Right, cities in general fucking suck at dealing with heat because they're concrete jungles with little greenery, and Paris in particular as pointed out in your article in parts due to the Zinc roofs. Doesn't change the fact few have AC (which also increases death risks during heatwaves) and that building techniques in general were made to more naturally keep houses cool, but yes that's more true with country houses and especially the more south you go. I didn't mean to imply cities didn't suffer from heat.

Heat is actually surprisingly easy to moderate with green spaces, water, shade, and wind.

Unfortunately, roads, roofs, and buildings fuck that all up.

Plant trees along every road. Line every building roof with greenery. Water that greenery, and centrally control how it's watered to create temperature/humidity differentials and thus wind throughout the entire city.