Shawky Saifelnasr, Shady2020-02-252020-02-2502/12/2020https://t.ly/VZWLZThe main objective of this paper is to introduce a simple quick tool for architects represented by a design chart that determines the sizing of vertical windows for providing minimum or average amount of daylight as a function of the properties of the window, the room, and the surrounding environment. One of the most important purposes for introducing windows to a building envelope is providing adequate daylight suitable for the different uses within the different functional spaces. And daylighting might be one of the main reasons for the sizing of those windows. Different calculation methods could be used for daylight calculation and analysis; formula methods, graphical methods, scale models, and computer programs. Although formula methods are not the most accurate daylighting calculation method, they could be used as a rule of thumb especially within the preliminary stages of design. The proposed design charts are derived from formula methods to be used by architects as a simple quick tool that could be used for both design and analysis. They could be used within the design process by finding the sizing of vertical windows. Moreover, they could be used in the analysis of an existing case by finding the available daylight factor. The design charts are a combination of more than one graph to include most of the specifications of the window, the room, and the surrounding environment, to find the sizing of vertical windows, that would ensure the minimum or average amount of daylight for any city all over the world, within the low, middle, or high latitudes.en-USOctober University for university of Design chartsSizing windowsDaylightingArticle