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“London will flood and when it happens, it will be dramatic”

A failure of the Thames Barrier is inevitable, the London Underground is already flooding, so is City Hall: Anna White reports on the challenges facing the capital

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Kingston flooded in 1974 after severe drought was followed by heavy rain Photo: Rex
Kingston flooded in 1974 after severe drought was followed by heavy rain Photo: Rex

Picture this: a fierce northerly wind whips up a storm surge in the narrow North Sea, battering the east coast of England. It funnels into the Thames Estuary and gathers pace towards London.

 

The rain is lashing down on the capital, the wind is raging, the tide high, the pressure low and the Thames Barrier shuts.

 

This precise swell of factors creates the perfect storm. Waterloo’s Lower Marsh floods and waves penetrate Westminster. No amount of armed security guards or crash bollards can prevent this environmental attack on the heart of Britain’s political establishment.

 

“The 500-year storm has become a one-in-20-year occurrence or even less. London will flood and when it happens, it will be dramatic,” says Asif Din, sustainability director of global architectural firm Perkins+Will.

 

The combination of rising water levels and increasing frequency of catastrophic weather events means climate change can no longer be dismissed as a futuristic threat to communities, buildings and infrastructure.

 

After heavy rains last month, four London Underground stations were flooded, and City Hall flooded twice in September. There are 57 London Tube stations at high risk of flooding, representing a third of all stations, says Caroline Russell, author of the Climate Change Risks for London report, Green Party councillor and chair of the London Assembly Environment Committee.

 

“The short-term impacts are getting worse just as long-term change is taking hold – it is a double whammy,” says Ian Allison, global head of climate resilience at engineering group Mott MacDonald. It is a “right-now problem”.

 

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Surely the Thames Barrier, which opened in 1982 and sits just east of the Isle of Dogs, will protect the Greater London floodplain against storm surges?

 

The iconic blockade, which shut only 10 times in its first decade, shut 74 times in the past decade to March this year. “A failure of the Thames Barrier is inevitable and, on current projections, will happen soon,” says Din.

 

In the 1940s, a tidal surge of 3.66 metres was recorded in the Thames but hit at low tide, leaving the city unscathed. If it had coincided with the highest possible tide of the year, the waves would have increased to 6.86 metres – just 14cm shy of the height of the Thames Barrier.

 

Given the effects of global warming since then, it is not hard to imagine London’s last line of defence being overwhelmed in a worst-case scenario.

 

Architect Rory Bergin of HTA Design agrees: “Half of the South depends on the Thames Barrier – a breach really is the elephant in the room.”

 

Most central London developments rely on the future implementation of Thames Estuary 2100 (TE2100), the Environment Agency’s £300m tidal defence and flood risk programme of construction across the Thames Estuary.

 

According to an insider, climate change is no longer the elephant in the room at Lloyd’s of London, the global insurance sector headquarters.

 

“A failure of the Thames Barrier is inevitable and, on current projections, will happen soon”

 

The insurance broker told The Developer: “Climate change is the topic of the moment in the corridors of Lloyd’s of London. The industry is panicking about how to tackle it.”

 

A recent report from the Urban Land Institute (ULI) summarises the scale and complexity of this right-now problem for the insurance industry.

 

“In the long run, the consequence of climate risks such as sea-level rises and extreme heat will increasingly highlight the vulnerability of individual assets, locations and entire metropolitan areas,” it reads.

 

Real estate investors are fearful of insurance premiums being driven up as a result of climate change, but the cost of failing to insure is astronomical.

 

The repair bill after Hurricane Katrina, which hit the US and Caribbean in 2005, is estimated to be £83bn. In 2016, losses from natural disasters worldwide totalled £142bn, but only £39bn was covered by insurance, according to insurance firm Munich Re.

 

In 2017, the year that Hurricanes Harvey and Maria hit the US and spin-off storms battered central and northern Europe, insurance companies paid out $135bn. That year, the actual damage done by storms and natural disasters in the US alone stood at $307bn.

 

The unpredictability of future weather patterns plays havoc with actuarial modelling, and therefore adds another layer of complexity for underwriters.

 

Insurance companies rely on historical loss records to guide underwriting and pricing. However, with the climate acting in a manner that is increasingly hard to predict, the historical data is losing its value.

 

According to the ULI report, a growing group of investors and investment managers are exploring new approaches to find better tools and common standards to help the industry get better at pricing in climate risk in the future.

