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IN 2006, Communities and Local Government’s (CLG’s)Sustainable Buildings Division commissioned the BuildingResearch Establishment (BRE) to carry out a three-year

research programme, Fire Spread in Car Parks . Te results werepresented at a one-day conference in October 2009 which was attended by over 100 delegates to enable a forum for theirdiscussion. Tis article is a summary of the conference and

highlights the main issues raised by the research programme.

Conference summary 

Te rst speaker, Brian Martin – a principal constructionprofessional within the Sustainable Buildings Division at CLG– summarised the objectives of the research. He explainedthat the basis for the existing guidance for car parks, set outin Approved Document B1 (ADB) to the Building Regulationsin England and Wales, relates to res involving cars whosedesigns are decades old. A key objective of the project was toproduce up-to-date experimental data representative of thecurrent stock of road vehicles so that re safety guidance canbe reviewed and updated, where necessary.

Martin Shipp, BRE project leader, then explained thebackground to the research. He said that, while there havebeen few deaths or injuries recorded in car parks in theUK to date, new research is necessary due to the changes inmaterials now being used in vehicles – for example, plasticfuel tanks, glass reinforced plastic panelling and alternativefuels. He discussed a number of issues, including:

• is the re load well dened?

• is there a ‘low probability’ of re spread from one storey toanother?

• what is the probability of re spread between vehicles?

• how robust is the current guidance?Next up, BRE consultant, David Crowder, described the

literature review undertaken as part of the research. Currently,new cars are designed around safety, comfort, performance

The ndings from a three-year 

BRE research programme on

re spread in car parks werepresented at a recent event.

Róisín Cullinan reports

 

Parking lessons

and the environment, but not re safety, he explained. Te useof plastics in vehicles is increasing and alternative fuels arenow available to consumers. Liqueed petroleum gas (LPG),biofuels and electric/hybrid vehicles are gaining in popularity as a result of environmental concerns, he asserted. In addition,car park designs are changing and are now often integratedinto shopping centres, residential ats and oce buildings.Mr Crowder added that in urban areas, where space is a factor,automated stackers are becoming commonplace, although therehas been little or no consideration of their associated re risk.

  A review of re incidents in car parks followed.Tis included: re spread between multiple cars; re spreadthrough interlocking oors; signicant structural damage dueto re; and reghter fatalities.

Te review included discussion on an incident whichoccurred in the UK in December 2006. Te incident resultedin a fatality in the sprinklered Monica Wills House carehome2 which was built above an unsprinklered, partially open-sided car park where 22 cars were destroyed in a re.

Statistical analysis

Te statistical analysis of res in UK car parks was thenpresented by BRE consultant, Róisín Cullinan. Te data wasgathered from re brigade incident reports (FDR-1 forms)

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from 1994-2005 and produced the following key ndingsduring the 12-year period:

• there were 3,096 res in car parks in buildings – of which1,592 started in a vehicle

• the average number of res each year in car parks withinbuildings was 258, with data showing an overall declineof such res over the period

• in total, two fatalities and 87 non-fatal injuries were reportedfor the period

• res in car parks rarely spread to additional cars, however, where this does occur, signicant structural damage is possible

• res in car parks rarely spread to additional oors

• res in car parks represent a very small percentage of all resin the UK. For example, in 2006 they represented less than0.1% of the UK’s total res

Ms Cullinan explained that there was a disproportionatenumber of injuries in car parks res when associated withats: res in car parks in ats accounted for 5.5% of the total

res in car parks reported, but resulted in 26% of the injuries.BRE carried out re investigations on car parks over the

three-year project, she explained. One re investigation wasof a car park re which occurred in a busy shopping centre inDecember 2007. Te re started in the engine compartmentof a large vehicle and resulted in re damage to multiplevehicles, with at least one vehicle being completely destroyed.However, a soft-top vehicle in the adjacent space to thedestroyed vehicle was entirely undamaged, apart from sootdeposits. While the experimental tests showed a high potentialfor re spread, this real incident highlighted the lack of re spread under seemingly conducive conditions. Te low

frequency of re spread is also shown by the statistical data.

