Purpose of an air test on new house?

[conny]

Exactly what it says in the title.
Apparently, they do an 'air test' on new houses to check for 'leaks/draughts', etc.
Then they bang on about having adequate insulation to remove draughts but make sure their is plenty of ventilation to prevent mould/rot etc.
I find new homes stifling regarding air circulation, and if you open windows to let some fresh air in it becomes chilly quite quickly.
Someone once said that if it fails the air test, they have to trace it and fill the 'hole', which may even be where cables come into the back of a socket!
Can someone please explain what this is all about?

 

[George_engineer]

It's controlled vs uncontrolled ventilation.

Controlled ventilation takes wet air and allows fresh air in, where and when you want. You also have the option to do heat recovery.

Uncontrolled ventilation leads to drafts, condensation and hidden issues. Too much uncontrolled ventilation will make insulation ineffective.

The backbox example could lead to corrosion and damage to the cabling if there is air leakage in/out.