November 2004

.

Top Ten Approaches to Lowering Fan Energy in Cleanrooms

Rumsey Engineers, Inc.

First the Basics

Fan Power = CFM x Pressure Drop (in inches) 6345 x Fan Eff x Motor Eff

Rumsey Engineers, Inc.

Ten – Use Best-in-class Motors

Use Motor Master Software

Rumsey Engineers, Inc.

Nine – Use Efficient Fans

Rumsey Engineers, Inc.

Eight – Use Variable Speed Drives

Thank you cube law!

Often fan systems are turned down after startup. This is done most efficiently and most simply with VSDs.

Rumsey Engineers, Inc.

Seven – Select a Low Pressure Drop System

Recirculation Air Handling Systems in Cleanrooms Pressurized Plenum Ducted Hepa Fan Filter Units

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

Fac. AClass 10Press.Plen.

Fac. AClass100

Press.Plen.

Fac. B.1Class100

Ducted

Fac. B.1Class100 FFU

Fac. B.2Class100

Ducted

Fac. B.2Class100 FFU

Fac. CClass100

Press.Plen.

Fac. DClass 10Ducted

Fac. EClass

100 FFU

Fac. EClass100

Press.Plen.

Fac. FClass 10Press.Plen.

Fac. FClass 10Press.Plen.

Fac. FClass 10Press.Plen.

Fac. FClass10k

CF

M /

kW

(h

igh

er i

s b

ette

r)

Averages (cfm / kW)FFU: 1664

Ducted: 1733Pressurized Plenum: 5152

Rumsey Engineers, Inc.

Six – Use Low Face Velocity Air Handlers

Rumsey Engineers, Inc.

Five – Use Demand Controlled FiltrationTimeclock, occupancy sensor or particle counter

RAH-Y Power

0

5

10

15

20

25

30

35

3/19/04 0:00

3/19/04 12:003/20/04 0:00

3/20/04 12:003/21/04 0:00

3/21/04 12:003/22/04 0:00

3/22/04 12:003/23/04 0:00

Date

kW

40% setback = 70% energy savings

Rumsey Engineers, Inc.

Four – Select Most Efficient FFUs

FFU Performance is a function of: - Airflow (CFM) – NOT Velocity- Filter Efficiency- External Static

Rumsey Engineers, Inc.

Three – Exhaust Optimization

Courtesy of Northwest Energy Efficiency Alliance Website (www.nwalliance.org)

Wet Bench - 574 to 254 scfm

Vertical Furnace - 628 to 474 scfm

• Turn off canopy and snorkel when not in use• Lower Exhaust Air Change Rates when unoccupied• Minimum Air Change Rates – 12 ACH, 10 ACH, 8 ACH, 6 ACH??

Rumsey Engineers, Inc.

Two- Use Mini Environments

Can be coupled with reduction in overall cleanliness rating

Wafertech

Rumsey Engineers, Inc.

One - Select Appropriate Air Change Rate

Cleanroom Benchmarking 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

Mea

sure

d A

ir C

han

ge

Rat

e (A

C/h

ou

r)

TYPICAL RECOMMENDED DESIGN RANGE

Results when implemented as a system

Rumsey Engineers, Inc.

Successes – Air System Optimization

Rumsey Engineers, Inc.

Air System Optimization – 75% Savings

Same Facility, Equivalent BaysRecirculation Air Handler System Energy Cost Comparison ($/sf/year)

$-

$2.00

$4.00

$6.00

$8.00

$10.00

$12.00

$14.00

$16.00

$18.00

$20.00

Area 1 (Fan Filter Units withSensible Air Handler)

Area 2 (Rumsey EngineersDesign - Presurized Plenum with

Air Handler)

Area 3 (Rumsey EngineersDesign - Pressurized Plenum with

Plenum Fans)

(US

$/sf

/yea

r)

Rumsey Engineers, Inc.

To Summarize….

10 – Use best in class motors 9 – Use efficient fans 8 – Use VSDs 7 – Select a low pressure drop system 6 – Use low face velocity air handlers 5 – Use demand controlled ventilation – Timeclock or particle sensor 4 – Select most efficient FFUs 3 – Exhaust Optimization 2 - Use Mini Environments 1 – Select appropriate air change rate