### Drive Efficiency Fan Efficiency System Effects &

System Leakage

Fan Selection System Design 

# Potential for Air System Savings

# Fan Efficiency Ratio ( FER ) = Fan Efficiency

Baseline Efficiency

• Varies along the fan curve

• Independent of fan type or category

• Two test configurations: ducted and non

- ducted

• Think of the Baseline Efficiency as a minimum

allowable fan efficiency (FER ≥ 1.0 is compliant)

6/9/2015 2 

# Fan Efficiency Ratio6/9/2015 3 

### AirflowPressureFan Input Power



### Power Pressure 

# Fan Efficiency Ratio (FER)

Efficiency 

# FER varies along the fan curve6/9/2015 4 

### AirflowPressureFan Efficiency Ratio-FER



### 0 1.0 2.0

FER

Pressure 

# Fan Efficiency Ratio (FER)

FER varies along the fan curve

# Static vs. Total Efficiency

• **Ducted** fans can use both static and velocity

pressure to overcome system pressure losses.

Ducted fans should be selected using total

pressure and total efficiency is the correct

measure of fan efficiency.

• With **non**

**- ducted**  fans, any velocity pressure at

the fan discharge is immediately dissipated,

making it unusable for any further work. Non

ducted fans must be selected and compared using

static pressure, so static efficiency is the

appropriate measure.

6/9/2015 5

# Baseline Efficiency

6/9/2015 

## Increasing Fan Size

6Increasing System Pressureand Fan Complexity

# Baseline Efficiency

6/9/2015 

# Efficiency above the surface exceeds the baseline (FER>1)

7

# In terms of efficiency:

Fan Efficiency Ratio = Fan Efficiency

Baseline Efficiency

In terms of power:

Fan Efficiency Ratio = Baseline Power

Fan Input Power

6/9/2015 8 

# Fan Efficiency Ratio

# Baseline Efficiency Equations

For fans tested with a ducted outlet :

η t

, baseline 

# = η t

, target 

# × Q

Q + Q 0 

# × P t



## P t 

## + P 0



# For fans tested with a non

- ducted outlet :

η s

, baseline 

# = η s

, target 

# × Q

Q + Q 0 

# × P s



## P s 

## + P 0

6/9/2015 9

# Baseline Power Equations

For fans tested with a ducted outlet :

H baseline 

# = Q + Q 0 

# × P t 

# + P 0



# 6343 × η t

, target



# For fans tested with a non

- ducted outlet :

H baseline 

# = Q + Q 0 

# × P

s 

# + P 0



# 6343 × η s

, target



# parameters in blue are constants, 6343 is for I

- P only

6/9/2015 10

# Baseline Power Equations

For fans tested with a ducted outlet :

H baseline 

# = Q + 250 × P t 

# + 0

. 4

6343 × η t

, target



# For fans tested with a non

- ducted outlet :

H baseline 

# = Q + 250 × P

s 

# + 0

. 4

6343 × η s

, target



# parameters in blue are constants, 6343 is for I

- P only

6/9/2015 11

# FER Baseline Constants

6/9/2015 12 P 0 impacts this

curvature. P 0 was

established at 0.40”

(100 Pa) to match

range of products

available. Q 0 impacts this

curvature. Q 0 was

established at 250

cfm (0.12 m 3 /s) to

match diameter

effect of FEG curves. Target efficiencies,



### η s,target and 

### η t,target determine the overall

level of the entire surface.6/9/2015 13 

### AirflowPressureFan Efficiency Ratio-FER



### 0 1.0 2.0

FER

Pressure 

# If this is what the metric looks like,

what will the regulation look like?

# F AN 

# E FFICIENCY 

# R ATIO

FER = 1.10 means 10% energy savings over baseline **Body FER Requirement** 

Federal

Regulation FER ≥ 1.0 at Peak & Design Point

ASHRAE 90.1 FER ≥ 1.0 at Design Point

ASHRAE 189.1 FER ≥ 1.1 at Design Point

Rebates FER = Savings over Baseli ne 

# How could FER be used?

14

# What does this mean to Fan Selections?

6/9/2015 15 1 in. wg 2 in. wg 3 in. wg 4 in. wg 5 in. wg 6 in. wg

CFM RPM BHP FER RPM BHP FER RPM BHP FER RPM BHP FER RPM BHP FER RPM BHP FER

6000 830 1.39 1.47 1051 2.79 1.33

7000 900 1.72 1.38 1092 3.18 1.35 1267 4.83 1.28

8000 979 2.14 1.26 1142 3.64 1.34 1306 5.41 1.30 1458 7.34 1.25

9000 1064 2.66 1.14 1209 4.28 1.28 1358 6.13 1.29 1499 8.15 1.27 1633 10.3 1.23

10000 1152 3.28 1.03 1280 4.95 1.22 1411 6.86 1.28 1550 9.11 1.26 1674 11.3 1.25 1798 13.8 1.22

11000 1242 3.98 0.93 1359 5.79 1.15 1479 7.84 1.22 1597 10.0 1.26 1722 12.5 1.24 1835 14.9 1.24

12000 1336 4.82 0.84 1441 6.73 1.08 1549 8.82 1.19 1660 11.1 1.23 1770 13.6 1.25 1883 16.3 1.23

