One of the most effective passive cooling strategies is the use of thermal mass . Materials such as stone, adobe, and concrete have a high specific heat capacity, meaning they absorb heat during the day and release it slowly at night when temperatures drop. In the ancient city of Yazd in central Iran, buildings constructed from thick mud-brick remain cool during scorching summer days. Similarly, the stepwells of India — deep, multi-storey structures carved into the earth — maintain consistently low temperatures because the surrounding ground acts as an enormous heat sink.
Despite their efficacy, natural cooling methods have limitations. They require careful building orientation, local climate analysis, and often, larger land areas than modern high-rise construction permits. Nevertheless, a hybrid approach is emerging: ‘active’ cooling systems that work with passive designs, rather than against them. For instance, a building with high thermal mass can be mechanically ventilated at night to ‘charge’ the coolth, then sealed during the day. As the world seeks to decarbonise, these time-tested strategies are no longer a curiosity — they are a necessity. IELTS READING QUESTIONS Questions 1–5: True / False / Not Given Do the following statements agree with the information in the reading passage? Staying Cool Naturally Ielts Reading Answers
More surprising is the use of radiative cooling , a principle that has only recently gained scientific attention but has been used intuitively for centuries. Certain whitewashed buildings in the Greek islands are not merely aesthetic; the lime-based paint reflects up to 80% of solar radiation. At night, the same surfaces radiate heat back to the cold sky, a phenomenon known as ‘night-sky radiation’. In 2017, researchers at Stanford University developed a ultra-white paint that reflects 98% of sunlight, potentially paving the way for zero-energy cooling. The oldest example of radiative cooling, however, may be the ancient Egyptians, who soaked mats in water and hung them in windows; as water evaporated, it cooled the incoming air, but the effect was enhanced by the clear night sky radiating heat away. One of the most effective passive cooling strategies
Staying Cool Naturally A. For thousands of years, before the invention of air conditioning, human civilisations developed ingenious methods to keep buildings cool in hot climates. These ancient techniques, which rely on natural principles such as convection, evaporation, and thermal mass, are now being rediscovered by architects and engineers seeking sustainable alternatives to energy-intensive cooling systems. With global temperatures rising and air conditioning accounting for nearly 10% of global electricity consumption, the wisdom of the past offers a timely solution. Similarly, the stepwells of India — deep, multi-storey
In hot, dry climates, buildings made from materials with high ___________ absorb heat by day and release it at night. The Persians invented 7 ___________, which are tall structures that direct wind downwards, sometimes over water for extra cooling. In humid regions, houses on 8 ___________ allow air to flow underneath, and courtyards help regulate temperature. A more recent discovery is radiative cooling, where special white paints reflect sunlight and emit heat through 9 ___________ radiation at night. Questions 10–13: Matching Features Match each feature (A–E) with the correct description (10–13) below.
In humid tropical regions, evaporative cooling is less effective because the air is already saturated with moisture. Here, traditional architecture prioritises ventilation and shading . The Malay house, for example, is raised on stilts to allow air to flow underneath the floor, while large overhanging roofs and porous bamboo or timber walls permit cross-ventilation. Courtyards also play a crucial role: they act as thermal regulators by providing shaded outdoor spaces and drawing cooler night air into surrounding rooms. Research from the University of California has shown that a well-positioned courtyard can reduce cooling energy requirements by up to 30%.
Another elegant solution is the wind catcher , or badgir , also originating from Persia. These tower-like structures rise above the roofline of a building and are designed to capture prevailing winds. Internal vertical partitions direct air downwards, often passing it over a pool of water or a qanat (an underground water channel) to provide additional evaporative cooling. Even when there is no wind, the temperature differential between the top and bottom of the tower can create a natural updraft, drawing hot air out of the building. Modern computational fluid dynamics simulations have confirmed that well-designed wind catchers can reduce indoor temperatures by up to 12°C compared to the outside.