How Air Conditioning Changed Indian Architecture

For most of its history, Indian architecture was a cooling machine. The courtyard of a Gujarat haveli, the deep verandah of a colonial bungalow, the stone jaali of a Mughal tomb, the thick walls of a Rajasthani fort and the high ceilings of a Mumbai chawl were all answers to one question: how do people stay comfortable through long, hot summers and heavy, humid monsoons without any machine at all? The answers varied by region, but they were always built into the plan, the section and the walls of the building.

Air conditioning changed the question. Once a room could be cooled by a box on the wall, the building no longer had to do the work. Plans became deeper, ceilings dropped, windows became sealed sheets of glass, verandahs were enclosed to gain carpet area, and the facade of the typical Indian apartment block became a grid of outdoor units hung on brackets. Some of these changes were sensible responses to dense cities, noise and dust; others simply moved the heat outside, onto the street and into the electricity bill. Today India is one of the fastest-growing markets for room air conditioners in the world, and the way buildings are designed for cooling has become an energy question, a health question and a design question at once.

This article traces that story: the passive cooling devices Indian builders relied on for centuries, how the air conditioner arrived and spread, what it changed in plans, sections, facades and interiors, and where cooling design is heading now that codes, energy labels and climate change are pushing architects back towards ideas their predecessors already knew. It closes with practical rules for designing a home or office in which the AC is a helper rather than the whole strategy.

Before the machine: how Indian buildings kept cool

Traditional Indian buildings used four strategies, usually in combination: keep the sun off, let air move, store coolness in heavy materials, and add moisture to dry air. Which strategy dominated depended on the climate. In the hot-dry belt of Rajasthan, Kutch and central India, thick masonry walls, small openings, shaded courtyards and evaporative cooling were the main tools. In warm-humid coastal regions such as Kerala, Konkan and south Gujarat, where the air is already moist, the emphasis was on light construction, deep overhangs, raised plinths and as much cross-ventilation as possible, because moving air is the only thing that makes humid heat bearable.

The courtyard was the heart of the system in much of north and west India. In the pol houses of Ahmedabad and the havelis of Rajasthan and Gujarat, a small, deep courtyard is shaded for most of the day by the surrounding walls. At night it collects cooler air that settles into the rooms around it; by day, as the courtyard heats, it draws air through the house. Rooms opened onto the courtyard through doors and jaalis, and the street side was kept relatively closed for privacy, dust and sun. The same logic is still taught in architecture schools today as the stack effect and night flushing.

Inside, people used devices that look quaint now but were effective. The punkah — a large cloth fan hung from the ceiling and pulled by a rope — was a fixture of colonial-era offices and homes until electric ceiling fans replaced it in the early twentieth century. Khus tatti screens, woven from the fragrant roots of vetiver grass and kept wet, were hung in doorways and windows in hot-dry summers so that incoming air was cooled by evaporation and scented as it passed. Stepwells in Gujarat and Rajasthan, built around deep, shaded water, were noticeably cooler than the surrounding land and served as gathering places through the hottest months. Earthen pots, wet floors and terraces sprinkled with water at dusk all used the same physics: water absorbs a great deal of heat when it evaporates.

The machine arrives: air conditioning reaches India

Modern air conditioning is usually traced to 1902, when the American engineer Willis Carrier designed a system to control humidity in a printing plant in Brooklyn, New York. The first purpose was not human comfort but the stability of paper and ink. Comfort cooling followed in cinemas, department stores and offices in the United States over the following decades, and the small room air conditioner that sits in a window developed through the 1930s to the 1950s.

In India, air conditioning first appeared in the same kinds of buildings: cinemas, banks, hotels, some government and corporate offices, and the homes of the very wealthy. Indian manufacturing grew after independence; Voltas, set up in 1954 as a joint venture involving the Tata group, became one of the early household names in air-conditioning and refrigeration. For decades, though, an AC was a luxury. Imported units were expensive, electricity supply was unreliable, and the vast majority of homes relied on ceiling fans, and in the north, desert coolers.

The real turning point came after the economic liberalisation of the early 1990s. Prices of room air conditioners fell in real terms, consumer finance became common, and multinational and Indian brands competed for a rapidly growing middle class. The noisy window unit was gradually replaced through the 2000s and 2010s by the quieter wall-mounted split AC with a separate outdoor unit. At the same time, the new IT parks, malls and corporate towers of Gurugram, Bengaluru, Hyderabad, Pune and Mumbai were built as fully air-conditioned, sealed glass buildings modelled on international office towers. Within a generation, air conditioning moved from a luxury to an expectation in offices and an aspiration in homes.

