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AOV (Automatic Opening Vent) - A guide to Smoke Vent Rooflights

What is a Smoke Vent or AOV?

What is a Smoke Vent or AOV?

Heat and Smoke Vents are installed in buildings as an active fire protection measure. They are openings in the roof that are designed to open and vent the heat and smoke developed by a fire inside of a building. This is done by the action of buoyancy which is why they are sometimes known as "gravity vents". These vents are designed to open automatically when the system is triggered, usually by a Smoke Detector or Manually triggered when a person sounds the alarm. Which is why another term often used is AOV.

AOV is simply an abbreviation for "Automatic Opening Vent". An AOV system is a control system designed to vent air or smoke for use in natural & smoke ventilation.

Smoke Vents usually are supplied in 2 systems for AOV control; AOV single zone or AOV multi zone. Each panel can be triggered by Smoke Detectors or a Manual Call Point. This will then activate actuators to open or close.

At The Skylight Company we offer Smoke Vents from the UK's leading manufacturers and all of our Smoke Vents are available with Smoke Detectors, AOV Control Panels, Manual Call Points and Firemans Priority Switch which may all be needed for the installation.

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How do I decide which AOV system to fit?

How do I decide which AOV system to fit?

This can be a tricky question and your architect or development manager should be able to advise on exactly what is needed for your Smoke Vent installation.

You first need to decide what items you need to control on your system. If it is a new development you are going to to need the Smoke Vent and a Control Panel. You should then work out how many items like Smoke Detectors, etc you will need to open the smoke vent(s) separately & then class each one as a zone.

Here is an example:

Example 1:
You have a single smoke vent or window which must open when the fire alarm is triggered.

This would be you have 1 zone. For a new development you will need a single Smoke Vent and a Control Panel. If there is already a fire system in place there may be a control panel and smoke detectors already fitted fitted, you will need to contact us to see if our AOV will work with already installed products. So in this situation you can link an AOV single zone to your fire system which will trigger when smoke is detected in that area. The AOV actuator when triggered will open, when reset it will close. VCS Call Points (Yellow Casing) can be added for override or system test.

Example 2 :
You have 3 floors, a window on each, and a vent for a shaft on the roof.

This type of scenario would give you with 4 zones. Here you would use an AOV multi zone panel which will be able to open/close each zone independantly. Under this condition it may be that the vent should open together with any zone that is triggered. (A roof vent will be on a smoke shaft or stairwell. Opening it together with a window will then create a chimney effect clearing smoke.)

In this case you can set the AOV multi zone with zone 1 as a "master". A simple solution that will then trigger zone 1 together with any of the zones 2 - 4.

You would need to link your existing fire system or purchase a Control Panel (Multi Zone) and/or add VCS call points & smoke detectors to the AOV multi zone system to trigger.

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Building Regs

Building Regulations - What you need to know

It is also worth noting that Smoke Vents and AOV's have their own set of Building Regulations, so this must be adhered to, to avoid any issues.

Basic Requirements for installaing an AOV Smoke Vent

Only BS EN12101 certified and CE marked smoke vents (AOVs) comply with the UK building regulations. When choosing an AOV, make sure to check for the CE marking.

Smoke Control and Ventilation - Approved Document F
This document describes the requirements of the specific ventilation methods used in specific types of buildings. What type of ventilation is deemed adequate depends on the type of building, its purpose, the number of floors, how you can reach the upper floors (elevators/stairways etc) and also on the number of occupants that are regularly within the building.

The main aim of smoke ventilation and control is to avoid the build-up of smoke within the building. Having the correct number of AOVs in place (mainly above the staircases in multi-storey buildings) is a significant factor in achieving this outcome.

Conservation of Fuel and Power - Approved Document L
This is the document which governs how much heat insulation should be present within the roof opening. Smoke Vents especially should have the correct design for trapping heat and preventing it from escaping through the roof. The unit of measurement which is given to measure heat loss is called the U Value, and the lower the U Value means the less amount of heat which is being lost. In order to meet the regulations, any Smoke Vent or Roof Hatch must have a U-Value of 3.5 W/m2.K or lower.
BS EN12101 and CE Marking

Any smoke vent (AOV) which is chosen, purchased and installed in the UK needs to meet with the European Standards as set in BS EN12101 and must have the CE Marking.

One of the rules in BS EN12101 is that the vent must have an additional source of energy in case the electricity fails. Even with a heavy load of snow on top of the vent, it still needs to be able to open far enough to allow a large enough airflow to be able to extract the smoke. The CE Mark certification indicates that the AOV has passed all the tests required.

Fire Safety - Approved Document B
This document describes the rules and regulations regarding Fire Safety. It covers information on exactly what a building needs to be equipped with to prevent the spread of fire. As a rule of thumb, the very basic requirements for a residential building are as follows:

1: Installation of fire detection and fire alarm systems
In the terrible event that a fire does occur, it is of the utmost importance that there is an immediate detection and alarm system in place to let you know there is a problem. The quicker that action is taken, the better chance there is to prevent further damage or even catastrophe.

2: Means of escape
There should be more than one escape route, ultimately to destinations in the open air. Unfortunately, it is not always possible to have more than one escape route or to have a safe destination in open clear air. In certain situations, it is acceptable to have a single escape route leading to a place of relative safety.

What are my options?

What are my options?

Sertus Smoke Vents (Part of Whitesales Group) are a leading UK manufacturer of fully integrated smoke ventilation systems and roof access hatches.

Combining their cutting edge safety performance with installer-friendly plug and play technology, Sertus provide value and performance across the life of a building.

Informed by 30 years of experience in smoke control, every Sertus product is CE marked and meets or exceeds British Standards without exception for priceless peace of mind.

We also offer Brett Martin's famous Mardome Trade Smoke Vents. Mardome Trade Smoke Vent Rooflights are individual polycarbonate domes intended for easy installation on flat roofs of all modern building types to provide natural smoke and heat exhaust, as well as comfort ventilation.

Designed, fully tested and certified in accordance with EN 12101-2, they meet standards for safety, security, non-fragility and fire safety and we offer the full guarantee of an established, accredited UK manufacturer.

All of the above comply with current regulations.

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