The opinion editorial by Thomas Nowak discusses the potential of recovering and recycling waste heat to create a circular energy economy in urban areas. As cities face the need to improve infrastructure and services due to the climate crisis and population growth, the transition to clean heating and cooling becomes crucial. By utilizing thermal networks, heat pumps, and renewable energy sources, cities can reduce CO2 emissions, improve air quality, and enhance their resilience to extreme weather events. The article emphasizes the importance of low-temperature thermal networks that collect waste heat from various sources and distribute it efficiently to where it is needed. Heat pumps play a key role in extracting heat and providing both heating and cooling services, contributing to high energy efficiency. The symbiosis of heat pumps and renewable electricity/heat offers a sustainable solution for urban areas. The benefits of transforming heating and cooling infrastructure in cities include better air quality, reduced heat island effect, and improved resilience to climate change. By replacing fossil fuels with clean energy and utilizing waste heat, cities can become more sustainable and independent of fossil energy sources. However, the adoption of heat pump technology and thermal networks faces challenges such as upfront costs and regulatory barriers. To overcome these obstacles, the article suggests incentivizing modern technologies, raising public awareness, and making thermal networks part of public waste heat collection infrastructure. In conclusion, the article highlights the potential of clean heating and cooling technologies in creating sustainable and resilient cities. It advocates for the incorporation of these technologies as a cornerstone of Europe's energy and climate policy to achieve decarbonization and efficiency in urban heating systems.