Fire completely devastated the automated Andover warehouse of on-line supermarket Ocado on 6 February 2019, despite attendance by 200 firefighters and 20 fire engines. The cause of the fire is not so far disclosed. The warehouse is reported to have contained sprinklers, which raises important points about the use of sprinklers in large open spaces full of combustible items. Sprinklers should not be in isolation, but advisedly used in compartmented zones, part of a holistic fire protection strategy.

The fire in Ocado’s flagship robotic warehouse killed nobody.  But it serves to remind us that fire can cause major disruption and costs in the destruction of property and building contents. The blaze lasted at its height for 48 hours, destroying a £45 million state-of-the-art modern handling facility, temporarily wiping £1 billion off the retailer’s stock market value. 100 local residents had to be relocated because of the risk of a pressured tank exploding and concerns over fall-out from the smoke plume, down-wind for 1.6 km. Stock worth £6 million is reported lost, along with the hundreds of robots used throughout the facility for the assembling of orders (at around 30,000 orders per week).

Dr Jim Glocklin, Technical Director of the Fire Protection Association (on behalf of the insurance industry), reported in the specialist on-line news portal IFSEC Global, observes that the intended function of sprinklers is to stop the growth and development of a fire – to hold fire at a manageable size so that it can be more easily extinguished by the fire and rescue service when they arrive.

Dr Glocklin emphasized the importance of holistic fire safety design.  He draws attention to the need for sprinklers to be designed within a compartmented structure, i.e. with the building divided into control zones intended to restrict the ability of fire to spread very far, very fast, by the use of robust barriers that are fire resistant, to prevent the physical movement and transfer of fire.

It’s implicit that the use of a sprinkler system should be designed carefully with the characteristics of the protected space in mind, especially including considerations on what the maximum compartment size should be.  It would also be sensible, as part of the holistic approach, to give thought to the ability of the compartmentation boundaries to remain in one piece under fire conditions where there is the chance of water impingement, not just from sprinklers but also from firefighter hose streams.  

That applies particularly to glazed partitions and glass vision panels or internal glazed ribbons assemblies, which can be so important in large internal compartmented spaces to provide natural lighting and allow through vision from one side of a compartment to another.  Standard glass products have no significant resistance against fire: traditional glass is notoriously vulnerable to thermal shock and stress.  Ceramic glass, however, is exceptional in its immunity to thermal stresses.

Councils are now thinking more seriously of better levels of protection for residents in residential tower blocks. That’s signalled by commitments from some to install sprinklers and to look more closely at fire door performance. Both point to an increasing consideration of wider holistic fire safety – combining different systems since no single measure on its own can provide the full level of assured protection that is needed, given the risks that can apply in high-rise and multi-occupancy residential buildings that were originally designed and built, perhaps refurbished, at a different time when fire safety was not as prominently on the public agenda as now applies.

Where the main attack/defence strategy against fire is to use water – either as sprinklers or reliance on firefighter action – then equally part of the strategy should be to consider transparent glazing panels that are resilient against cold water thermal shock should events turn out to be more severe and different from those originally anticipated.

Ceramic glass is a distinctive glazing product that characteristically has in-built resilience against water under fire conditions. It is specifically designed to resist thermal stress.  Thermal shock is a major failure risk for glass in fire.  But water and ceramic can happily co-exist, without fears that a ceramic glass panel can so easily crack and fall apart under thermal stress and cold-water shock.

• Ceramic glass is transparent, 5mm thick, easily glazed, handled and cut (using a basic tile cutter) to suit basic vision panel sizes or larger panes alike. It is readily available and obtained.

• The core property of ceramic glass is resilience against thermal stress, ideal for fire conditions.  That’s because of its marginally negative and close to zero thermal expansion coefficient, so that significant thermal stresses just cannot be generated in fire.

• Compatibility with water.  It is even possible to combine glazed screen arrangements with sprinklers to form large area water curtains, which function as normal glazed screens, without the risks of screen failure in fire due to uneven or sporadic water flow over the glazed surface.

