The past decade was the hottest in human history. Apocalyptic fires and floods, cyclones and hurricanes are increasingly the new normal, and emissions are 62 per cent higher now than when international climate negotiations began in 1990.
The evidence is clear. We are in a race against time to adapt to a rapidly changing climate – one of the three planetary crises we face along with biodiversity loss, pollution and waste.
Accounting for 38 per cent of total global energy-related CO2 emissions, the construction industry will play an important role in achieving our goal to limit global warming to well below 2°C. According to some estimates, investing in more resilient infrastructure could also save humanity a whopping $4.2 trillion from climate change damages.
UNEP’s new report, A Practical Guide to Climate-resilient Buildings and Communities, shows how buildings and community spaces can be constructed to increase resilience, especially in developing countries, where settlements are largely self-built. The report also demonstrates how combining ‘grey’ building solutions with ‘green’ nature-based solutions can have promising results.
As Asia-Pacific Climate Week kicks off, we look at five ways to make buildings resilient to climate change with some examples from the region:
1. Building resilience to heatwaves
Studies show that by 2050, 1.6 billion people living in more than 970 cities will be regularly exposed to extreme high temperatures. Coupled with the ‘urban heat island effect’ which makes cities warmer than the surrounding rural area, this puts urban dwellers at high risk.
But nature provides powerful solutions. Communities can create urban forests and green spaces to reduce heatwaves in cities as trees and other plants cool the surrounding environment by offering shade and releasing water through their leaves.
Structural designs can also help reduce heat inside buildings. In Vietnam, traditional housing designs such as the optimum orientation of buildings, high-rise rooms, and large openings improve ventilation. Trombe walls - heavyweight structures of concrete, stone, or other heavy material that capture solar heat are used in China, Chile, and Egypt. Green roofs and reflective surfaces can also reduce temperatures in and around buildings.
2. Building resilience to drought
Climate change is affecting rainfall patterns across the world. Rainwater harvesting and recharge systems that capture water on the roofs of buildings are commonly used to store water during drought and reduce flood risk during heavy rains. The collected water can be stored in tanks and used inside the building during periods of drought.
Another cost-effective, nature-based way to address droughts and flooding is to plant trees or other vegetation around buildings. The roots of the plants act like sponges to recharge groundwater, and during heavy rainfall, the roots allow water to penetrate the soil and reduce the risk of flooding. In China, the Sponge Cities Project is piloting eco-engineering solutions to absorb and reuse rainwater in over 30 metropolises to reduce flooding risks.
3. Building resilience to coastal flooding and sea-level rise
By 2025, 410 million people in coastal communities could be at risk of coastal flooding and sea-level rise. In Kerala, India, flood-resistant houses are constructed on pillars to allow floodwater to flow underneath. On Malaysia’s coasts, buildings elevated 2 meters above the ground allow waterflow and wetland vegetation to grow underneath, with houses and public areas connected through elevated passages.
One approach proposed in Bangladesh is to build a buoyant multi-purpose building that would rest on pillars with buoyant tanks that raise it during floods. The building would function as a community center and also provide emergency shelter during flooding.
4. Building resilience to cyclones and strong winds
Cyclones and storms are expected to become more frequent and stronger with climate change. They can affect buildings in many ways, such as blowing off roofs and damaging the structures and foundations of the building. To mitigate this damage, communities can build round-shaped houses and consider optimum aerodynamic orientation to reduce the strength of the winds.
Roof design also plays an important role. Strong connections between foundations and the roof are critical to building wind-resilient houses. Roofs with multiple slopes can stand well in strong winds, and installing central shafts reduces wind force and pressure to the roof by sucking in air from outside. Roofs that cover balconies or patios can also be designed to break during strong winds to prevent additional structural damage to the essential parts of the house. This is called frangible architecture or ‘planning for damage’ approach.
5. Building resilience to cold
Adapting to cold and temperate climates requires capturing heat and minimizing heat loss. Insulations in roofs, walls, ceilings, and double-glazed windows help to minimize heat loss and lead to more energy efficient buildings.
In colder regions, Trombe walls can absorb heat by day and radiate it out by night when it is colder. Water has a high capacity to store heat and can be used in “water walls” – that instead of concrete, contain drums of water to store heat. Buildings should be also be oriented to maximize sun exposure, and external surfaces of walls should be painted dark.
Green roofs that support plant growth on rooftops are used in many cities around the world and have been shown to provide insulation and reduce the energy demand for cooling during summer and heating during winter.
Asia-Pacific Climate Week (APCW) is being held from 6 to 9 July 2021, hosted by the Government of Japan with global organizing partners - UNEP, UNFCCC, UNDP and the World Bank. APCW 2021 is accelerating collaboration and integrating climate action into global pandemic recovery. Building back opens an opportunity to address social inequalities and invest in economic development that is good for humanity and nature.