Designing buildings to cope with extreme climate events: Part 2
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17 March 2020
As the global temperature continues to increase, so too does the frequency and intensity of the catastrophic climate events it causes.
Last year was the second warmest on record and brought to an end the hottest decade in human history. In January this year, there were fierce bush fires in Australia, caused by severe droughts and strong winds, that have burned an estimated 18.6m ha (46m acres) of bush, forest and parks across the country. At the time of going to print the BBC reports that at least 29 people have lost their lives due to the fires.
It seems undeniable that climate change is ushering in a new world of extremes, with each posing a unique risk to different elements of the built environment. With that in mind, we take a closer look at precisely what those threats are and, perhaps more importantly, what can be done to mitigate their potentially disastrous effects.
Heat
The recent bush fires in Australia provide a tragic and stark example of how prolonged periods of drought, extreme heat and dry weather can devastate a country. But while it’s all but impossible to control wildfires once they spread, innovative design can help protect buildings in the event of a fire.
Ian Weir, Research Architect at the Queensland University of Technology, is known worldwide for his bush-fire-resilient housing designs, including his acclaimed H House, which can withstand strong fires. Located in bush-fire-prone Point Henry, Western Australia, the home is elevated on steel stumps and clad in galvanised steel. Bush-fire-rated reflective glazing and fire-rated roller shutters were also installed to the outside of the building to protect against fire embers – which Weir explained to the Guardian in 2016 were the primary cause for house loss in bush fires – as well as timber decks and verandas that are protected by sprinklers.
A more unusual building concept, meanwhile, is being tried out by Baldwin O’Bryan Architects elsewhere in Australia. Based on so-called “earth-sheltering” construction, the idea behind the design is that the building is enclosed under stabilised compressed earth blocks – building blocks made from soil – much like a bunker, which reduces the number of entry points for flames and ember attacks. The blocks have the same bush-fire-resistant qualities as reinforced concrete, which is typically used in earth-sheltered buildings. However, they are a cheaper and more sustainable option, since they can be made from soil taken from the building site.
Elsewhere in the world, heatwaves – like the one that hung over France last July, pushing the temperature to 46.1°C (115°F) – are expected to become a more frequent problem. Indeed, in December 2018, the Met Office in the UK said that heatwaves were now 30 times more likely than they would be naturally.
For Asif Dan, Head of Sustainability at architect Perkins & Will, the buildings most at risk are residential, particularly in northern Europe, where most homes have no air conditioning, which itself doesn’t offer a sustainable solution for the long term.
Statistics from energy analyst International Energy Agency (IEA) show that carbon emissions from space cooling tripled between 1990 and 2018 to 1,130 million tonnes. The group says that without significant efficiency improvements, electricity demand for cooling in buildings could increase by as much as 60% globally as soon as 2030.
“Without significant efficiency improvements, electricity demand for air conditioning and cooling in buildings could increase by as much as 60% globally as soon as 2030”
For Asif Dan, Head of Sustainability at architect Perkins & Will, the buildings most at risk are residential, particularly in northern Europe, where most homes have no air conditioning, which itself doesn’t offer a sustainable solution for the long term.
Statistics from energy analyst International Energy Agency (IEA) show that carbon emissions from space cooling tripled between 1990 and 2018 to 1,130 million tonnes. The group says that without significant efficiency improvements, electricity demand for cooling in buildings could increase by as much as 60% globally as soon as 2030.
As such, Dan says the built environment will have to think about more passive design to cool properties. Passive design looks to control building temperature using natural and low-energy solutions and techniques, including thermal mass, an example of which can be seen in Council House 2, an award-winning office building located in Melbourne, Australia.
Thermal mass is essentially a heat storage system, in which the heat arising during the day gets stored in exposed concrete ceilings. Then at night, when the external temperature has fallen below that of the internal concrete ceilings, windows beneath the low points of the vaulted ceiling automatically open, allowing cool air to flow through.
Melbourne is also carrying out a “cool roofs” initiative in a bid to control internal building temperatures – as is New York City. This relatively low-cost solution works by layering specialist paint on the roof of a building. The paint includes additives that reflect the sun’s heat, and it also absorbs radiation and emits it back into the atmosphere at a higher rate than standard materials could.
Cold
At the other end of the temperature scale, cold snaps are an increasing blight across the world. This year, a polar vortex swept in from the Arctic causing temperatures in the American Midwest to drop to -35°C (-31°F), with wind chills as low as -50°C (-58°F).
Many buildings in areas susceptible to cold snaps will need improved insulation
With that in mind, adequate insulation will be a critical factor for many homes in the UK, which has a lot of vulnerable heritage stock, says Floyd. He points to the Rocky Mountain Institute’s Innovation Center in the US as an example of the types of solution that could be applied.
The building uses what it calls “aggressive insulation” against the elements and is surrounded by thick concrete walls and levels of insulation three times thicker than that required by regulation.
The centre has also been made 97% more airtight than a conventional commercial building, using advanced materials combined with strict construction details, including two coats of airtight tape and air barriers and seals to avoid leakage.
“This protects against swings in internal temperature, hot or cold, and creates a more stable atmosphere inside the building and comfort for the inhabitants,” explains Floyd.
WSP’s Head of London Building Services, Austin Wikner, meanwhile, says it’s worth contemplating how tall structures in dense city areas, that are not used to extreme cold, would need to adapt. “If we get to climates where we’re regularly experiencing temperatures of -10°C (14°F) or -15°C (10°F), you’ve got a real potential issue of the build-up of snow and ice, which means there is a risk to pedestrians from falling hazards,” he cautions.
“If we get to climates where we’re regularly experiencing temperatures of -10°C or -15°C, you’ve got a real potential issue of the build-up of snow and ice, which means there is a risk to pedestrians from falling hazards.”
Austin Wikner
Head of London Building Services, WSP
“This is a problem they deal with regularly in parts of America, but the UK and London don’t tend to have that problem because – at the moment – temperatures don’t often get that cold. But as things change, and if we’re going to be heading for more extreme temperatures, that’s something that could impact design.”
As a consequence, he says, the actual shape and form of buildings would need to ensure that snow and ice couldn’t build up along any overhangs. Also, consideration would need to be given to the design of the public realm at the base of the building, which may have to include “no-go” zones to protect the public.
