there is a useful confusion to clear up: quiet does not mean beige.
a quiet interior is one where the colours agree with each other. it can be burgundy, plum, blue or sage green and still be a room you can sit in for hours.
where the tiredness comes from
a room becomes tiring when too many things ask for attention at once. three strong colours, each on a different surface, each at the same intensity: the eye does not know where to go and rests nowhere.
the colour is not the problem. the missing hierarchy is.
how we build one
we pick one tone to lead the room and let it take the large surface: a sofa, a wall, a run of cabinetry. the other colours fall in behind it, in far smaller amounts, as accents.
a room with a blue sofa, a terracotta rug and everything else in warm, settled tones is a room with plenty of colour in it. but only one thing speaks loudly, and that is why it is quiet.
a design without emotion is only geometry.
texture does half the work
wool, raw wood, a plaster that is not perfectly smooth: all of these change how a colour reads without adding another colour. one shade across three different textures looks rich. the same shade on three glossy surfaces looks flat.
this is why we work material and colour together, never separately.
the test
we see a colour on the wall, in its own room, at the hour it is used. if after ten minutes you still want to look at it, it is right. if it starts to tire you, it is too strong for that surface, but it may be perfect on a smaller one.