Sun Path and Orientation for Indian Homes

Orientation is the one design decision that costs nothing and lasts for the life of the building. Two houses with the same plan, the same walls and the same windows can feel completely different in May if one has its bedrooms and glass facing west and the other has them facing north and south. Air-conditioning can hide a bad orientation, but only by running longer, and the electricity bill records the mistake every month for decades.

Yet orientation is often decided by accident in India. The road fixes the plot's facing; the builder repeats a plan that worked on another site; the family's Vastu concerns settle the main door; and nobody draws the sun. Common results are a glass-fronted living room facing the afternoon sun, a master bedroom on the west wall with a large window, and shallow chajjas that look neat on the elevation but shade nothing. Another common misconception is that the north side never gets sun — which is not true in Indian summers.

This guide explains how the sun actually moves over India, with numbers for Surat at about 21° N and for other cities from Chennai to Srinagar, and turns that geometry into orientation, room placement and shading rules. It complements this blog's east-versus-west-facing house article, which covers the Vastu perspective in detail; here the focus is the climate logic underneath.

How the sun moves over India

The Earth's axis is tilted by about 23.4° to the plane of its orbit, so the latitude at which the noon sun is directly overhead moves between the Tropic of Cancer (about 23.4° N) in late June and the Tropic of Capricorn (about 23.4° S) in late December. Mainland India stretches from about 8° N at its southern tip to well above 32° N in the north, and the Tropic of Cancer runs across the middle of the country, through eight states including Gujarat. That single fact explains much of India's solar behaviour.

Everywhere in India, the sun rises due east and sets due west at the two equinoxes, around 20–21 March and 22–23 September, and at noon it stands in the south at an altitude of 90° minus the latitude. In winter the sun rises south of east, stays lower and swings through the southern sky, so south-facing walls and windows receive long, low sunshine. In summer it rises north of east and sets north of west — by about 24–26° in most Indian cities and nearly 29° in Srinagar — so the north-east and north-west corners of a building receive early-morning and late-evening sun.

South of the Tropic of Cancer, something unusual happens. The noon sun passes directly overhead twice a year, and between those dates it is slightly to the north at noon. Surat, at about 21.2° N, has the sun overhead around late May and again around late July, and in June the noon sun is a little north of overhead. In Chennai or Bengaluru, at about 13° N, the overhead dates come in late April and mid-August, and through May, June and July the sun sits clearly in the northern half of the sky at noon. North-facing walls in southern India are therefore not permanently shaded at all — in summer they receive sun for much of the day.

The figures above are calculated from latitude and the sun's declination and rounded; day lengths are sunrise to sunset including the usual allowance for atmospheric refraction, to the nearest minute or so. They show two practical patterns. In the south, the winter sun is still high (about 53° at noon in Chennai), so there is little useful winter sun to welcome and shading is needed nearly all year. In the north, the December noon sun drops to under 40° in Delhi and about 32° in Srinagar, so south-facing glass becomes a welcome heater in winter — provided the summer sun is kept out.

Which facade gets the most heat

Heat gain through a wall or window depends on how directly the sun strikes it and for how many hours. The roof receives the most solar radiation of any surface in the Indian summer, which is why roof insulation, reflective coatings and shaded terraces matter so much on top floors. Among walls, the east and west facades receive the sun at low angles, almost perpendicular to the surface, for several hours each morning and afternoon. The west is worse than the east because its sun arrives in the afternoon, when the air is already at its hottest and the building has been absorbing heat all day; the heat stored in a west wall is then released into rooms through the evening, just when bedrooms are being used.

The south facade in most of India receives sun for many hours in winter but much less in summer, because the summer sun is high and, south of the Tropic, partly in the northern sky. A south wall with a correctly sized overhang is therefore one of the easiest facades to control: shaded in summer, sunlit in winter. The north facade receives the most even daylight and the least direct sun overall, but in summer it is hit by early-morning and late-afternoon sun from the north-east and north-west, and in southern India by midday summer sun as well.

Shading the south: the chajja rule

For a south-facing window, a simple rule sizes the horizontal overhang so that the window is fully shaded at noon at the equinoxes, and therefore for the whole of the hotter half of the year, while the lower winter sun still reaches into the room. The depth of the overhang, measured from the wall face, is the height from the window sill to the underside of the overhang multiplied by the tangent of the latitude. In Surat, at about 21° N, a window 1500 mm tall needs an overhang of about 580 mm — the same figure used in this blog's net-zero homes guide. In Delhi it is about 820 mm, and in Chennai about 350 mm.

The rule is a starting point, not a law. In warm-humid cities, where winter sun is pleasant for only a few weeks, designers often make the overhang deeper than the rule to buy shade in March, April and October, when the sun is lower than at midsummer but the air is already hot. Monsoon rain is another reason to deepen chajjas on the west coast. In the north, over-shading south glass throws away valuable winter warmth. A sun-path tool or energy simulation can test the choice for a specific window, but the rule gets most homes close.

The west problem: vertical shading and buffers

A horizontal chajja on a west window does very little. By late afternoon the sun is only 10–30° above the horizon, so it shines almost straight under any practical overhang. The west needs vertical elements — fins, screens, jaalis, louvres or shutters — that block low sun coming from the side, or deep verandahs and planting that keep the sun off the wall altogether. The simplest solution is planning: put rooms that do not need large windows or that are used little in the afternoon — staircases, toilets, stores, utility areas, wardrobes — on the west, so they act as a thermal buffer for the rooms behind them.

