AOV System (Automatic Opening Vents)

Apr 17, 2023

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Automatic opening vents, also known as an AOV system, are becoming increasingly popular. After all, businesses are required to provide a clear and safe exit in the event of a fire, automatic opening vents provide smoke control and ventilation.

AOV systems can be used to open windows, vents and doors automatically. As a result, employees and visitors are capable of evacuating safely, minus any smoke and dangerous fumes. With AOV systems, we can provide our emergency services with breathable air when entering the premises. In this article, we’ll discuss the importance of AOV systems, how they work, and the various options available.

What is an AOV System?

An AOV system is an automatic opening vent system. In brief, an AOV system is designed to extract and control the density of smoke during a building fire. Given that smoke is dangerous, this system will improve visibility and reduce the chances of asphyxiation. Typically, an AOV system will incorporate venting, windows, doors and an actuator. Our systems will be opened automatically, allowing smoke and fumes to escape.

In summary, using an AOV system, we can create a clear escape route for occupants, as well as, provide fresh air for emergency services. The AOV system is controlled by a central control panel that receives signals from a range of sensors. This includes smoke detectors, heat detectors and manual call points.

AOV System Explanation

UK Legislation Surrounding an AOV System

The UK law requires that all buildings, including workplaces, must have clear escape routes that are free from smoke in case of a fire. An AOV system allows businesses to alleviate the potential vision and respiratory restrictions caused by smoke. Also, this helps businesses when adhering to The Regulatory Reform (Fire Safety) Order 2005 (FSO). Given that, the RRO 2005 sets out the legal requirements for fire safety in non-domestic premises in England and Wales. The Fire (Scotland) Act 2005 and the Fire Safety (Scotland) Regulations 2006 apply in Scotland.

What is BS EN 12101-2?

BS EN 12101-2 is a British Standard that specifies the requirements for natural smoke and heat exhaust ventilators (NSHEVs). These are used as part of a smoke control system. This standard is part of a series of standards that cover smoke control systems for buildings.

BS EN 12101-2 provides specifications for the design, manufacture, installation and maintenance of NSHEVs. These ventilators are designed to exhaust smoke and heat from a building in the event of a fire. In addition, they are designed to create a clear escape route for occupants and to aid firefighters in tackling the fire.

The standard covers various types of NSHEVs, including:

  • Roof-mounted ventilators.
  • Wall-mounted ventilators.
  • Facade-mounted ventilators.

It specifies requirements for the materials and components used in the construction of NSHEVs, as well as performance testing and certification procedures.

Compliance with BS EN 12101-2 is often required by building codes and regulations. Also, it is important for architects, engineers, and building owners to ensure that NSHEVs are designed and installed according to the standard. This ensures the safety of building occupants in the event of a fire.

Why Do I Need An AOV System?

An automatic opening vent (AOV) system is typically installed in commercial buildings. Given that this is to provide natural smoke ventilation in the event of a fire. Above all, the primary function of an AOV system is to create a safe escape route for occupants in the building. As mentioned above, this allows firefighters to access the building to extinguish the fire.

In the event of a fire, smoke can quickly fill a building. This will cause asphyxiation and make it difficult for occupants to see and breathe. An AOV system can help to remove smoke and heat from the building, which can make it easier for occupants to evacuate and for firefighters to enter the building and locate the source of the fire.

In addition to providing a safe escape route, an AOV system can also help to limit the damage caused by a fire. By removing smoke and heat from the building, an AOV system can help to prevent structural damage and reduce the amount of damage caused by smoke and heat. Overall, an AOV system is an important safety feature in buildings and can help to protect the lives of occupants and limit the damage caused by a fire.

The Benefits Of An AOV System

The implementation of an AOV system yields several advantages. First, it lessens the quantity of smoke and heat trapped inside a building during a fire, which minimizes the amount of harmful smoke that people inside are likely to inhale during evacuation.

Moreover, the presence of an AOV improves visibility by allowing smoke and heat to rise and leave lower levels more transparent than they would be without ventilation. Additionally, AOV systems decrease the risk of ‘flashover’, a scenario in which heat is drawn back down into a building, as natural air flow helps regulate the heat throughout the structure.

Apart from enhancing safety, AOV systems also have a positive financial impact on a building by allowing smoke to exhaust, resulting in lower overall damage caused by a fire.

Lastly, having an AOV system installed can potentially lower insurance premiums for the building owner, as it demonstrates a commitment to fire safety. Overall, an AOV system can provide a range of benefits for building occupants, owners, and managers, making it a worthwhile investment for improving fire safety and ventilation in buildings.

AOV System Window Actuator

What Are the Different Types of AOV System?

Natural AOV System

The technique of Natural Smoke Ventilation utilises natural airflow dynamics to eliminate smoke in the case of a fire. This can be achieved through various means, such as opening windows or vents, employing automatic opening vents (AOVs), or installing a vertical smoke shaft in buildings without an external wall. This allows for the removal of smoke and the influx of fresh air, making evacuation safer and aiding firefighters in their efforts.

Notably, Natural Smoke Ventilation provides a cost-effective solution that meets the requirements of Approved Document B. The system is activated by smoke detectors during a fire, which triggers a natural airflow to expel the smoke from the building and disperse it into the atmosphere. This strategy also utilises the building’s existing facade, including windows, to optimise smoke ventilation, which can be especially helpful in structures with large atria.

