Traditional buildings laws were influenced by nature and climate. The structures seem to be tailor-made to provide maximum comfort even without the modern air conditioners or heating devises. See how it's done.

Hot air rises and cool air sinks - This creates a difference in pressure that makes air flow from high to low pressure areas. The two main forces that initiate pressure differences are wind force and thermal force or stack effect.

Bitter cold
One of the most intriguing house designs is an igloo - the icehouse that shelters Eskimos in perhaps the most hostile climate on Earth. The igloo is a squat round structure that reduces stack effect and conserves the heat that is built up inside. The most important feature for buildings in cold climates is to use the stratification of air inside the dwelling and the igloo fully exploits this. Inside the igloo hot air rises and the occupants live on a high self inside to take advantage of the warm air. The cold air sinks and is collected near the entrance, which is used, as a storehouse.

Hot Deserts
The same principle of air pressure is used in desert areas to keep buildings cool. In deserts where the maximum and minimum temperature variations are huge people have built houses ingeniously to beat the heat. While the igloos trap heat and reduce stack effect, the desert buildings use the stack effect to allow natural ventilation for structural cooling. The buildings here use convective cooling and are generally tall and have certain structural elements that enhance this natural principle.

Wind catchers and towers are one of the most effective features of natural cooling systems that are found in many regional houses in deserts. You will find them scattered throughout the hot and dry regions from Sind in Pakistan, Iran and Arabia to Egypt and Northern Africa. Windcatchers can be both single and multi directional. The multi directional ones have several openings to catch the slightest air movement. The single directional ones face the most favourable breeze as in Egypt or Sind, where they receive cool sea breeze. How does it work?

The house and the wind catchers work together to make a natural self-regulating thermostat based on the differences of air pressures. If the interior has cool, high-pressure air, this stops the warm, low-pressure air from entering the building. When the interior warms up the reverse happens - the cooler air form outside is sucked in.

The coolest one!
The old city of Jaisalmer in Rajasthan, combines many cooling techniques. The city planners had studied the solar orientation and wind patterns carefully when they designed the city.

Clusters - houses in Jaisalmer are planned in clusters, with narrow streets in-between. While today narrow streets are seen as an unavoidable inconvenience, they served some definite purpose in earlier times. They cut off the sunlight exposure of building walls and provide maximum shade.

Courtyards - most houses in this fort city have internal courtyards, which are considered to be the most appropriate design for hot regions. These open spaces enhance daylight availability and lowers the overall cooling load because lamps need not be lit for illumination. The buildings and the streets have a unique relationship here. In combination with the buildings the narrow streets and courtyards help in creating a microclimate in the city that ensures air movement and ventilation. The shade line of buildings is a very important factor in initiating differences in air pressure.

Water coolers
The science of evaporative cooling was much practiced. Buildings in many deserts regions use water in combination with the structural components to enhance ventilation.

Wind openings: In Oman the window openings have a porous water jar placed under a sunshade. When breeze passes through the jar it cools and displaces the hot air inside that escapes through ventilators placed high up in the walls.

Centre wells: many houses in Bikaner have small wells in the courtyards that are called tanka. These serve a dual purpose - people use the water for drinking and the water absorbs heat from the air creating differences in air pressure.

Towers and channels: in Iran people have built elaborate tunnel systems called qanats to extract groundwater. The tunnels are connected with the wind towers. Hot dry air enters the tower and is cooled as it flows along the water.

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