In traditional buildings, different spaces were used at different times of the day based on comfort. Stepwells in Gujarat are among India’s outstanding architectural achievements. Though primarily made for water storage, they were also meeting places on hot summer afternoons. The water provided the cooling effect.
In winter when the wells were uncomfortably cool, people would rest in the open. In the rainy season they used the verandah.
Till recently in the north, people spent the hot summer days in the lower floors of the buildings but spent the nights on the cool roof-top. In winter, it was the reverse.
The image shows a section view of a stepwell with the various verandahs used during different times of the day during summer.
Source ( Text & Image): Vinod Gupta, “Indigenous Architecture & Natural Cooling”

Microclimate control was an important passive cooling technique. Landscaped vegetation, internal water bodies and fountains were used to create evaporative cooling.
The entire Red Fort in Delhi was surrounded by garden. In Mughal buildings, water channels passed through internal spaces of the building to modify internal environment. They were called Nahar-i-Bahisht (canal of paradise).
The image shows fountains and water canals at Fatehpur Sikri fort.
Source (Text & Image): Asif Ali, “Passive Cooling in Mughal Buildings”

Traditional cooling methods in India often used khus (grass roots) screens hung over windows or doors. When kept wet, these screens cooled the incoming air via evaporation. They cooled and also have a pleasant and natural fragrance. Since khus curtains rely on evaporative cooling, they work best in non humid environments and were more used in the drier north.
Khus seeds or khus syrup made from its roots are also used to cool the body.
In Red Fort Delhi, the emperor’s throne at the centre of ‘Diwan-e-Khas’ is surrounded by two sets of openings four meters apart from each other. These openings were covered with grass mats with sprinkled water during summers and heavy quilts were suspended during winters.
The image is a top view drawing of the Mughal throne in Delhi which used both water canals and khus curtains for cooling.
Source (Text & Image): Asif Ali, “Passive Cooling in Mughal Buildings”

Nalukettu (meaning four blocks) is a Kerala courtyard house while Nadumuttam is the courtyard.
‘Aangan’ or ‘Sehan’, a courtyard inside a house surrounded by rooms but open to the skies was a common feature in old houses. The courtyard prevents the internal spaces from solar radiations and hot-and-dusty winds. It is always shaded throughout the day. The heated floor of the courtyard raises the temperature of the air present in the courtyard. The hot air rises up and a fresh and cool breeze replaces the space (stack ventilation effect).
In many cases, the courtyard was lined by a verandah (a walkaway) which provided additional cooling effect, regulating the airflow. Research suggests that courtyards are the most effective passive cooling technique reducing natural heat by 25%.
The Wikimedia image by Soumyavn shows a Kerala house courtyard surrounded by verandah.
Source: Asif Ali, “Passive Cooling in Mughal Buildings”

Natural cooling is achieved by cutting off the sun’s radiations, reducing the
absorption both on windows and walls. Old buildings had deep and inclined sun shades which were very effective. Modern architecture also uses Brise Soleil (French for “sun breaker”), a series of horizontal or vertical aluminium blades on a building’s front that help to control the solar heat gain in a building.
The image shows the long chajjas at the Red Fort in Delhi.
Source (Text & Image): Asif Ali, “Passive Cooling in Mughal Buildings”

Jharokhas are the enclosed projected openings or balconies overhanging from the wall usually in the upper stories. A repetitive pattern of Jharokha covers the outer layer of the building façade. These added to aesthetic appearance and allowed privacy to ladies to watch the street below.
Their main use is to minimize area of building surface exposed to sun and form outer layer protecting from direct radiation. They channel cool air through the front façade of haveli which circulates inside the building and then escapes out through the courtyards taking out the hot air.
The image shows multiple jharokhas on a traditional Rajasthani haveli.
Source (Text & Image): Mohit Adwani & Vidya Singh, “Architecture before Air Conditioning in India”

