In fact, yakhtang was the first "refrigerator" ever. This unique structure from mud bricks looks like a huge tandyr ( 10 m in height).
By the way, when the structure was actively used it was even higher - up to 30 m. In the Middle Ages yakhtangs were used to store foodstuffs: huge khums with oil and wine, dried meat. Indeed, when you get inside of such storehouse you feel the cold air.
The similarity between yakhtang and a hearth is not accidental; the history has preserved its national name - "Tandyr Khadzhimelek".