Gaps in access to effective cooling have implications for thermal comfort, productivity and health Yet, of the 3.5 billion people who live in hot climates, 1 only about 15% owned AC in 2021, with even lower ownership levels in Sub-Saharan Africa and South Asia. In addition, most buildings in these areas are not equipped with sufficient passive or low-energy-consumption cooling solutions. An estimated 2-4 billion people in the Global South, or 25-50% of the world’s population, are potentially exposed to heat stress due to lack of effective indoor cooling. In particular, AC is unavailable to households with no electricity and remains unaffordable for many low-income households with electricity. Even households that can afford the initial investment in AC often cannot afford the electricity bills associated with its operation. Lack of access to indoor cooling puts a very large part of the population in the Global South at high risk for heat stress, adversely affecting thermal comfort, labour productivity, and human health.

Population-weighted heat stress exposure, top ten countries/regions, 2021

When exposed to excessive heat, the human thermoregulatory system, including sweating for evaporative cooling and increased skin blood flow for transfer of heat away from the skin, can become impaired or fail, leading to heat-related illness or even death. Heat can cause heat exhaustion or heat stroke (a medical emergency that is often fatal); can trigger acute health events, including acute kidney failure and heart attack; and can exacerbate pre-existing chronic diseases, such as heart or lung disease. There are a number of risk factors for heat-related illness that make people more vulnerable to rising temperatures and extreme heat events. Older populations and people with chronic disease are particularly at risk, as are homeless people, people who work outdoors, and those who live in inadequate (e.g. poorly insulated) housing. Some areas within cities are particularly hot due to especially dense urban infrastructure, a high volume of automobile traffic, and lack of green space (such as parks, gardens, trees, and shrubs) and blue space (such as bodies of water including lakes, rivers, and ponds).

Effective cooling saves lives, whether through AC or more sustainable, lowerenergy-consumption approaches. In the remainder of this document, we discuss the sustainability challenges associated with AC and the promise of alternative cooling solutions that, if adopted widely, can provide effective cooling whilst substantially reducing energy demand for AC.

Global heat-related deaths and deaths avoided in individuals aged 65 years or older due to AC, 2002-2021, and percentage increase of cooling degree days and household AC ownership over 2002-2006 average

Additional high-priority measures to reduce AC energy demand include naturebased solutions (such as green and blue space), high-albedo (i.e. high ability to reflect the sun’s rays) streets and sidewalks, and advanced building design (such as high-albedo or green roofs, low-emissivity windows, and suitable insulation). AC sustainability can also be improved through proper installation, maintenance, and end-of-life material management, particularly for GHG refrigerants. Accelerated efforts to decarbonise power generation with clean energy sources are fundamental to reducing the negative impacts of AC. These energy sources are already economically competitive and are being deployed throughout the world. Almost 30% of electricity was generated using renewable sources in 2021 (of which about 35% was from solar photovoltaics and wind). Decarbonisation is not only a climate imperative (along with a shift toward low- or zero-GWP refrigerants), but will also eliminate emission of toxic air pollutants – most notably fine particulate matter – from the power sector, and increase overall system resilience against price shocks.

Technical response measures to the challenges associated with AC growth and heat-related illness and death

Source:http://IEA