Chris

First … do you have double glazing? That doesn’t eliminate the problem but it does reduce it (by preventing the house getting as cold, as quickly as it otherwise would).

Second … are there extractor fans in the kitchen and the bathroom, and do you use them? In the kitchen, in particular, if you boil a lot of stuff an extractor is useful. Note that many over-cooker hoods are installed so as to filter fats and odours only. They don’t extract air to the outside, even though they are designed to be able to do so with the necessary additional steps during installation.

Third, yes the temperature of your house does make a difference and if you’re living in a space but not heating it adequately then the relative humidity of the air in that space will rise. Air’s ability to absorb moisture is relative to its temperature. See if you have room in your budget to turn the heating up a bit. If the house is poorly insulated then running the heating for longer but not hotter might make for a better outcome.

Finally … we have persistent issues in our master bedroom because it’s downstairs, north facing, and has a party wall with a neighbour who doesn’t use the equivalent space, so doesn’t heat it. That all means the solid brick wall tends to get cold and there’s an ever present risk of moisture on the wall that can lead to mould - especially in the summer months when the house isn’t heated. Our solution is to run a dehumidifier in the bedroom. It’s not the cheapest option but it’s extremely effective. Provided you have the money to buy a sufficiently powerful one at the outset, you can bring the humidity level down below 50% in under a week or two and then keep it there easily using the machine’s humidistat. If you have a general problem rather than just confined to one room, a decent sized dehumidifier, placed centrally in your house, can deal with it.