Glass is widely used for its properties of transparency. It has been favoured by architects for the last two decades and used to deliver a distinct style of architecture. However, the conflicting performance requirements make the decision making on glass selection in building envelopes a complex process. This paper investigates the factors affecting the selection of glass used in building facade, and proposes a hierarchy of decision making to facilitate the information flow. This may provide an integrated and robust approach to reach an informed decision.