ISO 12759-4:2019/DAM 1:2026(en)

ISO/TC 117/WG 11

Date: 2025-12-20

Fans – Efficiency classification for fans

Part 4:

Driven fans at maximum operating speed

AMENDMENT 1: addition of Annex F providing an example of the use of efficiency classification and editorial changes.

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Fans – Efficiency classification for fans
Part 4:
Driven fans at maximum operating speed
AMENDMENT 1: addition of Annex F providing an update of the use of efficiency classification and editorial changes.

Scope

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This document establishes a system for the classification of fan efficiency for all fan types driven by motors with an electrical input power of 0,125 kW and above. It applies to driven fans only, but not to the system (finished original equipment manufacturer’s product, for example box fans and roof fans or ventilation system) in which they might be installed. This document, as well as ISO 12759-3, ISO 12759-5 and ISO 12759-6, describe a number of different procedures to classify the efficiency of a fan or to apply a minimum efficiency limit (MEL).

Appendix F shows how procedures described in this document can be used to set MELs.

There is no method described to compare these classifications and MELs.

NOTE 1 The electrical input power is at the fan’s optimum efficiency.3.17

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conventional output power which is the product of the mass flow rate and fan static work per unit mass, or the product of the inlet volume flow rate, the compressibility coefficient and the fan static pressure.

3.26

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fan air power divided by the drive/control electrical input power for the fan and motor combination with a variable speed drive

3.26 Note 3

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The drive/control input power as defined in 3.22

3.28

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fan static air power divided by the drive/control electrical input power for the fan and motor combination with a variable speed drive

5.2 the four bullet point

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— category A installations – ISO 5801:2017, 6.2;

— category B installations – ISO 5801:2017, 6.3;

— category C installations – ISO 5801:2017, 6.4;

— category D installations – ISO 5801:2017, 6.5.

Annex F

Add the following new annex after Annex E, before the bibliography.

1. 
   (informative)
   
   Ecodesign requirements for fans driven by motors with an electrical input power between 125 W and 500 kW
   1. General

The European Union regulation applying ecodesign requirements for fans driven by motors with an electric input power between 125 W and 500 kW was published in 2024. It uses two equations to set energy efficiency limits for axial, forward curved centrifugal, radial, mixed flow, and centrifugal backward bladed fans with and without housing.

This annex provides some information, such as minimum energy efficiency limits and use of compensation factors. There are other aspects that may be of interest, and these are described in the European Regulation.

• • 1. Minimum efficiency limits

Two equations specify rating limit curves as described in section 6. The output of the equations is the minimum energy efficiency that fans need to achieve. The equations are as follows:

P_e < 10 kW:           

P_e ≥ 10 kW:           

where

P_e is electrical power input to the motor or variable speed drive at the best efficiency point (kW);

Ƞ_min is the minimum energy efficiency expressed to one decimal point (%);

N_G is the energy efficiency grade set in the regulation

Ƞ_min is the minimum energy efficiency of the fans based on the electrical input power at its best efficiency point. The energy efficiency is calculated as described in section 5.3

• • 1. Correction factors

The European Union regulation applies correction factors to the calculated efficiency of the fan to adjust for certain conditions. Both fan air power and input power were directly measured. The efficiency equations (1), (2), (3) and (4) of section 5.3 are adapted as follows.

where

Ƞ_e is the calculated efficiency of the fan;

P_u is the fan air power;

P_e is the motor input power;

C_p is the correction factor for power conversion

C_c is the correction for part load;

C_guard is the correction factor for guard compensation

NOTE The above is using equation (1) as an example. The correction factors are applied to equations (2), (3) and (4) in the same way.

C_p is a correction factor for power conversion losses with a value of 0,9 for fans equipped with a DC motor with a rated voltage lower than 100 V when the converter transforming AC into DC is not part of the fan, and 1,0 otherwise:

C_c is a correction factor for part load compensation with one of the following values:

C_guard is a correction factor for guard compensation that may be applied when calculating fan efficiency in case the fan is equipped by permanently fitted protective guards that cannot be removed without making the fan inoperable. The value of C_guard is:

Bibliography

Add the following reference.

[7]   Commission Regulation (EU) 2024/1834, implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for fans driven by motors with an electrical input power between 125 W and 500 kW and repealing Commission Regulation (EU) No 327/2011