I've got 2 velux windows, one in our dining area and the other in the bathroom.
They have never been opened in all the time we have lived in this house, so about 2 years.
The bathroom one is more important as its the only window in there.
But because they're so high up you can't get them open. Not even step ladders get you high enough.
There must be something out there that would open them or people sensible enough to not have them fitted that high to start with?