What is a curtain walls used for?

A curtain wall was built to keep out air and water, absorb sway caused by wind & seismic forces operating on the structure, endure wind loads, and maintain its own weight. Curtain walls can be designed as "systems," with the frame, reinforced cement, and weather resistant materials all working together. Aluminum extrusions, generally infilled with glass, have virtually replaced steel frames, providing an architecturally beautiful look with advantages such as daylighting. When employing considerable volumes of glass infill, however, the impacts of sunlight on visual performance and also solar heat in a house are much more difficult to control.