Interior design is usually presented as work on appearance. That is a misreading. What an interior produces is invisible: it is measured in muscle tension, heart rate, quality of attention.
Four levers that act on the body
Light
The most powerful lever, and the most neglected. Daylight sets the circadian clock through retinal ganglion cells — independently of vision. A badly oriented room disrupts its occupant's sleep without them ever making the connection.
Colour temperature matters as much as intensity. Above 4000 K, light supports alertness. Below 2700 K, it permits release. The same living room at 3000 K in the evening and 5000 K in the morning is two different rooms.
Material
Noble materials — stone, solid wood, linen, wool, plaster — are not preferred for prestige but for behaviour. They absorb, regulate humidity, and age visibly. A surface that keeps the trace of time gives a room a depth no perfect finish achieves.
Touch precedes sight: we assess a material with the hand before judging it with the eye, and that assessment is very hard to fool.
Acoustics
An over-reverberant interior tires you without your knowing why. Reverberation time in a living room should sit around 0.4 to 0.6 seconds. Rugs, heavy curtains, full bookshelves and wall textiles bring it down — with no visible acoustic treatment.
The threshold
The passage from one room to another is what Japanese architecture works hardest and Western fit-out works least. A change of level, floor, width or illuminance is enough to change the state of whoever crosses it.
A successful interior is not a photogenic one. It is one you stay in for a long time without noticing, and leave rested.
Not everyone needs the same room
Spatial needs vary considerably between people and are fairly stable over time. Some need their back to a wall and a clear view; others seek envelopment and cope badly with large volumes. Some cannot hold a room without daylight; others settle into one willingly.
These differences are not preferences to be corrected: they follow individual sensory thresholds. A scheme that ignores them produces a room that is correct for everyone and right for nobody.
What your way of occupying a space reveals
RÉSONANCE measures exactly that. The chamber holds no instructions: twelve steles, a floor of water, light falling from the ceiling. The distance you keep, the zones you avoid, the time you give to shadow rather than clarity — all of it composes a spatial profile.
That profile then feeds recommendations of rooms, materials and objects derived not from a declared style but from an observed behaviour.