ISO 12759-5:2021

Overview

ISO 12759-5:2021 - Fans - Efficiency classification for fans - Part 5: Jet fans - establishes an energy-efficiency classification system for jet fans driven by motors with an electrical input power from 5.5 kW to 155 kW (typical impeller diameters ~500 mm to 1600 mm). The standard defines how to express jet‑fan performance by thrust and how to calculate overall efficiency based on thrust (η(T)). It is explicitly not applicable to jet fans used in enclosed car parks and is intended to support manufacturers, test laboratories and regulators in setting energy‑saving targets.

Key topics and technical requirements

• Scope and definitions: Terminology for fans, jet fans (configuration E), drive systems and efficiency metrics consistent with ISO/IEC vocabularies.
• Reference installation: A typical rating configuration is an axial jet fan with 1× diameter silencers at inlet and outlet and standard inlet devices (e.g., bell‑mouth). Any additional appurtenances must be recorded.
• Efficiency metric: Overall efficiency is defined from thrust (T) and motor input power (Pe). The document provides calculation guidance (Annex A) and an efficiency‑grade determination method (Annex B).
• Energy grades: Jet Fan Motor Efficiency Grades (JFMEG) and Jet Fan Grade Number (JNG, integer part) classify fans according to best efficiency at full speed. A fan’s JFMEG is determined from motor input power and calculated efficiency.
• Correction factors: Adjustments for reversible fans and dual‑use emergency/smoke‑control configurations (per EN 12101‑3) are supplied (e.g., correction factors for reversible operation and for F200/F300/F400 emergency categories).
• Calculation support: Annex B gives formulas to compute motor input power and overall efficiency and provides curve‑fit coefficients (A = 0.46633, B = 0.05419, C = 0.03202) used in grading.

Applications and who uses it

• Manufacturers use ISO 12759-5 to rate and label jet fan efficiency and to design products that meet regulatory energy targets.
• Test laboratories and certification bodies apply the test configuration and calculation methods to verify JFMEG/JNG ratings.
• Building services engineers, ventilation and smoke‑control designers, and fire protection specialists reference the standard when specifying jet fans for tunnels, large spaces and dual‑use systems (excluding enclosed car parks).
• Legislators and regulatory bodies can adopt the classification to define minimum efficiency limits or future energy‑saving standards.

Related standards

• ISO 13350 (jet fan performance testing)
• IEC 60034‑30‑1 (motor efficiency classes)
• EN 12101‑3 (smoke control fan configurations)

For specification, procurement or regulatory adoption, consult the full ISO 12759-5:2021 document or your national standards body.