EC vs AC motor payback calculator
Enter the fan duty, the existing AC motor's IE class, the new EC motor's efficiency and your energy price, and get the annual savings and simple payback period for switching — with a breakeven chart showing exactly when the upgrade pays for itself.
How to use this calculator
- Enter the fan's rated shaft power and average load factor.
- Pick the existing AC motor's IE class and pole count.
- Enter the new EC motor's efficiency.
- Enter operating hours, electricity price and the extra investment for the EC motor.
- Read the annual savings and simple payback period.
How this calculator works
The existing AC motor's efficiency is looked up by rated power, pole count and IE class from IEC 60034-30-1 data — the same table used by the Motor Efficiency Calculator. IE4 values are flagged as approximated, since IEC 60034-30-1 only formally publishes IE1–IE3. EC (electronically commutated) motor efficiency has no equivalent published standard table — manufacturers quote it directly — so it's a plain input here; check your motor's datasheet for the real figure rather than trusting the default.
P_shaft = rated power × load factor
P_in = P_shaft / efficiency (for AC and EC separately)
Annual saving = (P_in,AC − P_in,EC) × hours × price
Payback = extra investment / annual saving
This is a simple payback calculation (no discount rate, no energy price escalation) — the standard first screening method for a motor upgrade decision. It assumes a constant load factor rather than a real duty cycle, so treat the result as a screening estimate, not a guaranteed return.
This page checks one motor at a time. CloudAir's selection programs surface FEI, IE class and running-cost figures for every fan in your catalogue automatically. See how CloudAir handles it →