For many, the world changed on September 11, 2001.

For others, the Grenfell building fire in 2017 was the game changer.

(above image: Grenfell Tower fire by Natalie Oxford via Wikipedia By Natalie Oxford)

Among the many new concerns brought about by these tragedies, building fire safety has been a front-and-centre issue.

As a result of these and other disasters, fire safety professionals have been working hard to debunk many of the prevalent myths about fire safety in buildings. These myths have been perpetrated not only by lay persons, but sometimes by design professionals.

Myth 1: Passive systems are 100% reliable

First, there is a common perception amongst some industry practitioners that passive fire systems such as fire compartment walls and floors or fire rated shafts are always reliable and do not require regular inspection and maintenance. Such persons often suggest that active systems such as automatic sprinkler systems are less reliable as they require regular inspection and testing.

This myth often persists because original defects or subsequent failures in what is otherwise solid construction are hidden to many building owners, managers and occupants.

However, building audits regularly uncover problems with passive systems.

These include:

• cables and pipes being punched through fire rated partitions and not fire not being stopped
• smoke walls above ceilings being penetrated by building services without dampers for smoke stopping, and
• fire doors not being sealed properly or being chocked open.

Just as is the case with their active system counterparts, passive fire protection systems require special attention to be given to regular inspection and maintenance.

Myth 2: People Always Panic in a Fire

A second common myth holds that people will panic during a fire. Even many fire safety engineers believe this to be the case.

But research shows the contrary. In fact, most people make rational decisions in the face of adverse circumstances.

In studies of a British subway station, researchers J.D. Sime and G. Proulx long ago refuted this myth¹. They call for clear and effective information to be provided in order to maximise evacuation efficiency. They believe that emergency procedures should be designed to recognize that people will start to move safely, if given proper instructions, in the early stages of a fire.

Additional research by G. Ramachandran suggests that it is stress – often caused by lack of information – which may cause people to act inappropriately in a fire. But rarely do they panic and behave irrationally². And Nilsson tells us that emergency management should not be built around the concept that people will panic³.

What is clear is that we can assist rational decision-making by occupants and improve the efficiency of evacuation through measures such as:

• architecture in which occupants have a clear “cognitive map” or feel for where they are in a building, to aid their movement towards exits;
• provision of escape paths which are linked to normal building circulation paths; and
• use of good signage and clear emergency instructions.

(image: AI generated vis freepik)

Myth 3: Sprinklers Destroy Property

Another common myth holds that if one sprinkler operates in a fire, all sprinklers will ‘go off’ and deliver vast quantities of water, inundating the building and destroying its contents.

This notion is especially popular among managers of computer centres, telecommunications facilities, art galleries, museums, libraries and historic buildings. It is perpetuated through Hollywood movies.

Fortunately, there is increasing recognition that this is rarely the case. In fact, research conducted by the National Fire Protection Association in the United States shows that 77% of fires are controlled by a single sprinkler head whilst 96 percent are controlled by five or fewer sprinklers⁴. This is far better than a 50mm fire brigade hose.

There is also growing acceptance by the arts and historic preservation communities of the notion “better wet than burned.” While there is minimal chance of extensive water damage to a building’s contents from sprinklers, that risk is preferable to significant or total loss of the building or of a valuable collection – as happened with Hampton Court Palace, Windsor Castle, the Los Angeles Library, the San Diego Space Museum and the Venice Opera House. The rebuilding of several of these buildings without sprinklers, however, suggests the myth about sprinklers is still alive and kicking.

Myth 4: Lifts are Hazardous

Another still wide-spread myth maintains that lifts (elevators) are an area of great fire hazard and should be avoided in fire and other emergencies. Fortunately, there is a growing awareness of the need to provide equity and better egress provisions for all people in a building, including those with a range with disabilities, and use by fire brigades for emergency intervention.

The critical thing here is that if lifts are to be used for emergency evacuation, they need to meet all the design and fire protection measures set out in guidance such as International Standard ISO/TR 25743 and ABCB guidance⁵.This includes having all the necessary signage and emergency management procedures to ensure a proper balance between traditional stairways and lifts to minimize the time for evacuation of all occupants.

(image by ‘Another believer‘ via Wikepedia)

Myth 5: Flashover is Inevitable

Some fire professionals believe that once a fire starts, it is inevitable it will grow to flashover, or total involvement of the compartment of fire origin, breaking all glazed openings. But, in fact, research by B.R. Cuzzillo and P.J. Pagni shows that glazed openings often do not break, particularly if double or triple glazed⁶. This often has the effect of limiting fire growth through ventilation control well before flashover occurs. It is also one of the bases of the management practice of removing patients and closing patient room doors quickly in hospitals and aged care facilities in order to limit fire size, smoke production and smoke spread.

