Pratley & Partners

The LJP Guide to Automatic Opening Vent Window Regulations

Wednesday, 8 July 2020

Automatic opening vents are now a required element of natural smoke ventilation and heat exhaust systems. When such windows are installed, for example in renovations and/or upgrading of older buildings, compliance with the building regulations’ section governing AOV systems is mandatory.

Automatic Opening Vents (AOVs) which form part of any smoke and heat exhaust system will typically be operated by way of electric window controls, which are further connected to the fire alarm system – smoke detectors will be the first line of defence. There are of course numerous sub sections of regulations which relate to fire prevention, safety and evacuation of building which are not dwellings, some of the more relevant are referred to in this article.

BS EN12101-2

BS EN12101-2 is a standard for smoke and heat control, harmonised throughout the European Union, and will probably continue to be the standard in the UK even after Brexit, although this may be modified moving forward.

All AOV systems have to be thoroughly tested; the procedure is quite stringent and must be performed before any window vent on the system can be certified. The standard applies to all components which are used as part of the smoke control system.


This document of the fire safety regulations relate to what a building should be fitted with, in order to prevent any potential fire taking hold and spreading. Volume 2 of the regulations covers buildings which are not deemed as dwellings (houses, bungalows etc) and specifies where window vents should be positioned etc.

It is also essential that users of the building and other stakeholders are aware of what the fire alarm sounds like and know where all escape routes are located within the building. They should also be vigilant in ensuring visitors to the building are aware of escape routes should evacuation of the building be required.


How and where ventilation should be provided and positioned for specific buildings is contained in detail in Approved Document F. Depending on the layout of the building, occupancy levels and the type of building and how the upper floors are reached also feature. Lifts, escalators and stairwells or alternative methods of access will have specifications about how smoke accumulation is prevented, as well as the means of escape in the event of a fire occurring.

More than one AOV may be required for adequate smoke control and ventilation, but all will be required to be connected to the smoke detection and fire alarm system which is installed in the building.

Projects undertaken by our dedicated team of designers and installers of window openers and control systems have included such historic buildings as Buckingham Palace (pictured above) and St Paul’s Cathedral.

Our design teams are on hand to help you through the maze of regulations so you do not have to. They also work with stakeholders to ensure that the fabric of listed and heritage buildings remains intact and not damaged in any way.

Calling the team today is your first step to ensuring the electric or manual window controls and smoke venting systems are in place, comply with current regulations and, should the worst occur, be operational as the regulations demand.

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