Cost Per CFM Calculator
This tool calculates the cost associated with delivering one cubic foot per minute (CFM) of airflow. Enter the total cost over a specific period and the total CFM produced during that period.
Enter Cost and Airflow
Understanding Cost Per CFM
What is Cost Per CFM?
Cost Per CFM is a metric used primarily in HVAC (Heating, Ventilation, and Air Conditioning) and industrial air handling to understand the efficiency and expense associated with moving air. It helps in comparing different systems, optimizing operations, and making informed decisions about equipment upgrades or maintenance.
It represents the total cost incurred (often over a period like an hour, day, or year, which should be consistent for both inputs) divided by the total volume of air moved (in CFM) during that same period.
Formula
The calculation is straightforward:
Cost Per CFM = Total Cost / Total Airflow (CFM)
Example Calculation (Simple)
EX: An air handling unit costs $50 per hour to run (electricity, maintenance, etc.) and moves 10,000 CFM. Calculate the cost per CFM per hour.
Cost Per CFM = $50 / 10,000 CFM
Result: Cost Per CFM = $0.005 $/CFM per hour.
Real-Life Cost Per CFM Examples
Click on an example to see the step-by-step calculation:
Example 1: Comparing Two Fans
Scenario: Company A uses Fan X (5000 CFM, costs $30/hour) and Company B uses Fan Y (7000 CFM, costs $40/hour). Which fan is more cost-effective per unit of air moved?
1. Known Values (Fan X): Total Cost = $30, Total Airflow = 5000 CFM.
2. Calculation (Fan X): Cost Per CFM = $30 / 5000 CFM = $0.006 $/CFM per hour.
3. Known Values (Fan Y): Total Cost = $40, Total Airflow = 7000 CFM.
4. Calculation (Fan Y): Cost Per CFM = $40 / 7000 CFM ≈ $0.0057 $/CFM per hour.
Conclusion: Fan Y has a slightly lower cost per CFM ($0.0057 vs $0.006), suggesting it is more cost-effective per unit of air moved.
Example 2: Annual Cost for a Factory HVAC System
Scenario: A factory's main HVAC system has an annual operating cost of $50,000 (electricity, filters, maintenance) and a total capacity of 200,000 CFM. What is the annual cost per CFM?
1. Known Values: Total Cost = $50,000, Total Airflow = 200,000 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $50,000 / 200,000 CFM.
4. Result: Cost Per CFM = $0.25 $/CFM per year.
Conclusion: It costs $0.25 per CFM per year to operate this system.
Example 3: Cost of a Specific Ventilation Project
Scenario: Installing a new ventilation system for a room costs $15,000 and provides 1500 CFM. Calculate the upfront cost per CFM.
1. Known Values: Total Cost = $15,000, Total Airflow = 1500 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $15,000 / 1500 CFM.
4. Result: Cost Per CFM = $10 $/CFM (upfront cost).
Conclusion: The initial installation cost is $10 for every CFM of capacity added.
Example 4: Operating Cost per CFM per Day
Scenario: An air purifier runs 24 hours a day, costing $1.20 in electricity per day and providing 250 CFM. What is the daily operating cost per CFM?
1. Known Values: Total Cost = $1.20, Total Airflow = 250 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $1.20 / 250 CFM.
4. Result: Cost Per CFM = $0.0048 $/CFM per day.
Conclusion: It costs roughly half a cent per CFM per day to run the purifier.
Example 5: Large Commercial Air Handler
Scenario: A large commercial building's air handler costs $500 per month to operate (power, filters) and handles 50,000 CFM. What is the monthly cost per CFM?
1. Known Values: Total Cost = $500, Total Airflow = 50,000 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $500 / 50,000 CFM.
4. Result: Cost Per CFM = $0.01 $/CFM per month.
Conclusion: The monthly operating cost is one cent per CFM.
Example 6: Impact of Maintenance on Cost Per CFM
Scenario: After performing maintenance, a system that previously cost $100/hour and moved 10,000 CFM now costs $90/hour and moves 11,000 CFM due to improved efficiency. Compare the old and new cost per CFM.
1. Known Values (Old): Total Cost = $100, Total Airflow = 10,000 CFM.
2. Calculation (Old): Cost Per CFM = $100 / 10,000 CFM = $0.01 $/CFM per hour.
3. Known Values (New): Total Cost = $90, Total Airflow = 11,000 CFM.
4. Calculation (New): Cost Per CFM = $90 / 11,000 CFM ≈ $0.0082 $/CFM per hour.
Conclusion: Maintenance reduced the cost per CFM from $0.01 to $0.0082, showing improved cost efficiency.
Example 7: Dedicated Server Room Cooling
Scenario: A dedicated cooling unit for a server room costs $300 per month and provides 3000 CFM. What is the monthly cost per CFM?
