1. NAFA Guide To Air Filtration
Fifth Edition
Chapter 13
Owning and Operating Costs
presented by the
National Air Filtration Association

2. Owning and Operating Costs
An owning and operating cost study should be conducted when comparing….
Two systems that provide equal performance
(apples to apples)

3. Owning and Operating Costs
Annual operating costs include:
Materials (including freight in)
Warehouse, Storage and Shrinkage
Labor to remove/install
Electric power
Disposal and other miscellaneous charges

4. Owning and Operating Costs
As outlined by NAFA, an owning and operating cost for new or retrofit systems comparison should include…
First cost of equipment
Installation cost
Electrical and/or plumbing
Initial filter cost and filter installation costs
Misc. such as gasketing, etc.

5. Owning and Operating Costs
The major operating cost of a filter system is…
Energy required to overcome filter resistance?
First Cost?
81%
18.5%
0.5%
Carlsson, Thomas; “Indoor Air Filtration: Why Use Polymer Based Filter Media”, Filtration+Separation, Volume 38 #2, March 2001, pp

6. Owning and Operating Costs
Electrical usage in a system is measured in watts and charged per 1000 watts – one kilowatt hour (kwh)
The actual power is the theoretical power adjusted for the efficiency of the fan, drive and motor.
kWa = kWt
(fan x drive x motor efficiency)

7. Factors Affecting Filter Life
Particle size distribution
Negative effect on panel filters – surface loading
Positive effect on extended surface filters – increased bed depth

8. Factors Affecting Filter Life
2. Underrating/Overrating
Underrating increases filter life more than directly proportional to the percent of underrating
Double effect with extended surface filters:
A. Reduces pressure drop
B. Reduces the rate of pressure drop increase

9. Factors Affecting Filter Life
Underrating/Overrating (continued)
Underrating may reduce the efficiency of a panel filter because the reduced velocity decreases the impingement process

10. Optimum Final Pressure Drop
The point where the sum of power costs and filter costs is at a minimum
Total Cost
Power
Cost per Hour
Filter Life
Time
Final Pressure Drop

11. Total Cost Total annual cost equals:
the sum of all first costs that can be depreciated plus the sum of the annual operating costs

12. Sample Questions
What percent of the total cost of a filter is energy costs?
81%
Fan efficiency, Drive efficiency and Motor efficiency calculate into what cost?
Energy cost
Underrating a filter may have the unintended consequence of?
Changing the efficiency curve
Running filters to their maximum pressure drop may?
Cost more in energy than the cost to change it sooner

13. Thank you.
Other Questions?