My gran (who I look after, but do not live with - she lives alone) is having an excessive build up of condensation inside her windows. I think it's because she is not putting her heating on, but the house is always warm when I get there in the evenings. I think she is only putting it on for half an hour before I get there so I don't go on about how cold it is. I've tried catching her unawares and the house was FREEZING. She gave me some excuse about how she'd been out all morning... (she can barely walk!) Now she's saying the windows must be faulty and she wants new ones installing. I think she's made an appointment with someone from the market, and I'm trying to persuade her to cancel as she will be sucked into a hard sell. The windows are old (about 20 years) but they are upvc double glazed and there is no fogging between the panes, just on the inside of the glass, which when I've been round with a drawer full of tea towels, is fine until the next day. Is this a under-heating issue, or knackered windows. I know a bit of condensation is to be expected, but this is pouring off the glass and pooling on the sill, and dripping down to the floor. It's not good.