The sash helps keep warmth with inert gas pumped into the air-tight space between two glasses.

According to Jo Jong Chol, section chief of the factory, the factory completed the modernly equipped production process in two months, along with the construction of buildings covering an area of several hundred square meters.

This streamlined process is capable of producing tens of thousands square meters of such sash per year, which will be used in constructing energy-saving, green buildings.