Hawa Mahal Jaipur: The Science of a Wind Palace

Few buildings in India are as instantly recognisable as the Hawa Mahal. Its pink sandstone face, rising in five tiers of small latticed windows above one of Jaipur's busiest streets, appears on postcards, tourism posters and textbook covers. Most visitors photograph it from the street, many are surprised to find that it is barely more than a facade, and almost everyone repeats the same story: that its hundreds of windows keep it cool, like a natural air conditioner.

The story is half true, and the half that is true is far more useful than the myth. The Hawa Mahal does not cool air by some secret mechanism. What it does is combine several simple, well-understood principles — shade, a porous screen, a very shallow plan, openings on two sides and the natural rise of warm air — into one building. Each of those principles can be measured, explained and reused in a modern flat or bungalow in a hot Indian city. That is why the building matters to designers today, and why it deserves to be understood rather than only admired.

This article sets out the history of the palace, what is known about its form, and the physics of how its facade handles sun, air and privacy. It then separates the myths from the facts and translates the lessons into dimensions and details that work in contemporary Indian homes.

A palace built for a planned city

Jaipur was founded in 1727 by Maharaja Sawai Jai Singh II as a new capital, laid out with the help of the scholar and architect Vidyadhar Bhattacharya on a grid of large rectangular blocks crossed by broad, straight bazaar streets. It was one of the most deliberately planned cities of its time in India, and its wide streets were designed for commerce, processions and festivals. The City Palace sits at the heart of this grid, and the Hawa Mahal was built as an extension of the palace's women's quarters, the zenana, on the edge of the palace complex where it meets one of the main streets.

The Hawa Mahal was built in 1799 by Maharaja Sawai Pratap Singh, the grandson of the city's founder. Its design is commonly credited to Lal Chand Ustad. The purpose was social as much as architectural: the women of the royal household observed purdah and could not appear in public, yet the street below was the stage for festivals, processions and daily city life. The latticed windows allowed them to watch all of it without being seen. The name, which means Palace of Winds, reflects the breezes that pass through those openings.

Jaipur's walled city was painted in its famous terracotta pink in 1876, for the visit of the Prince of Wales, and the colour has been maintained by regulation since. In 2019 UNESCO inscribed the walled city of Jaipur on the World Heritage List, recognising its urban planning and architecture; the Jantar Mantar observatory nearby had been inscribed separately in 2010. The Hawa Mahal is today a protected monument open to visitors, entered from the rear through courtyards rather than through the famous street face.

What the building actually is

From the street, the Hawa Mahal appears to be a large palace. In reality, the upper floors are extremely shallow. The building rises as a tall screen — commonly described as resembling a crown — with the upper storeys only about one room thick. Behind the famous facade lie narrow chambers, passages and small balconies where the women could sit at the windows. The lower levels widen into courtyards connected to the rest of the palace. Instead of staircases, the upper floors are reached by ramps, a common feature of Rajput palaces that made movement easier for people in heavy, formal dress and allowed palanquins and attendants to move between levels.

The facade is made of small projecting windows called jharokhas, each with its own little roof, brackets and latticed screen. A jharokha is a balcony that has been enclosed: it projects from the wall, so a person sitting in it can look along the street as well as across it, while the screen keeps them hidden. Repeated hundreds of times and stacked in tiers, these jharokhas turn a flat wall into a deep, sculpted surface full of small shadows.

The science: five mechanisms working together

The comfort of the Hawa Mahal is best understood as five ordinary mechanisms acting together. None of them is unique to this building; what is remarkable is how completely the form exploits all of them at once.

1. Shade before everything

In a hot, dry climate like Jaipur's, where summer afternoons commonly exceed 40 °C, the first job of any building is to keep the sun off people and off thin surfaces. The jharokhas project from the wall, each with a small overhang, so the openings sit in their own shadow for much of the day. The latticed screens break whatever sun does strike them into small patches, reducing glare and heat gain. The orientation also helps: the street facade faces east, so it receives the gentler morning sun and falls into shade in the afternoon, when outdoor temperatures peak.

2. A porous facade instead of one big window

Instead of a few large windows, the facade has hundreds of small ones. This changes the way air and light arrive. A single large opening admits a single beam of sun and a single stream of air that sweeps one part of the room. Many small openings spread the same total open area over the whole face, so the light is diffuse and the air movement reaches more of the space. Each small opening also limits how much direct sun can enter at any moment.

Popular accounts often say that the small windows speed up the breeze through a Venturi effect. There is a grain of truth: when a given volume of air passes through a narrower opening it must move faster at that point, so a person sitting close to a small lattice opening feels a quicker jet of air on the skin, which feels cooler. But small openings do not create additional air. The total airflow through the facade is set by the total effective open area and by the pressure difference driving the air — the wind and the stack effect. The real benefit of many small openings is distribution, privacy and shade at the same time, not a multiplication of the wind.

3. A shallow plan that lets air cross

Air moves through a room when there is an opening on the windward side and an opening on a side at lower pressure. Ventilation guidance commonly uses a rule of thumb: single-sided ventilation is effective to a depth of about 2.5 times the ceiling height, while cross-ventilation, with openings on opposite sides, can work to a depth of about five times the ceiling height. The upper storeys of the Hawa Mahal, being roughly one room deep with openings towards both the street and the inner side, sit comfortably within those limits. Air entering through the lattice can pass straight through rather than stagnating in a deep interior.

