The summer of 2023 not only shattered monthly temperature records, but was also followed by the hottest September ever recorded. Consequently, urban areas saw a steady surge in the demand for cooling solutions.
Feeling the heat
The “cooling degree days” value, a weather-based index that shows the energy required to cool down buildings, has increased significantly over the past four decades (1982-2022) in European cities. It’s 6.9 times in Paris and 3.2 times in Madrid. The International Energy Agency (IEA) predicts that the number of air conditioner units installed in EU countries will double between 2023 and 2050, reaching 275 million units. This is creating a vicious circle; higher air conditioning-use boosts energy consumption and greenhouse gas emissions, potentially accelerating climate change and contributing to rising temperatures, in turn increasing demand for cooling.
Asian cities at the centre
While cities all around the world face increasing cooling demands, Asian cities are way ahead of the curve as they have long grappled with severe heatwaves. Cities in South and Southeast Asia have much higher demand for cooling than European cities. For instance, in 2022, cooling degree days in Bangkok are about 46 times the level of Paris.
Source: OECD calculations based on Eurostat (2023), Cooling and heating degree days by NUTS 3 regions – annual data
Asia is emerging as a pivotal region in both mitigating and adapting to climate change, for two reasons. First, Asia is the largest emitter of CO2 among the world regions, being home to 60% of the world population and generating more than half of global emissions and 46% of global GDP.
Second, Asia is vulnerable to the impacts of climate change due to its geography and socioeconomic conditions. Under climate change, the region faces increasing frequency and severity of heat waves, storms, flooding, and droughts, along with sea level rise, all of which have the potential to inflict long-term harm on both lives and economies. S&P Global Ratings shows that South Asia is 10 times more exposed to physical climate risks than Europe, while the Asian Development Bank estimate that a high emission scenario could cost developing Asia 24% of GDP by 2100.
Looking for sustainable solutions
New techniques are being deployed to keep cool efficiently, including passive design strategies and district cooling systems.
Passive design strategies aim to optimise building elements such as orientation, thermal mass and natural sources of heating or cooling such as sun and breezes, ultimately leading to thermal comfort, energy efficiency, and reduced greenhouse gas emissions.
For example, Rajkot, India has introduced “Smart GHAR III (Green Homes at Affordable Rate)”, which reduces heat gains through windows, walls and roofs. For instance, the project used highly reflective roofing made of glazed tiles to reduce solar heat gain by reflecting rather than absorbing the sun’s rays. It is estimated to reduce peak summer room temperature by over 5°C.
Okinawa, Japan has established a green housing guideline for its semi-tropical climate, including a range of passive design strategies, such as installing heat-blocking rooftops, heat-resistant paint and ventilation block walls.
Cities are also working to make on larger-scale solutions, including district cooling systems. This approach cools water in a central plant, which is sent to various buildings to support air conditioning, eliminating the need for individual buildings to operate their own chillers. For instance, in Bangkok, Thailand, the “One Bangkok” urban megaproject is investing in district cooling infrastructure with an installed capacity of 36,000 refrigeration tons (equivalent to the energy required to produce 36,000 tons of ice at 0°C within 24 hours).
Another unique cooling approach is to use hydro-thermal energy. Seoul, Korea is starting a pilot project using the Han River’s water for year-round energy-efficient cooling and heating for buildings, which is expected to save around 90 megawatt-hours of energy annually. The city’s Lotte Tower, Korea’s tallest building, adopted this technology in 2014, resulting in a 35.8% reduction in energy consumption and a 37.7% reduction in carbon dioxide emissions compared to the same-capacity absorption chiller.
Chilling out
While rising temperatures are concerning cities across the world, Asian cities can and must lead the charge on energy-efficient cooling measures. Success here will not just keep their own citizens cool but – by cutting emissions – help cool an entire planet.
Find out more in the OECD report, Decarbonising Buildings in Cities and Regions.
Yosuke Kagaya worked as an intern at the Director’s Office of the Centre for Entrepreneurship, SMEs, Regions and Cities (CFE) in the summer of 2023. He is currently pursuing a Master of Public Policy at the University of Chicago. In 2013, he obtained a Bachelor of Law and subsequently gained 5 years of experience working for a software development company. Afterward, he worked for the Ministry of Land, Infrastructure, Transport and Tourism of Japan for 4.5 years, where he was responsible for policymaking to promote public transportation and bicycle use.
Ji-Soo Yoon is a Policy Analyst at the OECD Centre for Entrepreneurship, SMEs, Regions and Cities (CFE) where she actively contributes to the work of Decarbonising Buildings in Cities and Regions. Her role involves proving support to national and subnational policy makers in decarbonising building policies including energy efficiency in buildings, life-cycle approach (LCA) to embodied carbon, and the integration of digital technologies, all aimed at harnessing the building sector's potential to combat climate change through mitigation and adaptation measures.
Before joining the OECD, she worked in the energy division at the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) where she conducted research on blockchain technology application for clean energy transition, mainly on P2P renewable energy trading. She holds a Master’s degree in International Affairs from the Geneva Graduate Institute (Institut de Hautes Études Internationales et du Developpement, IHEID) in Switzerland and a Bachelor’s degree in International Studies from Ewha Womans’ University in Korea.
Takeshi Miyamori leads OECD’s work on Decarbonising Buildings in Cities and Regions. Before joining the OECD in 2022, Takeshi has worked for the Ministry of Land, Infrastructure, Transport and Tourism of Japan for more than 15 years developing polices on housing, buildings and urban planning as well as three years for the Prime Minister’s office. He holds two master’s degrees in urban engineering (University of Tokyo) and public economics (National Graduate Institute for Policy Studies).
Hiroko Suzuki is a senior counsellor at Director’s Office of the Center for Entrepreneurship, SMEs, Regions and Cities (CFE) where she involves the CFE projects on inclusive urban growth, smart city, sustainable urban infrastructure finance as well as Indo-Pacific outreach of CFE’s activities.
Before joining OECD, Hiroko worked for the United Nations World Tourism Organization (UNWTO) Regional Office for Asia and the Pacific, the Ministry of Land, Infrastructure, Transport and Tourism of Japan, and the Japan Bank for International Cooperation. She holds a Master’s degree from the London School of Economics in local economic development.