- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 30 Aug 2017
A windcatcher, also known as a windtower, is an architectural element used for natural ventilation. Windcatchers are traditional in Persian architecture, as well as in Ancient Egypt, and can be found across the Middle East.
They generally take the form of small towers installed on top of buildings, although they can be found in several different shapes and structures. The towers draw air from outside into a building, providing natural ventilation in hot, arid and humid areas. Windcatchers were typically built facing away from the wind to try and prevent ingress of blown dust and sand.
Windcatchers are passive systems that require no energy for operation.
The direction of airflow at that specific location will determine the windcatcher design. Windcatchers can be one of the following:
If wind tends to blow from one side only, then it will be built with one downwind opening, without openings in any other directions.
These windcatchers tend to be more efficient for airflow circulation and have better performance. They serve two functions – to blow and suck air into a building.
These tend to be either four, six or eight-sided windcatchers, and are bigger and taller than the two types above. The exact height and structure of each opening depends upon the specific region’s climate.
This is the most technical form of windcatcher and achieves better performance than the other types.
The dimensions of a windcatcher depend on the following:
- The flow rate required for thermal comfort.
- Building dimensions.
- Materials used in the building (a windcatcher will tend to be built from the same material as the building on which it will be installed).
- The region’s typical wind weather conditions.
- Building security.
The following components comprise a typical windcatcher:
- Head: Includes a moving column opened and closed either manually or electronically. This helps prevent rainwater ingress.
- Column: Fixed in place and can be installed on a rooftop (flat or inclined) using bolts.
- Windows: Installed at the lower end of the column to control airflow.
- Wind vane: Can be installed to detect the wind direction.
Windcatchers can function in a number of different ways.
 Downward airflow
When using a windcatcher to try and cool the inside of a building, a tall, capped tower with a uni-directional opening. This ‘catches’ wind on one side and brings it down into the building via the tower. While the air is not cooled by the windcatcher itself, the rate of airflow provides a cooling effect.
 Upward airflow using wind
Windcatchers can may be used in combination with an underground canal, known as a qanat. The tower’s open side faces away from the prevailing wind, and when hot air is drawn down the tower into the qanat it is cooled by coming into contact with the earth and cold water. The building is cooled by this air that is then drawn back up through the windcatcher.
 Upward airflow
In environments that experience minimal wind, or where a qanat is impractical, a windcatcher can be used to function as a solar chimney which allows hot air to travel upwards and escape from the top of the building. In this way, large buildings – especially those constructed with thick adobe to provide good heat transmission resistance – can be kept at chilled temperatures during hot periods.
Water is sprayed uniformly on the surface of a column which is constructed of materials such as unglazed ceramic conduits stacked on top of one another. By doing so, the column is dampened, and the effect of evaporative cooling delivers cooler air to the inside of a building.
 Windcatcher with wetted surfaces
This is proposed for use in areas of typically low wind speeds. It works by using pads made from a series of straws or cellulose placed at the apertures on top of the windcatcher. Water is continually sprayed onto them, meaning that the air that flows through is evaporatively cooled. Due to its subsequent density increase, a downward circulation of air is achieved.
Some of the limitations of conventional and traditional windcatchers include:
- They can allow the ingress of small animals, birds or insects.
- The head of windcatchers is fixed and doesn’t rotate with air flow direction.
- In regions with very low wind speed they have limited application.
 Related articles on Designing Buildings Wiki
Featured articles and news
Matt Rhodes, Quiss Technology, explains how an increasing number are falling victim to sophisticated cyber-attacks.
Assembly drawings represent items that consist of more than one component and show how they fit together.
Is the water sector under too much pressure from the regulator?
Everything you need to know about acoustics in under 800 words.
Check out our list of the 90 most unusual buildings of all time.
The government is to set a personal consumption target to reduce water use.
BSRIA calls for more education to promote fuels that are fit to burn.
Michael Gove admits air pollution is making people ill and shortening lives.
BRE call for a clearer, focused drive for the delivery of sustainable, quality developments.
Proposals for a 140m high observation wheel next to the Tyne.
Consistently one of our most popular articles - so just how much do you know about BoQ's?