Parking lot ventilation

Natural ventilation
Garages must be equipped with a natural ventilation system consisting of openings in the walls and/or ceilings and arranged in such a way as to allow for effective exchange of ambient air, as well as the disposal of heat and smoke from any fire. In order to ensure uniform ventilation of the rooms, the ventilation openings must be distributed as uniformly as possible and at a mutual distance of no more than 40 m.

Ventilation surface
Natural ventilation openings must have a surface area of ​​no less than 1/25 of the compartment's floor area. In cases where the mechanical ventilation system referred to in the following point is not provided for, a fraction of this surface area - no less than 0,003 mXNUMX per square meter of floor - must be completely free of windows.
The ventilation system must be independent for each floor.
For underground garages, ventilation can occur through cavities and/or chimneys; if the same cavity is used, to allow independence of ventilation per floor, vertical sectioning or the use of “shunt” type ducts can be used.
For garages divided into boxes, natural ventilation must be provided for each box. This ventilation can be obtained with ducts to the outside or with openings also on the manoeuvring lane, without windows and with a surface area not less than 1/100 of the floor plan of the box itself.

Mechanical ventilation – Read more:

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The natural ventilation system must be integrated with a mechanical ventilation system in underground garages with a number of vehicles per floor greater than that shown in the following table.

NUMBER OF VEHICLES IN UNDERGROUND PARKING:

– close-up 125
– second floor 100
– third floor 75
– above the third floor 50

For closed above-ground garages, the natural ventilation system must be integrated with a mechanical ventilation system on floors with more than 250 vehicles.

Mechanical ventilation. Characteristics
The capacity of the mechanical ventilation system must be no less than three changes per hour.
The mechanical ventilation system must be independent for each floor and operated with manual or automatic control, to be located near the exits.
The system must be operated during peak periods identified by the simultaneous start-up of a number of vehicles greater than 1/3 or by the indication of dangerous mixtures signalled by appropriately designed indicators.
The mechanical ventilation system can be replaced by independent chimneys for each floor or by “shunt” type chimneys with a section of no less than 0,2 m100 for every XNUMX mXNUMX of surface area. The chimneys must emit air into the atmosphere at a height above the roof of the building.
In garages with a capacity of more than five hundred vehicles, a double mechanical ventilation system must be installed, for intake and extraction, controlled manually by a controller who is always present, or automatically by continuous detection equipment for flammable mixtures and CO.

The number and location of CO and flammable mixture indicators must be chosen appropriately based on the surface area and geometry of the areas to be protected and the local conditions of natural ventilation; however, their number cannot be less than two for each type of detection.
The indicators must be included in alarm signalling systems and, where necessary, ventilation system activation systems.

The system must come into operation when:
a) a single indicator reveals instantaneous values ​​of CO concentrations above 100 ppm;
b) two indicators simultaneously reveal instantaneous values ​​of CO concentrations above 50 ppm;
c) one or more indicators reveal values ​​of concentrations of flammable mixtures exceeding 20% ​​of the lower flammability limit.

For garages with fewer than five hundred vehicles, the installation of flammable mixture indicators is sufficient.
In above-ground multi-storey car parks, natural ventilation must be provided equal to 1 m200 for every 2 m1,0 of volume. In underground car parks, mechanical ventilation must be provided equal to at least three changes per hour and a smoke disposal system with chimneys with surfaces equal to 10% of the surfaces of each floor, conveyed XNUMX m above the roof of the buildings within a radius of XNUMX m from the chimneys themselves.

Source: Eng. Mauro Malizia – Fire Prevention in Garages v5.2 – Consolidated text of the Ministerial Decree 1/2/1986.

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This category contains dwg files useful for designing: natural ventilation and aeration systems for underground car parks.
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