NAFA Guide to Air Filtration. Chapter 13 Owning and Operating Cost By Dirk ter Horst April 19 th, 2012 Another Approach…. Air Filter Comparison

OUTLINE  Objective  Energy Cost Calculation: 2 approaches  Calculation Example & Methodology Comparison  Total Filtration Cost Tool’s presentation  Conclusions

Objective Present a practical and easy approach to air filter evaluations + operation based on:  End user/customer experience (Pressure drop and filter life)  Standardized filter life indicator (ASHRAE 52.2 DHC)  All air filtration associated costs  Use of software

Assumptions and considerations NAFA  Customer experience (Pressure drop and Time)  Constant environmental conditions  Average pressure drop  Straight Line New approach  Customer experience (Pressure drop and time)  Constant environmental conditions  Time vs. Pressure Drop  Time vs. ASHRAE DHC  Air filter Pressure Drop vs. DHC Signature

Linear Pressure Drop Approach  Considering the pressure drop changes linearly with time the energy consumption is expressed by: Where: ΔP 0 = Initial Filter pressure drop [Pa] ΔP f = Final Filter pressure drop [Pa] t f = operating time[hrs] = average pressure drop

Filter Pressure Drop vs. Time Approach  Considering the pressure drop of the filter versus time, the energy consumption is expressed by:

Energy Cost  The energy cost is calculated by:  Linear pressure drop vs. time:  Filter pressure drop vs. time: Where: E= energy consumption [kWh] Q= airflow [m 3 /s] ΔP = pressure Drop across the filter [Pa] t= the time is operating the fan [hrs.] η= system efficiency (fan, motor & drive) [%]

Same results… $273/360X365=$277 $301.2/360X365=$305.4

Linear vs DHC curve..For 100 filters This example: Difference/year: $5, (22.5%)

Transposition… += Assumption: Air filters of the same efficiency and media type have captured the same amount of dust if they are exposed to identical environmental conditions over the same period of time

Two filters to work with… Example Filter A:  MERV x24x4 Box type.  Initial pressure drop: 0.35 inch H2O  DHC at 1.5” H2O: 67grams. ASHARE Dust  2000 cfm  $70.0/unit Filter B  MERV x24x4 Box type  Initial pressure drop: 0.3 inch H2O  DHC at 1.5” H2O: 143 grams. ASHRAE Dust  2000 cfm  $70.0/unit

Linear approach… for 100 filters Two different filters without DHC consideration Linear approach: US$ /year Two different filters with DHC consideration Linear approach… US$ 9,682,90/year

Curve approach… for 100 filters Two different filters With DHC consideration Curve approach US$ 9,173.82/year

Optimization Linear approach.. Pressure Drop of filters at change-out time for financial optimization: 0.85inch w.g. Cost reduction: $9,712.03/year (for 100 filters)

Optimization… DHC curves. Pressure Drop of filters at change-out time for financial optimization: 0.60inch w.g. Cost reduction: $10,134.13/year (for 100 filters)

Compare Apples to Apples…  Filter Type  Filter depth  Frame type  Frame material  Filter media material  Face screen  Incinerable  Filter brand/make  Test standard  Air flow  Maximum final pressure drop  Efficiency  Test dust  Test Laboratory  Test filter procurement/source  Age of test report  UL 900 compliance  Fan type  Reasons for change out time  Other considerations

Practical approach to TFC Easy calculation…. Let’s see a software tool:

LC 67 vs LC 143 Base

LC 67 vs LC143- High Energy Cost

LC 67 vs LC143-Low Energy cost

LC 67 vs 143 Base- Money Maker

LC 67 vs LC143- Production loss

Conclusions  Use the ASHRAE 52.2 DHC curve information when evaluating the financial impact of air filters.  Calculate the recommended filter change out pressure drop (optimization).  The cheapest filter nor the filter with the lowest initial pressure drop are necessarily the best solution.  There is a WIN-WIN opportunity for the customers and the industry!