Why do the windows still get condensation on them in the night ?
They are north facing ,whereas the southfacing ones get just half an inch at the bottom,even in the slept in bedrooms.
because your house is humid. When the air is warm and holding loads of moisture and meets a cool surface, it will condense even on double glazing. You have to make an effort to put less water vapour into the air. Ventilate more, don't dry clothes in the house, put lisd on saucepans, etc etc etc.