Les Fish of Ziehl-Abegg (right) outlines how the company has achieved EU- compliant efficiency well ahead of the deadlines.
January 1 2013 is the date when the efficiency of fans driven by motors with power inputs between 125 Watts and 500 kW become the subject of legislation, the result of the implementation within the EU of Lot 11 of Directive 2009/125/EC of the European Parliament.

From this date, fans having motor power inputs in the range outlined above, must achieve the first tier minimum efficiencies (static or total as applicable) for the category of fan in question, as set out in the directive.

More stringent second tier minimum efficiencies follow on January 1 2015; an example to illustrate how this will work is a backward curved radial fan, operating without a housing, where on January 1 2013, the fan must achieve a minimum static efficiency of 58 per cent, and two years later, the same type of fan must achieve a minimum static efficiency of 62 per cent.

It is perhaps rare that the introduction of this kind of restrictive legislation is welcomed.

However, in the case of Ziehl-Abegg, it provides vindication for the time and resources invested in developing an extensive range of axial and radial EC fans, named ECblue, whose efficiencies are already compliant with the more stringent minimum efficiency levels which will be enforced in 2015.


These EuP-compliant efficiencies are achieved by Ziehl-Abegg by ensuring that as much as possible of the electrical input power is used to move air, and as little as possible is consumed overcoming internal motor losses or generating unwelcome noise.

The solution then is the combining of class-leading Ziehl-Abegg EC motors with state-of-the-art axial and radial impellers. Both types of impeller feature innovations which enable the fans to achieve not only exceptional efficiencies, but also market-leading aerodynamic and acoustic performance.

High efficiencies

EC (electronically commutated) motors inherently exhibit relatively high efficiencies, due in part to the use of permanent magnet technology and the application of dc current to the windings, the direction of the current being reversed as required during the electronic commutation process. The electrical efficiency of these motors can be further enhanced by employing innovative manufacturing processes, details of which are normally closely guarded secrets.

Combining a highly efficient EC motor with an average impeller, be it axial or radial, makes little sense, and so, as well as developing the highest efficiency EC motors, Ziehl-Abegg has fully utilised its new InVent Technology Centre, located in Kuenzelsau, Germany, to develop impellers which are class-leading in terms of aerodynamic and acoustic performance. The axial impellers, featuring aerofoil section blades with winglets and serrated trailing edges, form the basis of the Owlet range of fans, with diameters from 250 mm to 1000 mm, while the radial impellers, also featuring aerofoil section blades, and optimised for acoustic performance and efficiency, form the basis of the Vpro range of fans, with diameters from 190 mm to 630 mm.


The desire to achieve ever higher efficiencies from the different categories of fan falls foul of the law of diminishing returns, and can be likened to Formula 1 teams investing millions of whatever currency into achieving mere tenths of a second improvements in lap times.

Ziehl-Abegg's InVent Technology Centre opened in May 2008, and represents a massive investment in r&d, but secures Ziehl-Abegg's future by providing its technicians with the equipment and resources to extract every last bit of performance from their fans.

The InVent Technology Centre has two combined test cells in which air performance tests and DIN 3745 Class 1 acoustic tests can be performed simultaneously.

The smaller of the two test cells works enables testing with air flows up to 25,000 m³/h, while the larger cell can handle air flows up to 100,00 m³/h.