A person becomes 1 ^{(enter +1, exit -1)}

The significance of this abstraction lies not only in what it excludes, but in what the resulting number is authorised to do. Once bodies have become units, their accumulation can determine whether a room is considered sufficiently occupied, overcrowded or unsafe. A numerical threshold can affect access, circulation, architectural requirements and permissible behaviour.

In Breathing Room, ten performs a similar operation. Ten is not the answer to how many people belong in 12m². It is the point at which this particular system has been instructed to respond. The distinction matters because it relocates authority. The sensor does not discover that ten people constitute a meaningful threshold. The number acquires significance because somebody has selected it, encoded it and attached a consequence to it.

I decided what the sensor should notice. I decided that an interrupted beam could stand for a person crossing a boundary. I decided that a person could become +1. I decided that ten of those ones should trigger a response. And I decided what that response should be. By the time somebody enters Breathing Room, much of what the room appears to “decide” has already been decided.

Franklin calls these kinds of arrangements “prescriptive technologies”. Their rules are established in advance, allowing a process to unfold predictably. She describes them, politically, as “designs for compliance.” That does not necessarily make prescription wrong. A fire-safety rule needs to work before a fire begins. A sensor needs some way of distinguishing one event from another. A computational system cannot respond without rules. The problem is how easily those rules can disappear into the behaviour of the system.