Sustainability, minus the brochure
Most of what gets sold as sustainable building is equipment — panels, fittings, systems. Useful, but secondary. The decisions that determine what a house costs to run in coastal Odisha are made long before any of that is specified, and most of them are free at the point of design.
The climate here is specific: long hot months, high humidity for most of the year, and a monsoon that tests every detail. Design for that and comfort comes cheaply. Ignore it and you buy comfort back, every month, in electricity.
Orientation and shade: the two that pay for everything else
The west wall is where the heat comes in. Put the rooms that tolerate it — stairs, stores, utility, bathrooms — on that face, and keep bedrooms and living spaces on the cooler ones. Shade the openings that need shading, with overhangs or projections sized to the sun angle rather than drawn for looks.
Neither decision adds cost when taken during planning. Both are effectively impossible to add later, which is why they belong in the first week of design rather than in a discussion about air conditioners in the last.
Cross ventilation is a section problem, not a window problem
Air moves through a house when it has a way in and a separate way out. One window in a room is ventilation on paper only. Openings on two sides, and a path for hot air to leave high up — a stair that vents at the top, a high-level opening, a courtyard — will keep a house usable for weeks of the year when otherwise you would be running a machine.
In humid conditions moving air matters more than lower air temperature. It is also the difference between a house that smells fresh after the monsoon and one that does not.
Water, both directions
Building on a plot stops it absorbing rain, and that water goes somewhere. Plan where — into a soak pit or a recharge structure rather than onto the road or your neighbour's ground. Rainwater harvesting is inexpensive when built in with the plumbing and awkward to retrofit.
On the supply side, the boring choices matter most: efficient fittings, short hot-water runs so you are not flushing cold water down a drain every morning, and tank placement that does not need a pump running to fill it.
What to spend on, and in what order
If the budget is finite — and it always is — spend in this order. First, planning and orientation, which cost nothing. Second, shading and ventilation, which cost a little. Third, the building envelope: roof insulation, decent glazing where the sun is worst, light external colours. Fourth, efficient equipment. Last, generation.
Doing it in reverse — panels on a house that was never designed for the climate — is the most common and least effective way to spend a sustainability budget.