That's why we need passive daytime radiative cooling. In theory, it could completely eliminate the urban heat island, but it still seems to be mostly at the pilot project stage so far. I did read somewhere that you can DIY with some packaging tape (which somehow has the right properties?) over a reflective backing. Maybe I'll experiment a bit this summer.
There is a lot of passive system to prevent heat to come in, in the first place.
Brise soleil (sun-breaker) - these systems prevent direct sun to go through the window in summer, but let it in to heat up the habitation in winter.
Trees ! - Trees have a cooling effect in summer and a keep the warmth in winter. They also improve air quality, physical and mental health. Increasing the areas covered by trees in city could bring down there temperature by several degrees.
Yeah, I'm a big believer in shade trees! The one in our front yard has grown tall enough to provide blessed relief from a blazing afternoon sun. The only problem is the dude next door, who's heavy into solar, is worried it'll block his panels. And I'm a believer in solar too, so I don't know what to say. Maybe we can come to some sort of compromise…
what an understatement. it's very unsexy but also incredibly effective. if your house is over 20 years old, you don't need fancy-ass blinds, you need to get your house insulated ASAP. everything else must wait.
insulation is the number one most effective thing anyone can do to improve the energy use of their living space. only when your house is properly insulated can you think of shade management, greenery, passive ventilation, heat pumps, etc. in an insulated house, those either won't work at all or will be wildly inefficient.
I'm planning on making some panels to help cool my garden in an attempt to help plants survive extreme heat and sun by shooting some of that heat into space! The combination of partial shading with cooling mass vs heating mass should help a bit. People think it doesn't work, but I'd imagine growing a garden on a asphalt blacktop vs white cement would make a few degrees difference. This technology does the same thing, it just pushes the boundaries further to cool below atmospheric temperature.
You're the first person I've seen bring this up, not sure why it's not more popular, just new I guess. Also, usually when I bring it up people say it's' bad because it will encourage more fossil fuel growth and they totally miss the point.