The impact of climate change is increasingly felt in cities, where extreme weather events such as prolonged heat waves are exacerbated by the urban heat island effect. With more than 55% of the world's population residing in cities, it has become crucial to address the climatic challenges in urban areas. This urgency has led to the development of the new Annex "Sustainable Cooling in Cities," which focuses on implementing climate actions in urban agglomerations.

First, there is an immediate need for effective measures to improve outdoor climate conditions in cities, ensuring comfortable and healthy living environments. This requires interventions at different spatial scales, from city-wide urban design to neighborhood-level initiatives and building-specific strategies. Urban design and landscaping can play a key role in optimizing urban morphology to enhance air and wind movement while integrating green and blue infrastructures to offer shade and lower outdoor temperatures. Additionally, utilizing cool materials in outdoor spaces can directly benefit people and indirectly improve indoor living conditions.

Second, cities need strategic solutions to address the cooling requirements of buildings: first, to reduce the cooling need, and second, to meet it in an energy-efficient, climate-friendly, socially beneficial and affordable way. The increasing demand for building cooling necessitates innovative approaches that consider the urban context. Instead of relying solely on decentralized air conditioning units, which contribute to heat and noise pollution as well as inefficient energy usage, cities should explore cooling methods such as district cooling, seawater cooling, and radiative cooling. Implementing balanced cooling and heating with seasonally balanced environmental heat sinks can further optimize energy use and reduce the environmental impact.

Third, the interdependence between outdoor climate mitigation and sustainable building cooling must be acknowledged. Sustainable cooling technologies depend ona favorable utdoor climate, making it essential to mitigate urban heat waves. Failure to address outdoor climate challenges can compromise the effectiveness of cooling strategies during extreme weather conditions. Conversely, the excess heat from air conditioners can significantly impact outdoor comfort especially during heat waves.