BRE FIRE CONFERENCE Research Conference 2015/4... BRE Fire Conference 2015 11th June 2015 Tom Lennon

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  • Part of the BRE Trust

    BRE FIRE CONFERENCE 2015

    11th June 2015

  • Part of the BRE Trust

    Compartment sizes – are they still fit for purpose?

    BRE Fire Conference 2015 11th June 2015

    Tom Lennon Fire Safety Team, BRE Global

  • Compartment sizes - Background

    – As part of a recent DCLG project dealing with Compartment sizes, resistance to fire and fire safety BRE Global have undertaken research into a number of linked work streams dealing with fire safety and the associated provisions in Schedule 1 of Part B of the building regulations 2010.

    – This presentation concerns Maximum fire compartment sizes. The aim of this work stream was to produce robust evidence and data to explore the potential to develop a systematic method for determining maximum compartment sizes based principally on life risk, but taking into account other factors such as environmental impact.

  • Maximum fire compartment sizes - Background

    – This project has explored the potential to develop a systematic method for determining maximum compartment sizes based principally on life risk

    – Compartmentation is used to sub-divide buildings so as to restrict fire size and minimise fire spread. For non-domestic buildings AD B (Volume 2) sets out maximum compartment sizes dependent on the height and use of the building. There are different values for certain categories dependent on whether sprinklers are installed or not

    – There is currently no recognised engineering method for establishing the appropriate maximum compartment size for a particular building

  • Current situation

    – Guidance to the building regulations (Approved Document B, Fire safety, B3 Table 12) provides limitations on the maximum size of compartments

    – For single-storey buildings there is no limit on the maximum size of compartment in the industrial category. Note this category would include large single -storey portal frames with a height to the eaves up to 18m.

    – Requirements from the insurance industry restrict the maximum floor area in industrial buildings to 7000m² in the absence of an approved automatic sprinkler system

  • Maximum compartment sizes

    Tasks – Review of background to existing AD B requirements

    – The maximum dimensions of buildings or compartments in Table 12 of AD B are based in large part on survey data from the 1940s. The background information has been reviewed and recommendations made as to areas where the existing requirements would benefit from a reappraisal.

    – Review of existing fires database – Existing published information has been reviewed to identify the relationship between

    compartment size and impact. Any trends relating to the impact of modern forms of construction on fire size and severity has been highlighted

    – Review of alternative approaches used to derive maximum compartment size – An international review of standards, guidance and accepted practice has been undertaken.

  • Review of background to existing AD B requirements

    – Current provisions based on Post-War Building Studies No. 20 Fire Grading of Buildings

    – Original restrictions in relation to maximum floor areas and maximum cubic capacities dependent on nature of construction and nature of fire hazard

    – Recommendations a balance between limiting potential losses and imposing barriers to trade

    – Original bye laws only applied to buildings incorporating combustible materials

    – Subsequent changes to the guidance have removed the distinction between combustible and non-combustible materials with performance based functional requirements applied to all forms of construction

  • Review of background to existing AD B requirements

    – Principal factors that influence the regulations governing the maximum size of fire compartments are: – The type of construction – The nature of the occupancy – The location and particularly the proximity of other

    buildings and – The nature of fire precautions including the

    provision of an automatic sprinkler system

  • Review of background to existing AD B requirements

    – Currently no limitation on compartment floor area for single storey industrial buildings

    – Original recommendations proposed a similar approach for single storey buildings of Construction Type 1,2 or 3 (protected or partially protected) for low fire load occupancies but did impose restrictions in relation to other types of construction or higher fire loads

    – Where restrictions are imposed (e.g. multi-storey industrial building) the compartment floor area can be doubled if a suitable sprinkler system is installed. This is in line with the recommendations of the post-war building studies report for incorporating the benefits of a suitable suppression system.

  • Review of background to existing AD B requirements

    – Very large single storey industrial and storage buildings have been constructed in recent years on green field sites where there are no issues around adjacent structures and no access problems for the FRS

    – In such cases structural elements only supporting a roof do not require any specific level of fire resistance

    – Although the current regulatory guidance does not specify any limitation in maximum compartment size for such buildings insurance industry requirements may limit compartment size

  • Review of background to existing AD B requirements

    – Property protection requirements limit the maximum compartment size in single storey industrial buildings to 7000m² and 14000m² where an automatic sprinkler system is installed

    – This is in line with the AD B guidance for mult-storey industrial buildings up to 18m high

    – The study has failed to find any scientific basis for the sprinkler factor

  • Review of existing fire database and compartment sizes

    Table 1 – Number of buildings of different sizes, in different occupancy classes

    Description

    Total area (m2)

    < 2,000 2,000 to

    4,999 5,000 to

    9,999 10,000 to

    20,000 > 20,000 Unknown Total

    Factories Workshops and Warehouses (Including Bakeries and Dairies) 296,100 16,750 5,180 1,840 70 230 320,170 Factory Shops 1,320 0 0 0 0 0 1,330 Food Processing Centres 140 20 20 10 0 0 200 Food Stores 510 0 0 0 0 0 520 High Tech Warehouses 20 0 0 0 0 0 20 Large Distribution Warehouses 20 50 160 370 510 0 1,120 Large Food Stores (750 – 2500 m2) 1,970 220 0 0 0 0 2,190 Large Industrials (Over 20 000 m2) 0 10 30 160 790 30 1,010 Large Shops (750 - 1850m2) 400 10 0 0 0 0 410 Large Shops (Over 1850m2) 190 1,300 320 100 20 0 1,940 Refuse Destructor Plants/Disposal Sites 0 0 0 0 0 0 0 Retail Warehouses and Food Stores 6,190 1,450 180 100 10 10 7,930 Shops 406,380 110 0 0 0 260 406,760 Storage Depots 1,650 280 80 20 10 10 2,050 Stores 68,920 290 50 20 0 60 69,340 Waste Incinerator Plants 0 0 0 0 0 30 30 Waste Recycling Plants 0 10 0 0 0 120 130 Waste Transfer Stations 0 0 0 0 0 620 630 Wholesale Warehouses 240 90 80 40 0 0 450 Cold Stores (Rental Valuation) 120 80 50 50 20 10 330 Warehouses Within/Part of Specialist Property 100 10 0 0 0 0 110 Workshops Within/Part of Specialist Property 130 10 0 0 0 0 130

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

    Afire = 2.79 Aroom0.69

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

    p(Afire) QAfire-0.2

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

    p(Afire) QAfire-1

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

    Equivalent fatalities:

    • Each actual fatality = 1 equivalent fatality

    • Each severe injury = 0.1 equivalent fatality

    • Each slight injury = 0.01 equivalent fatality

    • Each injury treated by first aid = 0.003 equivalent fatality

    • Each recommended precautionary check = 0.001 equivalent fatality

    • Each person rescued (uninjured) = 0.001 equivalent fatality

    • Each unspecified injury = 0.0003 equivalent fatality.

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

  • Review of existing fire database and compartment sizes

    Conclusions from fire statistics

    • Clear trend for average fire area to increase as area of room of origin increases

    • No obvious trend for life risk to increase as area of room of origin increases

    • Sprinklers reduce the life risk in non-residential buildings

    • In dwellings and other residential buildings, statistics are too sparse to draw any meaningful conclusions directly from the data

    • Primary benefit of sprinklers in non-residential buildings is property protection (since life risks are low anyway)

  • Review of alternative approaches used to d