Passive materials–based solutions for cool and “radiant” cities

Tokyo, the most populous city in the world and known for its mild northern climate, reached a record-high temperature of over 35°C in September 2024. Earlier this year, a heat wave swept through South America, with Rio de Janeiro, Brazil, experiencing a staggering heat index of 62.3°C. In May, Delhi, India, saw temperatures soar above 50°C. I recently moved to another densely populated city, Hong Kong, a gateway to mainland China. This high-density city has shattered its temperature records every summer for the past 3 years.