4 Materials and parts requirements 5 Requirements 5.1 Appearance, structure and general requirements 5.2 Fan blade size deviation 5.3 Performance requirements 5.3.1 Output air volume 5.3.2 Energy efficiency value 5.3.3 Standby power 5.3.4 Speed ratio 5.4 Durability 5.5 Noise 5.6 Electrical Safety 5.7 Electromagnetic Compatibility