Modernism's brief climatic moment

Interestingly, the first generation of Indian modern architecture was deeply climatic, precisely because air conditioning was not yet affordable. Le Corbusier's buildings in Chandigarh and Ahmedabad — including the Mill Owners' Association Building in Ahmedabad, completed in 1954 — used the brise-soleil, a deep concrete sun-breaker, to shade glass and walls while letting air through. Indian architects who followed developed this further. Charles Correa's Tube House in Ahmedabad, from the early 1960s, used a sloping section to drive hot air up and out by convection. B. V. Doshi's own studio, Sangath, in Ahmedabad (1980), half-sunk into the ground under vaults finished in broken china mosaic, used earth, shade and water to keep the interior cool. These buildings are now studied around the world as early examples of climate-responsive modernism — but in the 1990s and 2000s, many commercial developers abandoned their lessons for the sealed box.

Five things the air conditioner changed

Air conditioning did not change Indian architecture in one dramatic step. It changed it decision by decision, as developers, designers and owners realised that a building no longer needed to be shaped by heat if a machine could remove it. Five changes stand out.

1. Plans became deeper

A naturally ventilated room depends on windows, and cross-ventilation works well only up to a limited depth — rules of thumb used by designers suggest roughly five times the ceiling height for cross-ventilated plans and about two to two-and-a-half times for single-sided ventilation. Once cooling and fresh air could be supplied mechanically, offices and malls could be planned as deep floor plates with workstations, shops or cinemas far from any window. In housing the effect was smaller but real: flats became deeper and more compact, with more rooms opening onto internal passages rather than onto the outside.

2. Ceilings came down

High ceilings were a cooling device: hot air rises, and a 3.6 to 4.5 metre ceiling in a colonial bungalow or an old Mumbai building kept the hottest layer of air well above the occupants' heads. In an air-conditioned room, height is a cost, because every extra cubic metre of air must be cooled. The National Building Code of India 2016 reflects this logic: it sets a minimum habitable room height of 2.75 m, but allows 2.4 m for air-conditioned rooms. Most Indian apartment blocks now work with a floor-to-floor height of roughly 2.9 to 3.15 m and a clear height of about 2.7 to 2.9 m before any false ceiling.

3. Windows were sealed, and glass took over

In a naturally ventilated building, windows are designed for air first and view second: operable sashes, ventilators, louvres and shading. In an air-conditioned building, an opening window is a leak. Commercial architecture in the 1990s and 2000s moved to fixed, often fully glazed curtain walls — a look borrowed from cooler climates where glass makes sense because winter sun is welcome. In Indian sun, a west-facing glass wall can admit a very large heat load, and the result was buildings that needed more and more cooling to stay comfortable, with blinds permanently down to fight glare. The window-to-wall ratio, which for traditional Indian buildings was naturally modest, crept upwards until codes and energy simulations began pulling it back.

4. The verandah disappeared and the facade filled with boxes

In housing, the most visible change is outside. Verandahs and deep balconies, which once shaded the rooms behind them, were enclosed to add carpet area, and the facade became a flat surface of windows. Then each flat added an outdoor unit for every room, hung on angle-iron brackets, dripping condensate onto the balcony below and blowing hot air at the neighbour's window. In older buildings these boxes appeared one at a time, in random positions, and they are now a defining image of the Indian city. Newer projects plan AC ledges — dedicated shelves or recesses, often screened with louvres — so that units are serviceable, drained and hidden, but many still undersize them.

5. Interiors were rebuilt around ducts and pipes

Inside, air conditioning reshaped ceilings and walls. Cassette and ducted units need a ceiling void, so false ceilings became standard in offices, showrooms and increasingly in homes. Copper refrigerant pipes, drain lines and power points had to be planned before plastering; wall split units needed a clear wall above windows or doors. Heavy curtains and blinds were added to block sun that a chhajja would once have stopped. Interior design began to depend on early coordination with the HVAC contractor, and on decisions about AC positions being made before the furniture layout, not after.

