Keeping walls clean

We have a little bit problem with moisture in our house. Victorian houses are not famous for their "insulation". Our walls are solid and very cold and together with cooking, washing and just breathing we have too much of the moisture in the house. We have dehumidifier and it helps and also I open regularly windows for a few minutes every day but sometimes it isn't enough and we get this on our walls.

Yep, that is tiny mould spots on our coldest (north) wall. I check for it every week. After a year I know where to look for it.
As prevention I have painted walls behind furniture with bathroom paint and it keeps it mould free, but we can't paint it everywhere (paint has sheen) which will not look good in the bedrooms.

So I just keep cleaning it with bleach. It will kill it and also wall is nice and white again after application. Of course I keep window open so we don't breath it.

After bleach dry up I spray it also with mould killer so it will stay clean for a while.