Shading devices are only half of the west strategy. The wall itself matters: a west wall of solid masonry stores heat and releases it for hours after sunset, so insulated or cavity walls, light-coloured exterior finishes and external shading of the wall surface — a creeper screen, a pergola, a verandah — all reduce the evening heat that bedrooms receive. Glass on the west should be as small as the view and ventilation allow, and where it must be large, a high-performance glass with a low solar heat gain coefficient, together with an external screen, is the combination that works.

Placing rooms by orientation

Orientation decides which rooms should go where. The classic climate-led arrangement for most of India puts the long axis of the house roughly east–west, so that the largest facades face north and south, which are the easiest to shade and the most useful for daylight. Living spaces and bedrooms then take the north and south faces, kitchens often sit on the east to use morning light and cooler afternoons, and service spaces form a buffer on the west. Plots rarely allow a perfect arrangement, but even a partial shift — moving a bedroom window from the west wall to the north wall — makes a measurable difference to comfort.

Climate logic and Vastu agree more often than they disagree, particularly about the value of the east and north-east for morning light and the need to deal with the heat of the south-west and west. Where they differ, Aaditya Interior's approach is to respect the family's priorities and solve the climate side with shading, buffers and insulation rather than ignoring either. This blog's Vastu articles treat those choices in more detail.

How traditional Indian buildings answered the sun

Long before sun-path software, Indian builders worked with the sun through experience. In Gujarat's walled cities, pol houses were built in tight rows along narrow lanes, so the houses shaded each other and the streets; each house had a small internal courtyard that drew light down and let hot air escape upward. In Rajasthan, thick masonry walls, small openings and jharokhas with jaalis kept interiors shaded and cool. In Kerala, wide eaves and verandahs protected walls and windows from both sun and monsoon rain, and in many parts of India the deep chajja over every window was simply part of the vocabulary.

Tools: from the diagram to simulation

Designers today have accurate tools for what traditional builders learned by trial. Sun-path diagrams for any latitude can be generated by free tools and by most architectural software, and three-dimensional models can show shadows at any hour on any date. Climate data files for Indian cities — prepared from long-term weather records — allow energy simulation that compares orientations, overhangs and glazing before construction begins. The Energy Conservation Building Code and green rating systems such as GRIHA and IGBC use such methods for larger buildings. For a home, even a simple shadow study of the plan at 9 am, noon and 4 pm on 21 March, 21 June and 22 December reveals most problems.

Fig. 4 shows the logic on one of the most common and most challenging plots: a long, narrow plot with its road on the west. The road side cannot be avoided, so it becomes the buffer: staircase, toilets, store and parking take the afternoon sun, protected further by a jaali screen. The habitable rooms open to the north and south side setbacks, with chajjas sized for the latitude, and a small court in the middle brings light and air into the centre of the plan. The kitchen sits at the east end, away from the road, where morning light is welcome and the afternoon is cooler.

Orientation in apartments, and where design is heading

Most urban Indians live in apartments where orientation has already been chosen by the builder. Even then, orientation guides decisions. When buying, a flat whose main living spaces face north or south, with the west face taken by the lift core or neighbouring flat, will usually be cooler than one with a west-facing living room and bedroom. When designing interiors, west windows can be given external screens or high-performance films and lined curtains; bedrooms facing west benefit from insulated wardrobe walls along the hot wall; and light colours on external balcony walls help.

The direction of travel is clear. As summers grow hotter and electricity use for cooling rises, codes and rating systems in India are paying more attention to envelope performance, and passive design — orientation, shading, insulation and ventilation — is being recognised as the cheapest form of cooling. Parametric facades with fins and screens tuned to each orientation are becoming common in commercial buildings and will filter down to homes, as the jaali once did. The basics in this guide will not change, because the sun's path will not.

Rules for orienting an Indian home

• Draw the sun on the plot before drawing the plan: mark sunrise and sunset directions for June, March and December.
• Keep the longest facades facing north and south wherever the plot allows; keep east and west faces short.
• Size south chajjas at about window height × tan(latitude), and extend them beyond the window edges.
• Use vertical fins, jaalis or screens on west and east windows — horizontal chajjas alone will not stop low sun.
• Place staircases, toilets, stores and utility areas on the west as heat buffers.
• Do not assume the north is shaded: in summer it gets morning and evening sun, and noon sun in southern India.
• Insulate and shade the roof first on top floors — it receives more sun than any wall.
• Keep west glass small, use high-performance glass where it must be large, and add external shading.
• Check every decision with a simple shadow study at 9 am, noon and 4 pm on the solstices and equinoxes.

Frequently asked questions

Which direction gets the most sun in India?

The roof receives the most sun. Among walls, the west receives the most troublesome heat, because low afternoon sun strikes it when the air is hottest. The south receives long sun in winter but much less in summer, and the east receives morning sun all year.

Does the north side of a house get sun in India?

Yes, in summer. From roughly April to August the sun rises north of east and sets north of west, so north walls get early-morning and late-evening sun. South of the Tropic of Cancer — including Surat, Mumbai, Chennai and Bengaluru — the noon sun is also slightly north for part of the summer.

Which is the best orientation for a house in a hot climate?

With the long axis running east–west, so that the main facades face north and south, and with short east and west faces protected by service rooms, shading and few windows. Combine this with roof insulation and cross-ventilation for the best results.

How deep should a chajja be?

For a south window, roughly the window height multiplied by the tangent of the latitude: about 580 mm for a 1500 mm window in Surat, 820 mm in Delhi and 350 mm in Chennai. In warm-humid and rainy cities, deeper chajjas are often worthwhile. West and east windows need vertical shading as well.

Is a west-facing house bad?

Not necessarily. A west-facing plot simply needs the road side treated as a buffer — services, screens, few windows and good shading — with the main rooms opened to the north and south. Designed well, a west-facing house can be as comfortable as any other.