1 INTRODUCTION
1.1 General
This report presents a fire strategy for a proposed school project. The school is to be located on the outskirts of a metropolis. The school structure is proposed to comprise a 3-story building (G+2). The school height is 7.2 m from the fire service access level on the ground floor to the highest level of the building that has meant for occupation. A school population of 900 students is projected for the school. It is also estimated with appreciable certainty that the students will be evenly distributed over the three floors of the building.
To provide an ideal learning environment, safety is paramount. In light of this, this document aims to provide the fire strategy to be adopted at school.
1.2 Applicable Legislation and Guidance
The fire strategy provided in this document follows the principles stipulated in BS 9999:2007 to conform to the Building Regulations 2010.
1.3 Risk Profile
The school risk profile is determined in accordance with BS 9999, which provides a methodology for the determination of the risk profile based on the building occupants’ characteristics and the fire growth rate. Accordingly, different buildings are provided with different characterization based on the two parameters. Tables 1 and 2 show the BS 9999:2017 definitions of occupancy characteristics and fire growth rates.
Table 1: Occupancy Characteristics [1]
The school risk profile is built based on occupancy characteristics as category A. As presented in table 1, this category comprises occupants who are awake and familiar with the building. In the school case, the students are expected to use the building for learning-related activities and thus are expected to be awake and familiar with the building.
Table 2: Fire Growth rates [1]
Based on table two, the school building is evaluated to be category 2, which comprises a medium fire growth rate with a fire growth parameter of 0.012 [1].
Combining the occupancy characteristics and the fire growth rate for the building yields the risk profile of A2. Table 3 shows the risk profiles categories as per BS 9999:2017.
Table 3: Risk Profiles [1]
2 MEANS OF WARNING AND ESCAPE
2.1 Evacuation Philosophy
The school fire strategy will adopt a simultaneous evacuation strategy. A simultaneous evacuation strategy refers to a system of evacuation that requires all the occupants of the building to proceed with the exit of the building at the prompt of a fire emergency such as an alarm [2]. The simultaneous evacuation strategy is deemed appropriate for the school building based on its associated benefits and the characteristics of the occupants. A vast majority of the building is expected to be children, who are bound to be affected psychologically in the event of a fire with a default of flight. Thus, the occupants cannot be expected to remain calm in the building for a prolonged period especially when other parts of the building are being evacuated. BS 9999:2017 notes that the psychological response of the occupants should be considered in the selection of the evacuation strategy and the simultaneous evacuation strategy adopted as the default in cases where the occupants cannot stand prolonged periods in the fire. Thus, a simultaneous evacuation strategy will be most appropriate and suited for the school building.
2.2 Fire Detection and Alarm Systems
The building falls under the A2 risk profile, and An M fire detection and fire alarm system shall be installed for the school as provided in the BS 9999:2017. The installation will be undertaken in accordance with the provision of BS 5839-1:2017. Automatic fire detectors shall be installed in all areas of the building. Additional layers of security shall be provided by providing a manually activated fire alarm system to support the automatic systems. In addition to the fire detection and alarm system, the school shall be provided with additional systems to help in the event of a fire that includes: –
• Have all the exits clearly marked with both electronic and physical markers;
• Automatic opening of all electronically operated ingress and egress points and deactivation of the systems after opening;
• Activation of smoke and fire suppression systems along all exits and at the fire event points;
• Deactivation of ventilation systems in the building.
2.3 Variations of Risk Profile
BS 9999:2017 provides for a reduction of the risk profile through the provision of localized suppression systems. Considering the mixed uses of different parts of the school project, sections with higher risk profiles than A2 will be provided with suppression systems such as sprinklers in accordance with the provision of BS EN 12845 to ensure that each section of the building falls in A2.
2.4 Horizontal Escape
The school shall be provided with adequate horizontal escape points and facilities in accordance with BS 9999:2017. Among the critical considerations shall comprise: –
• A number of exits – A minimum of 3 exit routes shall be provided for each storey.