13000 1431 5.80 0.75 1528 7.86 1.00 1627 10.1 1.13 1728 12.4 1.19 1828 14.9 1.23 1932 17.6 1.23

14000 1527 6.94 0.67 1617 9.09 0.93 1707 11.3 1.07 1799 13.8 1.15 1897 16.6 1.18 1987 19.1 1.22

15000 1625 8.23 0.61 1706 10.4 0.86 1791 12.8 1.01 1878 15.5 1.10 1964 18.1 1.16 2054 21.1 1.19

16000 1724 9.68 0.55 1798 12.0 0.80 1879 14.6 0.95 1957 17.2 1.06 2038 20.0 1.12

17000 1823 11.3 0.50 1892 13.7 0.75 1967 16.4 0.90 2041 19.1 1.01

18000 1923 13.1 0.46 1986 15.6 0.69 2056 18.4 0.85

# What does this mean to Fan Selections?

6/9/2015 Fan

Size

(in.) Fan

Speed

(rpm) Fan

Power

( bhp ) Actual

Total

Efficiency Baseline

Power

( bhp ) Baseline

Total

Efficiency FER H

18 3238 11.8 40.1% 7.96 59.4% 0.67

20 2561 9.56 49.5% 7.96 59.4% 0.83

22 1983 8.02 59.0% 7.96 59.4% 0.99

24 1579 6.84 69.1% 7.96 59.4% 1.16

27 1289 6.24 75.8% 7.96 59.4% 1.28

30 1033 5.73 82.5% 7.96 59.4% 1.39

33 887 5.67 83.4% 7.96 59.4% 1.40

36 778 6.01 78.7% 7.96 59.4% 1.32



## Electronic Fan Selection Software based on Total Pressure

Design Point 10,000 CFM at 3.0 ” Pt

16

# What does this mean to Fan Selections?

6/9/2015 

### AirflowStatic Pressure

FER 1.1

FER 1.0 FER 1.2 

## Multiple Speed Fan Performance Curves

“Relatively High Efficiency Fan”

– Large selection area

FER 0.9 Peak Efficiency

17

# What does this mean to Fan Selections?

6/9/2015 

### AirflowStatic Pressure 

## Multiple Speed Fan Performance Curves

“Relatively Low Efficiency Fan”

– Small selection area

FER 0.9

FER 0.8 FER 1.0

FER 0.7 Peak Efficiency

18

# What does this mean to Fan Selections?

6/9/2015 

### AirflowStatic Pressure 

## Multiple Speed Fan Performance Curves

“Relatively Low Efficiency Fan”

– Small selection area

FER 0.9

FER 0.8 FER 1.0

FER 0.7 Peak Efficiency

Maximum speed

in which FER ≥ 1.0 at

Best Efficiency Point Regulation

...FER must be

1.0 or greater at the

Best Efficiency Point at

the Maximum RPM.

19

# Case Study: Square Inline Fan

• Ducted inlet, ducted outlet

• Inexpensive

• Easy to install

• Easy to maintain

• Low efficiency

Fan shown without side for

viewing internal components

6/9/2015 20

# Square Inline Fan

– Size 30 (30” wheel)

Entire Selection Range

Min RPM Max RPM

6/9/2015 21

# Square Inline Fan

– Size 30

Best Efficiency Point

Min RPM Max RPM

**Best Efficiency Point (BEP)**

6/9/2015 22

# Square Inline Fan

– Size 30

Range of Fan Total Efficiency

Min RPM Max RPM **Best Efficiency Point**

**(BEP)**

6/9/2015 23

# Square Inline Fan

– Size 30

Actual Fan Selections from 2012

295 Fans with Motors ≥ 1 hp

6/9/2015 24

# Square Inline Fan

– Size 30

Proposed Regulation: FER ≥ 1

Approximately 40% of fan selections met the requirement

6/9/2015 25

# Square Inline Fan

– Size 30

Selections covered by size 36

Approximately 70% of fan selections met by size 30 and 36

6/9/2015 26

# Square Inline Fan

– Size 30

Selections covered by size 42

Approximately 90% of fan selections met by sizes 30, 36, and 42

15,000 CFM

at 0.5” Pt

6/9/2015 27

### Fan Model Design

BHP FER Oper Cost

($/year) Weight

( lbs ) Housing

Width Budget

Cost Payback

(years)

Sq Inline 30” 5.33 0.62 $1363 571 46” $3300

-

Sq Inline 42” 2.92 1.12 $758 735 58” $4050 1.22

Mixed Flow 27” 2.77 1.18 $719 611 41” $6700 5.28 

# Product Substitution

Design Point: 15,000 CFM at 0.5” Pt

30” Sq Inline 42” Sq Inline 27” Mixed Flow New

Square Inline

Fan with

Improved

Efficiency!!!

New

Lower Cost

Mixed Flow

Fan!!!

# Allowable Selection Range:

FER ≥ 1 at the Design Point of Operation

6/9/2015 29

# Allowable Speed Range:

FER ≥ 1 at the BEP at the Max RPM

6/9/2015 30

# Square Inline Fan

– Size 30

Actual Fan Selections from 2012

Reduced max RPM eliminates

8% of fan selections and

15% of connected load

6/9/2015 31

# Extended Products (wire

- to

- air)

6/9/2015 32Shaft Power (BHP)Electrical Power (kW)



### AMCA 207