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Do you know your E from your EI?

Fire safety glass is integral to ensuring a building’s compliance with Building Regulations. However, with three different fire glass classifications available, each with its own performance characteristics, there can be confusion regarding which classification should be specified and where. Here, Andy Lake, UK Projects Director provides some clarity.

Royal Holloway University Fire Rated Windows

Fire safety glass can have multiple applications and classifications within a mid or high-rise building, all working together to form a vital part of a its passive fire protection. Detailed within Building Regulations and, more specifically, Approved Document B: Fire Safety, compartmentalisation involves the creation of fire-resistant compartments within a building, ensuring that, in the unfortunate event of a fire, it would be contained within a designated area.

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 – Integrity

E offers the base level of fire performance and is also the minimum requirement stated by the UK Building Regulations. While it provides an effective barrier against smoke and flame, it does not prevent the transmission of heat.

EW – Integrity & Radiation

EW represents a step up in the level of protection offered. Fire glass that achieves the EW classification will maintain the same level of protection against smoke and flame as E but, in addition, will also deliver a reduction in the amount of radiant heat transmitted to the protected side. Specifically, EW keeps the amount of radiant heat to below 15kW/m2.

EI – Integrity & Insulation

The EI classification offers the highest level of protection. As well as providing a robust barrier against smoke and flame, 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 140oC. In simpler terms, this means that there could be a raging fire on one side of the glass, with temperatures above 800oC, and yet you could make an escape on the unexposed side, remaining protected from the heat.

Of course, it is important to remember that, while the type of protection offered is determined by the product’s classification, the length of time for which this protection can be maintained will vary. Typically, with fire rated glass, from 30 minutes all the way up to 180 minutes.

So, how does this translate to on site?

As aforementioned, compartmentalisation is integral when considering a building’s passive fire protection scheme, meaning that the classification of fire safety glass required will likely differ depending on whether it is to form part of the compartment barrier, is to be installed within the compartment or is for elsewhere on a building. The creation of safe areas, for example, such as a data centre, museum archive or evacuation zones within a hospital are likely to require higher levels of passive fire protection, such as EI classification fire safety glass.

With no two construction projects the same, it is important that architects, specifiers and contractors continually consult the Building Regulations throughout the design and specification process. Only then can they correctly determine what level of performance and classification of fire safety glass is required for each individual application and area within a project.

Of course, the classification stated in the Building Regulations is the minimum requirement and so architects may also choose to specify a higher classification of fire safety glass.

Having an understanding of the three fire glass classifications and their performance characteristics is key if architects are to make more informed specification decisions. As demonstrated, despite E being the minimum requirement stated by Building Regulations, it is clear that there are applications where higher performance products would be better suited. In fact, Pyroguard has witnessed a recent shift within the industry with more customers installing EW and EI glass, perhaps signalling an increased awareness of higher performance products and a greater duty of care in project design and building maintenance.

For more information, please contact us.

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