Choosing an IE efficiency class is rarely about the purchase price, it's about the electricity bill over 10-20 years. For continuously running motors, the difference between IE3 and IE5 can be thousands of euros per year. This guide shows when upgrading pays back, and when IE3 is perfectly adequate
Available from stock at Van Bodegraven. Stock in Dordrecht, Piraeus, Singapore and China; shaft, flange, terminal box and coating are adapted where needed in our own workshop. Typically delivered from stock within 1 to 5 working days.
What are IE efficiency classes?
IEC standard 60034-30-1 (2014) and the supplementary Technical Specification IEC TS 60034-30-2 (2016) classify electric motors by their efficiency at rated load. The higher the IE number, the less energy is lost:
| Class | Name | Typical efficiency (7.5 kW, 4-pole) | Standard |
|---|---|---|---|
| IE1 | Standard Efficiency | ~87.1% | IEC 60034-30-1 (no longer permitted in the EU for new motors) |
| IE2 | High Efficiency | ~89.1% | IEC 60034-30-1 (restricted use) |
| IE3 | Premium Efficiency | ~90.4% | IEC 60034-30-1 (EU minimum since July 2023 for 0.75–1000 kW) |
| IE4 | Super Premium | ~92.1% | IEC 60034-30-1 (mandatory since July 2023 for 75–200 kW, 2 to 6-pole) |
| IE5 | Ultra Premium | ~93.6% | IEC TS 60034-30-2 (usually PM motor or SynRM) |
| IE6 | Beyond Ultra Premium | ~94.5% | IEC TS 60034-30-2 (permanent magnet technology only) |
The percentage differences look small, but at 4,000 running hours a year and an electricity price of €0.24/kWh, those few percent add up fast. Some numbers make it concrete.
TCO calculation: 22 kW motor, 4,000 hours/year
Suppose you replace a 22 kW motor in a process application that runs 4,000 hours a year (standard two-shift operation). Electricity price €0.24/kWh (2026 benchmark). Load 75% (typical for a well-sized motor).
Annual consumption in kWh: 22 × 0.75 × 4,000 / efficiency. Multiply by €0.24 to get annual electricity costs.
| Class | Efficiency | kWh/year | Annual cost | Motor premium (estimate) | Payback vs IE3 |
|---|---|---|---|---|---|
| IE3 (reference) | 91.7% | 71,973 | €17,274 | €0 | - |
| IE4 | 93.0% | 70,968 | €17,032 | +€450 | ~2 years |
| IE5 (PM/SynRM) | 94.3% | 69,990 | €16,797 | +€1,200 | ~3 years |
| IE6 | 95.0% | 69,474 | €16,674 | +€2,500 | ~4 years |
Over a 20-year life an IE5 motor saves roughly €5,940 in electricity versus IE3 — and inflation and rising energy prices add on top of that. So do not calculate on purchase price alone: always use Total Cost of Ownership.
Energy savings calculator
Enter one or more motors and calculate the savings from an IE upgrade across your entire installation. Efficiency values follow IEC 60034-30-1 and IEC TS 60034-30-2.
2026 benchmark. Enter your own contract rate for an exact calculation.
Average NL grid mix. Adjust to your own factor if known.
Indicative calculation based on minimum efficiency per IE class. Actual savings depend on the exact motor efficiency and load profile. Ask our sales engineers for a concrete calculation.
When IE3 is sufficient
Not every application justifies the premium of IE4, IE5 or IE6. Choose IE3 when:
- The motor runs few hours. Under 1,000 hours a year (emergency, standby or seasonal use) the payback period of a higher class is too long to be worthwhile.
- The power is below 0.75 kW. Below this threshold absolute consumption is so low that savings in euros remain limited.
- The motor runs on a VFD in a variable application and spends most of its time well below rated power. At part load the classes converge.
- Standardisation matters more than energy costs. If your superintendent puts stock management and interchangeability above everything else, choose a consistent portfolio.
When IE4 or IE5 is worthwhile
Choose IE4 or IE5 when:
- More than 3,000 running hours a year. That is the tipping point where the premium pays back within 4 years.
- Power above 11 kW. Absolute energy consumption is then large enough that every percentage point of efficiency means concrete annual savings.
- The application runs at rated power, such as compressors, large fans and process pumps in continuous operation.
- Sustainability targets. An IE5 motor saves ~2.5% energy; multiplied across a fleet of hundreds of motors that is a measurable CO₂ reduction counting towards CSRD and ESG obligations.
When to consider IE6?
IE6 is only achievable with permanent magnet (PM) or synchronous reluctance (SynRM) technology and always requires a VFD. The premium is significant (2 to 5× compared with IE3), but for specific applications the investment is worthwhile:
- Continuous operation with high cost sensitivity: e.g. fans in data centres or compressors running 8,000+ hours a year.
- Variable load: PM motors maintain their efficiency better across a wide speed range than induction motors.
- Space or weight constraints: at equal power a PM motor is often one frame size smaller.
- Lower cooling and noise burden: less heat loss means cooler running and quieter operation.
Practical points for an IE upgrade
Frame size
IE4 and IE5 motors usually share the same frame as their IE3 predecessor (like-for-like replaceable), but there are exceptions. Always include the existing motor's dimensions in your enquiry, or fill in a Dimension Sheet.
Starting current
High-efficiency motors often have a slightly higher starting current. Check whether your existing protection and supply can handle this, especially with DOL start. For IE5/IE6 a soft-starter or VFD is usually required.
VFD compatibility
Permanent magnet motors (IE5/IE6) require a suitable VFD with PMSM control parameters. Not every existing VFD can correctly drive a PM motor. We prefer to supply motor and VFD as a matched set; see Variable frequency drives.
Certification
For marine applications the IE class must be certified by a classification society when the motor falls under essential service. This affects the choice between ABB M3BP, Dormot Pro or Core. Read more in our article "Marine class certifications explained".
Summary
- IE3 has been the EU minimum since July 2023 and is fine for most applications below 75 kW.
- IE4 is mandatory for 75–200 kW, 2 to 6-pole. Above 3,000 running hours the payback is usually within 3 years.
- IE5 and IE6 (PM/SynRM) are a serious consideration for continuous operation above 11 kW.
- Do not be guided by purchase price alone — always calculate TCO over 10 or 15 years.
- For variable load and part-power operation IE3 can match IE4 through smart VFD control.
No rights can be derived from the information in this article. Contact us for a concrete quotation and current delivery status.
Help choosing the right IE class for your application?
Our sales engineers review your specs, running hours and electricity price and calculate which class fits best. ABB SynRM and IE5 motors are also available from stock.