Low winds stopped what might have been new ‘great fire of London’, says expert | Climate crisis

Fires that burned in several parts of the UK last week spread in the same way as those that led to the great fire of London and would have been far worse with stronger winds, a fire expert has said.

Fires in Wennington, Uxbridge and Erith destroyed 41 properties last Tuesday, when temperatures went above 40C to make it the hottest day on record in the UK, and fire services had their busiest day since the second world war.

Guillermo Rein, professor of fire science at Imperial College London, said that strong winds played a major factor in spreading the 1666 fire, which lasted for four days and ended when soldiers blew up houses to create fire breaks, and the strong easterly wind died down.

“While it was blowing, the [great fire of London] was completely unstoppable,” he said. “So let’s put it this way. Tuesday could have been even worse if we had more wind.” Gusts reached 14mph last week, barely above average.

“Obviously the London of today is much safer than the London of 1666. But this was an urban fire, where fire spreads from one home to another, aided by vegetation. That’s what happened in 1666. This is what happened on Tuesday.”

After the 1666 fire, London’s mostly wooden houses and churches were rebuilt in stone, and the changing climate means that builders, architects and the public also need to change their approach to fire safety now, Rein and other experts said.

Most fires are started by people, usually accidentally, through sky lanterns, or by barbecues or camp fires that are thought to have been put out but continue to smoulder.

Anyone with a garden should be aware of how fire might spread into their home, according to Rein. A compost fire can spread to a wooden fence, which then might set light to an overhanging tree, and in turn to the roof of a house.

Embers carried by winds are also dangerous – the 1666 fire spread into different areas when embers landed on other houses.

“Tiles are tremendously fire resistant,” Rein said. “But if they are not well maintained, then embers can fall through a hole, and the structure of a roof is made from timber.”

Paul Bussey, a member of the Royal Institute of British Architects’ fire expert advisory group, said: “Our legislation does not cover anything about external fires spreading from one building to another. We’re not used to it. But we really need to start thinking about it.

“When you’re also dealing with a carbon-zero economy where we’re trying to use more timber and less concrete, it’s a challenging question.”

Green living walls, such as one at the ExCeL building in London, could be considered a vector for a fire to spread, he added. “We’ve got to get to a stage where we can reconcile all these conflicting issues in a proportionate way.”

The Bushfire Building Council of Australia published designs last April for a “disaster resilient house” called Fortis with the aim that Australians in areas prone to wildfires, cyclones or floods can evacuate but return to find their home intact.

Kate Cotter, chief executive of the body, said the designs included an aerodynamic roof to withstand cyclones, and metal mesh screens to protect the windows from embers and heat. Retro-fitting existing homes is also an option, depending on the type of building, she added.

“Ninety per cent of our homes are not resilient to their local disaster risks,” Cotter said. “The classic UK house has a lot of strengths – brickwork and stone are strong and resilient. What’s most important is the detailing, looking where we’ve got chimneys, vents, weep holes, exhaust fans and sealing them up using mesh screens so embers can’t get in.

“People should definitely look at toughened glass – double glazing isn’t usually fire resilient but toughened glass is.”