Sun Path Analyzer

Sun Path & Orientation in Indian Climates — A Working Reference

Building orientation — which way each room and each window faces — is the single decision with the largest long-term impact on an Indian home's thermal comfort and energy cost. A well-oriented Indian home stays 4-6°C cooler in summer than a poorly-oriented one of identical construction; the difference compounds across two decades of summer cooling load. Yet most Indian residential plots are bought without sun-orientation analysis, and the home is designed to fit the plot rather than orient to the climate. The sun-path analyser above is the diagnostic instrument that lets you check orientation before you commit.

India's Solar Context

India spans latitudes 8°N (Kanyakumari) to 37°N (Kashmir). The sun stays predominantly to the south of overhead for most of the year (becoming directly overhead between the Tropic of Cancer at 23.5°N and the Equator only on specific days near the summer solstice). Solar noon altitude in most Indian cities ranges from 70-80° in summer (June) to 35-50° in winter (December — lower in northern India). This means south-facing surfaces receive predictable, manageable solar exposure that can be shaded with proper chajja design. East and west surfaces face the most extreme problem — the sun is at 5-30° altitude in mornings and evenings, producing high glare and deep heat penetration into rooms.

Latitude is the variable that decides whether your shading strategy from north India translates to south India — or doesn't. The further north you are, the bigger the gap between the summer-solstice sun (almost overhead) and the winter-solstice sun (genuinely low). That gap is what makes a single horizontal chajja work at both extremes.

Window Orientation — A Working Set of Rules

• North — most universally useful in India. Diffuse soft daylight, no direct sun, ideal for bedrooms, study, kitchen, and any area requiring even illumination. Maximise glazing here.
• East — morning sun, useful for breakfast rooms and active spaces. Harsh in summer mornings (April-June); needs vertical louvres or deciduous tree planting for shading.
• South — most-discussed orientation. In northern India (Delhi, Punjab, UP), south-facing windows give usable winter sun (warming) and manageable summer sun with proper chajja. In southern India (Bengaluru, Chennai, Kerala) where summer is the dominant season, south-facing windows need deeper shading. Always plan with solstice diagrams.
• West — the most problematic orientation. Afternoon sun at low altitude penetrates deep into rooms and continues into the evening. Bedroom on west wall = poor sleep. Living room on west wall = afternoon heat gain that lingers. Minimise west-facing glazing; if unavoidable, use deep vertical louvres + horizontal chajja + double-glazing.

Chajja and Fin Design — The 0.4 × H Rule

For south-facing windows in India, a chajja depth of approximately 0.4 × window height blocks the summer sun (when it's high) while letting in the winter sun (when it's low). For a typical 1.5 m tall window, that's a 600 mm chajja. The exact depth depends on latitude and the specific solstice extremes — the sun-path analyser computes this precisely for your site.

For east and west windows, horizontal chajja alone is insufficient — the sun is at low altitude and a horizontal projection cannot block it. Vertical fins (louvres) at 30-60° angles are the standard solution, supplemented by chajja of about 0.6 × height. For thesis/design students working with parametric tools, the analyser's data feeds Grasshopper / Ladybug for refined optimisation.

Cross-References

• Passive Design Strategies for Indian Climate Zones — comprehensive climate-responsive design reference
• Cross-Ventilation in Indian Homes — wind + sun integration
• Natural Light Planning — daylight design
• Cross-Ventilation Analyzer — wind-flow tool

Disclaimer: The sun-path analyser uses the NOAA solar position algorithm with sub-arcminute accuracy for the time and location specified. Site-specific obstructions (trees, neighbouring buildings, terrain) are not modelled — verify shading on site before finalising design. This page is for informational purposes only.