Modelling studies

Principal consultant at BRE, Richard Chitty, then reported onthe results of computational uid dynamics (CFD) studies.Mr Chitty explained that following an investigation into theMonica Wills House care home re in 2006, BRE carriedout CFD modelling of the incident. Te model assumed thatre spread would occur to an adjacent car when a heat uxof 10kW/m2 was achieved on the exterior of the adjacent car.

Te car park in this incident was located beneath theresidential care home with ventilation openings on two adjacentsides. Te CFD model showed that, following the ignitionof a single car due to an electrical fault, the re spread to21 other cars in the car park within 31 minutes. Te CFDmodel of the re ran until the 22nd car ignited, and the heatrelease curve which was generated showed a peak of justunder 60MW. He explained that the re was still growingat this point and that this result was consistent with the reinvestigation ndings.

 Full-scale tests

Conference delegates were then shown footage of the full-

scale tests by senior BRE consultant, Phil Clark. Mr Clark presented some of the key ndings.

ests 1-3, he said, were carried out in the Burn Hall facility at BRE Garston under a large 10MW calorimeter. Te rig

design was based on current car park design guides, and BREutilised CFD modelling to determine an appropriate level of ventilation (see Figure 1).

est 4, which included an LPG car, was carried out ina similar rig without calorimetric measurements, in the openair, at the Health and Safety Laboratory (HSL) site inBuxton, Derbyshire, because of the associated explosion risk (see Figure 2 ). Te aim of est 4 was to determine the behaviourof res (and explosions) involving cars fuelled by LPG.

He went on to explain that all the vehicles used were lessthan ve years old or of a current model and in full workingorder, and that the cars used in the tests were selected solely on the basis of age, size and availability, and not on the basisof make or model.

Test 1: Tree car test (unsprinklered) small-to-medium carsTest 2: Tree car test (sprinklered) small-to-large carsTest 3: Same as est 1 but with larger carsTest 4: Four car test (unsprinklered) LPG car test

Te re was started on the driver’s seat of Car 1 for all of the above tests.

Hertfordshire Fire and Rescue Service was on hand forests 1-3. est 4 (carried out at HSL) was allowed to burn out.

Te key results were:

• re spread occurred to cars 2 and 3 (across the gap) in bothunsprinklered tests (est 1 and est 3)

• in est 3, where the average car size was bigger than est 1,the time to re spread to cars 2 and 3 was signicantly reduced

• once the second car became involved in ests 1, 3 and 4, theremaining car (two cars for est 4) became involved within3 minutes in all tests

• the peak heat release recorded (see Figure 3) was 16MW inest 1 shortly after car 3 ignited. Te test was extinguishedshortly after car 3 became involved

• three of the hollow core roof slabs used in the construction of the test rig, which were situated above and near the ignitioncar, had to be replaced following est 1 due to the spalling, which occurred as a result of the re

CO, CO2 & O2 (%)

Heat Flux Measurement (kW/m2)

12.00

1.60

0.80

Duct to

Calorimeter

         6  .

         0         0

Thermocouple Tree (1.5 mm Type K)

Flow measurement & Temperature

Slab temperature

Figure 1: The test rig indicating the car and instrumentation locationsfor Tests 1, 2 and 3

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• in est 2, the sprinklered test, there was no re spread outsideof the ignition car, only minor heat damage to car 2

• the peak heat release for est 2 was 7MW, which occurred52 minutes after ignition

• in est 4, the pressure release valve on the LPG tank operatedsuccessfully. Te tank did not rupture or noticeably impacton the re size or development

Mr Clark went on to briey discuss the six single-car re tests which were carried out under the calorimeter at BRE Garston,to investigate the potential for re development with dierentignition scenarios (engine res, compartment res and radiantpanel res, in a large and a small/medium-sized vehicle).

Te nal test of the experimental programme was a‘stacker’ test. Te increasing popularity of automated ‘stacker’car parks in recent years is deemed a signicant issue for carpark re safety, since the parking congurations could increasethe potential for rapid re spread. Te results of a two-carvertical stacker re showed that re spread occurred from

car 1 (the bottom car) to car 2 in about ve minutes, which was much faster than in ests 1, 3 and 4.