Jharokhas and Jaalis together can reduce temperature by 4-9 degrees centigrade.
The orientation of Hawa Mahal is on the east-west axis in the direction of wind flow. The wind enters the palace from the west through open grounds and picks up moisture from the water body placed in the courtyard through convection currents. The moisture-laden wind then moves towards the 953 jaalis (lattice windows) mounted on jharokhas (balconies). This cools the air down via the Venturi effect – air flows through a constricted passage (jaalis in this case), increasing the wind velocity while dropping the pressure.
Hawa Mahal literally means ‘palace of wind’.
The Wikimedia image of Hawa Mahal is by Marcin Bialek.
Source: Hawa
Mahal: How India’s ‘palace of winds’ was ahead of its time | CNN

Wind towers or wind catchers are common in west Asia. We can see them in forts and havelis of Rajasthan. A wind tower projects above the terrace level of a building with openings on top towards the favorable prevailing winds. Its prime function is to induce air from above and transmit it inside the building. It works best when there are clear openings with no jaalis or vents.
Wind towers are the most effective passive cooling technique after courtyards, reducing temperature by 12-15 degrees centigrade.
The Wikimedia image of the town of Hyderabad in Sind in the 1800s shows individual houses having their own wind towers oriented in the direction of the wind.
Source (Text & Image): Mohit Adwani & Vidya Singh, “Architecture before Air Conditioning in India”

Mughal forts, used natural ventilation effectively. A small window on a huge wall, as we see in most of the Mughal buildings allows the wind to move inside the building with a greater force. Tapered windows with smaller section inside also increase the velocity of entering air. When the air with a greater velocity enters into a wider space, sudden expansion results in lowering down of interior temperature. The hot air rises up in a domed space and small vents near the ceiling allow hot air to escape.
The image shows the five storey Panchmahal at Fatehpur Sikri, diminishing from bottom to top, designed for Akbar’s wives to enjoy their summer evenings. The asymmetrical design ensures natural ventilation at lower levels. It is sometimes mistaken with a wind tower.
Source (Text & Image): Asif Ali, “Passive Cooling in Mughal Buildings”

The Kumbhalgarh fort near Chittor in Mewar is 36 km long at a height of 3600 ft above sea level. Its walls are 15 feet thick at places where 6 horses could stand side by side. In older buildings, walls were thick to ensure structural support in absence of steel. Thick stone or brick walls were more difficult to break or burn and provided natural insulation. They absorbed heat slowly during the day and released it at night keeping the interiors cool in summer and warm in winter.
Source (text & image) : Incredible India

Kath kuni is derived from two words ‘kashth or kath' for wood in Sanskrit and ‘kona' for corner. It is earthquake resilient and many traditional kath kuni structures have survived earthquakes. It has an alternate layering of wooden beams and stone without any cementing material. The walls are double-skinned. There is an air gap between two parallel wooden beams and it is filled with loose, small stone pieces. This insulates the structure, keeping it warm in cold weather and cool in summers. The air gaps also dissipate the seismic force during earthquakes preventing caving-in of the walls. The mix of texture of stone with wood creates interesting patterns on the walls.
Source (text & image) : Architectural Digest website

Chala architecture has shaped the cultural identity of Bengal. The word ‘Chala’ simply means ‘roof’. Over time the curved thatched roofs of humble huts became the prototype for the signature arched clay roofs of the terracotta temples of Bengal. The design was suited to the hot and humid monsoon climate of the region. The number of slopes of a roof created different styles - Ek-chala (one slope), Do-Chala (two slopes), Tin Chala (three slopes), Char chala (four slopes), At-Chala (eight slopes).
There are more complex structures as well. One Do-Chala is termed as ‘Ek Bangla’ and Jor-Bangla structure is a compilation of two ‘Bangla’s or two Do-chalas.
The image from West
Bengal Tourism shows the famous Jor Bangla temple of Bishnupur.
Source: Oaklores.com