GL-03
Community Safety Directorate
GUIDELINE: Enclosed Carparks Without Sprinkler Systems
Guideline No: GL-03
Prepared By: MFESB Community Safety Advisory Group
Authorised By: Director Keith Adamson
First Issued: 27 February 2002
Version No: 5
Reviewed: 4 June 2009
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Carparks Without Sprinkler Systems (41.2kb)
1. Purpose
2. Scope
3. Definitions
4. Introduction
5. BCA Requirements
6. Main Issues
7. Design Fires
8. Advantages of Sprinklers
9. Recommendations
10. Documentation
11. Acknowledgements
12. References
1. PURPOSE
The purpose of this guideline is to provide a consistent MFB position for report and consent applications that are made under Regulation 309 of the Building Regulations 2006 in respect of building solutions that comprise enclosed carpark buildings that are not afforded automatic sprinkler protection.
The types of carpark buildings considered within this guideline include –
Enclosed below ground (Basement);
Enclosed above ground;
Partially open (but not deemed "open deck" by the BCA);
Mixture of the above with multiple levels; &
Enclosed, partially open single or multi-level incorporating automated or manually operated multi-tiered vehicle stacking devices.
2. SCOPE
The application of this guideline relates to all carpark buildings that are constructed without sprinkler systems that are located within the Metropolitan Fire District.
3. DEFINITIONS
“BCA” means the Building Code of Australia 2009 and includes any amendment, remaking or replacement of the BCA.
“DTS” means the deemed-to-satisfy provisions of the BCA.
“MFB” means the Metropolitan Fire and Emergency Services Board.
4. INTRODUCTION
The Deemed-To-Satisfy (DTS) provisions of the Building Code of Australia (BCA) require all enclosed carparks containing more than 40, cars to be sprinkler protected; however, carparks deemed to be "open deck" are excluded from this provision. There is little scientific data or fire engineering evidence to prove that the limit of 40 cars is more than an arbitrary figure. The limitation does, however reflect the perception of relative fire risk, whereby limiting the number of cars, limits the fuel load and indirectly the volume of the space or compartment size.
Anecdotally fire incidents within general vehicle parking areas, relative to other classes of buildings are not frequent [1]. However, since the Metropolitan Fire and Emergency Services Board (MFB) is legislated by the Metropolitan Fire Brigades Act 1958 to attend, control and extinguish all fires, then broader issues must be considered. Aspects of design that do not manage fire growth and spread have the potential to increase losses in a facility. This may increase business interruption and have other economical, social and environmental impacts.
5. BCA REQUIREMENTS
With the advent of the performance provisions in the BCA, the MFB are seeing new designs for enclosed carparks with more than 40 cars without sprinkler protection. The concern with sprinklers not being installed, where they would otherwise have been required under a DTS application, is that Practitioners (including Building Surveyors and Fire Engineers) may not be addressing the following Performance Requirements to the satisfaction of the Fire Service:
Meeting the Performance Requirements is mandatory and therefore all relevant aspects of the above requirements should be addressed in each design.
6. MAIN ISSUES
There are a number of issues that are required to be considered, when assessing whether or not an acceptable level of safety has been achieved in carpark buildings that are not afforded sprinkler protection..
6.1 Arguments of variable merit for not providing sprinkler protection
(i)Saving in cost, sprinklers are relatively expensive to install and maintain.
(ii) Sprinkler heads are prone to accidental discharge in carparks more frequently than in other occupancies.
(iii) Sprinklers do not contribute to the aesthetics of a building (although generally less critical in carparks).
(iv) Sprinklers do not seem to attract tenants/clients.
(v) Sprinklers do not attract reduced insurance premiums.
(vi) Sprinklers will only be effective once fire spread is beyond the vehicle of fire origin. (vii) Low risk of fire, low risk of fire spread, low fire load and low numbers of occupants.
(viii) Alternative measures can be used to achieve a satisfactory level of life safety without sprinkler systems.
(ix) The arbitrary figure of 40 cars has little justification and appears to be based on old regulations.
6.2 Issues to be considered
(i) The concerns from a firefighting perspective are mainly due to the fuel load such as, plastic products, Petrol/LPG and tyres. Once multiple cars become involved, a volatile situation exists. Fires in unsprinkered basement carparks are a significant hazard due to heat build up and the need for firefighting access being made from above.
