23 June 2018

The Windcatchers of Persia

They appear throughout the Middle East: Iran, Afghanistan and Pakistan have these antique Persian designs dotted around their towns and cities. They are windcatchers, known in the area as Bâdgir. Serving as ventilation systems they have given the people of the Middle East air conditioning for thousands of years. Yet despite their antediluvian origin, windcatchers may even provide a solution for some very modern architectural problems.

Windcatchers come in a vast array of sizes and a number of different styles. They function in one of three ways. Some direct the airflow downwards and use direct wind entry. Others direct airflow up either using a temperature gradient assisted either by the sun or the wind.

The earliest settlers in the Middle East, once towns were created, had a problem. The insides of their homes would become swelteringly hot as the day progressed, making life uncomfortable for the occupants. It also meant that the shelf life of perishable goods was short – they may just as well have been placed in the direct heat of the sun.

The windcatcher was the solution.  When fed down in to courtyards and domes it acts as an all in one ventilation and heat management system. A capped tower with an open side facing the wind simply and effectively brings down cooling drafts in to the heart of the structure below.

The air caught in the windcatchers (also known as wind chimneys) and then circulated down into the bigger area is not cooled, as you might expect. What happens is that the circulation gives the feeling of the air being chilled. As the air moves it increases an evaporative cooling effect.

They are certainly effective, so much so that they have been used to refrigerate and can store water or goods at temperatures near freezing even during the hottest months of the year. In central and eastern Iran the atmosphere is extremely dry, with extremes of temperature throughout the day and icy at night. Windcatchers assist in the moderation of this climate in both homes and storage areas

Some associate the windcatcher with mosques - perhaps connecting them in some way to the minarets. Yet although the they add to the overall aesthetics the windcatchers are there for a more earthly reason.

Often the windcatcher will lead down to a reservoir. However, in public buildings their lower interior can often be exquisitely architectured and designed. There is sometimes a small pool of water at the center of its base, with corridors leading off in many directions.

The corridors will often have holes at the top, to encourage the warm air to rise and leave the building. As such the coolness is maximized and will also help to create the almost idyllic courtyards redolent of much Persian architecture.

Windcatchers do not come as one size fits all. They can have a single aperture if the wind only blows in one direction and can come four sided if the wind is multi-directional. They are even known to come eight sided to maximize the collection of the cooling power of the wind.

Sometimes the windcatchers are built over running water. In this way they pull up the cold air in to buildings. Yet even those which are built to catch the wind from their high towers are not useless when there is no wind. When this is the case they act as a funnel and pull the hot air up from below and outside through their vents.

It is little surprise that this ancient and ingenious technology is the subject of some serious research. Many modern architects are now looking at them in order to supply environmentally friendly answers to the problem of heat distribution.

From Utah (the Zion National Park Visitor Center, above top) to the Kensington Oval in Barbados, this ancient technology has been utilized to catch wind and to help regulate temperature – although nowadays the structures are built from aluminum. Yet the examples found in the Middle East remain the most aesthetically pleasing, without a doubt.

First Image Credit Flickr User Erwin Bolwidt