The heritage of wind

by Josep Grau-Bove

Designing with wind

The city of Hyderabad, close to the mouth of the river Indus, was once known to travelers by a very poetic name: ‘manghan jo shaharu’, which in the local Sindh language means “the city of wind catchers”. It had the most peculiar skyline: thousands of chimneys emerged from the roofs of the buildings, like organ pipes, with their large openings facing south. The few pictures that can be found in google show a dreamy view, like something Marco Polo might have seen in his travels.

Each building, in fact each room, from palaces to the humblest house, had a wind catcher, or mangh. Their function was to capture the cold wind that blew from the sea, and to avoid the hot winds from the desert north of the city. Judging from what I could find online, none of these structures remains today. I ignore the factors that led to their disappearance and how fast it happened, I can only speculate that the reasons were socioeconomic, and that the disappearance of this heritage might have occurred during the 20th century.

Today we can only guess how they operated, how high were the air exchange rates, and which flow patterns they induced indoors. Only simulations can give us an idea of how this air flow might have looked like, and indeed, I managed to find some simulations (of which I unfortunately don’t know the author, the source is another blog post).

This little simulation is our only window to this bit of ancient design. Looking at the low-resolution arrows of the diagrams, I can’t help thinking that these flow patterns, this tiny air recirculation, was designed by someone. This lost pattern of air movement was an object of human design, albeit an object made of wind and not rock or stone.

In fact, if we consider a canal, a pond or a lake in an English-style garden to be heritage, why not a pattern made of air movement? Air has a density, and a viscosity, it can be felt, and if not seen, it can be at least heard, and perceived.

In warm climates, many cultures designed devices similar to the manghs of Hyderabad. Windcatchers are known as badgir in Persian, and malqaf in Arabic. They exist in many forms, and have had different roles in the traditional architecture of many regions. Even the romans might have used them, according to some of remaining depictions in mural paintings. And some of them, such as this Egyptian malqaf from Cairo, have even been explored using CFD (Computational Fluid Dynamics).

Figure taken from Aini et. Al. J. Basic. Appl. Sci. Res., 2(3)2405-2410, 2012

Figure taken from Aini et. Al. J. Basic. Appl. Sci. Res., 2(3)2405-2410, 2012

Designed by wind

The heritage of air motion is present in all the scales of human design, we have interacted with it over metres and kilometres, over hours and centuries.

The heritage of wind has another unique property: the wind direction has never changed, and it’s not going to change much. Most predictions of climate change predict moderate or zero changes in wind direction. The structures that shape wind may fade away, and the wind patterns designed by humans be lost, but wind will remain more or less constant as long as there is sun, air, oceans and the continents are in the same position.

That means that wind has its ruins, it’s old and long-abandoned roads. When the Portuguese and Castillian ships ruled the seas, during the Age of Discovery, ships returning from the West African coast used to perform a navigational technique called “Vuelta del mar” or “Turn of the sea”. They did the following: instead than sailing to the north, directly back to the Iberian Peninsula, they sailed westwards towards America. This might have seemed like suicide to some, but in fact it was a faster route: after some days, the ships were taken by the great permanent wind wheel, the North Atlantic Gyre, which returned them to southern Europe.

Source: Wikimedia

Source: Wikimedia

This is a clear example of wind acting as a defining factor of human activities. The wind pattern of the North Atlantic Gyre had a direct translation into social and economic structures, but also into ink lines in old maps.

It seems clear that as much as we can shape wind, wind can shape us. But, in the end, isn’t that true for iron, stone, paper? Can’t we say that iron tools have shaped humans as much as we shaped the tools? Perhaps, quite simply, we should say: heritage shapes us, as much as we shape heritage.

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