Technical Annexe 13.15

Enclosed Shopping Centres

This Technical Annexe contains benchmarks (in addition to those in the other annexes) for enclosed shopping centres with malls on 1 or 2 storeys, against which the existing level of provision can be compared.

Where these benchmarks are not achieved and the results of the risk assessment indicate risk reduction measures are required, consideration should be given to implementing improvements.

1. Enclosed shopping centres can be extremely complex in their design, with large fire loads and large numbers of people all within a complicated series of spaces, where most people are relatively unfamiliar with the layout and only know one way in or out of the building.

2. For the purposes of this annexe, the reference to shop includes all uses with a frontage to the shopping mall, for example; cafés, banks or other use tenancies.

Fire Compartmentation

3. The fire compartmentation in an enclosed shopping centre is unlimited, provided an automatic fire suppression system is installed in accordance with the guidance in this annexe and Technical Annexe 13.14.

Smoke and Heat Exhaust Ventilation Systems

4. A smoke and heat exhaust ventilation system (SHEVS) should be installed in the mall of an enclosed shopping centre and in shops with a storey area more than 1,300m².

5. SHEVS should be designed in accordance with the principles set out in the Building Research Establishment Report, BR 368, as read in association with CIBSE Technical Memorandum 19 (1995) and in accordance with the following where appropriate:

1. the underside of the mall roof should be divided into smoke reservoirs, each of which should be not more than 2000m² in area and at least 1.5m deep measured to the underside of the roof or to the underside of any high level plant or ducts within the smoke reservoir or the underside of an imperforate suspended ceiling.
2. the smoke reservoirs should be formed by fixed or automatically descending smoke curtains which are no greater than 60m apart, measured along the direction of the mall, and follow the guidance in BS 7346: Part 1.
3. the design should ensure that smoke will not descend to a height of less than 3m above any floor level.
4. each smoke reservoir should be provided with the necessary number of smoke ventilators or extract fans to extract the calculated volume of smoke produced, spaced evenly throughout the reservoir.
5. where mechanical extraction is used, there should be spare fan capacity equivalent to the largest single fan in the reservoir and which will operate automatically on the failure of any one of the fans, or which runs concurrently with the fans.
6. any fans, ducts and reservoir screens provided should be designed to operate at the calculated maximum temperature of the smoke within the reservoir in which they are located, but rated to a minimum of 300°C for 30 minutes, in accordance with BS 7346 or BS EN 12101-3.
7. structures supporting any fans, ducts or reservoir screens should have the same performance level as the component to be supported.
8. the fans or ventilators within a smoke reservoir should operate:
   • on the actuation of any automatic fire suppression system
   • actuation of the smoke detection system within the reservoir
   • actuation of more than one smoke detector anywhere in the shopping centre
   • following a delay not exceeding 4 minutes from initiation of the first fire alarm signal anywhere in the shopping centre
9. replacement air should be provided automatically on the operation of the ventilation or exhaust system. The replacement air should enter below the smoke layer at a level at least 0.5m below the calculated level of the base of the smoke layer.
10. any power source provided to any elements of the smoke and heat exhaust ventilation system should be connected by mineral insulated cables or by cables which are code A category specified in BS 6387 or by cables protected from damage to the same level.
11. an automatically switched standby power supply provided by a generator should be connected to any fans provided as part of the SHEVS capable of simultaneously operating the fans in the reservoir affected and any of the two adjacent reservoirs.
12. simple manual overriding controls for all smoke exhaust, ventilation and air input systems should be provided at all fire and rescue service access points and any fire control room provided.
13. where outlets are provided with weather protection, they should open on the actuation of the fan(s) or ventilators.
14. smoke from areas adjoining the smoke reservoirs should only be able to enter one reservoir.
15. where there is an openwork ceiling, the free area of the ceiling should not be less than 25% of the area of the smoke reservoir, or, for natural ventilation, 1.4 times the free area of the roof mounted fire ventilator above (3 times where the height from floor to roof ventilator is more than 12m), whichever free area is the greater, and be evenly distributed to prevent an unbalanced air flow into the reservoir.
16. when a natural ventilation system is used and the smoke reservoir includes a suspended ceiling, other than an openwork ceiling, the free area of the ventilator opening in the suspended ceiling, or any ventilator grille in the ceiling, should not be less than:
    • 1.4 times (3 times where the height from floor to roof ventilator is more than 12m) the area of the roof mounted fire ventilator above in the case of a ventilator opening
    • 2 times (3.5 times where the height from floor to roof ventilator is more than 12m) the area of any roof ventilator grille

