In building fires, more than 60% of fatalities are caused by smoke poisoning. Automatic smoke ventilation devices allow the life-threatening smoke to be expelled into the open or its concentration to be diluted. This reduces the danger before smoke spreads through the building and escape routes such as halls and staircases become impassable.


Automatic opening vents (AOVs) are used in the staircases of buildings such as flats and office complexes. Their primary function is to protect common escape routes in the event of a fire, extracting smoke to enable the safe evacuation of occupants.

If a fire breaks out and communal corridors and staircases are filled with smoke, an AOV system evacuates smoke from these areas. As smoke is extracted through the system, the stairwell ventilator provides replacement air to the area. This is vital in enabling people to escape safely, and for firefighters to enter the building easily to tackle the fire.


  • Expels smoke automatically to enable safe evacuation in the event of a fire
  • Allows unhindered access for firefighters to tackle the blaze and evacuate occupants
  • Can be used for daily ventilation to evacuate heat or to provide fresh air to an area
  • Transparent ventilators can provide natural daylight to inner staircases


Small single staircase buildings

Small single staircase buildings are those that have a top floor less than 11m above ground, and no more than three storeys above ground floor level. All that is required is a ventilator at the head of the staircase that can be operated remotely from the fire service accesslevel.

Buildings over 11m

For buildings with a top floor exceeding 11m, there is a legal requirement to provide a means of protecting communal corridors with access to the escape staircase in order to control smoke. This can be achieved by natural or mechanical ventilation.

Natural ventilation is achieved through either using AOVs directly to the outside, or through a shaft up to the roof. A stairwell ventilator is required with both of these options.

Mechanical smoke ventilation systems are commonly used instead of natural shafts as they occupy less space in a building. As with natural ventilation, these systems also require a staircase vent for air inlet purposes. Pressurisation systems, which are an approved mechanical smoke control system, are more complex systems and do not require a stairwell ventilator to operate.

AOV systems are now being specified more as retrofit options in existing high rise accommodation and office blocks.

What’s the next step?

BusinessWatch install and maintain all types of AOV system, and also install addressable interfaces to existing AOV systems to modify them to automatic control.

Although AOV systems should be maintained annually to comply with legislation, it’s recommended that AOV systems are maintained every six months to ensure they work effectively in the event of a fire.

If you’re:

  • looking to install an AOV system in a new build or retrofit to an existing building
  • need to upgrade an existing AOV system
  • looking to automate an existing AOV system
  • require a maintenance/repairs programme for your AOV system

then contact us on 0330 094 7404 for a free, no obligation quotation today. One of our expert Fire Safety Consultants will be able to discuss your requirements, and if required, arrange a suitable time to conduct a free site survey.

Alternatively, complete your details and we’ll get back to you asap.

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