INTRODUCTION:

• Represents the ventilation as a sustainable cooling system in Iranian architecture.
• To counter the harshly variable climates of the country, Iranians invented wind towers which still stand in various desert towns.
• Important elements in Iranian architecture, providing air-conditioning in hot, dry and humid climates for thousands of years.
• Rise not only on ordinary houses but also on top of water cisterns and mosques.

PROPERTIES:

• To introduce cool outside air, driven by positive wind pressure.
• The internal partition allows the low pressure on the lee side of the tower to suck air from inside the building.
• In order to provide occupants with comfort, they were built with a four-directional orientation to catch wind from all directions and guide it into the house.

Wind towers consist of four parts:

1. The body containing shafts
2. Air shelves which catch hot air and prevent it from entering the structure,
3. Flaps which redirect wind circulation,
4. A roof covering.

MECHANISM:

• Wind travels through the shafts on top of the tower to reach the interior of the building.
• The air flow inside the structure travels in two directions, up and down.
• The temperature difference between the interior and exterior of a building causes pressure variations which results in the creation of air currents.
• In cities where the wind blows only from one single direction, only one of the shafts operates to receive the breeze.

There are three types of wind towers:

• The most elementary type of wind tower was built over cellars and underground water tanks known as ab-anbar.
•  These cellars kept food refrigerated and also served as sitting rooms where people could remain cool on hot summer days
• In hot climate cities, one to six wind towers were used to cool the water.
• They prevented stagnant air and the formation of dew or humidity inside, resulting in pure, clean and cold water all year round.
• The second type transferred the flow into the basement where it hit damp walls and its humidity increased while its temperature decreased. The flow could be directed into other rooms using valves.
• The third type of wind tower was taller and mainly used in multi-roomed one-story buildings. A dome-roofed hall under the tower helped ventilation.
• Wind towers display the compatibility of human-built architectural forms with the environment and the ingenuity of Iranian engineers.
• Following the introduction of western architecture,  structures such as wind towers gradually became part of the past though many still remain in use.
• Modern architecture can make use of traditional Iranian methods to utilize air currents and evaporation in cooling and air-conditioning living quarters.

Burj al-Taqa – The Energy Tower Dubai, United Arab Emirates:

• Order Year: 2006-07
• Estimated Investment: £200m
• Height: 322m (1,056ft)
• Construction Start: 2008
• Design: Gerber Architeckten international

ENVIRONMENTAL CONCERNS:

• Dubai temperatures can reach 50°C, so the cylindrical shape of the building is designed to minimise exposure of the surface to the sun.
• All energy is generated from wind turbines and solar panels; the main 60m (197ft) roof-mounted turbine
•  The windows are protected from indirect sunlight elsewhere on the tower by a mineral coating, which also helps improve the effectiveness of the air conditioning.

DUBAI ENERGY TOWER CONSTRUCTION

• The tower is constructed from cutting-edge vacuum glazed glass, which will be mass- commercialized in 2008, to reduce heat absorption and maximize the available daylight.
• The central atrium and a five-perimeter atria contain transparent ducts that look like plastic cylinders running up through the ceiling on all levels of the building.
• A double-skin glass façade protects the Solar Shield and helps to clear stale air from the rooms.

Talking of air conditioning, the main system for cooling the air inside the tower uses a convection system which pulls in cold air at the ground level, and sucks it up out of the top of the tower. The air conditioning will use seawater, and underground cooling units lower the temperature inside to 18 degrees C / 64.4 degrees F. This building may be a technological beacon for environmentally friendly skyscrapers, but as a commenter on metaefficient points out, new building designs don’t do much to solve the inefficiency of older buildings in cities. Although that doesn’t mean we can’t imagine what it’d be like to work and live in a sea of glass and metal without feeling slightly bad about it.

“Such a building