What caused the Grenfell fire? Here’s what we know

Never again. Image: EPA/Neil Hall.

The Grenfell Tower fire resulted in the greatest loss of life from a fire in Britain since World War II. A year on, we know that the fire’s rapid spread was at least partly due to the cladding that enveloped the building. Although a public inquiry is ongoing, and we’re still waiting for the full results of forensic evidence, there is no doubt that changes are needed to prevent this catastrophe from happening again.

This includes new regulation for high-rise buildings and the use of flammable materials in their construction. In addition, experts and researchers in fire safety need to work more closely with the government and construction companies. More immediately, for buildings similar to Grenfell, that were built according to old regulations, simple and immediate actions should take place now. Evacuation routes, sprinklers and fire retardant materials need to be installed as quickly as possible.

Construction problems

Grenfell Tower was built in 1974 and contained 120 flats, housing between 400 and 600 people. It was like a small vertical village. In 2016, the building was refurbished at a cost of £8.6m; this was when the cladding was introduced.

From the first media reports on the morning of 14 June 2017, engineers and scientists raised concerns over how quickly the fire spread, especially on the outside of the building.

It seemed that the fire was unable to be contained within a compartment. The concept of compartmentation in fire engineering is widely used in constructing buildings. By adding fire barriers, often fire resistant doors, fires are supposed to stop spreading quickly and so allow time for evacuation and treatment. But at Grenfell this did not happen: the fire quickly found access to the outer side of the building. Something had gone horribly wrong and the fire safety advice to residents to stay inside has since come under scrutiny.

The flammable cladding was instrumental in the fire spreading so quickly. Image: Flickr/ChiralJohn/creative commons.

Immediately, the focus was put on the new exterior skin (cladding). This not only contained flammable materials (polyethylene insulation covered by thin aluminium sheets that buckle in high temperatures and expose the internal material to flames), but was also installed onto the existing incombustible reinforced-concrete structure, in a way that left a gap between the facade and the building’s structure. This enabled what is known as the “chimney effect”. Put simply, the gap between the facade and the structural skeleton of the building meant that the fire sought oxygen and quickly travelled vertically, while burning more of the flammable skin.

It seems that the facade system, even if it was designed according to some regulations, did not perform properly. Such a catastrophic failure can never be the result of one single factor but rather was a chain of unforeseen events happening all at the same time.

Making sure it doesn’t happen again

Materials are still being fire-tested and several blocks remain evacuated. But although changes to building regulations are likely, these changes have yet to happened. This is partly because of the sheer complexity of the issue.

But some of the regulations that need to be implemented are clear. For a start, each type of building should be designed or refurbished with the appropriate regulation. So for example, all buildings that are higher than five stories ought to be provided with alternative evacuation routes such as more (or external) staircases, be equipped with sprinklers, and only be allowed to use fire-retardant materials, such as cementitious boards, ceramics, or glass facades.


Buildings like Grenfell should further be equipped with more sophisticated early warning systems that can detect the smoke and fire early enough. Not only could these systems set the alarm on and activate the sprinklers, but they could also restrict the fire within an area by making the building “active”. This could include automatically closing windows and self-controlled ventilation systems and elevators.

Another major positive change for tall residential buildings, would be the increasing use of performance-based fire resistance design. This is when each particular building is designed so that it performs under certain safety and strength criteria, allowing engineers to fully understand how the building will respond thermally and structurally to a fire incident.

Currently in the UK, for some buildings a general prescriptive-based approach is followed, which simply states how a building is to be constructed. The problem with prescriptive guidelines is that engineers ignore the actual response of the building and the effect of real fires, making the level of safety and robustness an unknown. Although this might be more costly in time and expense, when you have so many people living in one building it is necessary.

Each building design is also a different entity with its own limitations. So each building should be treated accordingly.

Collaboration and communication

Forensic evidence is still being collected and preserved. Once all the evidence is in, researchers and investigators will be able to review the causes and reasons why the fire spread in more detail. But right now we still do not have a deep enough understanding of the flammability of the facade systems, or the toxicity of the materials used.

Once we do, collaboration between academic researchers and companies producing cladding and other construction materials will be key. This is the only way of ensuring that products are developed to meet or exceed rigorous safety standards when put under pressure. This will be crucial for giving housing residents and the public greater confidence. Better communication between building regulators, local authorities, manufacturers, developers, and designers is also important.

