Five climates, one country
A detail that is correct in one Indian climate zone can be a defect in another. The zones are not a formality.
The National Building Code divides India into five climate zones — hot and dry, warm and humid, composite, temperate, and cold — on the basis of mean monthly maximum temperature and relative humidity. The classification is old, coarse, and far more useful than the attention it receives.
The same wall build-up cannot be right in Jaisalmer and in Kochi. It is routinely specified in both.
Zones differ not only in severity but in which phenomenon governs. Hot and dry is a solar problem with a night-cooling resource. Warm and humid is a moisture problem with no night-cooling resource. Composite is both, six months apart. Temperate is mild enough that the envelope can be simple. Cold is the only zone where the imported cold-climate playbook applies more or less as written.
Because the governing phenomenon changes, the order of design decisions changes with it — and a strategy is only transferable if the resource it depends on exists at the new location.
Our climate atlas exists to make that concrete: which zone, which governing phenomenon, which resource available, and therefore which decisions come first.