Fire Separation

6. A fire separating wall is not necessary between a shop and a mall other than where shops have mall-level storey areas more than 2000 m² and are located opposite each other. In such cases, at least 1 shop should be separated from the mall by a separating wall. Opposing shop frontages are those which make an angle of less than 80° with each other.

7. The mall width should at no point be less than 6m. However, hard mall seating or similar controlled furniture can be ignored when measuring the minimum width of the mall.

General Guidance for Escape

8. An enclosed shopping centre should have a layout so that:

• From every part of the mall and from every mall-level shop there should be at least 2 directions of travel leading to an unenclosed safe area beyond the premises without passing through. any space in single occupation. However, this does not apply to a kiosk of not more than 25 m² and in which either the general public are not admitted, or the depth of the kiosk from the mall is not greater than 5m.
• Each shop having a frontage to the mall should be provided with an alternative escape route that is not through the mall.
• The travel distance from a mall-level storey of a shop may be measured to the mall; Travel distances are given in Table 5 of Technical Annexe 13.8.
• In the case of an upper storey in a shop, an escape stair may lead to the mall if an alternative escape route is provided from that upper storey which is not through the mall.

Occupancy Capacity

9. The occupancy capacity is obtained by dividing the area in square metres by the relevant occupancy load factor. The occupancy capacity of the individual shops can be determined using the occupancy load factors in Table 7 of Technical Annexe 13.8.

10. When calculating the occupancy capacity of the entire shopping centre, an occupancy load factor of 0.7 should be used for all mall areas up to a maximum width of 6m. An occupancy load factor of 2 should be used for all remaining areas beyond the 6m. An occupancy load factor of 1 should be used for food courts forming part of the mall. An additional factor of safety should be applied when calculating the occupant capacity of the entire shopping centre. That factor of safety is an occupancy loading applied to all non-mall areas. For that purpose an occupancy load factor for shops and all other tenancies should be taken as 4. Once established, all the figures should be added together to give the overall occupancy capacity of the entire shopping centre.

Mall Escape Widths

11. The aggregate unobstructed width, in mm, of all escape routes from a mall should be at least 2.65 multiplied by the occupancy capacity of the entire shopping centre as described above.

12. A shop of more than 1300m² in area at mall level, where the means of escape has been designed independently of the mall, need not be included in this calculation. Similarly, a kiosk not exceeding 25m² which is not accessible to the general public, or where the depth of the kiosk from the mall is not more than 5m, need not be included in the calculation.

13. The unobstructed width of each individual exit from the mall should be at least 1.8m wide. However, account should be taken of localised areas where the occupancy levels will be higher than in other parts of the shopping centre. In such cases, a wider exit would be appropriate in those parts of the shopping centre. In addition, the entrances accessible to the general public should have the greatest escape route width as evacuees will tend to use the access and egress routes with which they are most familiar.

Shop Escape Width

14. The aggregate unobstructed exit width, in mm, from each shop and the unobstructed exit width of a route, or routes, which do not enter the mall should be at least 5.3 x the occupancy capacity of the shop.

15. A shop with a storey area at mall level more than 1300m² where the means of escape has been designed independently of the mall need not be included in this calculation. Similarly, a kiosk not exceeding 25m² which is not accessible to the general public, or where the depth of the kiosk from the mall is not more than 5m, need not be included in the calculation.

