The size of the window is a major cost factor, with larger windows requiring more material and being more challenging to install. The location of the window also matters, as windows on the second floor are naturally more dangerous and difficult to install. The quality of the glass (single-, double- or triple-glazed) is a huge cost factor as well, with more efficiency costing more. The functionality of the window is a minor cost factor, with openable windows costing more than fixed options.