Sunlight Intensity: Measuring for Window Facing South

[TSN79]

A research center measures sunlight intensity every hour every day. The measuring device stands on flat ground and therefore measures light accordingly. The output is W/m^2. The problem is that I need to utilize this value for a vertical window on a wall facing south. How can I best do this?

 

[berkeman]

Take the value from the research center at noon as the baseline for the insolation. Then just do the math to integrate the amount of sunlight that makes it through the window at each time of the day (as the angle of the window to the normal insolation angle changes). Seems pretty straightforward...