November 2004

Low Hanging FruitLow Cost Energy Efficiency Opportunities in Cleanrooms

Free Cooling

Psychrometric Chart for San Jose

San Jose, CAWYE Psychrometric Chart

RH = 20%

RH

= 4

0%

RH

= 6

0%

RH

= 8

0%

h = 20 Btu/lb ¾ ¾ ®

h = 30 Btu/lb ¾ ¾ ®

h = 40 Btu/lb ¾ ¾ ®

h = 50 Btu/lb ¾ ¾ ®

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0.0160

0.0180

0.0200

0.0220

0.0240

0.0260

0.0280

0.0300

30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

Dry Bulb Temperature (F)

Hu

mid

ity

Rat

io (

lbs

H2O

per

lb

s d

ry a

ir)

50°F Wetbulb Line

3,200 Hours Minimum

Free Cooling Configuration #2 - Series PCW Only

M

M

M

Comparison of Low Temperature and Medium Temperature Chillers

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

200 300 400 500 600 700 800 900 1000

Tons

Eff

icie

nc

y (

kW

/to

n) 1000 Ton Chiller operating at 42 F

CHWS Temp and 70 F CWS Temp

1000 Ton Chiller operating at 60 F CHWS Temp and 70 F CWS Temp

An Innovative Layout Possibility

1100 BELL CHILLED WATER PLANT

VFDCHILLER

NON-VFDBACKUPCHILLER

VFDCHILLER

40-45°F LOOP 50-55°F LOOP

Dual Temperature Chilled Water Plant

Pumping Problems

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Existing Best Practice

Eff

icie

nc

y k

W/t

on Cooling Tower

Condenser Water PumpChilled Water PumpChiller

Current Primary - Secondary Pumping

VFD Chillers

High Efficiency Chillers with and without Variable Speed Drives

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0% 20% 40% 60% 80% 100%

Percent Load

Ch

ille

r E

ffic

ien

cy

(k

W/t

on

)

Chiller without VSD

Chiller with VSD

Data Provided by York for 1000 ton Chillers Running at 42 deg F CHWS and 65 deg F CWS

Impact of Varrying Condenser Water Temperatures for 1000 Ton Chiller without VFD (CHWS = 42 Deg F)

0.4

0.5

0.6

0.7

0.8

0.9

1

200 300 400 500 600 700 800 900 1000

Load (Tons)

Eff

icie

nc

y (

kW

/To

n)

85F

80F75F

70F65F60F

Lower Chiller Condenser Water Temperatures

Impact of Varrying Condenser Water Temperatures for 1000 Ton Chiller with VFD (CHWS = 42 deg F)

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200

Load (Tons)

Eff

icie

nc

y (

kW

/To

n)

85F

80F

75F70F65F60F

Use Variable Speed Drives

0

20

40

60

80

100

0 20 40 60 80 100

Air Flow (%)

Fan

Po

wer

(%

)

Inlet Guide Vanes

Variable Frequency Drive

Theoretical Minimum FanPow er

Good for fans, even better for pumps, which are typically controlled and balanced by throttling

Remove Booster Pumps and close bypasses

Close 3-way Valves

B8 has a highly variable load due to air washer capacity, yet a constant flow

878 Flow

0

500

1000

1500

2000

2500

3000

5/17/0216:33

5/17/0217:02

5/17/0217:31

5/17/0218:00

5/17/0218:28

5/17/0218:57

5/17/0219:26

5/17/0219:55

5/17/0220:24

GP

M

878 Building Load, Tons

0

100

200

300400

500

600

700

5/17/0216:33

5/17/0217:02

5/17/0217:31

5/17/0218:00

5/17/0218:28

5/17/0218:57

5/17/0219:26

5/17/0219:55

5/17/0220:24

Aim for Highest Possible CHW Delta T

Pumping Energy Is Dramatically Reduced as Coil Temperature Rise Is Increased

-

50

100

150

200

250

300

350

400

450

500

4 6 8 10 12 14 16 18

Chilled Water Temperature Rise Through Coil

Re

lati

ve

Pu

mp

ing

En

erg

y (

10

0 a

t 1

0 d

eg

F)

