Hmm, my house during winter is usually between 18-20. If I keep the window vents closed (most UK houses have vents above the windows specifically for this reaso

Hmm, my house during winter is usually between 18-20. If I keep the window vents closed (most UK houses have vents above the windows specifically for this reason), I get a lot of condensation around the windows which gets mouldy. Leaving those vents open makes all the difference - no condensation, no mould. Also the house humidity seems to stay under 50% with the vents open.