There are various regulations and controls which are put into place to ensure a building and its inhabitants are safe from a variety of risks. One of the utmost importance is fire safety. The primary objective for fire safety is to reduce the potential for death and injury to the occupants and others who may become involved such as the fire and rescue services.
There are a number of fire safety strategies, the main options are:
- Prevention: Controlling ignition and fuel sources (Non Flammable materials)
- Communications: Ensure occupants are made aware of any potential risks through Active Fire Protection (Systems that communicate which sounds alarms, engages sprinklers and any smoke ventilation systems are triggered in case of fire)
- Escape: Ensure occupants can safely escape (Provide a safe means of escape, smoke ventilation)
- Containment: Limiting and containing the fire is important to limiting damage and injuries (Fire rated access panels and hatches)
- Extinguishment: Ensure fires can be safely and quickly extinguished
Fire prevention generally focusses on two measures, by eliminating the risk of ignition or reducing ignition sources. Natural phenomena, human carelessness, equipment failure or fuel fires are the most common sources of ignition and therefore must be designed against where possible.
There are a variety of methods for designing against this from fire doors to the use of non-combustible materials. It is also important to protect fuel and gas sources particularly service points concealed behind walls and under floors.
Communications & Extinguishment
When you think about the various measures and protocols that are put into place in buildings to protect people, the first things that come to mind are the fire exits, fire alarms, and water sprinklers. These methods are known as “Active Fire Protection Methods”, also known as AFP. AFP is a collection of systems and items that require a response in order to function. AFP systems consist of a huge range of methods and fire resistant systems that can be activated manually. This would include firefighting with fire extinguishers and dry/wet risers by a trained set of people.
A very important system that is part of the active fire protection includes “Automatic Smoke Ventilation”.
Smoke vents do not have any fire rating however are tested in extremely controlled conditions in order to ensure they operate correctly in case of a fire. Smoke vents work by automatically opening when a smoke alarm or other BMS system is triggered. The aim of a smoke vent is to open (Over 120° degrees) to create a ‘chimney effect’ where smoke can be dispersed allowing safer access and escape. Smoke is the single biggest killer in terms of fires which means that effective Smoke Ventilation is crucial to a successful Fire safety plan.
Automatic opening smoke vents should be positioned at key exit and escape points; in particular stairways and corridors. This ensures a safe exit route is provided for occupants in case of a fire. A minimum airflow of 1m² is required by the European Harmonised Standard this can be achieved by a 1050 x 1050 structural opening. It is important to take opening mechanisms into account as these intrude within the opening and restrict ventilation.
Smoke vents can also be provided as an additional means of escape in some circumstances. The mechanism, which is usually set in the middle, can be offset to the side for easier access through means of a retractable ladder or otherwise. Again, it is crucial to take the required airflow area into account when introducing elements that restrict this opening. A standard retractable ladder can take up to 0.4m² off the total airflow so the opening needs to be adjusted to accommodate.
Escape & Containment
Passive Fire Protection involves the containment of fires to slow them down from spreading further. In a fire accident, the first thing you need to do is control the fire; this is where passive fire protection plays an important role. These PFP systems are designed in a way that they make the building as fireproof as humanly possible. They cause the fire to burnout quickly before it finds more flammable material.
All the new buildings in UK are required to have this facility of passive fire protection to ensure the security and safety of the building occupants.
Wall and ceiling fire rated panels with smoke seals can be used to protect sensitive services and electrical systems, these work by an intumescent smoke seal which expands to create an airtight seal. These specially tested and certified panels also carry 3 point locking. They come with a 1 hour rating in a ceiling or 2 hours fire rating in a wall.
Roof access and escape hatches can also be offered with fire rating. This fire rating is for integrity which ensures the hatches do not collapse under intense heat. These roof hatches are often insulated with a Polyisocyanurate insulation otherwise known as PIR which is generally regarded as being more fire resistant then other insulation materials such as PUR. The fire rating allows escape to an upper floor or roof in case of a fire. They can be electrically operated at the push of a button and linked to a Building Management System.
Floor hatches, often used for plant and equipment access to floors below can also be fire rated. Ideal to protect buildings from underground plant and machinery rooms which can be prone to equipment failure leading to fire hazards. Floor hatches can also be used to escape outwards from underground car parks and buildings. Examples of this can be seen in the Porto Metro Case Study where large floor covers were supplied for the Metro system. These covers featured emergency buttons which automatically opened the covers. A control system with battery back-up was used to ensure that in case of a power cut, the door would still open.
Without active and passive fire protection facilities and the methods of fire prevention described above, people are vulnerable to injury and even death, as we saw in the recent Grenfell Tower Fire tragedy in London. These systems are extremely important in order to ensure that there are adequate measures of life protection in the buildings of UK.