In article ,
John Rumm writes:
Possibly out of date, but I did check with our BCO when I did our loft
conversion, and he would have been happy with the two position lock
instead of the trickle vent...

Yes, 9 years ago when mine were done, trickle vents were required on
any windows which couldn't be locked in crack-open position (which
would only have been patio doors, except I didn't have any;-)

Trickle vents can be closed when you don't want the ventilation.

--
Andrew Gabriel
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