The moment I knew I had to take action was a freezing January morning in my Edinburgh flat. I woke up to find frost on the inside of my bedroom window and a puddle of condensation on the sill. I was wearing a hat indoors and still shivering. My gorgeous period windows were bleeding heat, and my gas bills were terrifying. I tried everything – thermal curtains, draught excluders, even that cling-film stuff you shrink with a hairdryer. Nothing made a real dent. Then a builder mate told me about Low E window film, and I found exactly what I needed at https://www.tintfit.com/shop/energy-saving-insulation. This film has a microscopically thin metallic coating that reflects heat back into the room in winter and blocks solar heat in summer. It's practically invisible once installed and can reduce heat loss through glass by up to 30%. Installation took me about half an hour per window with just soapy water and a squeegee. Now my flat stays warm without the heating constantly running, my energy bills have dropped noticeably, and I've even noticed less condensation on the glass. It's rent-friendly too – I can just peel it off when I move out. Such a simple solution, but it's transformed my winter.