Estimate your dust collector's VFD energy savings. Keep the drive you already own.
Estimate annual kWh and electricity-cost savings for a centrifugal fan, including dust collection and industrial ventilation systems. If the numbers look worthwhile, GRIT checks whether on-prem demand control can work with the VFD already on your fan.
See what running your fan slower could save each year.
Compare full-speed operation with a lower target speed. The calculator estimates the theoretical reduction in fan power, annual energy use, and electricity cost.
What happens next
- Run the estimate.Enter four operating numbers and see the theoretical annual savings.
- Add equipment details.The VFD model and fan application are optional, but they help us check compatibility and operating limits.
- Get a practical go/no-go.GRIT tells you whether the opportunity is worth a closer engineering look.
Why fan speed matters
For a centrifugal fan, the affinity laws estimate that power changes with the cube of fan speed: power ratio = (target speed / full speed)3.
The calculator treats motor HP as the full-speed fan load and converts it at 0.746 kW per HP. That makes this a first-pass estimate, not a savings guarantee.
We'll review your numbers. If you include the VFD model and fan application, we'll also check whether GRIT can work with the installed drive. We typically respond within one business day.
What a 20% speed reduction means on paper.
For a centrifugal fan, airflow changes roughly with speed and power changes roughly with speed cubed. That is why a modest speed change can produce a much larger theoretical power reduction.
| Fan speed | Power used | Power reduction |
|---|---|---|
| 100% | 100.0% | 0.0% |
| 90% | 72.9% | 27.1% |
| 80% | 51.2% | 48.8% |
| 70% | 34.3% | 65.7% |
| 60% | 21.6% | 78.4% |
Example: 100 HP fan at 80% speed
At 4,000 operating hours per year and $0.12/kWh, the calculator estimates about 145,600 kWh and $17,500 in theoretical annual savings.
That example assumes the motor is fully loaded at full speed and the fan operates at 80% speed for all 4,000 hours. Use the calculator with your numbers for a first-pass screen.
Match fan speed to the work running now. Keep the VFD already on the fan.
For dust collectors and industrial ventilation systems, GRIT works on-prem with compatible installed VFDs. We review the fan, motor, drive, ductwork, minimum airflow, and available control interface before recommending a retrofit.
Why a VFD alone is not enough
The drive can change fan speed, but it does not know which machines are running, which airflow paths are open, or how much airflow the active work requires. GRIT supplies that on-prem demand signal and coordinates the operating sequence.
Know what is running
Supported machine or process signals tell the GRIT Hub which equipment is active.
Tell the VFD what the fan needs
GRIT sends configured start, stop, or demand commands to a compatible drive.
Open the right airflow path
Mapped gates and zones can open before the fan setting changes.
Run it on-prem
The operating sequence runs on the GRIT Hub at your facility. No cloud round trip is required.
What can change the actual savings?
Your fan and duct system set the safe operating range.
This calculator uses the theoretical cube-law relationship for centrifugal fans. Real systems do not follow that curve perfectly. Static pressure, fan and system curves, minimum airflow, motor loading, motor and VFD efficiency, control limits, active tool combinations, and the hours spent at each speed all change the actual savings.
Do not reduce airflow below the level required for capture, process safety, cooling, combustion protection, or code compliance. Final settings should be established and commissioned from the actual system by qualified personnel.
How do you calculate VFD energy savings for a centrifugal fan?
Start with the fan's full-speed power, annual operating hours, electricity rate, and target speed. Under the fan affinity laws, the theoretical power ratio equals the target speed ratio cubed. At 80% speed, the fan uses 51.2% of full-speed power on paper, a 48.8% reduction. Actual savings depend on the installed system.
Can on-demand control reduce dust collection energy use?
It can when the system safely reduces airflow during periods of lower demand. Tool activity, open airflow paths, minimum conveying velocity, static pressure, and the dust collector's operating limits all affect how far fan speed can be reduced.
What sets the safe minimum fan speed?
The safe minimum is system-specific. Required capture airflow, minimum transport velocity, fan and system curves, static pressure, filter condition, duct configuration, active machines, and process-safety requirements all matter. Final limits should be set and commissioned from the installed system.
Why does GRIT ask for the VFD manufacturer and model?
It does not affect the calculator result. It helps us check whether the installed drive has a control interface GRIT can use and what commands it supports. You can run the estimate without it.
Why does the fan application matter?
It does not change the cube-law calculation. It helps us understand the airflow requirement and operating constraints. A dust collector, process exhaust fan, and general ventilation fan do not necessarily have the same safe minimum airflow.
Is the calculator a guaranteed savings quote?
No. It is a theoretical first-pass screen based on the values entered. A useful review still needs the fan, motor, drive, airflow requirements, operating schedule, and current control sequence.
Free first-pass review
Send us the numbers. We'll tell you if it's worth pursuing.
If you have the VFD model and fan application handy, include them. We'll review the estimate's assumptions and whether GRIT can control the installed drive on-prem.
