Retrofitting trickle vents in PVC double glazed window unit

[google]

Has anyone any experience in this area?

I've recently moved into a new house which is double glazed, but none of the units have trickle vents (they're were installed a while back before it became a standard fitting). Found a few patches of mold on some of the walls, and part of the problem may be a lack of ventilation.

I was wondering how easy it would be to retrofit some trickle vents onto some of the windows?

[Owain]

I wouldn't. They let draughts in. Have a google for 'passive stack ventilation'

Owain

[Mathew Newton]

Can they not be locked open in a slightly-ajar position?

Mathew