Air leakage can be defined as:
"The uncontrolled movement of air in to and out of a building or indeed an enclosure such as computer rooms, switch rooms, floor voids etc which is not for the specific and planned purpose of exhausting stale air or bringing in fresh air."
Building Testing Limited (BTL) have tested the air tightness of the Devar Corner Lock calcium sulphate core raised access floor system, as outlined here.