These 5 cities are embracing passive cooling for a sustainable urban future

The Global Cooling Watch Report 2023: Keeping it chill, released on 5 December 2023, highlights the importance of passive cooling alternatives to energy-hungry air conditioners.

The report, produced by the United Nations Environment Programme (UNEP), points out that between now and 2050 the global installed capacity of cooling equipment will triple, resulting in a more than doubling of electricity consumption.

Cooling is a double burden on the climate: air conditioners and refrigerators have both indirect emissions from electricity consumption and direct emissions from the release of refrigerant gases, the majority of which are much more potent at warming the planet than carbon.

By 2050, unless humanity dramatically lowers its emissions of climate-altering greenhouse gases, close to 1,000 cities will experience average summer highs of 35°C, nearly triple the current number. The urban population exposed to these high temperatures could increase by 800 per cent, reaching 1.6 billion by mid-century.

Last year, UNEP launched the Nature for Cool Cities Challenge as part of the Cool Coalition, a global network connecting over 80 partners which aims to drive a rapid global transition to efficient and climate-friendly cooling.

So, what are some alternatives to air conditioning that can help keep people cool without leading to a rise in emissions? Here are five examples from around the world.

Located on the dusty outskirts of the town of Koudougou, Burkina Faso, the Schorge Secondary School shows what is possible when builders mix traditional techniques and new materials. The school consists of nine modules arranged around a central courtyard, protecting the central space from wind and dust. Each module is built out of locally sourced laterite bricks, which absorb the heat during the day and radiate it at night. A secondary façade made of local eucalyptus wood wraps around the classrooms like a transparent fabric and creates shaded spaces to protect students from stifling daytime temperatures.

Following an intense 2010 heatwave, Ahmedabad, India developed a plan to rein in temperatures, which spike in the months before the annual monsoon. Some 7,000 low-income households saw their roofs painted white, a simple step that dramatically reduces inside temperatures by reflecting sunlight. The city also planted trees and provided free water to the public in an effort that saves an estimated 1,100 lives a year. Ahmedabad has served as a blueprint for 30 other cities in India, which have released or are developing similar cooling plans.

The 28th session of the United Nations Climate Change Conference (COP28) is being held from 30 November to 12 December, 2023 in Dubai, the United Arab Emirates. It aims to drive action on climate change by reducing emissions and halting global warming. COP28 will explore the results from the first-ever Global Stocktake, which assesses progress toward the Paris Agreement goal of limiting global temperature rise to below 1.5°C. You can follow live COP28 updates on UNEP’s climate action feed.

The Maldives is at the forefront of the climate crisis, with rising sea levels and surging temperatures devastating the low-lying nation. The Ministry of Environment – with support from UNEP – has been working to ensure residents can keep cool without raising electricity consumption. The centrepiece of that effort is the construction of the Maldives Meteorological Services building in Addu City. Based on guidelines developed by UNEP, it emphasizes passive cooling measures, using shading, insulation and even its orientation to keep temperatures down.

In Cambodia, demand for building cooling is set to double between 2020 and 2040. UNEP and the United Nations Economic and Social Commission for Asia and the Pacific (UN ESCAP) are working with two property developers to counter that trend. The partners are testing the effectiveness of passive cooling measures, like insulation, shading and roof design. Ultimately, the project aims to integrate the most successful strategies into national building regulations and urban planning standards, reducing energy demand for cooling while bringing heat relief to building occupants.

The 11km Cheonggyecheon Stream in the centre of Seoul was hidden under a 10-lane road and a raised four-lane motorway until 2005, when the local government dismantled the infrastructure and revitalized the stream. This has reduced the heat-island effect the city endures, with temperatures along the stream 3.3°C to 5.9°C cooler than on a parallel road just blocks away. The project illustrates the profound effect natural solutions can have on urban temperatures.

The 28th session of the United Nations Climate Change Conference (COP28) is being held from 30 November to 12 December, 2023 in Dubai, the United Arab Emirates. It aims to drive action on climate change by reducing emissions and halting global warming. COP28 will explore the results from the first-ever Global Stocktake, which assesses progress toward the Paris Agreement goal of limiting global temperature rise to below 1.5°C. You can follow live COP28 updates on UNEP’s climate action feed.