In 1930, the American engineer C.D. Haven developed an insulating windowpane. It was patented in 1938 and became the registered brand “Thermopane” under the Libbey-Owens-Ford Glass Company in 1941.
The insulating pane contains two layers of glass held together by metal spacer bars that were lead-welded to the glass. The space between the two layers of glass was filled with dry air. The "thermopane" became very popular in the 1950s and '60s.