Between now and 2050, worldwide installation of cooling appliances, like air conditioning, is projected to triple, resulting in a twofold increase in energy consumption. This reliance on such devices, often seen as exacerbating global warming, poses a paradox: how can we fight rising temperatures in cities while simultaneously contributing to them through our dependence on these solutions?
Using air conditioning extensively on scorching days not only strains the power grid but also contributes to raising a city's temperature by around 2°C. This happens because the process expels hot air. Moreover, access to cooling technologies, whether at home, work, or school, is limited and varies depending on people's financial circumstances.
Seen as a solution to combat heatwaves, air conditioning is selective and exacerbates discomfort for other residents. While it provides thermal comfort for some, it leads to discomfort for many others.
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How to Design for Optimal Thermal Comfort (And Why it Matters)Even though it is hard to imagine a world without these appliances, reconsidering architecture and urban design to tackle global warming is crucial for providing equal access to thermal comfort and reducing our reliance on technology. Passive cooling strategies involve design decisions that engage with the environment. They are not quick fixes but require a concerted effort towards awareness and change across various fronts.
It is incredibly easy to press a button on the remote and watch the room temperature drop by 10 degrees Celsius in a matter of minutes. However, perhaps we would not be so reliant on this sudden cooling if our cities offered high-quality and accessible urban design featuring vegetated surfaces, shaded areas, or water elements that help reduce overall urban temperatures. The revitalization of the Cheonggyecheon River in Seoul is a practical example of how we should approach our cities. Following its revitalization and integration into Seoul, it was observed that temperatures along the river decreased by between 3.3°C and 5.9°C compared to a street just a few blocks away.
In addition to urban considerations, when it comes to architectural strategies, passive mitigation of high temperatures relies on several well-known yet perhaps equally underestimated measures. These include shading (via vegetation or built volumes), reflective surfaces, generating thermal mass through materials, proper solar orientation, and cross ventilation. Research suggests that combining these passive strategies can result in an average internal temperature decrease of 2.2°C, a 31% reduction in cooling load, and a 29% energy savings.
The Lycee Schorge Secondary School by Francis Kéré is one project that embodies these strategies, using locally sourced bricks that absorb heat during the day and release it at night. Additionally, a secondary facade made of local wood wraps around the classrooms like a transparent fabric, creating shaded areas to protect students from suffocating daytime temperatures and eliminating the need for cooling equipment.
These strategies do not demand specific financial resources but must be incorporated from the beginning of the design process. Due to limited access to professional architectural services, many communities end up utilizing ineffective thermal and environmental solutions. Initiatives have emerged that directly involve vulnerable communities, focusing on simple and practical strategies for improving their homes.
The Mahila Housing Trust (MHT) is an example of an organization that assists low-income women in Indian cities in addressing neighborhood overheating. Their initiatives include simple measures like applying white paint to create reflective roofs. This is because standard or dark roofs can reach temperatures as high as 65 degrees Celsius in intense heat, while "cool roofs" can remain as low as 10 degrees Celsius under similar conditions. Since its founding decades ago, MHT's initiatives have positively impacted the lives of over two million people and trained more than 21,000 construction workers. The group recognizes that integrating green spaces, reflective surfaces, and cross-ventilation can help reduce thermal stress and provide comfort amidst urban heat islands. "By investing in these solutions, we bring to life the vision of a cooler, safer, and healthier urban habitat for the underprivileged," the organization states. In 2021, MHT was honored with the Ashden Award for cooling in informal settlements.
Besides those initiatives, some recent solutions leverage indigenous knowledge to offer accessible cooling methods. Ant Studio, for instance, has reimagined traditional Indian evaporative cooling techniques to create a prototype of cylindrical clay cones functioning as air conditioners. Although still in testing, this model has shown promising results, reducing ambient temperatures by approximately 6 degrees Celsius.
In the era of global warming, cooling systems are no longer a luxury but a fundamental necessity, akin to sanitation or drinking water. Heat stress negatively impacts physical and mental well-being, hindering basic tasks and leading to illness. Our buildings and cities must adapt to this new reality, especially considering that the solution is not as simple as pressing a button on a remote control.
