Windmills (asiab-e badi) are mud-brick structures erected in eastern Iran and western Afghanistan to harness wind power to move the runner stone of a mill to grind flour. These mills rely on a consistent wind known as the "120-day wind" (bad-i sad-o-bist rooze), which blows southward from the Qizil-Qum steppes in Turkmenistan toward the Baluchistan desert during the summer months. The strip along which this wind blows includes the eastern parts of Khorasan and Sistan provinces in Iran and the western border of Afghanistan.
The greatest number of well-known windmills are located in villages around Khaf in Khorasan, including Nashtifun and Neh (located midway between Birjand and Zahedan), where they can be found in rows along the outskirts of villages, where the terrain is higher in elevation. Building windmills in rows appears to be a practical way to save material and space while providing safety and protection for the millers. Free-standing and semi-detached windmills are more common on the Afghan side of the border.
Some scholars have proposed that eastern Iran is the origin of the first windmills, which then spread as far as China in the east and Europe in the west. Historical sources suggest that these windmills predate their European equivalents by at least five hundred years. The first written reference to Persian windmills was found in 644 C.E. in the work of the famous medieval historian Masudi. An explanation of the architectural and functional characteristics of windmills is found in a fourteenth-century document written by the Syrian geographer al-Dimashghi, whose description also includes a schematic illustration. The construction date of the area's existing windmills is unclear, as they have been rebuilt and renovated over time. Some of them are considered to be Safavid or Qajar constructions, although no solid evidence exists.
A typical windmill with a vertical axis has two main components, the wind-wheel and the millhouse. The design of these windmills is determined by the north-south direction of the "120-day wind." While its northern wall is diagonal, in order to augment the wind pressure, there is no wall on the rear side of the wind-wheel. Two supporting lateral walls flank the wind-wheel and rise to the same height as the front wall (about five meters). The walls are approximately 90 centimeters thick, narrowing to 50 centimeters at the top. The top bearing of the wind-wheel is usually a ring of apricot wood set into a beam that lies directly on the lateral walls.
The lower part of a windmill, the millhouse, is a room typically measuring six meters long by six meters wide and three and a half meters tall. These measurements vary slightly in different regions. Similar to other structures in the area, millhouses are roofed by mud brick vaults. In Nashtifun, millhouses are divided into three bays. In the final bay the wind-wheel is connected to two circular stones, placed on a raised platform about one meter above the floor. The runner stone revolves while the lower one (often the larger) is fixed in place. The middle bay collects the flour, and the winnowing takes place in the bay adjacent to the entrance.
Mud brick is the main construction material for a millhouse, which is then coated with mud plaster. The wind-wheel itself is made out of wooden parts, sometimes with metal joints, which transform the wind power into the force needed to turn the millstones. The wooden parts used in the wheel are different woods sourced from various regions. Generally, the millhouses have no decorative elements, although some freestanding windmills, such as the one near Zabol, are decorated on the eastern and western walls with brickwork, where empty spaces between the bricks create patterns.
Up until the 1970s, a number of windmills were still in use in Iran and Afghanistan. With the advent of mechanical engines, abandoned windmills have fallen into disrepair and ruin. In recent years, some windmills have been renovated and restored by the National Heritage Organization of Iran. The best-preserved examples are in the Khorasani villages of Neh and Nashtifun, where thirty-three out of forty original windmills are still standing.
Beazley, Elisabeth and Harverson, Michael. 1982. Living with the Desert: Working Buildings of the Iranian Plateau. Wilts: Aris & Philips, 88-102.
Wulff, Hans. 1966. The Traditional Crafts of Persia. Cambridge: Massachusetts Institute of Technology, 284-289.