Research implications

Martin Shipp, technical development director at BRE, thendiscussed the potential implications of the research, explainingthat the study should enable the re safety community,

Figure 2: The experimental set up for Test 4. Note that the fire damage to car 4 occurred in a previous test and only affected one side

in particular re engineers and enforcers, to develop saferdesigns from a position of knowledge.

Te implications of the project from the perspective of the  wider re safety community were also discussed. HowardMorgan, chairman of the British Standard Institution’sStandards Committee FSH/25, asserted the importance of thisproject work to the committee. FSH/25 has responsibility forkeeping smoke control codes up-to-date and acts as a liaison  with the European standard committee CEN/C191/SC1:Smoke and heat control systems and components , explainedMr Morgan. Given the outcomes from this project, thecodes of practice may need rethinking, he urged, and sprinklersin car parks may need to become more prevalent.

Gordon Dewar of Westminster District Council thenspoke on enforcement issues in car parks, specically inrelation to smoke control and ventilation. With the ADBguidance potentially not being updated until 2016, Mr Dewarasked whether we should concentrate on making amendments

to BS 7346-7: 2006: Components for smoke and heat control systems. Code of practice on functional recommendations and calculation methods for smoke and heat control systems for covered car parks 3 and look at design re sizes and ventilationrecommendations?

Ian Gough of the British Automatic Fire Sprinkler  Association (BAFSA) described an additional stacker test,commissioned by BAFSA and carried out at BRE Garston

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using the existing stacker rig, this time with sprinklers.Te re did spread from the ignition car to the car above,

but was controlled by the sprinklers. Mr Gough pointed outthat the particular system that was used in the test may notbe suitable for car stackers of dierent congurations andthat specic tests may be required for each type of car stackerconguration. Also, the lack of data available on water mistsystems suggests that, where such systems are proposed, relevanttest data should be requested.

Informed design

Te implications of the project ndings for the re andrescue service were then outlined by group managerPaul Jenkins of London Fire Brigade’s Fire Engineering Group.Sometimes, explained Mr Jenkins, where sprinklers have beenspecied in car parks, smoke control systems are used as areplacement. As such, this research should enable designersto create an informed design in the future.

Te biggest implication from the research, said Mr Jenkins,is related to res in stackers, where the need and benets of suppression systems in stackers was clearly demonstrated by the test commissioned by BAFSA.

Finally, team leader of public sector property at Zurich,Stuart Blackie, provided an insurer’s perspective. While theresults of the LPG test were comforting, the issue of respread between cars is an issue for the insurance industry,

explained Mr Blackie. Car parks should not be looked at inisolation, he said, and the adjoining buildings should be takeninto consideration when determining the potential destructiveeects of a re.

Figure 3: Heat release rate curves for the large-scale tests

Te conference oered delegates the chance to debate thendings and their implications with an open discussion but,

  with some years before the next revision of ADB, delegatesquestioned how the re community could eect change in thenear future. Attendees at the conference agreed that thoseconcerned with re safety must identify areas where actionor further research is required, and that the ndings of thisresearch should be utilised as a sound basis for future design.

  A summary of this project has been published3 andthe full report will soon be available on the CLG website,www.communities.gov.uk  

Róisín Cullinan is a consultant with theFire Safety Engineering Group at BRE

Te author wishes to acknowledge many individuals and organisations for their assistance in the project. Please note that the views expressed here are not necessarily those of CLG.

 A DVD showing a range of the full-scale tests conducted in the research is available to purchase – e-mail: mallowsr@bre.co.uk 

References1. Te Building Regulations 2000, Approved Document B

(Fire Safety) Volume 2 – Buildings other than dwellinghouses (2006 Edition).

2. ‘A careful attitude’, Fire Prevention and Fire Engineers 

 Journal , July 2007, pp 54-56.3. Shipp, M., Fraser-Mitchell, J., Chitty, R., Cullinan,

R., Crowder, D., Clark, P., Fire Spread in Car Parks,Fire Safety Engineering , pp14-18, June 2009.