*2.1. The Pharaonic Era*

Windcatchers have been depicted in Ancient Egyptian paintings, indicating that the concept of the windcatcher traces back to the early Pharaonic era [11]. For example, the Pharaonic house of Neb-Amun was portrayed in a painting on his tomb dating back to the Nineteenth Dynasty (1336–1294 BC). It displays a windcatcher with two openings, one facing windward to receive cool air and the other facing leeward to expel hot air by suction [11,12], as seen in Figure 3a. Furthermore, a papyrus (Figure 3b) from the *Book of the Dead* (1543–1292 BC) references windcatchers' existence during the Pharaonic era. The elevation at the right end of the drawing shows two similarly aligned triangles, which are presumably windcatchers [13].

**Figure 3.** (**a**) Windcatchers of the Pharaonic house of Neb-Amun, recreated by authors based on [14], (**b**) *Book of the Dead* showing a building with a wind tower at the lower right corner shown in the red square (about 1336–1294 BC) (modified by the authors, based on [13]).

A papyrus displaying the floor plan of a house constructed in the second century BC was one of the papyri found "in a former dump near Oxyrhynchus in Egypt" (modern el-Bahnasa) (Figure 4). By "extracting their volumes from the redrawing of the plan and the average height typical of the interiors' volume, the speed was 1.5–2 m/s, assuming that the chilly air inside was descending at that rate. This indicates that it takes about 4–5 s to completely refill the air. It is important to note that the presence of an atrium significantly increases internal comfort and improves efficiency [13].

**Figure 4.** (**a**) Ground plan and (**b**) section of a house found on a papyrus that dates back to the second century BC and is currently located in the Museum of Art and Archeology, Oxford (modified by the authors; adapted from [13]).

#### *2.2. Medieval and Ottoman Eras*

Windcatchers were prominent in Cairo during the Fatimid and Mamluk eras, from the 10th century to the 19th century. However, according to King, the origins of Medieval Cairo's windcatchers are unknown. They could have been introduced during the time of the new city's establishment in 969 AD or shortly afterward [12]. According to Hassan Fathy's book, *Architecture for the Poor* (1973), the old houses in Cairo relied on windcatchers for ventilation in the principal halls (*qa'as*) that caught the wind at a high elevation "where it is strong and clean". As shown in Figure 5, the hot air escaped through the high central part of the *durqa'a* (a small, covered court) [15].

**Figure 5.** Arrows showing the air movement in Qã'a of Muhib Al Din Ash-Shãf'i Al-Muwaqqi with a red box highlighting the location of the wind catcher (modified by the authors; adapted from [16]).

The primary typologies of buildings with windcatchers were mosques, *madrasas* (religious schools), and mausolea. However, relatively few windcatchers were observed after several were restored around 1900 AD [12]. According to David King [12], the medieval windcatcher in Cairo is the most overlooked historical Islamic architectural feature in the mainstream literature, but it was significantly used in Cairo (known then as Fustat) from the 10th to 19th centuries. During this time, most of the homes in Cairo were built with windcatchers on their roofs to drive the cool northern wind down to refresh the living quarters below [12]. Pages 125–128 of King's book show photographs dating back to the 19th century, depicting the presence of windcatchers all over the city [17].

The medieval windcatchers in Cairo were designed to capture the cool northern wind, as can be concluded from their unique shape. According to Williams (2008), a medieval windcatcher resembled the head of a stairway, the shape of which dates back to the Pharaonic era [18]. This distinguishing feature emerged beyond a flat roof, usually at a 30-degree angle. A simple medieval windcatcher consisted of a lightweight wooden rectangular awning that covered an opening in the ceiling of the room below. It was frequently connected with a vertical duct made of masonry or a light structure that directed the flow deep into the building's lowest floors. The opening into the room was either a horizontal opening through the ceiling or a vertical opening in one of the walls. The windcatcher successively supplied rooms on different levels, whereby the first openings of the column or duct were through vertical openings in the wall, and the last was opened through a horizontal opening in the ceiling [19,20]. Windcatchers could also be built into the windward façades of a building, which differ very little from simple windows [19].

