This is a scene with a room 4m square (about 12 feet square for the metrically challenged) with a nice modern window in one wall (about 3m wide). The room was built using PICK because it has no textures applied, so is a literal blank (white) canvas.

The sun is behind the camera. If the sun is due south, the window faces due east. No direct light on the window at all.

This was with the single infinite set at 100% and the skydome (non HDR) set at an ambient level of 1.