The hidden costs of cheap cooling

The air conditioner solved an immediate problem for each room, but the way it was adopted created costs that fall on the city and on the owner. The most basic is physics: an AC does not destroy heat, it moves it. Every unit pumps the heat removed from a room, plus the energy used to run the compressor, out through its outdoor unit. In a dense neighbourhood of closely spaced towers, thousands of outdoor units discharge hot air into streets and narrow gaps between buildings, adding to the urban heat island effect that already keeps Indian cities warmer than the surrounding countryside, especially at night.

The second cost is electricity. Space cooling has become one of the largest and fastest-growing loads on Indian electricity grids during summer, and peak demand on hot evenings is driven heavily by ACs. The India Cooling Action Plan, released by the Ministry of Environment, Forest and Climate Change in 2019, identified cooling demand as a long-term national challenge and called for both more efficient equipment and better building design to reduce the need for cooling in the first place. For a household, the cost shows up as summer bills that can be several times winter bills.

The third cost is resilience. A building designed only for air conditioning becomes uncomfortable, sometimes dangerously so, when the power fails or the unit breaks down. Sealed rooms with no operable windows, west-facing glass and thin walls heat up quickly. Older buildings with thick walls, verandahs and cross-ventilation stayed habitable without any power at all. Designers increasingly talk about passive survivability — how a building performs during a power cut in a heatwave — as a design test in its own right.

The fourth cost is visual and social. Randomly placed outdoor units, sagging pipes and condensate stains damage facades and cause disputes between neighbours. Water dripping from units above onto balconies and pavements below is a common complaint in Indian housing societies. These are design failures that a few hundred millimetres of planned ledge and a drain pipe would have prevented.

Codes and labels catch up

For a long time Indian building regulation said little about cooling, beyond room heights and window areas for light and ventilation. That has changed over the last two decades. The Bureau of Energy Efficiency launched the Energy Conservation Building Code in 2007 and issued a revised version, ECBC 2017, for commercial buildings. It sets requirements for the thermal performance of walls, roofs and glazing, for shading, lighting power and the efficiency of HVAC systems, with compliance increasingly written into state and municipal rules. For homes, the BEE's Eco-Niwas Samhita sets out envelope guidance for residential buildings, aimed at reducing heat gain through walls, roofs and windows.

Equipment has changed too. BEE star labels, now mandatory for room air conditioners, allow buyers to compare efficiency, and the Indian Seasonal Energy Efficiency Ratio (ISEER) rates units over a typical Indian year rather than at a single test point. Since 2020, room air conditioners sold in India have been required to ship with a default temperature setting of 24 °C, a nudge away from the habit of setting the remote to 18 °C. The BEE has repeatedly advised that each degree higher on the thermostat saves a meaningful share of cooling energy — a commonly cited figure is about 6 per cent per degree. Refrigerants are changing as well: the older R-22 has been phased out of new equipment in favour of gases such as R-32, R-410A and, in some models, R-290, under India's commitments under the Montreal Protocol and its Kigali Amendment.

Comfort science has shifted in parallel. Older comfort standards assumed that people indoors want a narrow, fixed temperature. Research in India, including the India Model for Adaptive Comfort developed for Indian office buildings, found that people in naturally ventilated and mixed-mode buildings are comfortable across a wider range of temperatures, especially with fans and the ability to open windows. The National Building Code of India 2016, Part 11 on sustainability, recognises adaptive comfort and climate-responsive design. The practical consequence is that a well-designed building does not need to be cooled to 22 °C to be comfortable; 26 °C with good air movement is often enough.

Learning again: Indian architects and the return of climate

Even at the height of the sealed-box era, a strong line of Indian architects kept designing for climate. Laurie Baker's brick houses in Kerala used jaali walls, high roofs and courtyards to stay cool at very low cost. Institutional campuses in Ahmedabad and elsewhere used shaded corridors, courtyards and heavy walls. More recently, many architects working in India have built offices, schools and homes that use courtyards, shading screens, earth-air tunnels, evaporative cooling, radiant cooling in floors and ceilings, and careful orientation to reduce or replace mechanical cooling.

The idea that links these projects is passive first, active second. Instead of designing a building and then sizing the AC to cope with whatever heat it lets in, the designer first reduces the heat entering — through orientation, shading, insulation, reflective roofs and limited west glass — then provides air movement with fans and cross-ventilation, and only then adds mechanical cooling for the hours and rooms that still need it. A building designed this way may use a fraction of the cooling energy of a sealed glass box of the same size, and it remains usable during a power cut.