The ConversationWe must start rehabilitating tall residential buildings as soon as possible, before another disaster occurs. And out of this tragedy must come long lasting changes to the design of buildings, the construction materials used, and the way they are applied.

Konstantinos Daniel Tsavdaridis, Associate Professor of Structural Engineering, University of Leeds.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

It’s time to rethink how the British railway network works

Nothing doing: commuters await a long-delayed train. Image: Getty.

The recent meltdowns on Northern and Thameslink not only left many passengers besides themselves with frustration about not being able to get to work on time, if at all. It also led to a firestorm of criticism and condemnation from politicians and media alike.

With the immediate shock of that first Monday morning of the meltdown passed, there’s a now a bigger debate about whether the way that rail services are provided for cities needs some far reaching reform. But before coming to that, the first thing to say – and as we set out in our Rail Cities UK report, launched today – is that the fundamentals for urban rail remain very strong.

Here’s why. All cities want to become denser, more dynamic places which attract the best people to the growth sectors of the economy (including the ‘flat white economy’ of media, communications and information). In order to achieve this, as well as to improve air quality, cities are also reducing space for motorised traffic in favour of space for people.

It’s very difficult to see how this can be achieved without expanding rail networks and their capacity. What’s more, if housing need is to be met without creating more sprawl and traffic congestion, then again its rail that will be key – because it opens up former rail-connected brownfield industrial sites, it extends commuting range, plus housing can be built above or around new or existing rail stations and interchanges.

In some ways there’s nothing new here. From Metroland to Docklands, successful cities have always grown with their rail networks. And to be fair, there is significant investment going into urban rail at present. Northern will get a lot better (the pacers are doomed) and both Merseyside and Tyne & Wear are getting a whole new fleet of trains for their urban rail networks.

However, much (but not all) of this investment is incremental, or replacing rolling stock on its last legs. It stops short of the wider vision for the rail cities that we need.


What would that look like in practice? There comes a point when the biggest cities need more cross-city routes, because running trains in and out of edge-of-centre termini can’t cope with the numbers. That explains the push for Crossrail 2 in London, but also the need for more cross-city capacity in cities like Birmingham (on the Snow Hill route) as well as in Manchester (on the Oxford Road to Manchester Piccadilly corridor, as well as a potential new underground route).

Tram-train technology can also help – allowing the lucky commuter that benefits to get on board at their local station and get off right outside their city centre office on main street in the city centre, rather than piling out at a Victorian railway terminal on the edge of that city centre.

Tram-trains aren’t the only tech fix available. Battery packs can extend the range of existing electric trains deeper into the “look ma, no wires” hinterlands, as well as allow trams to glide through city centres without the expensive clutter of overhead wires.

More mundane but equally useful work to increase capacity through signalling, station, track and junction work offers the opportunity to move to turn-up-and-go frequency networks with greater capacity and more reliability – networks that start to emulate the best of what comparable German rail cities already enjoy. Interlocking networks of long distance, regional express, regional, S-bahn, U-bahn, trams and buses, all under common ticketing.

But in talking about Germany and common ticketing I am now getting back to where I started around the debate on whether some fundamental change is needed on how urban rail networks are provided. Obviously there is a bigger national discussion going on about whether the current structure is just too layered, with too many costly interfaces and too fractured a chain of command. And in addition another, on whether the railway should be publicly or privately owned and operated.

But it’s been heartening to see the growing recognition that – regardless of how these debates are resolved – more devolution for urban and regional services should be part of any solution. That’s not only because fully devolved services have been out-performing comparators both operationally and in passenger satisfaction; it’s because local control rather than remote control from Whitehall will mean that the dots can be joined between rail and housing, between rail and the wider re-fashioning of city centres, and between rail and local communities (for example through repurposing stations as wider hubs for local community use, enterprises and housing). It will also allow for rail and the rest of local urban public transport networks to be part of one system, rather than be just on nodding terms as is all too often the case at present.

The crisis on Northern and Thameslink has been a miserable experience for rail users, affected cities and the rail industry. If any good has come out of it, it is that it shows how important rail is to cities, and opens up a space for some bigger thinking about what kind of rail cities we will need for the future – and how best we can make that happen.

Jonathan Bray is the Director of the Urban Transport Group which represents the transport authorities for the largest city regions. You can read the group’s full report here.