light_volume

Baked lamp light for a room: a box (centred on the object, world-aligned) whose still lamps (point_light baked true) are worked out once with real ray-traced shadows into a grid of light from every direction. Surfaces and characters inside read the grid instead of shading each of those lamps every frame, and those lamps need no shadow maps: a room of many lamps runs like a room of few. It follows its lamps' brightness while they change together (power on and off) and rebakes by itself when they, their pattern or the room's still geometry change. Size the box over everything its lamps light (alcoves and passages too): their light that gets out of it isn't drawn while it is in use. Moving lamps stay live; a baked lamp whose brightness changes on its own (a flicker, a script) becomes a flicker layer by itself, and flames can be baked (flame baked) the same way.

In scene text

light_volume { size (0, 1, 0)  cell 1  enabled true }

Add it in the Inspector (Add Component), in scene text as above, or ask your AI. Fields you leave out keep their defaults.

Fields 3