The conversationJuly 05, 2021 2:14:48 pm
Climate change will affect all aspects of our lives, including the buildings in which we live and work. Most people in the US, for example, spend around 90 percent of your time indoors. Climate change is fundamentally altering the environmental conditions in which these buildings are designed to function.
Architects and engineers design buildings and other structures, such as bridges, to operate within the parameters of the local climate. They are built with materials and following design standards that can withstand the expected range of temperatures, rain, snow and wind, as well as any geological problems such as earthquakes, subsidence and groundwater levels.
When any of these parameters are exceeded, some aspect of the building is likely to fail. If there are strong winds, some roof tiles may break. If, after days of heavy rain, the water table rises, the basement could flood. This is normal and these problems cannot be completely eliminated. After the event has passed, the damage can be repaired and additional measures can reduce the risk of it happening again.
But climate change will create conditions in which these parameters are exceeded more frequently and to a much greater degree. Some changes, such as the higher average temperature and humidity of the air, will become permanent. What was once considered flooding once in a century can become commonplace.
Some of these impacts are quite obvious. Houses will be more prone to overheating, putting the lives of neighbors at risk, which is what has happened in recent years. “Heat Dome” over North America. Floods will occur more frequently and will flood larger areas, to the point that some places will have to be abandoned. The town of Fairbourne in Wales has already been identified as a possible candidate. Failure to comply with these two threats in the UK was highlighted in a recent report by the Climate Change Committee.
To some extent, these impacts will be localized and controllable, with fairly simple remedies. For example, overheating can be reduced by shading windows with awnings or blinds, good insulation, and ample ventilation. Perhaps more concerning are the insidious effects of climate change that gradually undermine a building’s core functions in less obvious ways.
Termites and melted asphalt
Heavier wind and rain will cause the outer coating to deteriorate more quickly and drip more often. Higher temperatures will expand regions where can some insects live. That includes wood-eating termites that can cause major structural damage, or malaria-carrying mosquitoes, whose living spaces need to be redesigned to protect us.
Materials expand as they heat up, especially metals, which can cause them to bend once the designed tolerance is exceeded. For a skyscraper in Shenzhen, China, high temperatures were partially blamed for causing the structure to shake, forcing its evacuation, since the steel structure was stretched by the heat. Extreme temperatures can even cause materials to melt, causing roads to “bleed” as they the surface layer of bitumen softens.
Subsidence, when the ground beneath a structure gives way, causing it to crack or collapse, is also expected to occur more frequently in a warmer world. Buildings with foundations on clay soils are particularly vulnerable, as soils swell when they absorb water, then harden and shrink as they dry. Changes in rainfall patterns will exacerbate this. Over the next 50 years, for example, more than 10% of properties in Great Britain will be affected by sinking.
Perhaps the biggest concern is how climate change will affect reinforced concrete, one of the most widely used materials on Earth. Used in everything from skyscrapers and bridges to lintels over house windows, reinforced concrete is made by placing steel rods into a mold and pouring wet concrete. Once dry, this produces incredibly strong structures.
But a warm climate wants wreak havoc with the durability of this material. When steel within concrete gets wet, it rusts and expands, cracking the concrete and weakening the structure in a process sometimes referred to as “concrete cancer.”
Buildings in coastal areas are especially susceptible, as the chloride in salt water accelerates oxidation. Rising sea levels will raise the water table and make it saltier, affecting the foundations of buildings, while salt spray will spread further in stronger winds.
At the same time, the concrete is affected by carbonation, a process in which carbon dioxide in the air reacts with cement to form a different chemical element, calcium carbonate. This lowers the pH of the concrete, making the steel even more prone to corrosion. Since the 1950s, global CO₂ levels have risen from approximately 300 parts per million in the atmosphere to more than 400. More CO₂ means more carbonation.
The recent tragic collapse of an apartment building in Miami, USA, may be an early warning that this process is picking up speed. While the exact cause of the collapse is still being investigated, some suggest it could be linked to climate change.
The local mayor, Charles Burkett, summarized the bewilderment that many felt:
It just doesn’t happen. You don’t see buildings falling in America.
Whether or not the link with climate change is true, it is nevertheless a wake-up call to the fragility of our buildings. It should also be seen as a clear demonstration of a critical point: wealth does not protect against the effects of climate change. Rich nations have the financial clout to adapt more quickly and mitigate these impacts, but they cannot stop them at the border. Climate change is indiscriminate. Buildings are vulnerable to these impacts no matter where in the world they are located, and if anything, modern buildings in developed countries have more that can go wrong than simpler traditional structures.
The only option is to start adapting buildings to meet the changing parameters in which they are operating. The sooner we start modernizing existing buildings and constructing new ones that can withstand climate change, the better.
Ran Boydell, Visiting Professor of Sustainable Development, Heriot-Watt University