BS EN 12101-2 Certified AOV Windows: Pivot, Centre-Pivot & Bespoke Options
Product Overview
Stairwell AOVs are Automatic Opening Vents installed at the head of stairwells to extract smoke and maintain clear escape routes in residential and commercial buildings. When the fire alarm activates, the AOV opens automatically: keeping the stair tenable for evacuation and accessible for firefighting. Vent Trade manufactures stairwell AOV products under the Ventec brand, certified to BS EN 12101-2 and held in stock for next-day delivery.
Centre-pivot EN 12101-2 smoke ventilation roof window with integrated actuator and 90° opening. Up to 2.5m² GFA. For stairwells and corridors.
EN 12101-2 certified smoke ventilation window for facade applications. High thermal performance with bespoke sizing. For stairwells and common corridors.
Centre-pivot EN 12101-2 smoke ventilation roof window with integrated 24V actuator. Standard 1m² GFA. Thermally broken aluminium frame. In stock.
EN 12101-2 certified louvre smoke ventilation system. Large free area with high thermal performance. Bespoke sizing for facade and roofline applications.
AOV windows are motorised window units that open automatically in the event of a fire, releasing smoke and heat from the building to keep escape routes clear and tenable. Vent Trade manufactures AOV windows under the Ventec brand in pivot, centre-pivot, top-hung and fully bespoke configurations — every unit tested and certified to BS EN 12101-2 and held in UK stock for next-day delivery.
An Automatic Opening Vent window is never just a window. It is a certified assembly of three parts that must be specified to work together: the window or rooflight itself, the window actuator that drives it open, and the smoke control panel that powers and monitors that actuator. Specifying any one element in isolation risks a non-compliant installation, which is why our AOV windows are supplied and tested as complete, certified units rather than loose components.
BS EN 12101-2 is the European product standard for natural smoke and heat exhaust ventilators (SHEVs). It is the standard an AOV window must be tested and certified to before it can be used in a UK smoke ventilation system, and the certification covers the complete assembly — window, frame, actuator and fixings — tested as a single unit. The resulting Declaration of Performance states the characteristics the fire engineer designs around:
Every Ventec AOV window is tested and certified to BS EN 12101-2 as a complete assembly, and the panel powering it is built to prEN 12101-9 with its power supply to BS EN 12101-10. Together with Approved Document B, these standards define a compliant natural smoke ventilation installation.
The right AOV window depends on where it sits in the building and what the fire strategy asks it to do.
Stairwell AOVs. The most common UK application is a vent at the head of a protected escape stair in a residential building. Under Approved Document B, blocks with a storey more than 11 m above ground level generally require smoke ventilation to the common escape stair, and an AOV at the top of the stair is the standard natural solution. Here the priority is achieving the certified free area specified in the fire strategy — commonly 1 m² — at the highest accessible point, so thermal buoyancy carries hot smoke up and out. Roof-mounted AOV roof vents and pivot AOV windows are both used in this stairwell role, often paired with a low-level air inlet to draw replacement air in at the base of the stair.
Façade applications. Where a roof-mounted vent is impractical — mid-rise façades, stairs that run against an external wall, or elevations where the architecture calls for a discreet, weather-resistant opening — a vertically mounted AOV window or AOV louvre is specified into the façade instead. Façade units must balance smoke performance with weather-tightness, thermal performance and visual integration into the window line, which is where bespoke sizing and finish options matter most. The same certified free-area logic applies: the unit must deliver the Aa the fire engineer specified, in the orientation it is actually installed.
The single most important number when specifying an AOV window is its certified free area. The fire strategy states a minimum — most commonly 1 m² geometric free area (GFA) for a standard residential stairwell under Approved Document B, or a specific aerodynamic free area (Aa) where a fire engineer has used a performance-based design. The AOV window you install must meet or exceed that figure in the configuration and orientation it is actually fitted.
Because Aa is always smaller than the physical opening, a window that looks large enough on a drawing can still fall short once the frame, restrictors and actuator geometry are accounted for. Always compare the certified Aa on the product’s Declaration of Performance against the fire engineer’s requirement, not the structural opening. Where a single vent cannot achieve the required area, the strategy may call for a larger bespoke unit or a roof-mounted vent instead. Our team can confirm the certified free area for any size before you order.
Because AOV windows are frequently installed in occupied, visible parts of a building, they are available in a range of glazing and finish specifications so the smoke vent can meet thermal, acoustic and aesthetic requirements without ever compromising its certified performance:
Finish and glazing choices never override certification: each configuration we offer is covered by the relevant BS EN 12101-2 test evidence for that size and build-up.
