Traditional building solutions tend to work well in their respective contexts, as they have withstood hundreds of years of testing and improvements, and use techniques and materials available locally. Although globalization and the democratization of access to technology have brought more comfort and new opportunities to humanity, it has also led to the homogenization of solutions in the construction sector and a dependence on global supply chains for construction materials and components. This has also caused a rupture in how knowledge is passed on to new generations and, eventually, the disappearance of traditions.
In particular, the topic of passive cooling solutions for buildings is currently having a resurgence, with an effort to recover ancient techniques used throughout history in locations that have always had to deal with hot climates. This is even more evident due to the high energy costs imposed by artificial cooling, the global warming scenario, and mainly because, among the projections of population growth, a significant portion of megacities will be located in the predominantly hot climates of Africa and Asia. When we think about the future, is it possible to be inspired by the past and apply ancient cooling techniques to contemporary buildings?
Fatih Birol, Executive Director of the International Energy Agency (IEA), says that "Growing demand for air conditioners is one of the most critical blind spots in today's energy debate." According to the IEA, the use of air conditioning and electric fans is responsible for nearly 20% of the total electricity used in buildings worldwide. Furthermore, the same source points out that by 2050, the number of air conditioning units will be more than three times what it is today, requiring as much electricity as the entire current energy consumption of India and China. At the same time, heat waves are becoming longer and more intense around the world, which could further exacerbate these figures.
It is not an exaggeration to say that cooling interiors will be the architectural challenge of the future. However, observing the solutions used in places that have always suffered with hot climates (arid or tropical) –long before the use of air conditioning mechanisms– can give us clues on how to solve this problem. Understanding these concepts and recovering traditional passive cooling techniques for modern buildings, without using electricity and with local materials and construction techniques, may be a good path forward.
From Persia: Wind Towers
Wind towers, also known as badgirs, are traditional cooling architectural elements that have been used for thousands of years in countries with hot and dry climates. Most researchers credit the invention of these elements to the Persians, but there are also traces in wall paintings dating back to 1300 BC that show something similar in Egypt. In any case, they consist of a tower with openings at the top that capture the prevailing local winds, directing them into the interior of the building through a series of ducts and openings. Commonly found in the Middle East, especially in Iran, Iraq, and the Persian Gulf region, they are mostly used in residential and commercial buildings.
Its operation is simple: as the wind blows at the top of the wind tower, it creates a difference in pressure between the interior and exterior of the tower, which in turn attracts air through the openings and into the interior of the building. As cold air enters the building, it circulates and cools the interior space, helping to keep it comfortable. The height of the tower, the number of sides, the number of openings, and the quantity and positioning of the interior blades all influence the efficiency of the wind towers, impacting the speed and turbulence of the airflow. In some cases, the towers are built over Qanats (channels), which supply water to homes. As they are completely shaded, they also create a cool and dense airflow caused by convection and evaporation.
From India: Jaali
Jaali, a type of perforated block, creates complex patterns of light and shadow while ventilating interior spaces. In the form of cement, earth, and wood pieces, the play between solid and void is a cultural symbol of Indian architecture, seen in many historical buildings including the Taj Mahal and the Red Fort in Delhi. They continue to be used in modern architecture as well, and their unique patterns and designs have inspired artists and designers around the world.
A jaali is typically installed as an external skin to the building, and its cross section usually shows a larger opening on the outside and a smaller opening on the inside. As the wind passes over the jaali, it creates a difference in pressure between the interior and exterior of the building. The cooling feature of the jaali depends on the Venturi effect: when air flows at a higher speed as it circulates through a narrower passage, it creates a negative pressure in the process, causing a partial vacuum that, in this case, propels the fluid. In the case of the jaali, the air is compressed and when released, it becomes cooler.
From the Arab world: Mashrabiya
Mashrabiya is a traditional architectural element used in many countries in the Middle East and North Africa. It is a type of wooden lattice or screen that is usually placed on windows, balconies and other openings in buildings, and they are highly decorative elements with complex geometric patterns. Its main function is to provide privacy and shade while allowing air and light to flow into the interior. To enhance the cooling effect, in some cases, clay pots are included, filled with water, sand or damp straw. As hot air passes through the perforations of the Mashrabiya, it also passes over the porous surface of the clay pots, where the moisture inside the pot evaporates, cooling the air. This cooled air flows into the building, helping to reduce the temperature of the interior space. This is a form of evaporative cooling, particularly effective in hot and dry climates, and is a highly sustainable and low-cost technique, without the need for electricity.
These days, designers and researchers are trying to bring together traditional knowledge with modern technologies. For example, the team at Ant Studio has reinterpreted traditional evaporative cooling techniques inspired by jaali to build a prototype of custom-designed cylindrical clay cones. Meanwhile, at the Al Bahar Towers, a pair of skyscrapers in Abu Dhabi, the façade is a unique system of dynamic shading panels inspired by the previously mentioned Mashrabiya. In this case, however, it is a "responsive façade," consisting of over 2,000 hexagonal elements that move in response to the movement of the sun, providing shade to the interior spaces of the building. The position of each element is controlled by a computer program that adjusts based on the angle of the sun, optimizing shading and reducing solar gain. The result is a façade that changes throughout the day, giving the building a dynamic and responsive appearance.
In addition to the devices mentioned, there are many other design elements and materials that can contribute to improving thermal comfort in indoor environments: materials with high thermal inertia, internal courtyards, water sources, and shading elements. It is important to emphasize that by using locally available materials and traditional architectural elements, architects and designers can create buildings that are well adapted to the local climate and environment, while also respecting and celebrating local traditions and cultural heritage. Undoubtedly, we have missed out on many solutions and good examples of cooling devices in this article. If you know of other examples used in your communities and regions, leave a comment below or on social media so that we can research and develop new articles.
