Safety is not a priority; it is a duty we owe to ourselves and others, particularly when it concerns fire safety measures. To a certain extent, fire control and resident escape can’t be accomplished if a building’s height is over 11 meters, and evacuation procedures are more crucial within a reasonable time frame. The same is true for places with large footfalls or mobility, such as hospitals, old age homes, universities, metro trains, stations, warehouses, auditoriums, etc. We constantly have issues with the way our buildings are designed to withstand fire, especially the façade system, which poses a serious risk when a fire breaks out.
In any modern building, the evacuation of the building occupants is a main consideration in the design of any building. Today, a general fire safety concept used in designing a building considers points like how fast occupants can egress, how fast the fire brigade can extinguish a fire, and how the fire spread could be avoided in surrounding buildings.
Structural Safety And Safety Of People’s Lives
The façade contains the highest risk we have seen so far in terms of the safety of the building. The majority of fatal fires occur in façade fires. There are two basic timelines on which fire phenomena can be divided:
- Start the fire to the first 5 minutes and
- Beyond the first 5 minutes.
The first 5 minutes define how the developed fire will be affecting your building. It can be a considerable risk factor for fire propagation in the external building envelope and rear ventilation walls, with potential flashover between floors and possible entry into the building interior.
Propagation Of Fire
Two physical properties of fire will increase the propagation of flames from one floor to the floor above on the exterior of the building:
- Convection: Products of combustion (heat, hot gases and fire) that are buoyant and will travel upward.
- The Coanda Effect: Will bring the steam of hot gases (and flame) back against building surfaces.
EN 13501-1 matters most as far as building material selection is concerned.
To offer the highest possible fire safety protection, all materials that become part of an external façade must achieve class A2-s1, d0 or class A1.
Fire-resistant vision panel glass combines visibility with effective flame and smoke spread prevention.
A1 class non-combustible class do not contribute to fire, do not contribute to burning or smoke development characteristics under the fire, do not emit any energy, and do not contain almost any organic materials inside them. Where organic substance contains a maximum of 1% volume and weight inside the item, we may consider it an A1 class product.
A2 class materials are limited combustible or hardly combustible.
The façade is required to be hardly flammable, which is a minimum C class when it is not a high-rise building. In the case of high-rise buildings that need stronger fire safety, all façades must be made with at least an A2 class or hardly combustible class of product.
Importantly, low-rise buildings with conventional façade systems must be insulated with harder materials for the first 1.5 meters of the height of the building. In the first 1.5 meters, where car parking and garbage bins are located, there is a high chance of fire as both garbage bins and cars can catch fire very easily. Hence, the first height of 1.5 meters of a building façade required additional non-combustible materials. Then there are some openings from where fire can easily enter inside the building façade; therefore, openings like windows should be insulated top and bottom with A1 class materials.
Open joint or ventilated curtain walling systems used in buildings must contain façade and insulation materials of minimum limited combustible (Class A2) class.
What happens to the façade in a developed fire situation in case the correct materials are not selected for facades?
Any sandwiched panel that contains polyeutherin (Class C materials – Hardly flammable) starts to emit smoke in the first few seconds, even before fire touches it. This smoke is polyisocinide smoke. It generates cyanide acetate /ureic acetate. Both are very poisonous to humans and animals. It is important to know that a one-meter cube of such materials generates a 10,000-meter cube of such poisonous gases within a minute. The heat is critical for structural collapse however, smog is deadly for the people living inside the building.
| Class A1 | Products in this class do not contribute to burning, fire development, or smoke development in any phase of the fire. | All uncovered and unpainted metals, homogenous mineral wools without organic binders or interphase layers, mineral-based products such as calcium silicate, gypsum, cement-based products, bricks, etc. where the organic substance content is less than 1% by volume and weight. |
| Class A2 | Do not contribute to fire effectively under fully developed fire circumstances. | Organically coated or painted mineral wools, with organic binders or interphase layers, organic additives containing cement-based products, gypsum boards with organic layers, etc. |
| Class B | This material is considered combustible but has a limited contribution to fire. | Treated wood with fire retardant coating, certain types of plastic panels, or composite boards. |
| Class C | Products in this class have a limited contribution to fire, meaning they will contribute to fire less than Class D or E materials. | Some types of wood treated with flame retardants, sandwich panels with polyurethane foam or phenolic foam |
Fire Safe Façade
Case -1
Building A (Insulated Façade)– One side of the tower completely burned. But the fire did not spread to the other sides. Because the rest of the sides were insulated by mineral wool and concrete. The material that completely burned down was the Aluminium Composite Panel (ACP). The total fire height was 140 meters, and the burning time was only 3.5 minutes. Hence average burning rate was 40 meters per minute or 2 meters per 3 seconds. So, even before the fire brigade could reach, the fire was out.
Case -2
Building B (Non-Insulated Façade) – Building height 67.3 meters. The whole building burned down, and 72 people died in this fire. It took only 12 minutes for the fire to spread all over the building. Due to a large fridge fire inside the building, a few uPVC windows caught fire and melted. Then, Aluminium Composite Panels (ACP) were ignited. It was impossible to escape from the building due to the dense smoke that filled the entire lobby.
