AbstractArchitectural design is the process of solving design problems until the final product emerges. Solving these problems altogether complicates this process. It is one of the most important stages of this complex process because decisions made at the early design stage affect the progressive process. The decisions made at this stage are especially important in educational buildings because they directly affect the learning performance and health of users. In this study, a fuzzy logic model enabling correct decisions by digitizing exact and partial information has been created to evaluate and classify the design efficiency of windows important for ensuring sufficient visual comfort in classrooms. Because it is close to human logic and perception in modeling, Mamdani-type fuzzy model was used. A primary school with 8 classrooms was designed by 30 architects for the operation of the created model. Window design efficiencies were obtained with data obtained from 240 classrooms in the primary schools designed. The developed model will provide information by using the windows of the classrooms at the early design stage. Learning this information prior to designing will help make more accurate and effective decisions after implementation, especially for irreversible results.