Where Are AOV Systems Required?

An AOV is an automatically controlled window, rooflight, louvre, hatch or smoke shaft damper. When smoke is detected, the system opens the designated ventilation point to help release smoke and heat.

As a result, AOV systems can support the protection of escape routes and provide better conditions for firefighters. Nevertheless, they must be designed as part of a complete smoke-control strategy rather than installed as an isolated product.

At AK Fire Safety , we provide professional AOV surveys, installation, commissioning, maintenance and repair services throughout the United Kingdom.

Which Buildings May Require an AOV System?

Automatic smoke ventilation is used in several types of residential, commercial and public buildings. However, the precise arrangement varies according to the risk and design.

Are AOVs Required in Apartment Blocks?

AOV systems are commonly found in purpose-built apartment blocks, particularly where communal corridors, lobbies and enclosed stairways require smoke ventilation.

During a fire inside a flat, smoke may enter the communal corridor when a door is opened. Therefore, the building design may include automatic ventilation to help remove smoke from the shared escape route.

Depending on the building, the system may include:

• An automatically opening corridor window
• A communal-lobby AOV
• A smoke shaft connected to each floor
• Automatic smoke shaft dampers
• A head-of-shaft roof vent
• A stairwell AOV
• A replacement-air inlet
• A mechanical smoke extract fan

Nevertheless, not every apartment block requires the same arrangement. Existing buildings may also have been designed under different guidance from newly constructed buildings.

Therefore, the building’s approved fire strategy and original design information should be checked before deciding whether an additional AOV is necessary.

Are AOVs Required in Communal Corridors and Lobbies?

Communal corridors and lobbies may require smoke ventilation where they form part of an apartment building’s protected escape route.

A corridor AOV may open directly to the outside. Alternatively, a smoke shaft damper may open and connect the affected corridor to a vertical smoke shaft.

A typical operating sequence may involve:

1. A smoke detector activates within the affected corridor.
2. The AOV control panel receives the signal.
3. The corridor vent or smoke shaft damper opens.
4. The vent at the top of the smoke shaft opens.
5. A replacement-air opening operates where required.
6. Smoke moves away from the communal escape route.

In a smoke shaft system, dampers on unaffected floors may need to remain closed. Consequently, the cause-and-effect programming must match the approved design.

Are AOVs Required in Stairwells?

A protected stairwell may require smoke ventilation where this forms part of the building’s escape or firefighting strategy.

A stairwell AOV is usually positioned at high level, such as at the head of the stair. It may be an opening window, rooflight or louvred vent.

When activated, the AOV helps release smoke and heat from the stair enclosure. In addition, firefighter controls may allow authorised manual operation.

However, an AOV should not be added to a stairwell without checking the building design. An uncontrolled opening could affect pressure relationships or the performance of another smoke-control system.

Are AOVs Required in Smoke Shafts?

Natural smoke shafts usually require automatic dampers or vents that connect the affected corridor or lobby to the shaft.

The system may also require an automatic vent at the top of the shaft. This provides the route through which smoke is released outside.

A smoke shaft arrangement may include:

• Smoke detectors on each protected level
• Floor-level smoke shaft dampers
• A dedicated smoke-control panel
• A head-of-shaft AOV
• Replacement-air controls
• Firefighter override switches
• Standby power supplies

Mechanical shafts may also include extract fans, pressure sensors and additional control equipment.

Are AOVs Required in Atriums?

Atriums can allow smoke to rise and spread through several levels of a building. Therefore, large atriums may require a purpose-designed smoke and heat control system.

The arrangement may use:

• High-level natural smoke vents
• Powered smoke extract fans
• Smoke curtains or barriers
• Smoke reservoirs
• Low-level replacement-air openings
• Automatic controls and detection

Atrium smoke control often requires detailed calculations or fire-engineered design. Consequently, a standard opening window may not provide the necessary performance.

Are AOVs Required in Warehouses and Industrial Buildings?

Warehouses, factories and industrial premises may use automatic smoke and heat exhaust ventilators at roof level.

These systems can help release smoke and heat from large internal spaces. They may also support firefighter operations and limit the spread of smoke beneath the roof.

However, the requirement depends on factors such as:

• Building size and height
• Storage arrangements
• Fire loading
• Compartment design
• Sprinkler protection
• Firefighting access
• Insurance requirements
• The approved fire strategy

Large industrial systems may also use smoke curtains to divide the roof space into controlled smoke reservoirs.

Are AOV Systems Required in Hotels?

Hotels may require smoke ventilation where enclosed corridors, protected stairways, atriums or firefighting shafts form part of the escape strategy.

Because guests may be unfamiliar with the building, clear escape routes and reliable automatic fire-safety systems are especially important.

Nevertheless, the correct arrangement depends on the hotel’s size, height, layout, occupancy and evacuation strategy.

Are AOV Systems Required in Care Homes?

Care homes may use phased, progressive-horizontal or other managed evacuation arrangements. Therefore, smoke control should be coordinated with the building’s evacuation strategy.

An AOV may be required within a stairwell, atrium or designated smoke-control zone. However, it should not be assumed that a standard apartment-block arrangement is suitable for a care environment.

The needs of residents, staffing levels, compartmentation and evacuation procedures must all be considered.

Are AOV Systems Required in Schools?

Schools, colleges and universities may require smoke ventilation within stairwells, atriums, assembly areas or other large internal spaces.

However, not every educational building needs an AOV. The requirement should be established through the approved design and fire-safety strategy.

Do All Commercial Buildings Need AOVs?

No. An AOV is not automatically required in every office, shop, restaurant, warehouse or commercial unit.

A small, low-rise building with direct external escape routes may not require automatic smoke ventilation. In contrast, a larger or more complex building may require smoke shafts, stair ventilation, atrium smoke control or mechanical extraction.

The decision should be based on:

• The approved Building Regulations design
• The fire strategy
• The fire risk assessment
• Escape-route design
• Building height and layout
• Firefighter access arrangements
• Relevant standards and guidance

Locations Where AOVs Are Commonly Installed

What UK Guidance Applies to AOV Systems?

In England, Approved Document B provides statutory guidance supporting the fire-safety requirements of the Building Regulations.

It contains guidance for residential and non-residential buildings, including provisions relating to escape routes, common areas and smoke-control arrangements.

Depending on the building and system, other relevant documents may include:

• BS EN 12101 series – smoke and heat control systems and components.
• BS 7346-8 – smoke-control system planning, design, installation, commissioning and maintenance.
• BS 9991 – fire-safety guidance for residential buildings.
• BS 9999 – fire-safety guidance for the design, management and use of buildings.