1. Delivering Sustainability Promise to HVAC Air Filtration
Dr. Christine Sun and Dan Woodman
Freudenberg Filtration Technologies, L.P.
Hopkinsville, KY42240, USA
2009 NAFA Annual Convention
Sep , 2009, Toronto, Canada

2. Outlines What is sustainability? How to evaluate sustainability
Classification of energy efficiency
Bernoulli’s equation
Wattage method
Pressure drop & new exponential model
Energy efficient air filter
Life cycle cost analysis 2

3. What is sustainability?
“Development that meets the needs of the present without compromising the ability of future generations to meet their own needs”
—1987 United Nation’s Brundtland Commission
“Sustainability for ASHRAE means energy efficiency and healthy, productive indoor environments”
— William Harrison, ASHRAE President
January 2006, ASHRAE Board of Directors approved ASHRAE’S Sustainability Roadmap-The approach to defining a leadership position in sustainability
Consider integrating sustainability principles into all appropriate ASHRAE standards, guidelines, handbook chapters and publications. 3

4. How to evaluate sustainability
Clean and healthy air
Filtration efficiency
ASHRAE
EN779: 2002
Energy efficiency
Currently no standardized method in the industry to classify filters’ energy efficiency. Need to develop.
The approach to defining a leadership position in sustainability 4

5. Energy consumption for air filters
15-20% of the total electrical energy consumption is used by fans in air handling units.
Approximately 1/3 of that is related to pressure loss of air filters.
One year at fixed volumetric flow rate of 2000 CFM a filter with an average pressure loss of 0.4” WC requires 1250 kWh if the fan efficiency is set to 70%.
The energy cost is generally greater than the filter cost, and pressure loss reduction becomes increasingly significant for energy reductions.
Lower pressure loss by 10 Pa means 125 kWh less energy in this example.
Energy efficient air filters can save energy
Current air filter classification does not consider energy efficient operation.

6. Industrial Air Filters
Energy rating options
How Should We Classify
Industrial Air Filters
For Energy Usage?
Marketing
Program
Technical
Standards
Combined
Attributes
Energy
Stand Alone
Energy
Star
Set Guidelines
Awards Recognition for Products that Meets Guidelines
KEP
Wattage
ECI
Defines a Single Scientifically Based Energy Measurement
Combines Efficiency and Energy Consumption into One Metric 6

7. Industrial Air Filters
Energy Star
Marketing
Program
How Should We Classify
Industrial Air Filters
For Energy Usage?
Marketing incentive program backed by the EPA to help consumers identify energy efficient products
Product standards are set by product categories
No product category exists for filters
Product category for room air cleaners:
Qualified models must meet minimum ratio of clean air delivered for each watt of energy (CADR/Watt >2)
Secondary features must meet energy efficiency requirements in standby mode.
Technical
Standards
Combined
Attributes
Energy
Stand Alone
Energy
Star
Set Guidelines
Awards Recognition for Products that Meets Guidelines
KEP
Wattage
ECI
Defines a Single Scientifically Based Energy Measurement
Combines Efficiency and Energy Consumption into One Metric 7

8. Key Energy Performance (KEP)
Combined
Attributes
Technical
Standards
How Should We Classify
Industrial Air Filters
For Energy Usage?
Proposed as a technical standard in Europe
1. Determine average pressure drop from AC Fine dust loading
Marketing
Program
G1 – G4 F5 F6 F7
800 g AC Fine F8 F9
200 g AC Fine
2. Determine the average efficiency according to EN 779 from ASHRAE dust loading
Energy
Stand Alone
Energy
Star
C = empirical constant; (here C = 22 Pa)
3. Calculate the kep number
4. Classify
kep number @ 3400 m³/h
energy class
kep  1 1
1 > kep  0,8 2
0,8 > kep  0,7 3
0,7 > kep  0,6 4
kep < 0,6 5
KEP
Wattage
ECI 8

