The first point to make is that high-quality double or triple-glazed windows installed after 2002 (with a FENSA certificate or stamp in the metal seal) should not require draught proofing. This is because the window installer complied with Building Regulations, used energy efficient products and was registered with the local council.
However, if your windows are older than this or you are not sure if the installation was FENSA approved, you may find issues with leaks and draughts in the gaps between the window and the frame, the caulk on the outside of the window frame, and the areas around any locks or catches. Just a small gap on each of your windows will add up to a significant amount of heat loss leading to costlier heating bills and increased carbon emissions.
To reduce heat loss, lower energy costs, prevent leaks, and stop dust or moisture getting into the home, you or a professional can take steps to draught proof the windows. Possible solutions include:
Silicone-based sealant or brush strips
Self-adhesive foam strips
Metal or plastic strips with brushes or wipers attached.