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
What the IE classes mean
IE classes (International Efficiency) are defined in IEC 60034-30-1:2014 (for line-operated motors) and IEC TS 60034-30-2:2016 (for variable-speed drive motors):
- IE1, Standard efficiency. Phased out in EU since 2011
- IE2, High efficiency. Required by EU Ecodesign since 2011 for most motors.
- IE3, Premium efficiency. Mandatory in EU since July 2021 for 0.75-1000 kW, July 2023 for 75-200 kW in 2/4/6-pole.
- IE4, Super Premium. Mandatory from July 2023 for 75-200 kW.
- IE5, Ultra Premium. Defined in IEC TS 60034-30-2. Typically achieved with SynRM (synchronous reluctance) or PMSM technology. 20% lower losses than IE4.
- IE6, Hyper Premium. Not yet formally standardized but increasingly offered by manufacturers. 20% lower losses than IE5. Typically PMSM or advanced SynRM.
TCO example: 22 kW motor, 6000 hours/year
Take a realistic case: a 22 kW motor running 6000 hours per year at 75% load (typical for pumps and fans), electricity at €0.15/kWh. Annual consumption at 75% load = 22 × 0.75 × 6000 = 99,000 kWh gross.
At IE3 (93.0% efficient): 106,452 kWh × €0.15 = €15,968/year. At IE4 (94.3% efficient): 104,985 kWh × €0.15 = €15,748/year, saves €220/year. At IE5 (95.8% efficient): 103,340 kWh × €0.15 = €15,501/year, saves €467/year. At IE6 (96.7%): 102,379 kWh × €0.15 = €15,357/year, saves €611/year.
The upgrade premium from IE3 to IE4 is typically €300-500, to IE5 €800-1500, to IE6 €1500-3000. Payback is therefore roughly 1-2 years for IE4, 2-3 years for IE5, 3-5 years for IE6, assuming continuous operation.
When IE3 is sufficient
Not every motor justifies a high-efficiency upgrade. IE3 is perfectly adequate for: intermittent duty (S3, S6), motors running less than 2000 hours/year, compressor standby, backup drives, applications where IE4/IE5 is not physically available in the required frame. In these cases, the purchase price premium is never recovered through electricity savings.
The rule of thumb: annual operating hours × load factor should exceed 2500 kWh-equivalent before IE4 or higher pays back. Below that threshold, stick with IE3.
SynRM vs PMSM for IE5/IE6
IE5 is typically achieved with SynRM (Synchronous Reluctance Motor) technology, no rare-earth magnets, simpler construction, sustainability-friendly. Some manufacturers also offer PMSM (Permanent Magnet Synchronous Motor) at IE5. IE6 is typically PMSM or advanced SynRM. The choice depends on application: SynRM is preferred for continuous loads and where magnet-free design is important (e.g., high-temperature or corrosive environments). PMSM offers higher power density and better part-load efficiency for cycling applications.
Both require a matching variable-speed drive (VSD). The combined motor+drive package is therefore essential to evaluate, an IE5 motor on a bad VSD can underperform a well-matched IE4 setup.
Frequently asked questions
Is IE4 mandatory now in the EU?
For 75-200 kW motors in 2/4/6-pole designs, IE4 is mandatory since July 2023 under EU Regulation 2019/1781. Below 75 kW, IE3 remains the minimum. Check the latest regulation for your specific motor.
How much can I save going from IE3 to IE5?
For a 22 kW motor running 6000 h/year at 75% load, about €467/year or €4670 over 10 years. For 55 kW motors or 24/7 operation the savings scale proportionally, often €1000-3000/year per motor.
Do IE5 motors need a variable-speed drive?
SynRM IE5 motors require a VSD to operate, they cannot run direct-on-line. PMSM IE5 motors can sometimes run DOL but typically use a VSD for optimal efficiency. Always specify the full motor+drive system.
Need advice on motor selection?
Our sales engineers are happy to help you find the right motor for your application.