This study looked at how the size of windows affects the ideal amount of insulation needed in walls facing different directions in Elazığ, Turkey's climate. They calculated heating and cooling needs for walls with various levels of insulation and window sizes. Results showed that more window area means less insulation is best, leading to lower energy savings and longer payoff times. For south-facing walls, with different amounts of single or double glazing, the best insulation thickness varied based on window size. The study confirmed that window area, type, or direction affects how much energy is needed and the right amount of insulation to use.