9. Energy Cost Index (ECI)
Combined
Attributes
Technical
Standards
How Should We Classify
Industrial Air Filters
For Energy Usage?
Proposed as a technical standard in Europe, currently used for marketing in US by a manufacturer
Uses artificially treated filter efficiency and basic energy cost to develop ratio of cost per efficiency.
KwH = 0.746*HP*Hours &
*Assuming 10 cent per KwH and 60% fan efficiency
Converts ratio by filter construction type in to 5 star rating scheme.
Marketing
Program
Energy
Stand Alone
Energy
Star
Set Guidelines
Awards Recognition for Products that Meets Guidelines
KEP
Wattage
ECI
Defines a Single Scientifically Based Energy Measurement
Combines Efficiency and Energy Consumption into One Metric 9

10. Industrial Air Filters
Wattage Rating
Energy
Stand Alone
Technical
Standards
How Should We Classify
Industrial Air Filters
For Energy Usage?
All rating systems need to determine ΔP to derive energy.
This method uses scientifically correlated method to determine lifetime average ΔP.
Rating system evaluated energy efficiency independent from efficiency.
Intuitive understanding of energy consumption by consumer (Watts)
Marketing
Program
Combined
Attributes
Energy
Star
Set Guidelines
Awards Recognition for Products that Meets Guidelines
KEP
Wattage
ECI
Defines a Single Scientifically Based Energy Measurement
Combines Efficiency and Energy Consumption into One Metric 10

11. Understanding of energy used to run a filter
Bernoulli’s equation (Energy Conservation)
Airflow
The energy of a volume V at any point is the sum of its kinetic energy and its potential energy (pV). Effects of gravitation and viscosity are neglected. The energy of a given volume of the fluid which moves from point 1 to point 2 is the same at both points. The related energy equation is 1 2 ? 11

12. Understanding of energy used to run a filter
Bernoulli’s equation (Energy Conservation)
Airflow
The energy of a volume V at any point is the sum of its kinetic energy and its potential energy (pV). Effects of gravitation and viscosity are neglected. The energy of a given volume of the fluid which moves from point 1 to point 2 is the same at both points. The related energy equation is 1 2
Energy loss
over filter + 12

13. Energy used to run air through the filter
Airflow 1 2
Energy loss
over filter/m3 +
The energy of a volume V at any point is the sum of its kinetic energy and its potential energy (pV). Effects of gravitation and viscosity are neglected. The energy of a given volume of the fluid which moves from point 1 to point 2 is the same at both points. The related energy equation is
As V1=V2, Z1=Z2, therefore,
Energy Loss
over filter/m3
=P1-P2=ΔP 13

14. Energy used to run air through the filter
Considering airflow through the filter as Q and system efficiency η (0-1), then
E: energy in kWh;
Q: airflow rate in m3/s
ΔP: pressure drop in Pa
η: system efficiency (0-1)
t: operation time (hr) 14

15. Energy eff. classification — Wattage
Energy in wattage used to run air through the filter:
W: power (Watt)
v: face velocity (m/s)
A: face area (m2) 15

16. Energy eff. classification — Wattage (Cont.)
For standard test duct, 24”x24” duct,
v = 2.5 m/s, and η = 70% 16

17. Average pressure drop 17

18. Average pressure drop models
Arithmetic:
Geometric:
Integral: 18

19. Actual pressure drop vs. dust loading19

20. Exponential pressure drop model
New exponential model developed based on actual loading curves according Ashrae 52.2
a and b: constants of filters
x: loaded dust (g) 20

21. Pressure drop model Filters a b R2 Value V-pack 1 79.69 0.082 0.996
89.49
0.0056
0.998
Box
55.01
0.0057
Bag 1
44.93
0.0018
Bag 2
36.17
0.0027
0.999
Panel
36.24 21

22. Comparison of pressure drop models
Filters
Arithm.
Geom.
Integral
Exp.
Max Err.
V-pack 1
216.2
146.6
163.2
168.8
28%
V-pack 2
226.3
170.5
176.7
185.0
22%
Box
233.6
185.9
186.5
196.0
19%
Bag 1
207.5
115.2
149.9
150.3
38%
Bag 2
210.0
129.9
147.7
140.6
49%
Panel
205.0
114.6
148.3
140.9
46% 22

