Posted By: WillInAberdeenFortunately the foggy air isn't any wetter than normal, just colder, so it isn't bringing any extra moisture into the indoors.

Oh I see. Thanks for that tidbit!

It is easily evaporated by warming up the air again by a few degrees above sea temperature, so once it's at indoor temperatures it doesn't make things damp. Is this what you are finding, or is it different that far south

Yes except we don't have any heating, haha. Except for a portable radiator. We haven't quite decided on best approach to heating yet. I want to see how this winter goes with the new windows.

This issue with the fog would be eliminated with whole house with heat recovery. Hmmm.

Smoke filters use a combination of a HEPA filter and activated carbon filter. I doubt you'll find one as a trickle vent but who knows?

Posted By: ShevekAbout 40-50 quid each I think.

So £100 a year if you replace them every six months as they say. The Urbino Select looks to have an activated carbon layer, which is what you need for odour removal. Performance isn't HEPA but not too bad. Remarkable for such a thin filter.