AC motor vs. EC motor - Annual energy savings with EC motor use

The following case study compares EC and AC fans with a 450mm impeller diameter used in industrial facilities. The aim is to highlight the differences between the two fan types and compare their annual energy consumption when operating at the same performance level.

Key thoughts:

• Maximum energy efficiency: The EC motor enables electricity savings of up to 59% annually compared to a standard AC motor.
• Precise control: Integrated electronics allow smooth, stepless speed control across the full 0–100% range.
• High efficiency: The unit delivers lower power consumption while maintaining the same airflow performance as an AC equivalent.
• Extended service life: The brushless EC motor design eliminates wear-prone components, ensuring longer, reliable, and maintenance-free operation.
• Cost reduction: The use of EC technology guarantees a real reduction in electricity costs, regardless of system load.

How do AC and EC motors differ in FR fans?

Fan motors differ primarily in design and the available speed control features.

Standard AC motors

Traditional AC induction motors are commonly used in the HVAC industry, where consistent airflow is important. Speed control is limited (in the case of single-speed fans, it is only possible through the use of voltage regulators).

Modern EC motors

EC motors are used in environments where flexible fan operation and reduced power consumption are needed. EC motors consume less energy at lower fan speeds, which is demonstrated in the study below.

Additionally, EC motors have built-in, precise control electronics. They are brushless, resulting in significantly longer lifespan and smooth speed regulation from 0 to 100%.

Comparison of EC and AC motors

Motor type	Standard AC motor	EC motor
Energy efficiency	Standard	Higher – up to 20–60% savings with proper speed control
Speed control	Limited (stepped), requires a voltage regulator	Smooth control (0–100%)
Power consumption	Constant	Lower at the same airflow rate

Case study: EC vs. AC fan operation

To effectively show the performance difference, two fan operating scenarios were considered. The first one assumes the same airflow at higher pressure losses [Pa], and the second at the same airflow with lower pressure losses [Pa].

• For the highest common airflow of 3000 [m³/h] and a pressure drop of 150 [Pa]:

EC motor: Power consumption → 423 [W] → at 10V control signal

AC motor: Power consumption → 495 [W] → at HIGH speed

Assuming 4 hours of daily operation and an energy cost of 1.1 PLN per kWh:

	EC motor	AC motor
Purchase Cost	—	—
Annual Consumption	618 [kWh]	723 [kWh]
Annual Energy Cost	680 [PLN]	795 [PLN]

Conclusion: Under these conditions, the EC motor consumed approximately 15% less energy over the year. 

• For the lowest common airflow of 4000 [m³/h] and a pressure drop of 15 [Pa]:

EC Motor: Power consumption → 118 [W] → at 6V control signal

AC Motor: Power consumption → 286 [W] → at LOW speed

Assuming 4 hours of daily operation and an energy cost of 1.1 PLN per kWh:

	EC motor	AC motor
Purchase cost	—	—
Annual consumption	172.3 [kWh]	418 [kWh]
Annual energy cost	190 [PLN]	460 [PLN]

Conclusion: Under these conditions, the EC motor consumed approximately 59% less energy annually.

Case study: summary

The results above show that EC motors, when properly optimised for speed, can significantly reduce annual energy consumption – an important factor when operating multiple devices simultaneously. These results may vary under different pressure conditions. Based on the scenarios above, the EC motor used approximately 59% less energy annually at the lowest common airflow rate and 15% less energy at the highest.