What happens to light (waves) when it falls into a room? For my project that includes to design an ideal window for studios and housing i need to know the science behind what happens to light that falls into a room. I know that the light rays, to some extent, get reflected and refracted by the window but what happens next? How is a room fully illuminated through daylighting. 
 A: Light will enter the room through the windows (without much loss) and then bounce (be reflected) off the walls and furniture.
The amount of light reflected is given by the LRV (Light Reflectance Value). LRV is measured from 100 (100% white reflecting everything) to 0 (100% black absorbing everything). White wall paint seems to have an LRV of about 65-70 meaning it reflects about $\frac 2 3$ of the light falling on it after the first reflection. Darker colours are less. If the finish is matt it will be reflected in all directions, more-or-less. A gloss surface will reflect more of the light in a single direction (like a mirror). If that light falls on another wall it will be reflected again, so potentially $\frac 4 9$ of the light can be reflected off the second surface. Eventually, after enough reflections, all of the light will be absorbed.
So you can see that the surface directly facing the window will receive the most light but other surfaces (as long as they are not completely obscured) will still get a significant amount of light. 