 

An unusually long heatwave last summer turned parks into ‘tinderboxes’. Photo: Getty
An unusually long heatwave last summer turned parks into ‘tinderboxes’. Photo: Getty
It is just a matter of time before the Thames Barrier is breached by a storm. Photo: Getty Images
It is just a matter of time before the Thames Barrier is breached by a storm. Photo: Getty Images

 

These include mapping physical risk for current portfolios and potential acquisitions; incorporating climate risk into due diligence and other investment decision-making processes; incorporating additional physical adaptation and mitigation measures for assets at risk; exploring a variety of strategies to mitigate risk, including portfolio diversification and investing directly in the mitigation measures for specific assets; and engaging with policymakers on city-level resilience strategies, and supporting the investment by cities in mitigating the risk of all assets under their jurisdiction.

 

There is also a vital need for an interplay between the insurance industry, the government (setting building regulations) and the development community (adhering to the regulations).

 

A scheme that might be resilient now will not be constructed to withstand a storm surge of a magnitude possible in 30 years’ time.

 

So who is ultimately responsible for a building or place that is doomed to fail?

 

Insurance companies rely on historical loss records to guide underwriting and pricing. However, with the climate increasingly hard to predict, historical data is losing its value

 

Currently, it would fall to the homeowner and an individual’s home insurance policy – which as yet might not account for the escalating magnitude of hurricanes, extreme precipitation, tornadoes, landslides, mudflows, drought, wildfires, heatwaves, flash floods and rising sea levels.

 

A spokesperson for Lloyd’s of London skilfully puts the ball in the government’s court: “Insurers provide insurance to properties that have been built in accordance with current government regulations.

 

“We… rely upon government and those with a more specialist building construction knowledge to provide the bulk of technical guidance to the government of the day to ensure dwellings are compliant with current regulations around life safety and construction regulations.”

 

One global initiative is lobbying policymakers, insurers and investors to take responsibility and ensure infrastructure is both financially and physically resilient.

 

Mark Carney, governor of the Bank of England, has called on major corporations to report their financial exposure to climate risk. Carney told a Tokyo conference that three-quarters of investors are already considering financial exposure to climate risk before buying shares.

 

The United Nations-affiliated task force, icebreakerone.org, is calling for a “new class of insurance combined with market standard risk transparency… and an open environment risk standard”.

 

Rather than wait for new building standards to be formalised, construction techniques must change now. “We can adapt to long-term incremental climate change but it is the ‘what if’, one-off catastrophic event that we have to plan for in our built environment,” says Din.

 

Urban areas are hotter than their rural surroundings. Materials such as concrete and glass, combined with a high level of movement from cars and motorbikes, public transport and even the motion of people, heat up the ground and air during the day while towers block cooling breezes.

 

In the wake of Hurricane Katrina, air conditioning failed and temperatures soared. The city’s hospital staff had to smash sealed windows in order to let air into the building

 

Buildings must be designed to reduce the amount of solar input with proper shading and passive ventilation. They also need to be comfortable on the inside, Din explains.

 

Overheating buildings are a public health crisis in the making. In the wake of Hurricane Katrina, air conditioning failed and temperatures soared. The city’s hospital staff had to smash sealed windows in order to let air into the building. “Patients were trapped in an overheating glass box,” Din says.

 

The vase-like new tower in Southwark, One Blackfriars, is made from 5,476 sheets of curved glass and sculpted to catch and reflect the light, changing colour at different times of the day. One architect describes it as “a building designed to overheat”.

 

But Rachel Haugh of SimpsonHaugh, the firm which designed the building, says: “One Blackfriars is often described as an all-glass building but this is a common misreading. Between two independent skins is a winter garden. In winter, the louvres on the outer skin close, offering an ‘overcoat’ of warm air to the inner building. In summer, louvres open, allowing the trapped heat to dissipate.”

 

One Blackfriars is unique as far as glass towers go, having been designed to Code for Sustainable Homes Level 4 standard. Its retail provision is rated BREEAM Very Good, with its hotel achieving BREEAM Excellent. The tower also features air-source heat pumps and rainwater tanks to reduce the chance of flash flooding.

 

Din says: “The days of the all-glass tower are numbered.” However, he does cite “fritting” as a useful technique when constructing resilient buildings. This is the addition of a porous glass sublayer that reduces the amount of solar energy.

 

 

The housebuilding industry is trapped in a vicious circle. In an escalating housing supply crisis and with limited space on which to build, the only way is up.

 

But Bob Weston, founder and chair of Weston Homes, argues that tall towers are prone to overheating as they have more surface area to absorb sunlight.

