How To Construct A City Fit For 50 Heatwaves

The Persian Gulf is already one of the hottest parts of the world, but by the end of the century increasing heat combined with intense humidity will make the region too hot for habitation, according to research published in Nature Climate Change.

Heating and air conditioning currently permit humans to live everywhere from Siberia to the Sahara. However the extreme heatwaves predicted for the Gulf, where temperatures will regularly make 50 or even 60, will reach the limitations of the thermal adaptation that buildings can provide.

Our ancestors lived without the sophisticated thermal control systems we typically use in modern buildings; they implicitly employed different bioclimatic designs, such as natural ventilation or south-facing windows, and these skills are still valuable in many climates today. But updated data indicate this will not be enough.

So is there a future for habitation in the hottest regions of the world? It seems mass migration is less likely than remaining set and taking on current challenges. However figuring out how to live comfortably and sustainably while its hot enough to fry an egg on the sidewalk may offer a fillip for environmentally sensitive design and urban planning throughout the world.

Living With Intense Heat

The climate is a problem but does offer some possibilities. The sum of sunshine available means there should be no dearth of solar energy, though we need to develop efficient storage systems too. We could also take advantage of day-to-night ambient temperature fluctuations utilizing thermal mass techniques to even out temperature fluctuations.

Dino-architecture? Bahrains twin towers are covered in glass. Allan Donque, CC BY

We will have to make significant changes to building design highly glazed structures that soak up heat will become architectural dinosaurs. Traditional notions from hot regions of the world will resurface: thick walls dedicating thermal stability( but enhanced with smarter materials such as composites with layers of insulation or perhaps embedded phase-change materials ), used together with small windows. Building surfaces will need to be coated with smart materials that reflect heat gain these already exist and researchers have looked at their perfomance in the hot summertimes of cities such as Athens.

Well need to optimise where and when we occupy buildings, to seek out the coolest places and take advantage of less intense night hour conditions. We may find ourselves living partly underground in order to benefit from lower and more stable temperatures to be found a few metres below the Earths surface.

In intense heat, find some tint becomes essential. Buildings, streets, services and even entire transportation systems need to be entirely shaded or even fully underground. Some of these features are already showcased in the Masdar City development in Abu Dhabi, though the project( which had significant design input from Norman Foster and partners) is not yet fully operational.

Switch On The Air Con Industry

Expect an air conditioner boom. This will cost a lot both to build and to operate, and well have to come up with systems specially designed for extreme temperatures. The thermodynamics of current designs which rely on temperature differences between heat absorption and heat rejection mean it would be very difficult to achieve sufficient and efficient heat removal as these change and narrow.

In Dubai even the bus stops are air conditioned. Jay Galvin, CC BY

One opportunity would be to use the Earth or the sea/ rivers as heat sinks, rather than the external air, as these will be at lower temperatures and are now able to absorb the heat, though perhaps with as yet unknown long term impacts. It is also likely that air conditioning might most effectively be used during the night-time to pre-cool the building; night-time air temperatures will allow more efficient refrigeration.

Urban design and the ways in which cities are used at hour of extreme heat will also need to be considered. Moving around outdoors without protection could become as unimaginable as strolling unprotected from a polar research station in winter.

This obviously causes significant problems for those who must work outside: places of refuge may need to be constructed and the very act of build may need to be restricted to the winter( or rather slightly cooler) months. Building products will also be obliged to change in order to cope with most extreme thermal stresses and expansion effects.

Heatwave Cities

The shape of cities and the massing of their major buildings will change so that groupings offer a degree of self-protection. Streets will be designed to optimise shading and, when available, cooling air ventilation. The spaces between buildings will need to be carefully designed and uses( such as what might happen underground) considered alongside services provided to citizens. Shopping malls could be submerged and used as links between regions, just as the underground streets found in northern latitude cities like Montreal are used in winter.

Cities themselves may change away from coastal to inland zones due to the problematic combining of high temperature with high humidities near to water masses. In drier atmospheres, technologies such as evaporative cooling( in their simplest form fountains and water sprays) can be used to reduce temperature.

A technological alternative to this might be the use of moisture assimilating materials( regenerated desiccants) to dehumidify the atmosphere, but this would be a significant and complex undertaking on the scale necessitated. Moving whole cities can only be a long term scheme but its something worth thinking about now, while there is time.

Read more: could turning to traditional techniques provide a solution? Amin Al-Habaibeh, professor of intelligent engineering systems at Nottingham Trent University, thinks so .

Adrian Pitts, Professor of Sustainable Architecture, University of Huddersfield

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