Vāstu śāstra prescribes how to orient and lay out buildings — part sound design, part disputed belief.
Vāstu texts specify orientation, proportion, light and the placement of rooms relative to the cardinal directions and a site 'energy' grid (vāstu-puruṣa-maṇḍala).
— Vāstu śāstra texts (e.g. Mānasāra, Mayamata)
Environmental/passive design — daylight, ventilation and orientation.
A popular claim that doesn't hold up — here's the honest story.
Some of Vāstu's rules encode genuinely sensible, climate-aware design: orienting buildings for daylight and prevailing breezes, placing kitchens and water thoughtfully, using courtyards for ventilation — principles that overlap with modern passive architecture in India's climate.
But Vāstu also makes strong, untestable claims — that specific directional placements bring wealth, health or misfortune via cosmic 'energy' — for which there's no scientific evidence, and which fuel a large commercial 'Vāstu correction' industry. Honest verdict: a tradition with a kernel of practical environmental wisdom wrapped in astrological/metaphysical rules that don't hold up to testing. Use the daylight-and-airflow parts; be skeptical of the fortune-by-direction parts.