How to stop floor material colour on walls and ceilings

[FONT=open sans]Whenever I use directional light to simulate a sun light falling on a room, the colour of the floor material is then projected on to the walls and ceiling as in the screenshot below. In the first picture , the wall is white but is turned into a mild yellow.

[FONT=open sans]However, in one of the projects on youtube, I saw that this was not the case as in the second picture.

Even though the floor is of similar colour to my scene above, the walls and ceiling stay white.

How do I achieve this effect? What settings in lighting, floor and ceiling materials should I change so that the walls and ceiling do not change into the colour of the floor when a directional light hits the floor? Thanks.

Try posting your settings for the floor and walls, and the directional light & skylight. It helps in honing in on the problem.

In the floor material, add a GI REPLACE node and the StaticInDIrect input, slot in a white colour