Be careful, there's a reason cavities have air bricks! In my rentals if the carpets don't lift in a strong wind I am concerned, static air breeds damp. It's in the tenancy agreements that no air bricks or inbuilt ventilation panels are to be blocked or restricted.
Houses with chimneys had a natural throughput of air, block them up at top or bottom and the place soon becomes damp without dehumidifying, which of course comes at its own considerably purchase and running costs.
Seal the place up like a drum, as desirable as it may initially appear, is just asking for damp and sky high humidity levels, with associated harm to the building structure and people's health