How to Cool Buildings on the Cheap

Article paywalled, can't read, it starts with white paint on buses.

Reflective white paints on building may cool by a few degrees.

Also, better to use district cooling, heard that buildings in Dubai/middle-east use district cooling.

Most of the liquids/gases used for heatpumps have extremely hight GWP (Global Warming Potential), best to use CO2, Ammonia or Water (for industrial or district).