I'm in a rented flat, so not a lot I can do. Hooray for plastic film double glazing. And expanding foam to plug the huge holes in the kitchen wall left by a plumber 20 years ago.
There was an eBay seller doing cuts of transparent 2 and 3mm plastic for cheap a couple of years ago. I used them to build a seedling greenhouse but I reckon they’d be useful for double glazing, if glued or sticky taped onto the sill.
I'm in a rented flat, so not a lot I can do. Hooray for plastic film double glazing. And expanding foam to plug the huge holes in the kitchen wall left by a plumber 20 years ago.