Estimate your dust collector's VFD energy savings. Keep the drive you already own.
Estimate annual kWh and electricity-cost savings for a centrifugal fan, including dust collection and industrial ventilation systems. If the numbers look worthwhile, GRIT checks whether on-prem demand control can work with the VFD already on your fan.
See what running your fan slower could save each year.
Compare full-speed operation with a lower target speed. The calculator estimates the theoretical reduction in fan power, annual energy use, and electricity cost.
What happens next
- Run the estimate.Enter four operating numbers and see the theoretical annual savings.
- Add equipment details.The VFD model and fan application are optional, but they help us check compatibility and operating limits.
- Get a practical go/no-go.GRIT tells you whether the opportunity is worth a closer engineering look.
Why fan speed matters
For a centrifugal fan, the affinity laws estimate that power changes with the cube of fan speed: power ratio = (target speed / full speed)3.
The calculator treats motor HP as the full-speed fan load and converts it at 0.746 kW per HP. That makes this a first-pass estimate, not a savings guarantee.
We'll review your numbers. If you include the VFD model and fan application, we'll also check whether GRIT can work with the installed drive. We typically respond within one business day.
What a 20% speed reduction means on paper.
For a centrifugal fan, airflow changes roughly with speed and power changes roughly with speed cubed. That is why a modest speed change can produce a much larger theoretical power reduction.
| Fan speed | Power used | Power reduction |
|---|---|---|
| 100% | 100.0% | 0.0% |
| 90% | 72.9% | 27.1% |
| 80% | 51.2% | 48.8% |
| 70% | 34.3% | 65.7% |
| 60% | 21.6% | 78.4% |
Example: 100 HP fan at 80% speed
At 4,000 operating hours per year and $0.12/kWh, the calculator estimates about 145,600 kWh and $17,500 in theoretical annual savings.
That example assumes the motor is fully loaded at full speed and the fan operates at 80% speed for all 4,000 hours. Use the calculator with your numbers for a first-pass screen.
Match fan speed to the work running now. Keep the VFD already on the fan.
For dust collectors and industrial ventilation systems, GRIT works on-prem with compatible installed VFDs. We review the fan, motor, drive, ductwork, minimum airflow, and available control interface before recommending a retrofit.
Why a VFD alone is not enough
The drive can change fan speed, but it does not know which machines are running, which airflow paths are open, or how much airflow the active work requires. GRIT supplies that on-prem demand signal and coordinates the operating sequence.
Know what is running
Supported machine or process signals tell the GRIT Hub which equipment is active.
Tell the VFD what the fan needs
GRIT sends configured start, stop, or demand commands to a compatible drive.
Open the right airflow path
Mapped gates and zones can open before the fan setting changes.
Run it on-prem
The operating sequence runs on the GRIT Hub at your facility. No cloud round trip is required.
What can change the actual savings?
Your fan and duct system set the safe operating range.
This calculator uses the theoretical cube-law relationship for centrifugal fans. Real systems do not follow that curve perfectly. Static pressure, fan and system curves, minimum airflow, motor loading, motor and VFD efficiency, control limits, active tool combinations, and the hours spent at each speed all change the actual savings.
Do not reduce airflow below the level required for capture, process safety, cooling, combustion protection, or code compliance. Final settings should be established and commissioned from the actual system by qualified personnel.
How do you calculate VFD energy savings for a centrifugal fan?
Start with the fan's full-speed power, annual operating hours, electricity rate, and target speed. Under the fan affinity laws, the theoretical power ratio equals the target speed ratio cubed. At 80% speed, the fan uses 51.2% of full-speed power on paper, a 48.8% reduction. Actual savings depend on the installed system.
Can on-demand control reduce dust collection energy use?
It can when the system safely reduces airflow during periods of lower demand. Tool activity, open airflow paths, minimum conveying velocity, static pressure, and the dust collector's operating limits all affect how far fan speed can be reduced.
What sets the safe minimum fan speed?
The safe minimum is system-specific. Required capture airflow, minimum transport velocity, fan and system curves, static pressure, filter condition, duct configuration, active machines, and process-safety requirements all matter. Final limits should be set and commissioned from the installed system.
Why does GRIT ask for the VFD manufacturer and model?
It does not affect the calculator result. It helps us check whether the installed drive has a control interface GRIT can use and what commands it supports. You can run the estimate without it.
Why does the fan application matter?
It does not change the cube-law calculation. It helps us understand the airflow requirement and operating constraints. A dust collector, process exhaust fan, and general ventilation fan do not necessarily have the same safe minimum airflow.
Is the calculator a guaranteed savings quote?
No. It is a theoretical first-pass screen based on the values entered. A useful review still needs the fan, motor, drive, airflow requirements, operating schedule, and current control sequence.
Free first-pass review
Send us the numbers. We'll tell you if it's worth pursuing.
If you have the VFD model and fan application handy, include them. We'll review the estimate's assumptions and whether GRIT can control the installed drive on-prem.