Circulation is not cooling.

Technically, parent says the issues was the temperature gradient, so this may have helped?

Normally, high precision measuring rooms have zero airflow, otherwise have a constant temperature in the room and on the piece is not possible.

Sorry, could you clarify? It seems like zero airflow would inhibit a constant temperature?

For example you putt those pieces like 24 hours (depends on thickness) before measuring in that room, the piece should have from it's core to the edges the same temperature.

Airflow inhibits a precise measurement, imagine you putt something in that room that changes the airflow just a bit, so more warm air from the ceiling hit's one side of the piece.

Always when you try to measure something, no outer energies should interfere (no temperature change and no force like airflow or even driving cars outside of the building), it could even be, that the airflow creates vibrations in the piece, like rolling cars do.

The issue is that the temperature in the room is non-uniform. The ceiling is 20 degrees hotter than the ground so over time the object will have the same distribution.

without HVAC wouldn't the temperature already change drastically throughout the day due to weather?

You'd need much more serious fans. And this method lacks any kind of real control. It would reduce the gradient though.