Key facts
- Rooftop solar in the UK can generate enough electricity for five hours of daily air conditioning use.
- Global space cooling, primarily AC, consumed 2,100 TWh of electricity in 2022, contributing to 1 billion tonnes of CO2 emissions.
- AC installations are projected to triple globally by 2050, potentially leading to significant CO2 emissions.
- Air conditioning systems use potent greenhouse gas refrigerants, contributing to climate change beyond electricity consumption.
- The EU and UK are actively phasing out harmful fluorinated gases in favor of more climate-friendly refrigerants.
Rooftop solar installations are providing European homes with several hours of free air conditioning daily during a significant heatwave, offering much-needed relief. An analysis by Ember found that typical UK homes with rooftop solar generated enough electricity to power an AC unit for five hours per day during the recent hot spell.
However, the environmental sustainability of air conditioning, even when powered by solar energy, remains a concern. The International Energy Agency (IEA) estimates that global space cooling consumed approximately 2,100 terawatt-hours of electricity in 2022, accounting for about 7% of the world's electricity and causing nearly 1 billion tonnes of CO2 emissions. Projections indicate that AC installations could triple in the next three decades, reaching 5.5 billion units, as climate change intensifies.
While AC has been proven to reduce heat-related mortality, preventing nearly 200,000 premature deaths in 2019, its growing demand poses a significant emissions challenge. Researchers have warned that AC could potentially produce more CO2 than the current annual emissions of the US by 2050 in a worst-case scenario.
Solar power is seen as a complementary technology to AC, with similar seasonal patterns. During recent heatwaves, UK rooftop solar installations generated the equivalent of 10 million solar-powered AC hours per day across 1.9 million homes.
Beyond electricity consumption, AC systems utilize refrigerants like hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), which are powerful greenhouse gases. The EU and UK are actively phasing out these gases, aiming for their elimination from the market by 2050, in favor of more climate-friendly alternatives. Despite improvements in energy efficiency, many AC units sold globally are half as efficient as the best available options, partly due to high upfront costs.
Furthermore, the process of absorbing heat from indoors and releasing it outdoors contributes to the urban heat island effect, where cities trap heat, leading to higher temperatures compared to rural surroundings. Experts warn of a potential 'arms race' where efforts to combat extreme heat exacerbate the problem, emphasizing the need for cleaner, more efficient cooling technologies and equitable access.