
400
500
600
700
FFU001
FFU002
FFU003FFU007
FFU009
FFU010FFU011
FFU013
FFU018FFU027
Total pow er efficiency
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Total pow er efficiency
90 ft/min60 ft/min
Airflow Speed at FFU Exit (m/s)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
T o t al P ow er E
f f i c i en c y (
0
5
10
15
20
25
30
35
FFU001
FFU002FFU003
FFU007
FFU009
FFU010
FFU011
FFU013
FFU018FFU027
Flow/ kW comparison
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Flow/ kW comparison
Average Outlet Velocity, m/s
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
F
l o w I n t e n s i t y , C M M / k W
0
20
40
60
80
100
120
140
160
180
200FFU A
FFU B
FFU CFFU D
FFU E
FFU F
FFU G
FFU H
FFU I-1
FFU I-2FFU J
FFU K
FFU L
FFU M
FFU N
ERL FFU (AC)
ERL FFU (ACS)
ERL FFU (DC)
FFU P-1
FFU P-2
4'X2' FFU2800 cfm/kW
Source: Industrial Technology Research Institute, Taiwan
Case study
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Case study
Good news/Bad news
A night time recirculationsetback was successfully
utilized and dramaticallysaved energy
Unfortunately air changerates were very high and aducted system was used
Ducted HEPA’s create
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more pressure drop
Case study – recirculation setback
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y
R A H - Z P o w e r
0 . 0 0
5 . 0 0
1 0 . 0 0
1 5 . 0 0
2 0 . 0 0
2 5 . 0 0
/ 0 4 0 :
0 0
3 / 1 6 / 0
4 0 : 0 0
3 / 1 7 / 0
4 0 : 0 0
3 / 1 8 / 0
4 0 : 0 0
3 / 1 9 / 0
4 0 : 0 0
3 / 2 0 / 0
4 0 : 0 0
3 / 2 1 / 0
4 0 : 0 0
3 / 2 2 /
D a t e
C h a n . 1
C h a n . 2
C h a n . 3
T o t a l k W
Based Solely on
Timeclock, 8:00 PM -6:00 AM setback
No reported process
problems or pushback 60% – 70% Power
Reduction on turndown
Case study – recirculation setback
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y
Annual fan savings from daily and weekend
setback:1,250,000 kWhapproximately $138,000
Cooling load reduction when setback:
234 kW65 tons
Case study - recommendation
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y
Air change rates exceeded IEST
recommendations during daylight operation Further large reductions in energy use are
possible by reducing air change rates andshould not affect the process occurring inthe room
Best practices/ conclusions
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p
Sizing of air systems:
Minimize clean space
Correct classification for contamination problem
Air change rate
Minimize pressure drop
VFD’s can help
Exhaust minimization
Best practices observed
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Factors affecting air flow resistance
duct size (oversized is good) low face velocity
minimize length of duct/air path
efficient, low pressure drop filters
raised floor air resistance (% open)
size and placement of return air chases Use of plenums
Integrated approach
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For new and retrofit construction, integration
of Mechanical, Electrical, and Architecturaldisciplines is critical. Examples: Sizing systems for real loads (mechanical and electrical
interface) Low pressure drop air systems (mechanical (HVAC) and
architectural interface
Ability to modulate flows (mechanical and controls)