Sustainable Urban Cooling Handbook

The Sustainable Urban Cooling Handbook is a report published by the United Nations Environment Programme (UNEP). It was released in November 2021. The report says that the cities are to become too hot to live in future. The handbook is an encyclopaedia  of solutions on sustainable urban cooling.

Key Findings of the report

• The world cities are heating up at twice the global average. This is mainly due to urban heat island effect.
• The urban population exposed to hot temperatures, that is more than 35 degrees Celsius are to increase by 800% by 2050 as compared to 2016. Around 1.6 billion urban population is to face this heat. The World Health Organisation says that between 2000 and 2016 the number of people exposed to heat waves increased by 125 million. Thus, further increase in city high temperatures are to create disastrous impacts.
• The International Labour Organisation predicted that 1.5 degrees Celsius temperature increase by 2030 will lead to lose of 80 million full time jobs. This will in turn result in 2.3 trillion USD of global economic losses. With increase in temperature in cities, the low income countries, especially in western Africa and southern Asia will be worst hit. Such regions are to lose 5% of working hours due to high temperatures.
• The report estimates that the heat related deaths are to increase to 92,207 in 2030 and to 255,486 by 2050.
• The electric grid failures during extreme weather are increasing. This along with increasing heat waves will expose large population to severe heat stress.
• The energy requirements for space cooling are to triple in 2050 as compared to 2016. This is because millions of new households will install air conditioners in coming days. The increased air-conditioned spaces will in turn increase the greenhouse gas emissions.

Impacts

The handbook lists possible impacts due to the increase in high temperatures. These impacts are predicted based on the assessment of 13 cities in different countries. The impacts are as follows:

• For each degree of increase in ambient temperature, the electricity demand will increase by 3.7%
• The space cooling will account 30% to 50% of peak electricity load. Today, in November 2021, this is 15% of peak electricity load. The biggest increase is to occur in India. The global space cooling demand is to increase by 300% in 2050 as compared to 2016.

Issues identified

• The current space cooling systems are energy intensive. Also, they are largely reliant on refrigerants and fossil fuel generated electricity. Such systems and practices are proliferating the inefficient cooling appliances rather than addressing the issue of increasing urban heat islands and rising emissions. This in turn is violently increasing the emissions in urban environment. Bottomline, space cooling is one of the major causes of increasing greenhouse gases and intensifying the heat in the urban areas.
• With the increase in use of air conditioner, additional grid infrastructure should be constructed. This will increase the waste heat expelled into the environment.
• The socio-economic inequities make the cooling more challenging. The urban poor are highly vulnerable to high temperatures.

Solutions

• A cohesive set of sustainable urban cooling interventions shall be implemented. This will help to reduce energy requirements, improve health and productivity, lower emissions and increase economic benefits.
• The report provides three main solutions. They are reducing heat at urban scale, reduce cooling needs of buildings and serve cooling needs of buildings efficiently.
• The handbook stresses on the achieving human thermal comfort. That is, there is a need for sustainable cooling. The cooling business has created madness in tropical cities where one carries a jacket to stay comfortable inside the building! Such conditions should be changed. Buildings should be cooled to comfortable temperatures. Thus, there is a need for whole system approach. This shall be achieved through energy efficient building, sustainable refrigerant use and efficient cooling technologies.