ISO 21927-2:2018

Overview - ISO 21927-2:2018 (Natural smoke and heat exhaust ventilators)

ISO 21927-2:2018 specifies requirements and test methods for natural smoke and heat exhaust ventilators (NSHEV) intended for use in smoke and heat exhaust ventilation systems (SHEVS) in buildings. The standard defines performance, reliability and safety criteria that NSHEV placed on the market must meet so they operate effectively during a fire to extract smoke and hot gases, support evacuation, reduce fire spread and assist firefighting operations.

Key topics and technical requirements

The standard covers a comprehensive set of technical topics and normative test methods, including:

• Scope and definitions: clear terminology for NSHEV components (opening mechanism, initiation device, aerodynamic free area, throat area, fire open position).
• Activation and response: nominal activation conditions, initiation devices (automatic/manual), response delay (response time) and reliability requirements.
• Performance under fire conditions: resistance to heat, mechanical stability and reaction-to-fire considerations.
• Environmental performance: tests and requirements for opening under snow/wind loads, low ambient temperature, stability under wind load and resistance to wind-induced vibration.
• Effectiveness of extraction: measurement of aerodynamic free area and coefficient of discharge to assess smoke/hot gas extraction capability.
• Durability and operational reliability: lifecycle performance, repeatability of response time and ongoing operational testing.
• Testing and assessment: normative annexes provide detailed test methods for operational reliability, opening under load, low temperature, wind stability and resistance to heat (Annexes B–G, etc.).
• Marking, labelling and packaging: manufacturer information, installation and maintenance documentation required for market placement.

Practical applications and who uses ISO 21927-2

ISO 21927-2 is essential for professionals involved in building fire safety, ventilation and façade systems:

• Manufacturers of NSHEV and rooftop/window ventilators - to design and certify products for compliance.
• Fire engineers and safety consultants - to specify appropriate ventilators and assess system performance in designs.
• Architects and building services designers - for integrating SHEVS and ensuring smoke control strategies meet regulatory expectations.
• Regulatory bodies, test laboratories and certification bodies - for type testing, conformity assessment and market surveillance.
• Facility managers and installers - to understand marking, installation, maintenance and declared performance limits.

Related standards

ISO 21927-2 is part of the ISO 21927 series and references related standards such as:

• ISO 21927-9, ISO 21927-10 (control and power output devices for SHEVS)
• ISO 11925-2, EN 13823, EN 13501-1 (reaction-to-fire tests and classification)
• EN 54-5 / EN 54-7 (fire detection devices)
• IEC 60584-1 (thermocouples)

For implementation, consult the full ISO 21927-2:2018 document and associated parts of the ISO 21927 series for complete test procedures and compliance criteria.