• Height of escape routes – All routes shall be maintained at a minimum of 2 m high;
• Escape route widths – for A2, provide 3.6 mm per person;
Assuming that the exits are less than 1050 mm wide, the number of persons accommodated by exits for the A2 risk profile is: –
500/3.6 = 138 persons;
Thus, a minimum of 300/138 = 3 exits for the building shall be sufficient for the evacuation of 300 occupants per floor of the building.
Assuming that the exits in all the floors shall be less than 1050 mm, the exit capacities for the school building is as summarized below: –
• Ground Floor – 552 persons (five exits)
• 1st Floor – 414 persons (Four exits)
• 2nd Floor – 414 persons (Four exits)
These exit capacities are adequate for the assumed occupancy of 300 per storey.
The school building will ensure that all inner rooms have an occupancy of less than 30 (assuming at any points the occupants will need assisted escape) and that no more than one access room is passed through the escape route.
The travel distances shall be as provided in BS 9999: 2017 for risk profile A2, which is summarized in table 4.
Table 4 – Travel distances
Risk Profile Travel in one direction (m) * Travel with alternatives available (m)*
A2 37 15
It is assumed that each occupant is aware of the building layout in determining the travel distances. As such, constant fire drills and training shall be required to ensure the validity of this assumption.
2.5 Vertical Escape
Each of the upper storeys of the building is served by three exit stairs with a width of 1200 mm each. Each stair serves two storeys for risk profile A2, which means the width factor is 3.8 mm/ person. Assuming that one exit gets blocked in the event of a fire, the exit capacity along the stairs shall be 630 persons for both levels of the upper storeys.
As the building is designed for a simultaneous evacuation, it is observed that the capacity of the stair shall be adequate to evacuate the storeys 1 and 2 occupants totaling 600 at once. Therefore, the stairs exit is adequate for the school.
All the stairways shall discharge to a final exit where the occupants shall be safe from fire. The escape of disabled people shall include assistance from specially trained persons and structural provisions (ramps).
2.6 Emergency Lighting and Exit Signage
Emergency lighting shall be provided both as an early warning sign and for prompt exit facilitation. The emergency lighting shall be designed and provided in the school following the guidance of BS EN 5266-1:2016. Each part of the building requiring emergency lighting shall be equipped with the same. Distinct coloring shall be used to direct the occupants to exits as provided by ISO 3864-1 and BS EN 5499. All the lighting shall be optimized to facilitate optimum illumination without impeding movement through glaring. Further, the lighting shall be used to emphasize critical elements in the building of significance to motion such as change of level, and to illuminate points of safety equipment locations as provided in BS EN 5266.
3 INTERNAL FIRE SPREAD (750)
3.1 Internal Linings
The provisions of BS 9999: 2017 shall be followed in the provision of internal linings. Therefore, the internal linings shale be provided as summarized in table 5.
Table 5 – Internal Linings
Area European Classification1
Circulation Spaces C-s3,d2
Rooms not more than 30 m2 D-s3,d2
Other Rooms C-s3,d2
3.2 Structural Fire Resistance
The school building has a height of 7.2 m. This is noted to fall between 5 – 18 m category, which means that the building will have to achieve 60 minutes of fire resistance in accordance with the classification of BS EN 13501. Thus, the design and materials selection for the construction of the school shall be such that these provisions are met.
3.3 Fire Resisting Construction and Fire Doors
The fire-rated walls and doors for the school shall be provided to ensure a minimum fire rating as provided in BS 13501. The different areas of the building and the corresponding fire rating and fire door provision requirement are summarized in table 6.
