: Their windows feature five insulating chambers that prevent thermal bridging—a process where heat flows through poor insulators.
: Lower is better. A lower number means the window is a better insulator and keeps more heat inside during winter and outside during summer. Eurocraft Energy Efficiency Features Eurocraft Windows U Rating
: Frames and sashes are fusion-welded to prevent gaps or splits that could lead to air leakage. Choosing the Right Rating for Your Climate : Their windows feature five insulating chambers that
: Use of Kommerling uPVC extruded profiles, which are designed for high insulation and durability against streaking or chalking. Eurocraft Windows U Rating
Your target U-rating should depend on your local weather patterns: Guide to Energy-Efficient Windows