Condensation is due to a couple of things, damp environment, ie, a house with occupants living in it. That’s unavoidable really unless you all stop cooking and breathing. It’s also to do with the temperature difference between inside and outside.
If there is a lack of ventilation, condensation will be seen, open windows for more ventilation, as mad as that seems in winter.
If condensation is on the walls, chances are the due point is occurring at the wrong point in the wall, that’s bad news by the way because the due point needs to happen within the external skin of brickwork and not before. I can’t remember my Building Services stuff from college but it’s simple enough to calculate if you know the make up of the wall.