3.4 Fire and Air Return Paths

Fire Separation
The spread of fire is an important consideration; as such the NAT Vent Attenuator can be made from Class O Foam. Additionally, it is common to install either an intumescent fire damper 13 or smoke damper into the corridor wall adjacent to the NAT Vent Attenuator. The requirement for fire/smoke dampers is dependent on the level of fire compartmentalisation of the building.

Air Return Path
Several methods can be used to provide air return paths. These include atriums, light shafts, ventilation shafts and stair cores. Stair cores were successfully used as an air return path as part of the ventilation scheme for the refurbishment of a Bristol University Education Building. In this development, smoke dampers were proposed to be incorporated within the walls to the stair cores. A cost saving was provided by allowing the flow of air through fire doors held back on magnetic holders. In the case of a fire, the magnet released the fire door, providing the required protection to the stair cores.