If you create a building orient strongly along coordinate system in SketchUp and do daylight analysis, you'll get a correct illuminance map.

2 same windows produce the same picture. If you turn the building a little bit, the map will change dramatically:

To understand why it is, you can edit an illuminance map and turn it manually back to be parallel to SketchUp axes. The map is the same:

You can find the original model here Please clarify this.

Update (moved from answers)

Things getting interesting. Simple model which produces weird results for daylight :)

each spot is duplicated by its previous position (one hour ago). Any idea?