Why do riads feel cooler inside than outside, even without AC?
The short answer
Walls forty to sixty centimetres thick absorb heat all day and keep it out of the rooms behind them. The courtyard pulls hot air upward. A fountain adds evaporative cooling. The whole system runs on geometry and gravity — 10–15°C below street temperature without electricity.
The walls are forty to sixty centimetres of rammed earth or stone — dense enough to absorb heat all day and release it overnight. By morning, after a desert night that can drop twenty degrees, the walls are cool again. The building resets every twenty-four hours.
The courtyard is the engine. Hot air rises from the sun-exposed centre and escapes upward. Cooler air pulls in from shaded rooms at ground level. A fountain adds evaporative cooling. Orange trees do the same through their leaves.