4. Height and the stack effect

Warm air is lighter than cool air and rises. In a tall building with openings at different levels, warm air leaving through high openings draws replacement air in through lower ones. This is the stack effect, and its strength grows with the height between the openings and with the temperature difference between inside and outside. The Hawa Mahal's tall, stepped section, with openings all the way up, allows this process to continue even on still days when the wind drops.

5. Mass, lime and a dry climate

Thick sandstone and lime-plastered masonry absorb heat slowly during the day and release it slowly at night. In a hot-dry climate with large differences between day and night temperatures, this thermal mass evens out the extremes. Lime plaster is also vapour-permeable, so the walls do not trap moisture. The building is comfortable not because it produces cold air but because shade keeps the sun off, mass slows the heat, and moving air carries heat away from the skin.

How much air can it move? An illustrative calculation

The two natural drivers of ventilation — wind and stack effect — can be estimated with simplified formulae found in standard ventilation references such as the ASHRAE Handbook of Fundamentals and CIBSE guidance. The numbers below are illustrative, not measurements of the Hawa Mahal; they show the order of magnitude and how each factor matters. Wind-driven flow is roughly Q = Cd × A × v × √ΔCp, where Cd is a discharge coefficient (about 0.6 for a sharp-edged opening), A the effective open area, v the wind speed and ΔCp the difference in wind-pressure coefficients across the building. Stack-driven flow is roughly Q = Cd × A × √(2 g h ΔT ÷ T), where h is the height between openings, ΔT the inside–outside temperature difference and T the absolute indoor temperature.

Two lessons follow. First, height matters: quadrupling the stack height from 3 m to 12 m roughly doubles the airflow, because the flow grows with the square root of height. A multi-storey screen like the Hawa Mahal, or a double-height stairwell in a modern bungalow, keeps air moving on still evenings. Second, open area matters linearly: doubling the effective open area doubles the airflow. A screen that looks open but has a low openness ratio, or windows that are permanently shut behind curtains, gives far less ventilation than the facade suggests.

Myths and facts

Because the building is so famous, it attracts exaggeration. Separating the claims helps designers borrow what genuinely works.

Lessons for modern homes

A modern Indian flat cannot be a five-storey sandstone screen, but its principles transfer almost directly. In a bungalow, the most powerful lesson is the shallow, cross-ventilated plan with a tall void — a staircase or double-height space — acting as a stack. In flats, where the building envelope is fixed, the lessons move to balconies, west-facing windows and internal partitions.

The bay in Fig. 4 is the jharokha translated into a contemporary detail: a projecting box on the west face, with a jaali on its outer face and openable glass set back about 1000 mm, under a chhajja. The screen stops the low afternoon sun before it reaches the glass; the gap lets heated air rise out; the person inside can sit in the bay and look out while staying screened from the street. Smaller versions — a jaali fixed 150–600 mm outside the glass, as discussed in this blog's jaali article — work where projections are restricted.

The future: from monument to method

The ideas inside the Hawa Mahal are becoming more relevant, not less. As Indian cities warm and air-conditioning loads rise, the Energy Conservation Building Code and green-building rating systems such as GRIHA and IGBC reward exactly what this building does: shading glass, controlling solar heat gain, using daylight without glare and supporting natural ventilation. Designers now use computer simulation of daylight and airflow to tune the openness of screens and the depth of shading on each facade, and parametric tools can vary the size of openings across a facade — larger where views are wanted, smaller where afternoon sun is strongest. Aaditya Interior's view is that the right way to honour a building like the Hawa Mahal is not to copy its look but to repeat its method: begin with the sun and the wind, then design the screen.

Rules borrowed from the Palace of Winds

• Shade the glass from outside first — a chhajja, fins or a jaali — before choosing curtains or tinted film.
• Use many small openings rather than one large one where privacy and glare matter; aim for 25–40 % openness.
• Plan rooms shallow enough to ventilate: up to about 2.5 × ceiling height for one-sided rooms, about 5 × with cross-flow.
• Always give air a way out: a window or grille on the opposite side, or a high vent in a stair or void.
• Use height where you can — a double-height stair with openable high windows keeps air moving on still nights.
• Put the most open, glazed rooms away from the west, or screen the west face heavily.
• Prefer breathable, massive finishes such as lime plaster on exposed walls in hot-dry regions.
• Check bye-laws before adding projections, screens or bays to a facade, especially in housing societies.

Frequently asked questions

Why is the Hawa Mahal called the Palace of Winds?

Hawa means wind or air and mahal means palace. The name refers to the breezes that pass through its hundreds of small latticed windows, which made the narrow chambers behind the facade pleasant places to sit and watch the street.

How many windows does the Hawa Mahal have?

The figure usually cited is 953 small windows, or jharokhas, arranged across five storeys of the facade.

Who built the Hawa Mahal and when?

It was built in 1799 by Maharaja Sawai Pratap Singh of Jaipur, the grandson of the city's founder Sawai Jai Singh II. Its design is commonly credited to Lal Chand Ustad.

Does the Hawa Mahal really stay cool in summer?

It stays more comfortable than a solid-walled room with large unshaded windows would, because it is shaded, ventilated across a shallow plan and built of heavy masonry. It does not make the air colder than outside, so on the hottest afternoons it is still warm; the moving air and shade make that warmth more tolerable.

Can the Hawa Mahal idea be used in a flat?

Yes, in smaller ways: a jaali or screen on the balcony or in front of west-facing glass, a jaali partition inside, transfer grilles or high vents that let air cross the flat, and sheer curtains behind openable windows. External changes in a housing society usually need permission, so check the society rules and local bye-laws first.