Termino iraní para Torre eólica. Es una estructura similar a una chimenea alta que se proyecta sobre el techo de un edificio para expulsar el aire caliente en el día y atrapar las brisas más frescas en la noche.
Torre eólica en azotea
Los Bagdirs surgen por la necesidad de cubrir la climatización de los espacios. Debido al difícil accesoa equipo de calefacción y enfriamiento moderno y tecnológico los arquitectos se vieron obligados a utilizar energías naturales para hacer cómodos los edificios.
Estas estructuras de ventilación operan según la condición del viento y de la radiación del sol. En tiempos antiguos y en los edificios tradicionales de regiones áridas y secas las trampas de aire funcionan como el sistema de aireacondicionado de la actualidad.
Function ¿Cómo funciona?
Is a device with real form and constant structure in architecture, it leads the suitable wind through the inner part of the building and it is the most effective function in making comfort.
There are 2 kinds of main functions:
The function according to the principle of traction of opening facing the wind and the suction of openings backsagainst the wind.
The way a wind-catcher works is mainly based on taking the fresh air into the building and sending the hot and polluted air out or “the suction functions” perhaps it is not so necessary to explain that when the wind hits against the walls of internal blades of the wind-catcher it necessary falls down, but it is necessary to refer this point that the other holes of thewind-catcher turning back to the wind direction, gives the hot and polluted air into the wind and so works like a ventilation and a sucked machine.
The function of this kind of a wind-catcher is actually performed according to this fact that when the wind hits an obstacle, and since the density of the air is thick on the side of the wind direction, so in this direction there is a positive pressure, buta negative pressure on the other side. Therefore, when the ventilation is open on the sided of the wind there will be a positive pressure to a negative pressure. In the wind-catchers, according to this principal, the opening facing the wind takes the e air into the porch and the air in the porch with its negative pressure on the opening back of the wind is drawn out. Sometimes according to thesuperficial evaporation the wind-catcher supplies the necessary moisture by conveying the wind over the weather and the cold-storage.
Function according to temperature difference
During the day, since the sun hits on the southern face of the wind catcher, the air heats in the southern face of the wind catcher, and goes up. This air taken above through the inner air of the porch is compensated andin fact it makes a kind of proportional vacuum inside the porch, and takes the cool air of the inner court into itself, so the existing air in the northern opening is pulled down too.
During the night it becomes cold outside, and the cold air moves down. This air is saved by the heat and becomes warm on parapets and then goes up. This circle continues till the temperature of the walls andoutside temperature become equal.
Due to high fluctuation of temperature differences between day and night in this climate and night time coldness, Badgir which is made with mud brick, gets cool by radiation and convection.
The system works, when there is no wind, but when wind is blowing this system does not have problems. Because during the day, if there is wind, then cool air flows fasterand at night, with wind, it may absorb the heat of the walls, because the night wind is cool enough.
LOCATION OF WIND-CATCHER
Wind-catchers are generally used in two kinds of building: water-reservoirs and houses.
Water-reservoirs. By considering the appropriate direction of wind blast, in city water-reservoirs, about seven wind-catchers are used, each wind-catcher acts its function with the...