ISO 12759-2:2019

Overview

ISO 12759-2:2019 - Fans - Efficiency classification for fans - Part 2: Standard losses for drive components provides a standardized method to estimate the input power and overall efficiency of electric-motor-driven fan systems when direct measurement is impractical. The document models commonly used drive components (fan, motor, motor controller/VFD, mechanical transmissions) so users can compare alternative fan system configurations consistently.

Key topics and requirements

• Scope and applicability

  • Applies to fan systems with: fan airflow performance per accepted test standards, polyphase induction motors (nominal motor efficiency specified in the standard), pulse-width modulated VFDs for single motors, and mechanical transmissions using V‑belts, synchronous (cog/timing) belts or couplings.
  • Other motor types and certain multi-motor VFD arrangements are explicitly excluded in the scope.

• Component modeling and calculations

  • Starts from the fan input power (determined per ISO 5801 / ANSI/AMCA test methods) and progresses through transmission, motor and controller losses to calculate overall system efficiency.
  • Defines transmission efficiencies for V‑belt, synchronous belt and coupling arrangements and a direct‑coupled assumption (η = 1).
  • Provides methods to estimate motor and VFD combined efficiency, using motor rated full‑load efficiency and load ratios, with coefficients and performance constants supplied in normative annexes.

• Annexes and data

  • Several informative and normative annexes supply performance constants and regional motor efficiency references (including IEC 60034‑30‑1 guidance, and annexes for horsepower/kW motor and VFD constants).
  • Requires reporting of calculated fan system input power and efficiencies in a standardized way.

Applications and who uses it

• Fan manufacturers and OEMs - to present consistent efficiency classifications for fan products and integrated systems.
• Specifiers and consultants - to compare alternative fan, motor and drive configurations during system selection or retrofit design.
• Energy auditors and facility managers - to estimate system losses and prioritize upgrades (e.g., VFD selection, belt upgrades).
• Regulatory bodies and procurement teams - to define minimum expected performance and ensure consistent efficiency claims.

Related standards

• ISO 12759 series (other parts)
• ISO 5801 (fan performance testing)
• ISO 13348 (fan data presentation)
• ANSI/AMCA 230 and ANSI/AMCA 260 (fan test methods)
• IEC 60034‑30‑1 (motor efficiency classes)

ISO 12759-2:2019 is a practical tool for anyone needing reproducible, comparable fan system efficiency estimates that incorporate realistic drive component losses.