SMOKE AND HEAT VENTILATOR

Fire protection measures for smoke and heat control are implemented through design and, consequently, through the application of systems for Smoke and Heat Evacuation or Smoke and Heat Venting, as well as for the removal of combustion products.

Essentially, there are three types of approaches:

The designer, in accordance with the provisions of Chapter S8 of the “New Fire Prevention Code – Ministerial Decree 18/10/2019,” may, depending on the required performance class, request the application of:

Natural or forced smoke and heat exhaust ventilators,
or

Smoke and heat ventilators.

Performance classes:

Performance level I – No requirements

Performance level II – Smoke and heat generated by a fire must be removable from compartments in order to facilitate the operations of rescue teams.
Performance level III – A smoke-free layer must be maintained within the compartment to allow:

protection of occupants and rescue teams;

protection of assets, if required;

prevention of the spread of smoke and heat generated within the compartment to adjacent compartments.
A. Natural Smoke and Heat Exhaust Ventilator (ENFC) (CE marking required)

Within a natural smoke and heat exhaust system, an ENFC may feature a hinged opening up to 165° or louvered blades.
The certified smoke exhaust capacity, expressed in square meters, is known as SUA (Aerodynamically Effective Area).

The application of a natural smoke exhaust ventilator designed in accordance with UNI 9494-1/2017 allows the creation of a smoke-free layer and therefore the control of the spread of smoke and hot gases during a fire, primarily ensuring the safety of occupants and subsequently the protection of property.
B. Forced Smoke and Heat Exhaust Ventilator (EFFC) (CE marking required)

This is essentially a propeller fan; performance is calculated volumetrically, i.e. in cubic meters per hour (m³/h) extracted.

The application of a forced smoke exhaust ventilator designed in accordance with UNI 9494-2/2017 allows the creation of a smoke-free layer and therefore the control of smoke and hot gas spread during a fire, ensuring first the protection of occupants and then the safeguarding of assets.
This system is typically used in small retail spaces or in locations not connected to roofs and walls.
C. Smoke and Heat Ventilator (SDF)

The smoke and heat ventilator in accordance with Annex G of UNI 9494-1/2017 is fully comparable to an ENFC.
This type of ventilator is used when the creation of a smoke-free layer is not required, but rather to allow fire brigades (VV.FF.) to vent smoke during intervention in order to access the premises and extinguish the fire.

The smoke ventilator category originates within Chapter S8, which defines the following types of use:
TYPE OF USE

SEa Permanently open

SEb Equipped with an automatic opening system activated by a fire detection system (IRAI)

SEc Provided with closing elements (e.g. windows, frames, etc.) with controlled opening from a marked and protected position

SEd Provided with non-permanent closing elements (e.g. windows, frames, etc.) that can also be opened from an unprotected position
SEe Provided with permanent closing elements (e.g. PMMA polymer sheets, polycarbonate, etc.) allowing opening under actual fire conditions (e.g. thermal conditions generated by a natural fire sufficient to melt the closing element) or immediate demolition by rescue teams.
If we analyze, for example, type SEc, the description allows for the use of virtually any type of window or frame.
Over time, the market has seen the development of “smoke ventilators” measuring up to 2.50 × 10.00 m (obviously not CE-marked), as the interpretation by designers and fire brigades has been that it is sufficient to guarantee the geometric air passage area in plan view of the opening.
It should be noted that a smoke ventilator is not dimensioned according to a specific standard or design calculation, but rather based on a table contained within the decree (Chapter S8), where the designer simply verifies the fire load of the environment and demonstrates that the chosen smoke ventilators—whether windows, pseudo-exhaust units, large openings, etc.—are suitable to expel smoke during fire brigade intervention.
Therefore:
A smoke and heat ventilator, intended exclusively to expel smoke and combustion gases only during fire brigade intervention, may simply be (depending on the type of use) a window or a basic plastic skylight.

Under these conditions, market demand often refers—at best—to the type of use (see table above, e.g. SEc, SEb, etc.), with dimensions that usually exceed those that can be certified.
For this reason, it would always be advisable to refer to smoke ventilators as exhaust ventilators, both in terms of dimensions and certification.