Service Corridors

16. Where a service corridor is used for means of escape directly from a shop or shops, the unobstructed width should be based on the total number of occupants of the largest shop that evacuates into the corridor, plus (other than at column positions) an additional width of 1m to allow for goods in transit. Where a service corridor is used as an escape route, it should not be used for any form of storage.

Crèches

17. Every crèche provided within an enclosed shopping centre should be designed so that it is:

• At ground level or exit level.
• Not sited on a storey higher than those where parents or guardians may be located, unless escape from the lower storey is via the upper storey where the crèche is located.
• Located adjacent to an external wall and has at least 2 exits, one of which should be directly to an unenclosed safe area beyond the premises.

Escape Lighting

18. An enclosed shopping centre should be provided with emergency lighting in all mall areas and all protected zones and unprotected zones. Refer to Technical Annexe 13.10.

Fire Warning Systems

19. An enclosed shopping centre, should be provided with an automatic fire detection and alarm system, designed and installed in accordance with the guidance in BS 5839: Part 1 for a Category L1 system and in accordance with the following:

1. the fire alarm should actuate upon the operation of the sprinkler system, manual call points or automatic fire detection.
2. on actuation of the alarm in a shop, evacuation may be restricted to the shop concerned for a delay period of not more than 4 minutes, unless during that time there is a further actuation of the alarm system in the mall, in which case the evacuation of the shopping centre should be commenced. Notwithstanding this delay period, immediately upon actuation of the alarm a message should be sent to the local fire and rescue service.
3. in the case of the actuation of the alarm anywhere other than in an individual shop, or on actuation of sprinklers anywhere in the shopping centre, evacuation should be commenced immediately and there is no delay period.
4. all areas of the shopping centre, including shops, should be alerted using a voice alarm system which follows the guidance in BS 5839: Part 8, however, individual shops may use conventional sounders within the shops themselves.
5. the fire alarm system should be interfaced with other fire safety systems, to operate automatically in the correct zones. On the operation of the fire alarm:
   • all escalators should come to a controlled halt and lifts should return to the ground storey (or exit level).
   • all systems within the mall or shops which play amplified music are silenced.
   • any smoke dampers installed to prevent the siphoning of smoke are activated.
   • subject to the 4 minute delay period where appropriate, all air-moving systems, mains and pilot gas outlets, combustion air blowers and gas, electrical and other heating appliances in the reservoir are shutdown.
6. the main fire alarm system control panel is installed within the control room and indicator (or repeater) panels are provided at each of the fire-fighting access points.

Remote Monitoring

20. On the actuation of the fire alarm, a signal should be transmitted automatically to a remote alarm receiving centre that is designed and operated in accordance with BS 5979.

Automatic Life Safety Fire Suppression Systems

21. An automatic life safety fire suppression system should be installed in an enclosed shopping centre and cover the entire area, other than:

• A mall or part of a mall with a ceiling height more than 10m.
• A stairway enclosure.
• A car park.
• Every area where sprinklers would prove to be a hazard such as main electrical switchgear.

22. The level of fire suppression should be appropriate to the occupancies within the enclosed shopping centre and be to the standard in Technical Annexe 13.15.

Fire and Rescue Service Facilities

Fire Control Rooms

23. An enclosed shopping centre should have a fire control room:

• Constructed as a separate compartment.
• Having access points away from the discharge points for the general public.
• Provided with an alternative means of escape.
• Located adjacent to a fire fighting access point and accessible from the open air.

Horizontal Dry Fire Main

24. Every single-storey enclosed shopping centre should be provided with a dry fire main with an outlet located not more than 5m from a fire fighting access point or points. However, a dry fire main need not be provided where no point within the storey (not being a protected zone) is more than 60m measured along an unobstructed route for the fire hose, from the access point or points.