Overview
ISO 21684:2025 - Fans - Laboratory test methods for air circulating fans specifies uniform laboratory methods for testing electrically powered air circulating fan heads and ceiling fans using air as the test gas. Its purpose is to establish reproducible procedures and reporting for performance rating. The standard applies to fans with an input power ≥ 125 W, except for ceiling fans larger than 1 800 mm (no lower power limit). The standard excludes jet fans, powered roof ventilators, induced-flow fans, certain positive pressure ventilators, compressors and positive-displacement machines.
Key topics and technical requirements
ISO 21684:2025 covers the full test lifecycle, with technical emphasis on:
- Scope and definitions - terminology and fan subcategories (see Annex A).
- Instruments and measurement accuracy - requirements for meters, thermometers, barometers, calibration and measurement uncertainty.
- Measured variables - airflow rate, thrust, rotational speed, input power and air density.
- Equipment and test setups - allowable configurations, load cell orientation and minimum testable dimensions (fan diameter limited by test figures).
- Test conduct and observations - equilibrium, run‑in, control of extraneous airflow, data recording.
- Calculations and results - calibration correction, ambient air density correction, thrust, airflow, fan total pressure, overall efficiency, circulating fan efficacy and Ceiling Fan Energy Index (C).
- Reporting - standardized test reports, required test data and personnel qualifications.
The standard also details symbols, subscripts, figures and procedures to ensure consistent, repeatable laboratory testing.
Practical applications and users
ISO 21684:2025 is designed for practical use by:
- Test laboratories and calibration facilities performing performance verification and type testing.
- Fan and ceiling‑fan manufacturers during product development, quality control and performance claims.
- Certification and regulatory bodies assessing compliance with energy labeling, performance standards and efficiency classification.
- HVAC engineers and specifiers who need validated performance data for system design and selection.
- Research and development teams optimizing aerodynamic performance, thrust efficiency and energy use.
Applying ISO 21684 ensures reliable data for product ratings, ENERGY/efficiency labeling, procurement specifications and competitive benchmarking.
Related standards
Relevant referenced standards include:
Keywords: ISO 21684:2025, fans laboratory test methods, air circulating fans, ceiling fans testing, airflow rate, thrust measurement, fan efficiency, Ceiling Fan Energy Index.