What is an AOV system?

Automatic Opening Vents (AOVs) or smoke ventilation systems are designed to help ventilate and extract smoke from buildings during emergencies and in the event of a fire to facilitate the safe escape of occupants.

Commercial and multiple occupancy buildings are required by law to provide clear escape routes, free from smoke to allow occupants unimpeded escape, as well as provide first responders and fire crews access during an emergency.

Whether the building application is residential, commercial, healthcare or educational, a smoke ventilation system should be included as part of the overall fire strategy for the building. 

How do smoke control systems save lives and protect property?

• By keeping escape and access routes free from smoke
• By facilitating fire-fighting operations
• By reducing the risk of the fire developing further
• By protecting the contents of the building
• By reducing the risk of damage to the building​

The chairman of the Smoke Control Association says: “Smoke is the greatest threat in a fire. A fire can fill an area of 10,000m2 with smoke within minutes. 5 breaths are all it could take to lose consciousness. Effective smoke control saves lives”.

Why do I need an AOV system?

Fire Safety – Approved Document B (ADB) covers building regulation in England covering fire safety matters within and around buildings. Requirement B1 addresses fire safety precautions which must be adhered to, to ensure the safety of occupants, firefighters and those close to the building in the event of a fire.

B1: Means of warning and escape

The building shall be designed and constructed so that there are appropriate provisions for the early warning of fire, and appropriate means of escape in case of fire from the building to a place of safety outside the building capable of being safely and effectively used at all material times.

In the Secretary of State’s view, requirement B1 is met by achieving all of the following:

a. There are sufficient means for giving early warning of fire to people in the building.
b. All people can escape to a place of safety without external assistance.
c. Escape routes are suitably located, sufficient in number and of adequate capacity.
d. Where necessary, escape routes are sufficiently protected from the effects of fire and smoke.
e. Escape routes are adequately lit and exits are suitably signed.
f. There are appropriate provisions to limit the ingress of smoke to the escape routes, or to restrict the spread of fire and remove smoke.
g. For buildings containing flats, there are appropriate provisions to support a stay put evacuation strategy.

The extent to which any of these measures are necessary is dependent on the use of the building, its size and its height. Building work and material changes of use subject to requirement B1 include both new and existing buildings.

What is the importance of a well-designed smoke control system?

If there is a fire, a well-designed smoke control system can save lives and help protect property. It will:

Keep escape and access routes free from smoke
Facilitate fire-fighting operations
Delay or prevent flashover, reducing the risk of the fire developing further
Protect the contents of the building
Reduce the risk of damage to the building

How does an AOV system work?

AOV systems are generally coupled with an alarm or detector system to work in the event of a fire. When a detector or call point is triggered an AOV control system will open actuators, windows or vents to create ventilation. This clears smoke for people leaving the building and vents smoke out of the area that has been triggered.

What are the benefits of an AOV system?

Using AOVs reduces the amount of smoke and heat contained in a building during a fire. This benefits residents or workers inside, as they are likely to inhale less harmful smoke during evacuation.

Enhanced visibility is created when an AOV is present in a smoke situation, as the smoke and heat is allowed to rise, leaving lower levels more clear than they would be without ventilation.

‘Flashover’ is also reduced; the situation in which heat is drawn back down into a building as natural air flow encourages regulation of heat throughout the building.

Aside from increasing life protection, AOVs also reduce the financial impact of a fire, simply by allowing smoke to exhaust, resulting in lower overall building damage.

What are the different types of AOV system?

Mechanical Smoke Ventilation Systems

Mechanical Smoke Ventilation systems are designed to keep escape and access routes free from smoke and to facilitate fire-fighting operations. The systems use powered elements such as fans to force the movement of smoke to allow it to escape through dampers, grills and vents. Mechanical systems are useful where natural airflow is insufficient or impracticable.

Smoke & Heat Exhaust Ventilation Systems (SHEVS)

Smoke and Heat Ventilation Systems (SHEVS) are designed primarily to remove smoke and heat from a burning building, maintaining escape routes and allowing clear fire fighting access. A SHEV system increases the escape time for buildings occupants.

On detection of smoke the AOVs, louvres or doors via actuators or magnetic locks will automatically open. With manual call points at selected locations within the building, fire fighters can also override the system if required. A central control panel is linked to all the devices and is battery backed in case of mains failure. The timing for opening all the vents is of great importance in order to enable people to escape quickly. Therefore, the use of an automated SHEV system is to be highly recommended.

Smoke Containment Systems

Smoke Containment Systems prevent the movement of smoke and heat from one area to another. They take the form either of physical barriers such as smoke curtains or fire curtains, or as pressure differential systems, also known as pressurisation systems.

Natural Smoke Ventilation

In the event of a fire, natural venting systems open airways, using natural airflow dynamics to remove smoke. This can be attained by opening windows or vents, automatic opening vents (AOVs) or, where there is no external wall, a vertical smoke shaft. Smoke can exit the building whilst fresh air can enter.

Natural Smoke Ventilation is a cost-effective method of meeting the requirements of Approved Document B. In the event of a fire, smoke detectors will activate the natural smoke venting system on that floor. This creates a natural airflow to purge smoke from the building and exhaust it into the atmosphere, offering a safe means of escape for occupants, with greater visibility and access for firefighters.

This approach allows the existing building façade, including windows, to be used as an integral element of the smoke ventilation strategy and is particularly useful in building with large atria.

Car Park Ventilation Systems

Induction/Impulse (or jet) fans clear smoke from enclosed or underground car parks. These are often combined with fume ventilation to prevent the build-up of vehicle exhaust gases in normal day to day use of the car park. Louvres, dampers, and powered smoke extraction fans are also often integrated into the scheme.

How often does an AOV system need to be maintained?

In UK law smoke ventilation systems must be regularly inspected and be operational. The owner or the management company of all premises are responsible for the statutory inspection & maintenance of smoke ventilation systems.

We recommend and advise bi-annual inspection and maintenance to ensure your system is in a working operational condition.

If you are unsure when your system was last inspected please Contact Us and we can schedule a visit from one of our engineers.

Smoke Ventilation Systems

Smoke Control Systems

Smoke Vents

Automatic Opening Vents (AOVs)

Smoke and Heat Exhaust Ventilation Systems (SHEV)