Medieval writings do not mention the materials used to make Cairo windcatchers. The oldest surviving example of a medieval windcatcher (shown in Section 2.2.7, is on the roof of the Qã'a of Muhibb al-Din), which indicates that the windcatchers could have been made of stone, thereby enabling them to survive for centuries. However, according to 19th-century paintings, they were primarily made of wood or reed and were plastered on both sides and hence, had a short lifespan [10]. Nonetheless, there are still intact grilles on the ceilings of historical buildings, indicating that windcatchers were not only present but prevalent [12]. Furthermore, to filter dust from the air, windcatchers were protected with bay wood [21].

Moreover, Olivier Jaubert's observations [19] showed that using wooden shutters on the upper aperture at the roof level controlled airflow and the shutting of the windcatcher [12]. Jaubert further discussed systems for controlling and closing the windcatcher during the medieval period [19]. The devices could be a door leaf on an opening fitted in the wall, horizontal shutters placed on the opening in the ceiling or halfway up the duct, or windows and shutters made of wood and directly applied to the inlet of the windcatcher, which delimited the northern opening of the windcatcher [19].

The windcatchers ranged in size from small structures to immense structures taking up the entire top floor of the building on which they were installed (as seen in the House of Alfi Bey in Section 2.2.9 and Musafirkh ¯ ane Palace illustrated in Section ¯ 2.2.10) [12]. According to Ibn Yunus, a medieval astronomer, the rectangular base of the windcatcher is suggested to have dimensions of 10:5 1/2. For example, the windcatcher on the Musafirkh ¯ ane is ¯ approximately twice as wide as deep, as shown in Figure 6a. On the other hand, those recommended by Najm al-D¯ın al-Mis.r¯ı, another medieval astronomer, were approximately 4:1, as shown in Figure 6b [12]. The following sub-sections of this manuscript present several examples of Medieval Egyptian windcatchers in various building typologies.

**Figure 6.** (**a**) Plan showing the range of wind directions in Egypt, according to the medieval 14th-century encyclopedist al-Qalqashand¯ı, in relation to the orientation and shape of windcatchers defined by Ibn Yunus four centuries earlier. ( ¯ **b**) Plan showing the range of favorable wind directions in Egypt according to Najm al-D¯ın al-Mis.r¯ı (modified by the authors; adapted from [17]).

2.2.1. Christian Hermitages in the Desert of Esna (Upper Egypt), Fifth–Sixth Centuries

Hermitages consist of a courtyard and peripheral rooms dug into the desert ground. Previous surveys carried out on hermitages do not provide evidence for the use of windcatchers. However, ventilation methods were found in these hermitages. Ventilation ducts

were arranged to establish the necessary cross ventilation since the entire hermitage was dug into the ground, and the rooms had only one façade in the courtyard on the opposite side of which there was a ventilation duct. The reserves usually had a ventilation chimney (Figure 7). Doors open into the courtyard and were exposed to the wind.

Similarly, horizontal ducts were sometimes circular and flared like a funnel open to the outside of the courtyard (Figure 8). Reliable archaeological traces confirm that this duct was equipped with a wooden shutter closing system. The direction of the wind determined the relative position of the different parts of the hermitage [19,22].

**Figure 7.** Illustrative sections of a reserve ventilation chimney, the arrows signify the air flow (modified by the authors; adapted from [22]).

**Figure 8.** Airflow in a hermitage in the desert of Esna, which was built in the ground, the arrows signify the air flow (modified by the authors based on [22]).

2.2.2. Christian Hermitage (Building No. 45), the Kellia, Fifth–Seventh Centuries

The Kellia hermitage included a non-central courtyard and half-excavated rooms. The rooms were generally attached to the northwest corner and along the north wall on the long side, exposed to the prevailing wind. "Amphora necks" integrated into the masonry allowed air to circulate from one room to another. In the roof, two or more holes were present on the domes, depending on the room size. On the north side, the hole was surmounted by a small conch-shaped edicule designed to catch the wind, and on the leeward side, a simple or round opening allowed the air to escape (Figure 9) [19].

**Figure 9.** Christian hermitage (building no. 45), the Kellia, the arrows signify the air flow (modified by the authors; adapted from [19]).
