As heatwaves become more frequent and cities grow hotter, air conditioning is becoming one of the most important architectural questions of our time. But the future of AC is not as simple as installing more machines everywhere.

In this final episode of The Architecture of Cool, we explore air conditioning, climate change, home comfort, urban heat, energy use, refrigerants, green roofs, street trees, passive cooling, district cooling, radiant cooling, and the challenge of keeping buildings comfortable in a hotter world.

From historic cities like Paris, Venice, Barcelona, and Rome to fast-growing hot-climate cities, the question is no longer whether we need cooling. The question is how we design better buildings, better streets, better rooftops, and better AC systems so comfort inside does not make the city outside hotter, louder, or harder to live in.