1. Known Values: Total Cost = $300, Total Airflow = 3000 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $300 / 3000 CFM.
4. Result: Cost Per CFM = $0.10 $/CFM per month.
Conclusion: The monthly cost is $0.10 for every CFM of cooling provided.
Example 8: Dust Collection System
Scenario: A manufacturing facility's dust collection system costs $12,000 per year (power, filter replacement) and operates at 40,000 CFM. Calculate the annual cost per CFM.
1. Known Values: Total Cost = $12,000, Total Airflow = 40,000 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $12,000 / 40,000 CFM.
4. Result: Cost Per CFM = $0.30 $/CFM per year.
Conclusion: The annual cost to move one CFM of air for dust collection is $0.30.
Example 9: Vehicle Ventilation System
Scenario: A vehicle's cabin fan system uses about $0.05 worth of fuel/electricity per hour when running at maximum (approx 300 CFM). What is the hourly cost per CFM?
1. Known Values: Total Cost = $0.05, Total Airflow = 300 CFM.
2. Formula: Cost Per CFM = Total Cost / Total Airflow (CFM).
3. Calculation: Cost Per CFM = $0.05 / 300 CFM.
4. Result: Cost Per CFM ≈ $0.000167 $/CFM per hour.
Conclusion: The hourly cost per CFM for the vehicle's fan is very low, less than a cent.
Example 10: Comparing Systems with Different Lifespans (Simplified)
Scenario: System A costs $10,000 upfront, lasts 10 years, 5000 CFM. System B costs $18,000 upfront, lasts 15 years, 6000 CFM. Assume upfront cost is total cost over lifespan for simplicity.
1. Known Values (System A): Total Cost (over 10 yrs) = $10,000, Total Airflow = 5000 CFM.
2. Calculation (System A): Cost Per CFM = $10,000 / 5000 CFM = $2.00 $/CFM (over 10 yrs).
3. Known Values (System B): Total Cost (over 15 yrs) = $18,000, Total Airflow = 6000 CFM.
4. Calculation (System B): Cost Per CFM = $18,000 / 6000 CFM = $3.00 $/CFM (over 15 yrs).
Conclusion: System A has a lower upfront cost per CFM over its lifespan ($2.00 vs $3.00), indicating better initial cost efficiency per CFM of capacity.
Frequently Asked Questions about Cost Per CFM
1. What does CFM stand for?
CFM stands for Cubic Feet per Minute. It is a unit of airflow measurement, indicating the volume of air (in cubic feet) that moves through a space or system in one minute.
2. Why is Cost Per CFM important?
It helps in comparing the operational or upfront cost efficiency of different air handling units, ventilation systems, or fans by providing a standardized metric based on the amount of air they move.
3. What kind of costs should be included in "Total Cost"?
This depends on the analysis. It could include electricity costs, maintenance costs (filters, repairs), labor costs, or even the initial purchase price (amortized over the expected lifespan). The key is to be consistent and use the total cost incurred over the same period for which you measure the total CFM.
4. Can I use this for different time periods (hourly, daily, yearly)?
Yes, absolutely. Just ensure that both your "Total Cost" and "Total Airflow" inputs cover the exact same period (e.g., cost per *hour* and CFM *per hour*, or cost per *year* and total CFM *capacity*). The resulting Cost Per CFM will then be for that same period ($/CFM per hour, $/CFM per year, etc.).
5. What if the CFM output varies?
If the CFM output varies over the period (e.g., a variable speed fan), you should use the *average* CFM over that period, or calculate the cost per CFM at specific operating points if needed.
6. Can Cost Per CFM be zero or negative?
The cost ($) input can be zero (e.g., for a purely theoretical calculation or if focusing only on non-monetary factors elsewhere), but the airflow (CFM) must be a positive value greater than zero to perform the calculation. A negative cost or airflow would not make sense in this context for a functional system.
7. What are typical units for Cost Per CFM?
The units depend on your input units. If cost is in US Dollars ($) and time is hourly, the result is $/CFM per hour. If cost is annual, it's $/CFM per year. Always be clear about the time period your cost represents.
8. How does system efficiency relate to Cost Per CFM?
Generally, a more energy-efficient system that provides the same amount of CFM for less power consumption will have a lower Cost Per CFM (specifically, lower operating cost per CFM).
9. Is a lower Cost Per CFM always better?
Not always. While lower is generally better for operating costs, factors like initial purchase price, maintenance reliability, air quality standards, noise levels, and space requirements also need to be considered when choosing an air handling system.
10. Can this tool help justify system upgrades?
Yes. By calculating the Cost Per CFM of your current system and comparing it to the estimated Cost Per CFM of a proposed new system, you can quantify the potential operational savings per unit of air moved, helping to build a business case for the upgrade.
