Electrics & Electronics

Energy efficiency of electric drives for domestic appliances

The aim of this project, run by Munich Technical University, is to highlight the energy saving potential of small electric drives in domestic appliances. Data on appliances in circulation and user behaviour will be used to calculate and represent the potential savings for the whole of Germany. 



The potential energy savings from preventing unnecessarily high losses in small electric drives are at least as high as by addressing the much-discussed standby mode. However, public awareness is practically zero.

The aim of the project is to highlight the potential energy efficiency of small electric drives in actual use in different appliance groups (refrigerators and freezers, washing machines, washer-dryers, dishwashers). The test objects selected were new appliances with standard technical solutions, special technical features, and low-cost appliances.

To clarify the realistic potential savings, the project partners are using a combination of electric load profiles for appliance use and bench tests to investigate the operating behaviour of the motor types used. The optimisation proposals derived attempt to improve the utilisation of the drives and identify potential savings.


  • Total potential savings of around 8.2 TWh/a for small electric drives were identified. The majority of this figure can be achieved by adjusting the dimensioning of the drives during the design of the appliance.
  • The most significant absolute potential savings in the study were 5.4 TWh in the refrigerator and freezer sector. It was shown that condenser motors with a peak efficiency of 70 % are only operated with 25 % utilisation in some unfavourable situations.
  • For tumble dryers and dishwashers, preventing incorrect adjustments and using condenser motors with a high peak efficiency enabled potential savings of up to 66 & to be demonstrated.
  • With the universal motors found in washing machines, the use of a rectifier more than doubled the motor efficiency in some instances at slow motor speeds in washing mode.

More Project Informations

Project number:  0327224

Project period:  1999 - 2001

Project region:  Germany (Bavaria)

Project contact:

Herr Prof. Wagner

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Source: German National Library of Science and Technology Hannover (TIB)