August in Abu Dhabi means average temperatures of 36°C. Designing a building to cope with such extremes of heat and glare is a challenge, to say the least. The solution developed by Aedas Architects for the twin Al Bahar towers draws its inspiration from traditional mashrabiya, latticed screens that filter the light and shield the sun’s intensity. Each 25-storey tower has a façade comprising 2,000 units that open and close in response to the movement of the sun across the building like the petals of a flower folding and unfolding. Along with creating a more comfortable working environment, the adaptive façades shrink the towers’ CO2 emissions by up to 20% by reducing the need for energy-guzzling air conditioning.
Cooling urban heat islands
Grid-locked city streets choked by exhaust fumes. Concrete and asphalt surfaces soaking up solar radiation. High-rise buildings trapping heat at pavement level. Cities in summer can become ‘urban heat islands’ with temperatures up to 10°C hotter than the surrounding landscape. But cranking up the air-conditioning to compensate only contributes to the problem, using more energy and pumping waste heat and greenhouse gases into the air.
One way to cool down cities is to use more reflective materials in their construction. The New York Cool Roofs initiative was launched in 2009 as a volunteer-based programme to support the city’s efforts to combat climate change. Since then it has covered more than 10,000,000 m2 of roof space with white reflective paint or membrane. While in Los Angeles, white-painted roads and pavements in the Winnetka neighbourhood have not only reduced the ground temperature by 5-8°C, but also cooled surrounding locations by 1°C.
Cities don’t have to think big to fight climate change. Even a brownfield site, smaller than a tennis court, planted with trees can make a difference. Mini forests are springing up in urban spaces around the world, inspired by the planting around Japanese temples. The method is based on the work of a Japanese botanist, Akira Miyawaki. He observed that the protected areas around shrines, temples and cemeteries planted had flourishing ecosystems because native species were allowed to thrive. Small patches of wasteland, planted in this way can become shady carbon-capturing oases.
The concept is a simple one. Rather than channelling away rainwater in concrete storm drains, ‘sponge cities’ work with nature to absorb water and prevent flooding. A network of natural and constructed wetlands, complemented by water storage systems, green roofs and green spaces, soak up and clean stormwater. China is leading the way with sponge cities, but they are catching on around the world as urban planners recognise their potential for flood management and urban cooling.