For decades, hobby greenhouses were constructed from an aluminum frame with glass as a glazing material. Most Juliana greenhouse models come with a 3 mm split glass as standard.
In recent years, glass has increasingly been replaced by polycarbonate insulation panels.
It is easy to understand why!
Polycarbonate sheets are constructed in 2 layers with embedded air channels and this construction provides many advantages over glass (10 mm poly are built in 3 layers).
Most professional growers use today polycarbonate instead of glass