Table 6 – Compartmentation and Fire Door Ratings
Area of the Building Fire rating*
(mins) Fire
doors*(min)
Escape stairs 30 FD 30S
Storerooms 30 FD 30
Server Rooms 30 FD 30
Dead-end corridors 30 FD 30S
Cross-corridor separation NA FD 30S
Changing Rooms 30 FD 30
Lift enclosure 30 FD 30
Kitchens 30 FD 30
Workshops 30 FD 30
Electrical risers 60 FD 60
Plant rooms and other service installation rooms 60 FD 60
4 EXTERNAL FIRE SPREAD
4.1 External Wall Construction
It is noted that the external wall height is at 7.2 m, which is less than the 18 m thresholds and the boundary is more than 1 m away from the building. Since the building is risk profile A2, it is noted that the building should achieve class B-s3, d2 or better. No restrictions are provided for the wall that exceeds 10 m height with regard to the spread of flames on the surface.
Cavities are noted to aid in fire spread, and therefore barriers shall be provided at all the edge cavities and external openings such as windows and ducts. All the junctions between the external wall and wall compartments that result in cavities shall also be provided with a barrier.
4.2 Space Separation
Fire spread can be facilitated by the inadequate separation of relevant boundaries. The school will utilize space separation to achieve adequate amounts of fire rating for the external facades of the building.
4.3 Roof Coverings
The roof of the school building will be constructed such that adequate fire resistance is achieved. This will be in the form of insulation and protection of adjacent compartments against the spread of fire. In this regard, material selection and separation strategies shall be employed. Table 36 of BS 9999:2017 provides the separation distances for the roof covering. Based on the provision, the appropriate separation distance for the roof shall be selected appropriately for the material roof designation of the covering as per the design.
5 FIRE SERVICE ACCESS AND FACILITIES
Adequate access for firefighters shall be provided to the school building to achieve building safety, occupants’ safety, and safeguard the safety of the firefighters. The critical areas of consideration are as follows: –
5.1 Vehicle access
Suitable access for fire fighting purposes is required for every building. In the case of the school building with a height of less than 11 m and floor area between 2000 – 8000 m2, the position of access of the fire and rescue service vehicle should be 15% of the building perimeter. As per table 20 of BS 9999: 2017, the typical measurements of the vehicle access are summarized in table 7.
Table 7 – Vehicle Access Route Specifications
Min. width of road between kerbs 3.7 m
Min. width of gateways 3.1 m
Min turning circle between kerbs 16.8 m
Min. turning circle between walls 19.2 m
Min. clearance height 3.7 m
Min. carrying capacity 12.5 tonnes
5.2 Fire hydrants
An additional private fire hydrant shall be provided in the event that the existing public hydrant is established to be more than 90 m away from the building. The hydrants shall be evaluated to ensure adequate flow of water and also provide adequate and clear marking for them.
5.3 Fire-fighting facilities
The height of the building does not warrant the provision of a firefighting shaft as it is less than 7.5 m.
6 FIRE SAFETY MANAGEMENT
This fire strategy is specific to the building in terms of occupancy, use, and design, and construction of the building. Any changes will necessitate a review of the strategy and fire safety management. Accordingly, a robust management system needs to be put in place to ensure that the provision of BS 9999:2017 is applied at all times in the building and the utilization and risk profile of the building remain commensurate to the applied safety measures.
Key factors emphasized in BS 9999:2017 for fire risk management strategy include risk assessment, recourses and authority definition, training, on-site control, maintenance and testing, communication, and emergency planning. Based on this list, the areas of critical importance to the school are identified as: –
• Fire safety training;
• Maintenance and safety; and
• Emergency planning.
A fire emergency department will be set up to plan and coordinate fire emergency preparedness programs and ensure compliance to safety measures as well as updating the strategy as appropriate.
References
[1] BSI, “Fire safety in the design, management and use of buildings – Code of practice,” The British Standards Institution, 2017.
[2] Surrey Council, “Evacuation strategy in the event of a fire,” Surrey Fire & Rescue Service, 2020 April 1. [Online]. Available: https://www.surreycc.gov.uk/people-and-community/fire-and-rescue/businesses/buildings/high-rises/evacuation-strategy. [Accessed 10 October 2021].
