Natural smoke and heat exhaust ventilation improve the indoor safety condition in case of fire inside a building.
Main Risks During Fire
In the event of fire inside of a building, smoke and hot gases rise up in the building, creating a layer of dangerous gases under the ceiling, which fill up the room in a very short time.
The smoke precludes the visibility of the emergency exit or impedes the prompt intervention of the firemen. Due to the toxic substance of the smoke, the 90% of fire victims die due to smoke inhalation. The second critical risk is the flashover caused by the very high temperature inside the building that could generate explosion or big damages to the building structures, with the consequent collapse.
Why Use Smoke Ventilation?
For avoiding the above dangerous events and keeping escape routes clear for longer, and also to ensure that the fire service can quickly and safely locate and extinguish a fire, a natural smoke and heat exhaust systems (NSHEV) must be integrated in the fire protection concept.
The NSHEV consist in a system of automatic opening windows installed in the upper sections of the façade or on the roof for letting the building free from smoke and heat. Ventilation openings in the lower area increase the thermal uplift, generating a “chimney effect”.
NSHEV systems can be divided in two main categories:
- Façade Exhaust System (vertical façade).
- Roof Exhaust System. The NSHEV consist in an electrical drive installed and operating on vertical or horizontal window design and developed for resisting to very high heat (up to 300°C) and reliability (up to 10,000 cycles) tests.
Summarizing, the following benefits can be achieved installing a NSHEV system:
- People protection against smoke inhalation.
- Grant visibility for firemen intervention.
- Preserve the building structures.
- Minimum use of extinguishing agents.
Façade Exhaust System
Façade Exhaust System is composed by electrical chain drive (or rack or spindle drive) installed in smoke and heat exhaust systems (SHEV); top hung or bottom hung window can be implemented.
Roof Exhaust System
Is composed by electrical drive (rack or spindle drive) installed in smoke and heat exhaust systems (SHEV), usually installed on the upper part of the building, directly on the roof or in the nearest area.
NSHEV systems need electrical power supply 24Vdc and should be connected to an electric system for smoke and heat extraction which are composed of a control unit and related smoke and heat detector and/ or emergency push buttons. The control unit should include power supply backup solution that aims to grant 24Vdc even if the main power supply 230Vac is down due to the blackout caused by the fire.