In homes, this approach is far from exotic. It means a shaded balcony instead of an enclosed one; a chhajja or vertical fin over every window that faces west; light-coloured or insulated roofs on top-floor flats; windows on two sides of the living room; ceiling fans in every room including the air-conditioned ones; and a planned position for every outdoor unit. In Surat and other hot-humid cities, where nights stay warm and sticky, air movement and dehumidification matter as much as temperature, and a well-ventilated plan with fans can reduce the hours when the AC is genuinely needed.

The future: mixed-mode buildings and cooling as design

The direction of travel is clear in codes, research and the work of better designers. Buildings will be expected to stay comfortable for much of the year without mechanical cooling, to use efficient equipment only when needed, and to handle heatwaves and power cuts without becoming unsafe. Several technologies support this shift: inverter compressors that run efficiently at part load; BLDC ceiling fans that use far less electricity than older fans; variable refrigerant flow and radiant systems in larger buildings; smart controls that switch off cooling when windows open; and envelope products such as insulated roof panels, high-performance glass and external shading systems.

Mixed-mode operation is the key idea. A mixed-mode room has operable windows, fans and shading, and an AC. In the cooler months and in the mornings and evenings, it runs on natural ventilation and fans. On the hottest afternoons and the stickiest monsoon nights, the windows close and the AC runs at a moderate setpoint, assisted by the fan. The building is designed so that both modes work well, rather than treating the window as a leak and the fan as obsolete.

Rules for an AC-ready home that does not depend on the AC

For a homeowner or developer planning a new home, the lessons of this history translate into a short set of design rules. None of them means giving up air conditioning; they mean designing so that the AC is used less, works better and does not damage the building or the street.

• Shade every window that receives afternoon sun — a 600–900 mm chhajja or vertical fins on west and south-west glass — before choosing curtains or AC size.
• Keep clear ceiling height at 2750 mm or more where possible, and keep false ceilings local rather than wall-to-wall, so the room still works with only a fan.
• Give the living room and master bedroom openings on two sides, or a high ventilator, so cross-ventilation is possible in cooler months.
• Fit a ceiling fan in every room, including AC rooms, and plan the AC so it blows along the ceiling rather than directly at a bed or sofa.
• Plan a dedicated ledge or recess for every outdoor unit with a drain, service access and a louvre screen at least 50 per cent open.
• Insulate or use a reflective finish on top-floor roofs; the roof is the largest heat source in a top-floor flat.
• Size ACs from a heat-load estimate, buy inverter units with a good star rating, and set them at 24–26 °C rather than the coldest setting.
• Keep at least one room in the home that stays usable during a power cut — shaded, cross-ventilated and with a battery-backed fan.

Frequently asked questions

How were Indian houses cooled before air conditioning?

By design and by simple devices. Houses used courtyards, verandahs, deep overhangs, jaalis, thick masonry walls and high ceilings with ventilators, combined with punkahs, later electric ceiling fans, wetted khus screens, earthen water pots and water bodies such as stepwells. The mix depended on whether the climate was hot-dry or warm-humid.

Why are ceilings lower in modern Indian flats?

Mainly because of cost and regulation. Lower floor-to-floor heights fit more floors within height limits and reduce structure, and an air-conditioned room needs less volume. NBC 2016 sets a minimum habitable height of 2.75 m, but allows 2.4 m for air-conditioned rooms. Most apartments work with a clear height of about 2.7–2.9 m.

Is it better to design a home for natural ventilation or for AC?

For most Indian climates, the best answer is both: a mixed-mode home with shaded, operable windows, cross-ventilation and fans for most of the year, and efficient ACs for the hottest weeks. Such a home uses less electricity and stays usable during power cuts, without sacrificing comfort on the worst days.

What temperature should an AC be set to in India?

Room ACs sold in India now ship with a 24 °C default, and the Bureau of Energy Efficiency recommends 24 °C or higher. With a ceiling fan running on low, 25–26 °C is comfortable for most people and uses noticeably less electricity than 20–22 °C.

Where should the outdoor unit of a split AC be placed?

On a ventilated ledge, terrace or balcony where it can discharge hot air into open space, with service access and a proper drain for condensate. Typical manufacturer guidance asks for a few hundred millimetres of clearance behind and around the unit; always follow the specific model's installation manual. Avoid closed ducts, narrow shafts and tight decorative screens.