Old windows lose a lot of heat in the winter and let warm air in during the summer.
Replacing them costs money, but you can improve insulation with simple solutions that reduce energy loss by 30-40%.
Checking for problems
Run your hand along the window frame and around the joints between the frame and the wall. If you feel a draft, you need insulation. Light a candle and hold it near the window. The flame will move if air is entering somewhere.
Check the condition of the glass as well. If you have single glazing, the losses are high even if the rest of the window is well sealed. Look at the rubber seals. If they are cracked, dry or missing, they need to be replaced.
Sealing gaps
Buy adhesive tape made of rubber or silicone from any DIY store. Clean the surface where you will stick the tape thoroughly, removing dust and grease with alcohol. Apply the tape to the fixed frame, where the sash closes. Press firmly so that it adheres evenly.
For larger spaces between the frame and the wall, use polyurethane foam or acrylic filler. Clean the joint of dust and old paint. Fill the space with foam, but don't overdo it as it expands a lot. Let it dry completely, then cut off the excess with a knife. Cover with acrylic filler which you smooth with a wet finger.
Improving glass insulation
