Thermal Mass

Many historic buildings in the Egypt have pleasantly cool interiors even when the hot
summer sun has been beating down on them for hours.
The secret is in their adobe walls-usually several cm thick-that take hours to heat up.
And when the sun sets and temperatures drop, the stored-up heat keeps the interior
pleasant through much of the night. This phenomena, called thermal lag or temperature
damping, is due to the mass of the walls.