What do I need to consider when designing mechanical ventilation to basement car parks?

National House Building Council, What do I need to consider when designing mechanical ventilation to basement car parks? In: Frequently asked questions on Building Regulations Part B: Fire Safety. TBA ed. Frequently asked questions on Building Regulations . National House Building Council, p. 1.

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The three traditional approaches to providing ventilation to car parks, taken from Approved Document B - Fire Safety, are:

Open sided (where there are no basement storeys and high levels of natural ventilation can be achieved) - Each storey should be naturally ventilated by permanent openings equal to 1/20th (5%) of the floor area, half of which is arranged equally on opposing walls.

Natural Ventilation - Where car parks that are not deemed to be considered 'open sided' are provided with more limited natural ventilation, permanent openings equivalent to 1/40th (2.5%) of the floor area are required, of which at least half (1/80th) should be arranged equally on opposing walls to achieve cross ventilation. Smoke vents at ceiling level may be used as an alternative to permanent openings in the perimeter walls however their distribution and equivalent ventilation area must be arranged to provide a through draught.

Mechanical Ventilation - Must be designed to run at a minimum 6 air changes per hour, increasing to 10 air changes per hour in the event of a fire, with an even distribution of high and low level extract points. It must also be provided with an independent power supply, designed to operate in event of failure of the main power supply. It should be designed to run in two parts, each capable of extracting 50% of the design extract rate. Have extract fans rated to run at 300 degrees centigrade for a minimum 60 minutes, combined with ductwork and fixings constructed of materials with a melting point not less than 800 degrees centigrade and ensure that the smoke discharge points are sited so as to avoid any risk from smoke being recalculated into building or affecting means of escape. Modern alternatives can also be considered (SHEVS).

Item Type: Book Section
Additional Information: mml-maui-text-analytics-keywords
Uncontrolled Keywords: equivalent area, permanent opening is a ventilation opening, purpose-provided ventilation, basement storey, ventilation opening, extract ventilation, ventilation, background ventilator, whole building ventilation, continuous operation
Subjects: Building standards
Depositing User: admin
Date Deposited: 06 Feb 2021 16:23
Last Modified: 13 Oct 2021 19:43
URI: https://buildvoc.co.uk/id/eprint/984

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