Ventilation & AOVs
Most types of glass and thermoplastic rooflights are available with some form of optional comfort ventilation, to support PART F Building Regulations.
Most configurations can be supplied with top/bottom hung hinged or moveable sections operated by 24 or 230 Volt actuators, or by manual means if required.
Many upstands for modular rooflights are also offered with ventilation options.
Rooflights with built-in ventilation can be used as part of a comfort strategy to maintain appropriate internal temperatures and air quality, with minimal energy consumption.
AOV Automatic Opening Ventilators for smoke ventilation in the event of fire
Smoke control using natural ventilation is a particularly effective means of protecting escaping occupants, those awaiting rescue and fire-fighters from the immediate dangers of fire and smoke.
In principle, high-level outlet vents and low-level inlet vents open automatically in the event of a fire to allow cool air into the building and allow smoke and hot air to flow out. This improves the conditions for occupants to escape and fire-fighters to enter. In the absence of ventilation, smoke fills the room, being drawn back down from the ceiling by convection as temperatures rise, leading to potential—and particularly dangerous—‘flashover’.
The specific design of an effective and safe smoke ventilation system requires specialist involvement, perhaps by the mechanical and electrical consultant, and may well form part of a fire engineering solution. In England and Wales, Part B of the Building Regulations covers fire and the Approved Document (AD B) Volume 2 provides guidance applicable to flats and non-dwellings. The following national, regulatory guidelines have similar requirements: Section 2 of the Scottish Building Standards Agency Technical Handbooks 2007; Technical Booklet E of the Building Regulations (Northern Ireland); Technical Guidance Document B of the Government of Ireland Building Regulations 2006. AD B identifies a number of situations where AOVs to provide natural ventilation are appropriate, including: Small single-stair blocks of flats Common escape routes in larger blocks of flats Basement areas Enclosed car parks Vertical smoke shafts, as part of a smoke control design In several cases, AD B specifies the minimum of ventilation—generally either 1 m2 or 1.5 m2.
NARM member companies can offer a variety of AOV options, from modular domes to structural glazing systems with integral AOV sections.
Typical hinged rooflight for comfort ventilation
Typical dual-pitch AOV unit
Below: AOV operation
In the event of a fire, actuators open high-level smoke vents and low-level fresh air inlet vents. This allows cool air into the building, forcing the hot air and smoke out via the roof, providing a smoke-free layer for safe escape. The smoke-free layer allows safe access for the fire to be fought and extinguished.