energy-efficient integrated glazing units (IGU) feature double or triple panes glasses, warm-edge spacers, argon gas fill, Low-E coatings, and fully tempered glass, greatly improve the energy efficiency of the entire door. They can not only create a comfortable and natural indoor environment but also save electricity bills and heating bills around 300~500USD per year according to your whole building’s fenestration areas. That’s a real bargain compared to choosing a regular glazing set