Rosenberg EC-fans have high energy saving potential under full load and especially under partial load. The efficiency losses are significantly lower than with conventional AC-motors at the same air flow. The improved energy efficiency results in fewer CO2 emissions. In addition there are lower investment costs for speed control of the fan. A control transformer, VFD or phase angle controller are not necessary. All necessary components are already contained in the EC-motor electronics. Modern EC-technology from Rosenberg is not only easy on the wallet, but also on the environment.
More info here: http://www.rosenberg-gmbh.com/en/ec-technology/calculation-examples