Exhaust Optimization

Exhaust Reduction Amount

Annual Electricity Savings (kWh)

Annual Gas Savings (Therms)

Annual Energy Cost Savings ($)

5,000 cfm 223,400 24,350 $20,800

10,000 cfm 440,000 48,700 $41,200

20,000 cfm 854,000 97,400 $81,300

Tool exhaust can be optimized via tracer gas or other accepted test methods

In most cases tool exhaust can be reduced 10 – 50% Fume containment testing required for optimization also verifies

worker safety

Case Study Savings Opportunity:

When replacing broken or worn out equipment Select the most efficient option

Efficiency often has little relationship to cost of equipment E.G. -----

Pumps Electric Motors Fans etc.

Air Compressors - (One minute data 10/12-10/13)Compressor 1 and 3 are Cycling Excessively

0

10

20

30

40

50

60

70

12:2

3

12:3

5

12:4

7

12:5

9

13:1

1

13:2

3

13:3

5

13:4

7

13:5

9

14:1

1

14:2

3

14:3

5

14:4

7

14:5

9

15:1

1

15:2

3

15:3

5

15:4

7

15:5

9

16:1

1

16:2

3

16:3

5

16:4

7

16:5

9

17:1

1

17:2

3

17:3

5

17:4

7

17:5

9

18:1

1

18:2

3

Po

wer

(kW

)

Compressor 1(75 hp)

Compressor 3(50 hp)

Standby power consumption is almost 20% of peak power

Variable Speed Drive Compressors and waste heat regen dryers

VSD Compressors address the cycling problem

Commissioning / Retrocommissioning

Retrocommission - on a regular basis commission key components of system

E.G. - Develop standard tests for key control loops

Effect - Supply Air Temperature is Deficient

AMAT AH-A2 AIR

Deg

F

AHU-A2.PL1

55.0

57.5

60.0

62.5

65.0

2 FriJul 99

3 Sat 4 Sun 5 Mon 6 Tue

SUPPLY AIR TEMP :DEG F

Design Supply Air Temp is 55 deg Fwith no SAT reset

Cause

AMAT AH-A2 COOLING COIL

De

g F

CHWTEMP.PL1

40.0

42.5

45.0

47.5

50.0

52.5

55.0

57.5

2 FriJul 99

CHW Supply CHW Return

Chilled Water Temperatures

Heating Boiler Measurement1,400 kBtu Boiler Was Unable to Produce More than 500 kBtu

0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

800.0

4/1/99 0:00 4/2/99 0:00 4/3/99 0:00 4/4/99 0:00 4/5/99 0:00 4/6/99 0:00 4/7/99 0:00 4/8/99 0:00 4/9/99 0:00

Time

kBtu

/h

Tower #2 Cell B Power

0

10

20

30

40

0:00 0:10 0:20 0:30 0:40 0:50 1:00

Time: Hour; June 16, 2000

Po

we

r (k

W)

Tower #2 Cell B Power

0

10

20

30

40

13:156/15

13:156/16

13:156/17

13:156/18

13:156/19

13:156/20

13:156/21

Time: Hour, Day; June 2000

Po

we

r (k

W)

Commission to avoid cycling

Control Optimization

0

STEP CHANGE DUE TO EXTRA PUMPS, COOLING TOWERS, AND 50% LOADED CHILLERS

1. Delayed start-up of next chiller saves substantial kW and running hours on cooling plant.

2. "Stretching" cooling capacity can be done by : a) Accepting a small CHW setpoint drift; e.g.

4.5°C to 5.3°C in winter. b) Unlimiting current timer on chillers; e.g.

FLA=300a, but motor rating=355a, so move Current Limiter to 355a.

c) Provide cooler condenser water; drive all cooling fans to 50 Hz.

d) Push more water through condenser tubes, such as running two pumps for one chiller,with upper limit set by chiller manufacturer.

e) Use tube cleaners on certain chillers.

THANK YOU!

Rumsey Engineers, Inc.

99 Linden Street

Oakland, CA 94607

(510) 663-2070

www.RumseyEngineers.com

prumsey@RumseyEngineers.com