An AOV window is only as reliable as the actuator that drives it and the panel that powers it. Ventec AOV windows are supplied with an integrated window actuator — chain, linear or rack, chosen according to the sash weight, the stroke needed to reach full free area, and the opening geometry — so the vent reaches its certified opening every time it operates.
That actuator runs on 24V DC and is powered and monitored by a smoke control panel such as the Ventec O Range 7. The panel interfaces with the building’s fire alarm, opens the vent automatically on fire detection, and holds the system on 72-hour battery standby so the AOV still operates during a mains failure. A firefighter override switch at the building entrance gives the fire service manual control. Specifying the window, actuator and control panel together — as one designed system rather than three separate purchases — is what keeps the installation compliant and makes commissioning straightforward.
When specifying AOV windows for a project, work outwards from the fire strategy: confirm the required certified free area, the mounting position (roof, façade or rooflight), the actuator stroke needed to achieve full opening, and the control and power arrangement that ties the vents back to the fire alarm. Our technical team can match a Ventec AOV window, window actuator and smoke control panel to your fire engineer’s specification and confirm the certification covers the exact size and configuration you need.
For product selection and technical support, call our team on 01202 725 689.
An AOV window (Automatic Opening Vent) is a motorised window or rooflight that opens automatically in the event of a fire to allow smoke to escape from the building. AOV windows are a critical component of smoke ventilation systems in residential and commercial buildings, providing a clear escape route for occupants and improving conditions for firefighting.
The window is fitted with an electric actuator, typically operating at 24V DC, and connected to a smoke control panel that receives signals from the building’s fire alarm system. When a fire is detected, the panel powers the actuator to open the vent to its full certified free area. AOV windows can also be manually controlled via a firefighter override switch at the building entrance.
In the UK, AOV windows are most commonly installed at the head of protected stairwells in apartment buildings as required by Approved Document B.
Selecting the correct AOV window requires matching the product to the fire strategy requirements and the physical constraints of the installation. The primary specification parameter is certified geometric free area: the unobstructed opening area through which smoke can escape, as verified by testing to BS EN 12101-2.
This value must meet or exceed the free area specified in the fire engineering design or prescribed by Approved Document B for standard residential buildings. The window type (pivot, top-hung, or centre-pivot) depends on the roof pitch, available headroom, and structural opening dimensions. For flat roofs, a rooflight-style AOV is typically specified, while pitched roofs use pivot or centre-pivot windows.
Confirm the actuator voltage and stroke are compatible with the smoke control panel and achieve the required opening. Always verify the product certification covers the specific size and configuration being installed.
AOV windows used in UK smoke ventilation systems must be tested and certified to BS EN 12101-2, the European standard for natural smoke and heat exhaust ventilators. This certification covers the complete assembly (window, frame, actuator, and fixings) tested as a unit to verify certified geometric free area, aerodynamic performance, thermal resistance, and reliability.
The smoke control panel powering the AOV must comply with BS EN 12101-10 for control and power supply equipment. The overall system must satisfy the requirements of Approved Document B of the Building Regulations, which sets out the fire safety provisions for buildings in England. For buildings in Scotland and Wales, equivalent regulatory requirements apply.
Additional standards include BS 7346-8 for maintenance of smoke control systems and prEN 12101-9 for firefighter control panels and override switches. All Ventec AOV windows are tested and certified to BS EN 12101-2.
AOV windows are most commonly installed at the head of protected escape stairwells in multi-storey residential buildings, including apartment blocks, sheltered housing, and student accommodation. Approved Document B requires smoke ventilation for escape stairs in buildings with a floor more than 11 metres above ground level, and AOV windows are the standard solution for natural smoke ventilation in these locations.
They are also installed in common corridors, lobby areas, and covered walkways where the fire strategy requires automatic smoke extract. In commercial buildings, AOV windows may be specified for atria, covered courtyards, and large enclosed public spaces.
The installation location depends on the smoke ventilation strategy: typically at the highest accessible point of the protected escape route to take advantage of thermal buoyancy, which causes hot smoke to rise naturally towards the vent opening.
AOV windows are life-safety devices and require regular testing and maintenance to ensure they operate reliably in a fire emergency. BS 7346-8 provides guidance on maintenance of smoke ventilation systems and recommends weekly visual inspections to check for obstructions, damage, or unauthorised interference, and monthly functional tests including full open and close cycling of the vent.
The actuator, wiring, and control panel should be checked for correct operation during each test cycle. Hinges, seals, and weatherproofing should be inspected for wear and damage, particularly on roof-mounted installations exposed to the elements.
A comprehensive annual service by a competent engineer is recommended, covering actuator force and stroke verification, electrical testing, panel battery condition, and overall system integrity. Building managers should maintain a log of all inspections and tests as part of the building’s fire safety management records, which may be required for building safety case compliance under the Building Safety Act.