Blender Eevee HDRI reflection makes the color surface of objects wrong I haven't been using Blender for a long time and keep coming back to some problems that give me headaches.
In this case I have the following parameters:

Render engine: Eevee
Integrated HDRI environment
My project is an apartment

Problem Eevee:
The underside of a surface takes on its color due to the reflection of the HDRI environment, that means my ceiling is not white, like the material properties, but olive green due to the reflection of the green background of my HDRI environment.
In my case, the underside of my floor is olive green which doesn't matter because I can't see the underside of the floor through the camera. The top of my floor has the right material property. So far so good. The problem is the ceiling, because the visible surface of the ceiling is not white, but olive green - see picture. 
At first I thought I had a problem with two-sided surfaces and I only had to assign &quot;flip normals&quot; to the surface in Blender / Editmode / Mesh / Normals and the problem would be solved, but it wasn't.
The problem is really strange, since the reflection on the floor could still be explained to me but not on the ceiling, which means that the reflection shines through other meshes.
Cycles:
If I change the render engine Eevee to Cycles everything is as it should be - see picture.
Solution:
Do I have to change something in the settings? Can you help me?
Thomas
Unlike Cycles, Eevee is not capable of global illumination. The objects in your scene are only lit by the hdri - which does not create shadows. This means that the ceiling is just going to reflect the grass, even though other objects are in the way.
Setting up realistic lighting in Eevee is a science in itself, but to fix the ceiling it should be enough to set up an irradiance volume to represent the bounced light in your room.
To do this, add an &quot;irradiance volume&quot; and scale it on the respective axis so it just encompasses the whole room. Then, under &quot;indirect lighting&quot; in the &quot;render&quot; tab hit &quot;bake indirect lighting&quot;. This will calculate the lighting conditions on each of the probes, which will then be used for reflections.

In the first picture you can see that the ceiling has the brown-ish look of my hdr. If i add an irradiance volume the room is properly lit, with the missing texture giving the light a pink hue.
But honestly, it takes quite some work to make lighting look realistic in eevee, especially if you want to use an hdri. I'd recommend using cycles for the final render and to check lighting, while limiting eevee for previews.