Conservation briefs often arrive as a number. Fifty lux. Sometimes lower. The number is necessary, but it is not a design. It says what the object can survive. It does not say how a person should enter the room, find a table, read a label, notice another visitor, or feel that the archive is open rather than hidden.
The useful work begins when the limit stops being an average and becomes a hierarchy. If the paper sits at forty lux, the wall behind it may need less. The shelf edge may need more contrast. The route to the desk may need vertical information rather than horizontal brightness. A room can feel legible without raising the most sensitive plane.
The mistake is to answer delicacy with gloom. Low light is not the same as reverence. Many archives become difficult because every surface is held down equally. The eye has nowhere to rest and no order to read.
Good conservation lighting is patient. It protects material by refusing waste. It gives light to decisions, hands, steps, labels, and faces. It leaves the rest alone.