Trickle vents are rubbish - I say that from having lived with them for 2 years. When they're new, they're great at stopping condensation at the top of the window, but the rest of the time they get clogged up with cobwebs and insects and then don't get rid of any moisture in the air. Cosmetically they can ruin a decent new frame.
Best form of ventilation in the kitchen and bathroom is a fan, elsewhere open/ajar windows when possible.
Best form of ventilation in the kitchen and bathroom is a fan, elsewhere open/ajar windows when possible.