Sorry, I forgot to reply to this. Thanks for the info! Sash windows aren’t the most common type in the UK unfortunately. The majority of windows open outwards from the top or side. If you live in a flat like I do, your windows also open outwards but only a few centimetres. I’m not sure it would be possible to create a temporary seal around the hose bit. I think the majority of UK homes will be dependent on fans and ceiling fans.