Mechanical AOV System

The primary purpose of ‘Mechanical Smoke Ventilation’ systems is to maintain clear escape and access pathways during a fire and support firefighting efforts. These systems employ fans and other powered components to direct the movement of smoke and enable its release through vents, grills, and dampers. Mechanical solutions are particularly beneficial when natural ventilation is limited or unfeasible.

In summary, these are often used in buildings with low ceilings, where natural ventilation is not possible.

Smoke & Heat Exhaust Ventilation Systems (SHEVS)

Smoke and Heat Exhaust Ventilation Systems (SHEVS) are crucial for removing smoke and heat during a fire to keep escape routes clear and support firefighting efforts. The system can provide more time for building occupants to evacuate.

When smoke is detected, the SHEVS automatically opens AOVs, vents, or doors using actuators or magnetic locks. Additionally, manual call points are located throughout the building to allow firefighters to override the system if necessary. The devices are all linked to a central control panel, which is battery-backed in case of power failure. To allow for quick evacuation, it is essential to open all vents at the right time. Therefore, an automated SHEV system is strongly recommended.

Smoke Containment System

The purpose of Smoke Containment Systems is to halt the spread of smoke and heat between different areas. These systems can be either physical barriers like smoke curtains and fire curtains, or they can take the form of pressurisation systems, which are also known as pressure differential systems.

How Can I Choose The Appropriate AOV System For My Needs?

Determining the suitable AOV system for your smoke vent installation may require guidance from your architect or development manager. Firstly, identify the elements you need to manage in your system. For instance, if you’re constructing a new property, you’ll need a Smoke Vent and a Control Panel. Then, determine the number of items such as Smoke Detectors that are required to open the smoke vent(s) independently, and classify each of them as a zone.

Examples for The Appropriate AOV System

Example 1: Suppose you have a single smoke vent or window that must open during a fire alarm. This corresponds to one zone. For a new development, a single Smoke Vent and a Control Panel would suffice. If a fire system is already in place, there may be a control panel and smoke detectors installed. In this scenario, you should verify with your AOV supplier if the AOV system is compatible with the pre-installed products. Often the AOV can be linked to your fire system and will activate when smoke is detected in that area. When triggered, the AOV Actuator will open, and it will close when reset.

Example 2: If you have three floors, a window on each floor, and a vent for a shaft on the roof, you will have four zones. In this case, you can employ an AOV multi-zone panel that can independently open/close each zone. When a zone is triggered, the roof vent and window may need to open together, creating a chimney effect to clear the smoke. In this instance, you can set the AOV multi-zone with zone 1 as the “master,” a straightforward solution that will activate zone 1 simultaneously with any of the zones 2-4. To activate the AOV multi-zone system, you must connect your current fire system or purchase a Control Panel (Multi-Zone) and add VCS call points & smoke detectors.

How Does an AOV System Work?

An automatic opening vent (AOV) system typically works by opening a vent or window system automatically. This will often be situated on the building’s roof or walls. In essence, the system allows smoke and hot air to escape from the building, helping to prevent the spread of fire and smoke. Typically, an AOV system is connected directly to a wider fire alarm system. The system will trigger all vents and windows to open immediately once the alarm is activated. Once linked to the control panel, any building managers and firefighters can manually activate the system if necessary.

It’s important to note that the design and operation of an AOV system will vary depending on the specific building and fire safety requirements.


In conclusion, automatic opening vents (AOV) systems are essential for commercial buildings to provide natural smoke ventilation in case of a fire. AOV systems can help to remove smoke and heat from the building, which can make it easier for occupants to evacuate and for firefighters to enter the building and locate the source of the fire. The UK law requires all buildings to have clear escape routes that are free from smoke in case of a fire, and AOV systems help businesses to adhere to the legal requirements. Compliance with Part B1 of the Fire safety regulations is essential to ensure the safety of people in and around buildings in case of a fire. Therefore, AOV systems are a vital safety feature in buildings that can help to protect the lives of occupants and limit the damage caused by a fire.

Complying with Fire Safety Regulations, Part B1

Fire safety regulations Part B1 applies to both England and Wales. This legislation sets out the fundamental requirements for ensuring fire safety for those in and around your building. Here are some key steps for complying with Part B1:

Conducting a Fire Risk Assessment

Firstly, conduct a fire risk assessment of the building. An FRA will identify any potential fire hazards associated with your premises. Once outlined, we can evaluate these risks and implement measures needed mitigate these risks.

Ensure Adequate Means of Escape

Adequate means of escape must be provided for all occupants of the building. This includes fire exits, fire doors, fire stairs, and other evacuation routes. The routes must be clear of obstacles and provide a safe means of escape in case of a fire.

Provide Fire Detection and Alarm Systems

Fire detection and alarm systems must be installed in the building. These systems will detect smoke or fire and alert the occupants of the building, allowing them to evacuate in a timely manner.

Provide Firefighting Equipment

Firefighting equipment, such as fire extinguishers and fire blankets, must be provided in the building. This will allow occupants to tackle small fires and prevent them from spreading.

Ensure Fire-resistant Construction

The building must be constructed with fire-resistant materials, such as fire-resistant doors, walls, and ceilings. This will prevent the spread of fire and provide additional time for occupants to escape.

Maintain Fire Safety Measures

All fire safety measures must be regularly maintained and tested to ensure they are in good working order. This includes fire detection and alarm systems, firefighting equipment, and means of escape.

Compliance with Part B1 is essential to ensure the safety of people in and around buildings in case of a fire. Building owners and managers have a legal responsibility to comply with the regulations and ensure the safety of occupants.

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