 

“Our understanding of the effects of weather on buildings has come on leaps and bounds in the past five years,” says Bergin of HTA. “However, some developers are still too focused on a building’s good looks rather than its good performance. Not everything has to be wall-to-wall glass. It’s about getting the ratio of wall to window right.”

 

Russell’s report states that two thirds of London flats could experience overheating by the 2030s, and that in the most vulnerable districts in London, the odds of dying from cardiorespiratory distress increases by more than 10 per cent for every 1°C increase in temperature, with ambulance call-outs increasing by 1 per cent for every 1°C increase over 20°C.

 

Air conditioning intensifies the problem, taking heat from inside and moving it outside, warming the external temperature and increasing the temperature of the urban heat island – perpetuating the need for more air con. “Unprotected glass buildings that need to be artificially cooled is a poor strategy,” Bergin says.

 

He favours a simple approach: keep the heat out by making the windows the right size for the amount of daylight needed with shading and shutters instead. “We should look to our continental neighbours. External shutters are the normal fabric of their residential buildings, and are left closed during the day,” he says.

 

A westerly-facing apartment will get a lot of sun, therefore it should be designed to have dual-aspect windows so that the resident can get a breeze flowing through.

 

Construction group Tide is building a 550-apartment development at 101 George Street in Croydon. On completion, it will comprise two of the world’s tallest modular towers, part-built in a factory and put together on site, at 44 and 38 floors.

 

“We’ve only got one generation of buildings to get this right”

 

The building is clad in green perforated terracotta panels that let in light but keep the heat out, therefore creating thermal stability. Each flat will have mechanical ventilation – a high-tech fan that whirrs away silently, bringing fresh air in and expelling out stale air. The outgoing air heats the incoming air, keeping bills low.

 

One Angel Square, the Co-operative’s headquarters in Manchester, was awarded BREEAM certification in 2013. The building has a heat recovery system to collect and recycle heat waste and 300,000 sq ft of exposed concrete that acts as a thermal sponge.

 

Then, there is the question of whole-life carbon, which includes not only the energy performance of the building after completion, but the emissions created by construction and in the making of its building materials such as brick, glass, steel and concrete – the worst offenders.

 

According to Steve Webb, director of Webb Yates Engineers, the best low-carbon cladding material in this post-Grenfell epoch is very thin metal or stone, which require less processing and are structurally sound; stone, unlike brick, does not require firing. As for wood and cross-laminated timber, Webb says: “There are real fire engineering challenges and rotting, but these issues need to be solved. The solution is not the abandonment of timber.”

 

“We’ve only got one generation of buildings to get this right,” says Basil Demeroutis, sustainability investor at the fund FORE.

 

Transport infrastructure is vulnerable, too. Even a slight increase in temperature can buckle train tracks, meaning rail operators have to apply speed limits during a heatwave, and hot tracks mean overnight maintenance cannot be carried out. As heavy rain and high winds result in landslides and fallen trees on railways, the dial moves from inconvenient to dangerous.

 

Construction for climate change is not just about future-proofing individual structures. True resilience lies in the holistic masterplanning of entire schemes and towns

 

Construction for climate change is not just about future-proofing individual structures. True resilience lies in the holistic masterplanning of entire schemes and towns.

 

The space in between is as important as the buildings. A business district comprising tall towers must be designed so that high winds do not get trapped between buildings and, forced to find a way out, create powerful wind tunnels at ground level.

 

It’s also about better planning. Heron Tower in the City has PV solar panels on one facade to harness solar energy. That side is now overshadowed by newer buildings. There is no point having an award-winning, resilient building that is not in a resilient area, explains Mott MacDonald’s Allison. “I’ve seen back-up flood barriers and back-up power sources that cannot be accessed in a storm.”

 

Adaptability, not strength, is key in designing for an unstable atmospheric future. “Sacrificial car parks should be designed at basement level. Through good communication the residents know to move their cars in advance, the basement is allowed to flood and after it recedes can be cleaned and put back into use. It’s all about flexibility,” he adds.

 

Disaster relief centres should be ready to use at any time and always accessible. Power sub-stations must not be built in the basement or on the ground floor and the materials on those lower levels must be robust and easily cleaned after the event. “It’s all about how quickly these sites and their communities can bounce back,” says Din.

