A unitized curtain wall system, also referred to as a panel system or a modular system is made up of panels consisting of glass, spandrels, and mullions that are prefabricated and delivered to the site. This system takes advantage of the speed and quality of prefabrication techniques.
The factory assembled panels reduce installation time in the field and require fewer skilled laborers on the job site, bringing costs down. The panels are typically at least one story in height, and are lifted to their location, where they are installed by workers.
There are several advantages to a unitized system over a stick built system. One large advantage is the speed of erection, as all the panels are pre-assembled prior to arrival on site. Quality is also easier to control due to the main assembly occurring in a carefully controlled factory environment. However, a project has to reach a certain economy of scale before these advantages become useful, therefore unitized systems are typically reserved for mid to high rise buildings with large areas of curtain wall.