(ii) Fires in enclosed basements can create an extreme heat and smoke environment, possibly compromising the structure. This may have a direct impact on not only occupants but also firefighter safety, especially in relation to search and rescue.
(iii) The BHP tests [2] on car fires showed that considerable amounts of smoke were produced by old model cars. It is reasonable to expect that current vehicles would produce more smoke due to an increased use of plastics. Therefore, modern car fires are likely to be more intense and toxic, increasing the associated risk for firefighting in enclosed places.
(iv) Even in partially open sided and undercroft carparks, severe acrid smoke would potentially make it extremely difficult to access, locate and fight a fire. Therefore ventilation openings in carparks need to be assessed so that an acceptable level of smoke spill to the outside of the building is provided.
(v) Access difficulties for firefighting personnel and equipment that could lead to a delayed response in terms of water setup and initial firefighting activities.
(vi) There are difficulties associated with accounting for the number of occupants, especially in public carparks. Therefore a search of the area is highly likely in a fire situation and may be the only way to confirm that all occupants have evacuated.
(vii) LPG tanks without the relief valve in older cars can be a problem, as a "BLEVE" of the LPG tank may occur within 10-12 minutes of flame impingement.
(viii) The smoke exhaust system (in accordance with AS1668) may not function as required by the BCA in an environment with hotter smoke, where sprinklers are not installed.
(ix) Complexity and unfamiliarity of the rarely used exit routes, exit provisions and smoke obscuring exit signage could be an issue.
(x) The rapid onset of untenable conditions as a result of smaller smoke reservoirs due to low ceiling heights is a concern.
(xi) Impact of smoke and fire spread to occupied floors above.
(xii) If sprinkler systems are proposed for other areas of a building then consideration should be given to extending these through to carparks.
(xiii) In an unsprinklered carpark, fire continues to develop, spread and generate large quantities of toxic smoke.
(xiv) With the inclusion of automated or manually operated car stacking systems, the vehicular fuel load is stacked horizontally as well as vertically. In an unsprinklered carpark, fire in a vehicle parked on the lower tier will rapidly spread to vehicles in the upper tiers. To a lesser extent although equally as significant, lateral fire spread will also occur between the car stackers, potentially involving more vehicles than in a carpark with a single tier of cars.
7. DESIGN FIRES
The key to a realistic fire engineering assessment is to use a "worst credible case" fire scenario. The following test results for car fires give an indication as to what may be considered reasonable or credible.
(a) A Heat Release Rate (HRR) of 3.5MW based on a fire test for a two car scenario from Mangs and Keski-Rahkonen [3] provides a limited representation of the types of vehicles that may be found in car parks. These tests have not accounted for larger vehicles (reference is made to 1970 passenger cars), however, this design fire may be used for design fires in sprinklered carparks as a comparison or sensitivity analysis.
(b) Profil ARBED Recherch [4] refers to a two and a three-car fire. The two car fire Heat Release Rate (HRR) is approximately 1.5MW at 4 minutes which remains steady until 17 minutes, at which time the HRR rises to 5.5MW at 24 minutes, and then rises to a peak HRR of 8.5MW at 26 minutes before decaying with completion at 70 minutes. The three-car fire HRR is approximately 4MW at 12 minutes and is constant until 15 minutes before rising to a peak HRR 16MW at 26 minutes, then decays to 9MW at 38 minutes, peaking again slightly to 11MW at 40 minutes and decaying further with completion at 60 minutes.
(c) EUREKA [5] fire tests show that a single large passenger car has a HRR of approximately 5MW and that 8MW is applicable for a two to three passenger car fire.
(d) Fire tests by others [6] show that a single car fire can have a HRR of up to 8.5MW and a van fire of up to 15MW. It is important to remember that large cars such as vans and larger four wheel drive vehicles make up a significant proportion of modern vehicles.
(e) Any storage areas near parked cars that could contribute to the overall fuel load should also be taken into account. High rise residential buildings commonly have storage areas within mesh enclosures inside the carpark.
8. ADVANTAGES OF SPRINKLERS
(a) Reduction in the amount of heat and smoke to assist with Fire Brigade Intervention, especially in search, rescue and locating the seat of the fire.
