STBA and Aereco have been working together on a Whole House Retrofit project in S Wales. Key tip about location of the trickle vents is:
Only install trickle vents in ‘wet rooms’ – kitchen, bathroom, utility, toilet.
Otherwise this creates a short circuit for air being drawn in from outside just to be immediately drawn out again by the extractor.
So specific trickle vents for ‘occupied rooms’ and also think about whether they need to be humidity controlled and / or noise reductions options.