23. Comparison of pressure drop models
Filters
Arithm.
Geom.
Integral
Exp.
Max Err.
V-pack 1
216.2
146.6
163.2
168.8
28%
V-pack 2
226.3
170.5
176.7
185.0
22%
Box
233.6
185.9
186.5
196.0
19%
Bag 1
207.5
115.2
149.9
150.3
38%
Bag 2
210.0
129.9
147.7
140.6
49%
Panel
205.0
114.6
148.3
140.9
46% 23

24. Average pressure drop
Exponential Model: 24

25. Filer energy efficiency — Wattage
Directly use wattage to run the air through the filter to classify filter energy efficiency 25

26. Filter energy efficiency class
Filters
Filter Energy Efficiency*
(Watt)
V-pack 1
220
V-pack 2
250
Box
260
Bag 1
200
Bag 2
190
Panel
C=60
*Round to 10 26

27. Energy efficient air filter — I
Electret enhancement
Electrostatic Attraction
Inertial Impaction
(-)
(+)
Filter
Fiber
Brownian Diffusion
Interception
Mechanical Filter + e-Charge = Electret Filter

28. Filter media energy efficiency
Filtration
Efficiency (%) ∆P
(Pa)
Energy Efficiency (Watt)
GF* 1
87.2
850.1
1130
GF 2
98.3
970.2
1290 PP
87.3
910.0
1210
PET
48.5
138.5
180
PP 1**
97.3
42.5 60
PP 2**
99.3
55.6 70
C=0, TSI 8130 test airflow 48lpm
*GF — glass fiber, **electret media
Tested by 48l/min using NaCl aerosol 28

29. Energy efficient air filter — II
+ gradient media structure
Nano fiber

30. Life cycle cost (LCC) analysis
Looking at total cost throughout filter service life:
Filter cost (LCCFilter)
Energy cost (LCCEngr)
Maintenance cost (LCCMaint)
Disposal cost (LCCdisp)
Freight cost (LCCfreight)
Miscellaneous
cost (LCCMisc.)
LCC = LCCfilter+ LCCengr + LCCmisc

31. Life cycle cost analysis — I
Operation data in a general air make up unit
Airflow rate (CFM)
80,000
System energy efficiency (η)
0.7
# of filters 40
Maint. labor cost ($/hr) 30
Face velocity (FPM)
500
Operating hours (hr/yr)
8,400
Utility rate ($/kw.hr)
0.08
Life cycle period (month) 36

32. Life cycle cost analysis — II
Data from a real AHU
Filter option
Depth loading filter
Surface-loading filter
Pre-filter
Final fiber
Filter size
24”x24”x26”
24”x24”x2”
24”x24”x30”
Cost per filter
98.00 $/ea
4.00 $/ea
40.00 $/ea
Filter cost ($)
5,880.00
960.00
3,200.00
Initial/final ΔP (”H2O)
0.21/0.40
0.30/0.60
Filter energy eff.
90 watt
130 watt
Total engr use
91,542 kw.hr
133,963 kw.hr
Engr cost ($)
7,323.32
10,717.06
Misc. cost ($)
720.00
936.00
1,020.00
Subtotal cost ($)
13,923.32
12,613.06
14,937.06
Total saving by using depth loading filters in 3 years ($)
13,626.79
CO2 emission reduction: 40.1 ton/yr

33. Life cycle cost share Depth loading Total $13,923.32 Surface-loading
$ %
Depth loading
Total $13,923.32
42.4% $5,880.00
52.4% $7,323.32
$1, %
$4, %
Surface-loading
Total $27,550.12
77.8% $21,434.12

34. Summary
Energy efficiency is a critical value to evaluate filters’ sustainability besides filtration efficiency.
Wattage provides a direct and scientific method to classify filter’s energy efficiency.
New exponential model showed excellent consistence to reflect actual pressure drop vs. dust loading.
Life cycle cost analysis is a useful tool to evaluate the sustainability of air handling units.
Energy use is a primary cost over filter service life, followed by filter cost and miscellaneous cost (incl. maint., freight, and disposal).

35. Thanks for your attention!
Let’s work together for a sustainable and healthy environment
Dr. Christine Sun and Dan Woodman Freudenberg Filtration Technologies, L.P.
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