Draughts from channels in concrete slabs in loft space. Can they be filled in?

[des606]

Hello,

Bought a top floor apartment a year ago. Some serious draughts coming into loft space via these circular holes / channels in concrete slabs in the walls. Photos attached.

Can I go ahead and fill them in with concrete? The draughts are full blast at times.

Thanks

 

[JohnD]

You say "loft"

Is this part of the habitable living area?

 

[Why Not Indeed]

Lofts are usually supposed to be draughty, to keep the damp at bay.