(b) Fires in a sprinkler protected carparks can often be extinguished with first aid firefighting equipment, whereas, non-sprinkler protected carpark fires require the use of hose lines by the responding fire fighters.
(c) As the BHP tests [5] showed, sprinklers may contain a fire and prevent spread to other vehicles.
(d) Design fire may be capped at 3MW due to sprinklers activating to control or suppress a fire so that only one car is involved.
(e) Sprinklers will control the fire size but in an unsprinklered carpark smoke exhaust fans may accelerate the fire growth, depending on ventilation environment.
(f) Increased level of life safety for occupants afforded by sprinklers in the car park due to a significant delay in the onset of untenable conditions.
9. RECOMMENDATIONS
Generally the MFB does not support large enclosed carparks without sprinklers, however Practitioners who wish to deviate from the DTS provisions must consider, all aspects discussed above. Further the following should be utilised as a guide to design development and validation:
(a) Conditions within the carpark should remain tenable for the duration of a primary search by responding firefighters. A primary search is limited to teams of 2 firefighters travelling along the primary vehicle circulation paths. Use of appropriate tenability limits for firefighters and the FBIM is critical.
(b) Tenability is considered to be exceeded when radiant heat and temperature conditions outlined in MFB Guideline GL-17 are exceeded.
(c) Smoke and fire separation is to be provided from other parts of the building connected to the carpark, such as lobby spaces where door or lift access is provided. This separation is a critical issue where carparks adjoins other occupancies on the same level.
(d) An "Interactive" type addressable detection system may be proposed to provide early detection and avoid spurious alarms in the carpark. A heat detection system may be considered, however, due to the delayed response time, would result in a slower intervention and evacuation time. (The expense of capital investment and maintenance with these systems should be analysed from a cost benefit point of view in comparison with sprinklers).
(e) A reliable and effective Emergency Warning and Intercommunication System (EWIS) is to be installed where required by the BCA. Building occupant training in emergency and evacuation procedures are to be provided.
(f) Development of site specific tactical fire plans. (g) Installation of exit signs and emergency lighting.
(h) First aid firefighting equipment, such as fire hose reels and fire extinguishers, appropriately located.
(i) Appropriately located fire hydrants, to ensure availability and accessibility for fire fighters.
(j) An AS1668 smoke exhaust system with appropriate fire mode operation.
(k) Strict adherence to maintenance of essential services and integrated testing of all fire safety systems during commissioning.
10. DOCUMENTATION
The following must be received, in writing, from the Practitioner:
(a) Reason for the sprinkler system not being installed and any redundant fire safety measures proposed in the design.
(b) Comment on occupant evacuation and how this will affect/assist the fire fighters attending a fire.
(c) Details of all the issues to be addressed in the Alternate Solution to the DTS provisions of the BCA and the assessment of each of these issues against the relevant Performance Requirements.
(d) Assessment in the fire scenario modelling of occupant evacuation and the intervention by the fire service using the Fire Brigade Intervention Model.
It should be noted that a decision made for one building does not automatically infer that the same decision will be made for another. Each building shall be reviewed on its own merits, with all justification documented.
11. ACKNOWLEDGMENTS
The MFB greatly acknowledges assistance provided, in development of this guideline by all fire services of Australia, especially the Queensland Fire and Rescue Authority.
12. REFERENCES
[1] MFESB AIRS data, "Fire Incidents within General Vehicle Parking Areas 1998-2000", February 2001.
[2] BHP, "Economical Carparks-A Guide to Fire Safety", March 1999.
[3] Mangs and Keski-Rahkonen, "Characterisation of the Fire Behaviour of a Burning Passenger Car", Fire Safety Journal 23, 1994.
[4] Profil ARBED Recherches, "Development of Design Rules for steel Structures Subjected to Natural Fires in Closed Car Parks", 1997.
[5] Verlang und Vertriebsgescllschaft, Eureka Project EU 499 Firetun: "Fires in Transport Tunnels; Report on Full Scale Tests", Dusseldorf, November 1995.
[6] Australasian Fire Authorities Council "Fire Safety Guidelines for Road Tunnels: Design Fires", June 2001.
Note: This is a controlled document and may only be modified by authorised personnel after review by the MFB Community Safety Advisory Group
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