Yazd is famous for its badgirs or wind towers. They are used for a traditional method of cooling the interiors of buildings.
The cross vents at the top of the towers catch the wind and funnel it downwards. At the base of the tower there is a giant vase full of water. The wind picks up the water and blows it through the house.
The water absorbs the heat from the room and then carries it out the other side.
- Budget Travel
Bagh-e Dowlat Historic Complex
This is a complex built according to the original Iranian architectural style and consists of a large garden and some building. Being watered by a qanat, until the very recent past it was used for the residence of the provincial governor. The most impressive part of the complex are a 33-meter high bad-gir (wind tower) on the roof and a water stream in the interior. The air was conducted into the interior and cooled through the action of the flowing water. Lattice doors and windows with stained glass patterns impart a pleasing sight to the complex.
This is a close-up of the material that the Old City walls of Yazd are made of. As you can see, it's actually a mixture of clay and wheat chaff. It is amazingly durable, as some of these walls have been standing for 800 years and some of the adobe buildings for more than a thousand years.
- Budget Travel
Badgir are wind towers - and Yazd is famous for them... there are plenty all over the old town, and they are still in use. Badgirs were (and are) a very simple but effective system of ventilaton. Being open at the top, as you can see from the photo, these wind towers can catch the faintest breezes and channel it to the buildings below, allowing them to remain fresh and cool even in the hottest summer desert temperatures. What I found amazing is that even the bazaar has its own badgirs, so one can really stroll about pleasantly at any time of the day, and anywhere.
Bagdirs are windtowers and they can be seen all over Yazd and in some other Iranian cities where it can be very hot.
You can say that bagdirs are natural air-conditioners. They catch the wind and direct it through a shaft to the rooms below, where there is a pool of cool water, cooling the air. Through a different shaft the hot air in the house is directed upwards.
- Historical Travel