A related myth holds that in large spaces, such as factories and warehouses, flashover involving all combustibles at peak heat release rate will occur throughout the space. However, G.C. Clifton⁷ and Stern-Gottfried⁸ has demonstrated that flashover as recognized in small compartments does not occur, and that a zone or zones of peak intensity can form a travelling fire, moving through the space over time as the material is consumed.

Myth 6: Alarms Sound Before a Fire

Another common myth is that smoke detectors sound an alarm ‘before the fire starts.’

This notion has a magical air, somehow suggesting that certain detectors have intelligence or premonition. If only we could link this capability through ‘expert systems’ to fire prevention programs! We’d save huge amounts of money spent on all the other fire protection systems.

The reality is that some detectors can detect fires in the incipient or smouldering phase, before flames break out.

Two points are worth noting.

First, while smoke detectors based on photo-electric principles will generally detect smouldering fires at an earlier stage, other devices (such as ionization detectors) often respond more quickly than the photo-electric detectors in fires which start with a flaming phase.

Second, in either case, performance depends on fuel type, the form of ignition, and the particle size and the colour spectrum of the smoke produced.

Myth 7: Concrete is Invincible, Steel and Timber are Not

A final myth relates to the primary structural materials of steel, concrete and timber.

It is common to think of steel as losing its strength quickly when heated. In fact, single steel elements retain approximately 50 percent of their ambient temperature strengths at 550oC. Research shows that due to load redistribution, unprotected steel structural frames and composite steel/concrete structures may withstand significantly higher temperatures than 550oC with only localized deformation⁹. In fact, reinforced concrete loses significant strength above 760oC as illustrated in the SFPE Handbook of Fire Protection Engineering.

Another common notion is that concrete does not lose strength at all in fire – that it’s ‘invincible.’ However, the loss of the concrete cover in the Channel Tunnel and other road tunnel fires with no water based suppression systems, are good examples of the failure of concrete through spalling under high fire loads.

Exposure of reinforcing due to spalling action can lead to the premature failure of members.

Lastly, the myth persists that timber has no place in structural systems for fire-protected buildings. But, on the contrary, while timber does burn, it also chars at a well-known rate, and much research has been undertaken into fire performance of timber over the past 10 years. As a result, timber structures have increasingly formed a key part of many new building designs. Sustainability is seen as a key attribute, and timber is seen as a resilient structural material, particularly in earthquake-prone buildings in countries like New Zealand and Japan.

(concrete buildings are not invincible in a fire. Image AI generated via freepik)

Education is the Key

Broad education remains the key to dispelling these and many other popular fire safety myths.

The good news is that the number of qualified and experienced fire safety engineers and other fire safety professionals are starting to have greater impact on building designs.

Equally, design guides on fire safety measures provided by the Society of Fire Safety and others such ABCB all help to educate the wider design and construction industry.

This article is based on a similar 2003 article published in the SFPE Fire Protection Magazine during early investigations into the New York 9/11 disaster.

References:

1. Sime, J.D. and Proulx, G., “To Prevent ‘Panic’ in an Underground Emergency: Why Not Tell People the Truth?,” Proceedings of the Third International Symposium of Fire Safety Science, Elsevier, 1991.
2. Ramachandran, G., “Human Behavior in Fires: A Review of Research in the United Kingdom,” Fire Technology, 46, 2, 149-155, May 1990.
3. Nilsson, D., “Panic in Fire Emergencies – Myth or Reality?”, SFPE Europe Magazine, Q4 2017 Issue 8.
4. McGree, T., “US Experience with Sprinklers”. NFPA Research, 1 April 2024.
5. “Lifts Used During Evacuation”, ABCB Handbook, 2013
6. Cuzzillo, B.R. and Pagni, P.J., “Thermal Breakage of Double-Pane Glazing by Fire,” Journal of Fire Protection Engineering, 9 (1), 1988, 1-11.
7. Clifton, G.C., “Fire Models for Large Fire Cells,” HERA Report R4-83, New Zealand, March 1996.
8. Stern-Gottfried, J. et al., “Travelling fires for structural design-Part II: design methodology”, Fire Safety Journal. (2012)
9. Robinson, J., Newman G., “Cardington Fire Tests: First Results,” New Steel Construction, June/July 1997, 23.