 

Barking Riverside is being built at a far higher level than planned, with more flood defences
Barking Riverside is being built at a far higher level than planned, with more flood defences
Kingston flooded in 1976, when severe drought was followed by twice the average rainfall. Photo: Rex
Kingston flooded in 1976, when severe drought was followed by twice the average rainfall. Photo: Rex

 

Long-term regeneration schemes can take 30 to 50 years from planning to completion, outlasting many a property or economic cycle. The Earth’s temperature and water levels may even go up faster than the next penthouse or public viewing gallery, and initial plans can become outdated before the first shovels cut into the ground. The UN’s latest climate report states that one-in-100-year events will happen annually by 2050.

 

Barking Riverside is being built at a far higher level than original proposals set out. “From a climate change adaption point of view, a major part of our approach has been to build resilience into our water management systems. We are raising and improving the flood defences along our 2km stretch of the River Thames to address the worst climate-change scenarios,” says Sarah Coutts, head of planning and design of the 443-acre, 11,000-home mini-town.

 

More than 1,000,000m3 of soil was used to raise the development platform above flood level from the Thames and local tributaries, and the drainage strategy incorporates living roofs, permeable paving rain gardens and landscaped ponds.

 

Extra capacity for floodwater will open up 270 acres of underused space to the north of the city for redevelopment, paving the way for the delivery of 3,000 new homes

 

“This creates sheltered micro-climates for wildlife and helps to reduce the effects of the urban heat island,” Coutts adds.

 

Encouraging rainwater to replenish aquifers and other freshwater sources of drinking water instead of sewers is leading to more stringent planning requirements for sustainable urban drainage projects such as swales, green roofs and other storm-water attenuation strategies. Russell’s research report says an increase of up to 40 per cent in water supply is needed by 2040 in order to meet the water deficit in London and the South East.

 

The development company behind the conversion of Battersea Power Station is “refurbishing and raising river walls” to protect against flooding, and using green and brown roofs for water attenuation.

 

The ‘Sponge City’ project in Glasgow is the creation of Europe’s first smart canal. Sensor and predictive weather technology will provide an early warning of wet weather, before moving excess rainfall from residential and business areas (via urban drainage ponds to a network of granite channels) into the canal where water levels will have been lowered by as much as 10cm. This will create extra capacity for floodwater – the equivalent of 22 Olympic swimming pools. In turn this will open up 270 acres of underused space to the north of the city for redevelopment, paving the way for the delivery of 3,000 new homes.

 

“By unlocking the inherent value of Glasgow’s canal and diversifying the asset, we are ensuring it continues to deliver for local people 250 years after it was first built… Not only will it reduce the flood risk impact of climate change but it will act as a catalyst for new investment, jobs, homes and businesses,” says Catherine Topley, chief executive of Scottish Canals.

 

It is not just the physical process of building that can crawl – the UK’s rigid planning system also lags behind today’s science.

 

Demeroutis believes there are good returns to be made from sustainable buildings: “Private capital is taking responsibility more seriously,” he says. “They will no longer fund greenwashing”

 

“We won work on a site three times over a 12-year period,” says Bergin. “The first two times, the site was handed back due to financial difficulties and by the third time, the flooding advice was dangerously out of date.” He adds: “The UK governance and planning systems are very slow to react – it takes five years to agree a local plan, for example.”

 

The large public-listed developers will have to start reporting on their environmental as well as financial performance due to pressure from investors and out of reputational concern. But Allison worries that the private builders will only be obliged to meet anachronistic building regulations. The regulatory framework struggles to keep up with ‘the now’ and yet climate change scientists are planning and modelling for the next 30 to 80 years.

 

Those developers who wish to build sustainable schemes that can withstand extreme weather events employ architects and consultants to generate different weather scenarios for 100 years from now. Clearly there is a cost to this level of expertise.

 

Demeroutis believes there are good returns to be made from sustainable buildings: “Private capital is taking responsibility more seriously,” he says. “They will no longer fund greenwashing.”

 

The UK’s Committee on Climate Change released a new report and new zero-emissions target for the UK in the spring. Britain is to be net zero greenhouse gases by 2050, in line with the United Nations’ Sustainable Development Goals.

 

The pressure is not only top down but homeowners should vote with their wallets, too. Becky Fatemi, founder of property firm Rokstone, believes future-proofed homes will appeal to the next generation of first-time buyers who have eco-anxiety and awareness.

 

“One of the best-selling apartment blocks in London has been the Manhattan Loft Gardens in east London’s Stratford, due to its three green sky gardens,” she says.

 

So what of London’s inevitable future flood? The Environment Agency will review its TE2100 plans next year. The entire development community must, for evermore, build for a breach.

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