When you first think about fire safety glass, perhaps the main image you have in your mind is of the glass preventing flame, hot gases and smoke passing through from one side to the other. But what about a fire’s intense levels of heat? Here, Andy Lake, our UK Projects Director, explores this further...
Despite the different classifications of fire safety glass being a key part of the Building Regulations on fire safety, there remains the potential for confusion around which classification offers what level of protection.
According to BS EN 13501-2, there are three main classifications of fire safety glass to be aware of: E (Integrity), EW (Integrity & Radiation) and EI (Integrity & Insulation).
E offers the base level of performance and is also the minimum requirement stated within the UK Building Regulations. However, while it provides an effective barrier against smoke and flame, which can be perfectly ample protection for certain applications, it does not prevent the transmission of heat.
Fire glass that achieves the EW classification represents a step-up in the level of protection offered, working to reduce the amount of radiant heat transmitted to the protected side, while also maintaining the same level of protection against smoke and flame as E. More specifically, EW keeps the amount of radiant heat transferred to below 15kW/m2.
The EI classification takes this even further, offering the highest level of protection. As well as providing a strong barrier against smoke, flame and hot gases, EI also delivers a significant reduction in the amount of heat transferred through the glass, keeping the average temperature of the unexposed side to below 140C.
So, how does this translate to on site? One of the primary purposes of fire safety glass is to contribute to a building’s passive fire protection strategy, used as a means of creating fire-resistant compartments or safe emergency evacuation routes.
In order for these evacuation routes to offer occupants a safe passage out of the building, it is important that they are protected from flame, hot gases and heat. Given the extreme temperatures in a building fire, heat could seriously impair a person’s ability to safely navigate their way out of a building, making it vital that the correct classification of fire safety glass is installed. In practical terms, there could be a raging fire on one side of a glazed partition or window, with temperatures in excess of 1000C, and yet, with the presence of EI fire safety glass, you could still make a safe escape, passing the unexposed side and remaining protected from the heat.
Reducing heat transmission can be just as important to restricting the spread of a fire within a building as the protection against flame and hot gases. For example, in certain settings and conditions, it may be possible for the level of heat transmitted to cause materials, such as papers or clothes, close to or touching the glass on the opposite side to ignite, should the incorrect fire safety glass classification be installed.
Installers should always consult Building Regulations prior to any on-site installation to determine the classification of fire safety glass required, for there may be buildings or applications that specifically require the installation of EI or EW glass. For example, a hospital will often be designed with fire safe evacuation zones, areas where patients can be moved to while awaiting rescue; the barriers of which will require a higher level of fire protection, including against heat.
While the initial perceived purpose of fire safety glass may be to offer protection against flame and hot gases, it is clear that reducing the amount of heat transference in the event of a fire can be just as crucial and effective. For this reason, installing EW or EI glass may be a requirement for certain building areas or applications and you should always first refer to Building Regulations. That said, even if E is the minimum requirement, you can always choose to upgrade and install a higher classification fire safety glass product instead, one that does offer this reduction in heat transfer. In fact, this is a trend that Pyroguard are pleased to see more often within the fire safety sector.