The daylight was and still one of the most important means and could put human in touch with his environment and architecture.
The aim of this research is to determine the proper design of window's area which achieves suitable level of daylight in Architectural spaces of Baghdad city. This area of window relate to the change of interior and exterior design characteristic with addition to the suitable light level for users and their activities.
The research treats windows in the same way followed in methods of designing artificial lighting and determining power size of electric lamp.
Because it's difficult to compute all the variables relate to this subject manually, the research depends on the (Microsoft Excel Program) to solve all design and environmental variables relate to daylight. The results were caring in:
First: determining area of windows suitable to spaces, after supplying the values of designing variables and environmental variables including the lighting level suitable to space.
Second: estimate the average daylight level in the space, after supplying the values of designing variable and environmental variable including the area of windows.
The conclusions of this research relate to determine the suitable areas of windows in spaces according to their characteristics design, and the possibility to improve the performance efficient of daylight in architectural spaces..