• The ceramic softening point due to its foundation composition is also high, much higher than standard glass and well above temperatures likely to be experienced in fire.   

Ceramic glass as a transparent and robust fire-resistant glazing has significant advantages in fire.  Those apply especially where risks and concerns lead to a higher level of assured protection that may have been the case in the past, to remove doubt and uncertainty.

The Hackitt Review concludes that change is needed.  It observes that a “race to the bottom” is not the right direction of travel. What is needed instead is a race to the top because of the uncertainties of fire – to drive standards up in the interests of dispelling uncertainties, risks and doubts about protection in fire, in a broader holistic context which combines the best of available technologies.

There should be no room for complacency and uncertainty in fire. Confidence has naturally taken a hit following the Grenfell tragedy, which at the same time also brings to mind the previous disaster at Lakanal House.  That should mean thinking more broadly and adopting available technical solutions, such as ceramic glass, that haven’t previously been given as much attention as they deserve.

Seventy-two individuals tragically lost their lives because of the horrific conditions of the Grenfell Tower fire in the early hours of June 14, 2016. The subsequent Hackitt Review pulls no punches. It concludes that there is a fundamental need for change in attitudes to fire safety. Life safety, says Government Minister the Hon James Brokenshire MP, must now be paramount. And that means paying more attention to the products and technologies that are used to provide resilience against fire.

The Grenfell Tower fire catastrophe has shaken the world of construction, design and fire safety. Such a fire was not anticipated. If it had been then so many would not have died in such horrific conditions – extremely intense fire spreading so easily from inside to outside then breaking back in at several levels, apparently from all sides, at height, followed by extreme dense smoke development and further fast fire spread within the building through what fire-retaining walls were in place.

• A key principle of fire safety design is called compartmentation – i.e. constructions to contain fire where it breaks out, and prevent its spread using designated fire-resistant constructions that are able to resist fire penetration from one side. Compartmentation evidently failed in Grenfell.

• The essence of compartmentation is to contain fire, to stop physical fire movement by using fire-proof barriers – to minimise the risk, for as long as possible and as effectively as possible.

  Fire isolation and separation from those trying to escape is crucial.

• Firefighters need to be able to get into the building with minimal risk, to carry out their rescue and firefighting roles. Sprinklers systems for suppression during the early stages of fire need to work in the place where the fire breaks out before they can be perhaps overwhelmed by fast fire spread.

A lesson from Grenfell should be how fast fire can grow and spread given the fire load from fixtures, fittings, furnishings and constructions in today’s residential environment. The key fire safety strategy of stay-put that has been such a focus in Phase 1 of the Grenfell Inquiry, under Judge Sir Martin Moore-Blick, critically depends on compartmentation and fire separation working reliably and dependably.

Most materials deteriorate in fire, some more catastrophically than others. Standard glass, for example, has no significant ability to resist fire: it is notoriously susceptible to failure due to thermal shock, easily cracks and can fall apart under even quite mild thermal stress. Even specifically developed fire-resistant glass types have their failure mechanisms. And their resilience is limited, as exemplified by standard test classifications which are typically just for 30 minutes or perhaps 1 hour, (with more sophisticated constructions needed for 90 minutes and longer, perhaps to 2 hours).

• FireLite ceramic glass is a different material compared with standard flat glass compositions.

• Ceramic is an engineered material designed to be resistant to thermal shock and thermal stress.

• It has a very high softening and flow temperature compared with standard glass types, much higher than temperatures likely to occur in typical building fires.

• Most importantly, FireLite ceramic is able to survive in one piece, untouched, under a water stream from sprinklers or firefighter hoses on the hot ceramic. Tests have conclusively demonstrated that.

• FireLite – only 5mm thick – has been tested several times for resilience under standard test furnace conditions for longer than 4 hours, remaining unchanged and still in place, in one piece.

• If extended time is required in holding fire back then ceramic is a real option to consider.