Added on July 22nd, 2015
Category FDS News
By Bijan Fard
Incorporating everything from single storey independent shops to large scale, open plan department stores, retail sector properties can differ greatly in their designs and occupancy levels.
Due to this diversity, certain considerations must be made when creating fire strategies, however by taking an engineered approach it’s possible to not only meet regulations in this varied sector, but to greatly increase design freedom.
Unlike in residential or office buildings, the majority of the occupants in a retail property – its customers – will be unfamiliar with the building’s design, including the location of escape routes which should be utilised in the event of fire.
Further issues are introduced by the stock on the shop floor, with flammable items such as clothing potentially causing fire to spread through the property at an increased rate. While the cellular nature of residential properties often assists in slowing the spread of fire and smoke, the desire for retail premises to feature large, open areas can have the reverse effect, making it even more important to ensure that an appropriate fire strategy is in place.
Requirements for retail premises
In recognition of this risk, Approved Document B (ADB) guidance states that the maximum size of a retail space, or compartment, must be limited to 2,000m² where no sprinkler system is put in place, with this extending to 4,000m² where a sprinkler system is included, which is often a requirement of the property’s insurers.
ADB also states that, in the case of buildings over 11m in height, two staircases must be included in the property’s design in order to provide means of escape for its occupants in the event of fire.
However, it is possible for these limits to be surpassed by taking an engineered approach to fire design.
By creating a comprehensive fire engineered solution, significant alterations can be made to a design including the removal of staircases and the extension of travel distances, maximising the amount of available space on site, which in turn unlocks additional space for stock or shop floor areas.
Methods of justifying a fire engineered solution
Often including the use of systems such as smoke ventilation systems, pressurisation systems, higher-rate life safety standard sprinkler systems or smoke curtains, these solutions can be justified in a number of ways.
For instance, ‘time equivalent assessments’ can be utilised to calculate the time taken from the beginning of a fire, and the sounding of an alarm, to the safe escape of all occupants to a place of safety. By using these calculations, combined with methods such as Computational Fluid Dynamics (CFD) Modelling and Evacuation Modelling, which allow engineers to visualise the spread of smoke and the number of escaping occupants, respectively, it is possible to justify the creation of far larger compartment sizes than would normally be allowed when taking a code-compliant approach.
Whatever a property’s size, occupancy levels or the approach to fire design that’s taken, it’s of vital importance that all staff are correctly trained in accordance with the strategy put in place, as even the most carefully devised of plans will not be effective if it isn’t followed once a fire breaks out.
Due to the simultaneous evacuation method utilised in the majority or retail premises, it’s key for staffing levels to reflect the number of customers in the store, and that all employees are aware of the location of escape routes in order to safely evacuate all of the building’s occupants.
From a project’s initial planning stages, through to the creation of a suitable fire strategy and the installation of fire safety equipment , involving experienced fire engineers can provide architects, developers, contractors and end users with not only improved fire safety, but increased design freedom and available space without additional costs.