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All individuals are entitled to the assurance that the structures in which they reside, work, or partake in leisure activities have been constructed securely and per the appropriate standards. Natural smoke and heat exhaust ventilation systems are safety equipment designed to play a beneficial role in a fire. Natural Smoke and Heat Exhaust Ventilators (NSHEVs) are devices that extract smoke and heat from a structure during a fire. They aim to improve safety and air quality in buildings by eliminating smoke and heat during a fire. 

The standard seeks to ensure a secure environment for building dwellers and firefighters by providing accessible escape pathways, preventing fire propagation, and minimising the risk of structural damage. Following EN 12101-2 ensures that NSHEVs work well, are reliable, and last a long time in a variety of settings. 

Smoke and Heat Exhaust Ventilation System (SHEVS)

Smoke and Heat Exhaust Ventilation Systems, or SHEVS, are either natural or powered systems that are designed to remove smoke from a building. This process ensures that low-level evacuation routes remain free of smoke, thereby reducing the risk of damage to the building. Buildings, especially those large or with multiple stories, consider it an essential component of their fire safety protocols. 

There are two ventilation options: mechanical and natural. To propel smoke through the ventilators, natural smoke ventilation draws on the inherent buoyancy of heated gases. These systems often serve a dual function, offering both daily ventilation and smoke suppression. Conversely, motorised smoke ventilation focuses on mechanical extraction through fans.

Natural Smoke and Heat Exhaust Ventilators (NSHEVs)

Engineered to automatically activate during a fire incident, the natural smoke and heat exhaust ventilator (NSHEV) is a passive ventilation device. This natural ventilation process helps structures get rid of heat and poisonous gases in the air outside. This stops fires from spreading and makes it easier for people inside and firefighters to see what’s going on. You can manually operate the product in specific cases. Convection fires result in the highest incidence of injuries and fatalities. NSHEVs inhibit the formation of smoke and odours, safeguarding building occupants. NSHEVs mitigate the risk of smoke inhalation and damage, as well as horizontal fire propagation and secondary ignitions, by expelling smoke. Construction Products Regulation 305/2011 mandates that NSHEVs adhere to the Building Regulations, Approved Document B, BS 9999, and BS EN12101-2. They also need to have a CE mark and a Declaration of Conformity. These key accreditations and certificates demonstrate the NSHEVs’ operational stability, outstanding quality, and performance. 

How NSHEVs work:

Principle of Passive Ventilation: 

• NSHEV utilises natural buoyancy (the ascent of hot air) to expel smoke and heat. During a fire, heated smoke ascends to the uppermost areas of a structure. 
• We strategically place the vents on roofs or walls to facilitate the escape of smoke.

Activation Mechanism:

• Automatic Trigger: Built with sensors (heat or smoke detectors) that engage the vents upon detection of smoke or elevated temperatures.
• Manual Trigger: Can be initiated by a building’s fire safety personnel or by remote/manual control.

Regular Airflow:

• The building’s natural ventilation is sustained by the influx of new air from lower levels or specific openings to displace the stale air.

Positioning of NSHEV

The effectiveness of Natural Smoke and Heat Exhaust Ventilators (NSHEVs) is greatly affected by their positioning. The appropriate location guarantees the effective removal of smoke and heat, the preservation of safe evacuation routes, and the facilitation of firefighting operations. The following information guides the location of NSHEVs:

Due to buoyancy, smoke and heat ascend naturally; therefore, NSHEVs are typically installed at the highest elevations of a building, including roofs, skylights, and atriums. This guarantees the effective removal of smoke and heated gases.

NSHEVs in Staircases:

• Installing NSHEVs on staircases requires careful compartmentation.
• Install vents about 1 meter above the tallest stair landing.
• Purpose: The staircase serves as a vertical shaft, facilitating efficient smoke and heat extraction while maintaining secure evacuation paths when compartmentalised doors close.

NSHEVs in Doorless Corridors:

• In corridors without compartmented doors, smoke dispersion depends on expanded vent openings.
• Suggested Opening Dimensions: A minimum free vent area of 1.5 m² is necessary to guarantee sufficient airflow and smoke evacuation.
• Installation: Position at intervals not surpassing 20 meters to adhere to smoke zone regulations.

Wall-Mounted NSHEVs:

• When affixed to walls, NSHEVs are generally
  • Bottom-hung: Operates from the lower edge to facilitate an effective upward smoke movement. 
  • Side-hung: Operates laterally, facilitating efficient smoke evacuation.

• Orientation: Distribute vents uniformly across the roof, ensuring each area has at least 1 m² of vent space for every 200 m² of floor space, per BS EN 12101-2 standards.

Flat Roof NSHEVs:

• On flat roofs, the positioning of vents varies considerably according to fire safety design.
• Vents must be uniformly distributed on the roof, with a minimum vent area of 1 m² for every 200 m² of floor space, per BS EN 12101-2 standards.
• Spacing: No single vent should exceed a distance of 20-30 meters from another.

Conclusion:

Natural Smoke and Heat Exhaust Ventilators (NSHEVs) are essential components of contemporary fire safety systems, as they not only provide life-saving protection but also maintain structural integrity during fire incidents. Their design, operation, and strategic positioning are per the principles of natural buoyancy, which enable the efficient extraction of smoke and heat, as well as the preservation of distinct escape routes and the efficient application of firefighting agents. 

BS EN 12101-2 and other regulations emphasise NSHEV’s operational stability, reliability, and quality. By following these standards, architects, engineers, and building administrators protect structural integrity, reduce fire risk, and make occupants safer. Whether installed in staircases, corridors, walls, or rooftops, NSHEVs quietly protect lives and property. Their duty goes beyond regulatory compliance to protect the human right to safety in our homes, workplaces, and gathering places.

Last but not least, installing NSHEVs carefully shows that you care about fire safety and make sure that the worst situations are dealt with using the most advanced methods available. In the process, these technologies exhibit accountability and ingenuity, thereby ensuring the security of ecosystems for future generations.