The scene is still a bit dark; increase its "dimming resulting intensity" values to about 1700.0. Then test render.
The scene now looks much brighter and balanced. Also, the burnt yellow rims around the sunlight's highlights are more apparent now. This phenomenon occurs mainly when the sunlight position is very low.
If desired, one can Increase the photometric light's length/width rectangle values, to diffuse the shadows further.
The next phase is to add portal lights close to the windows, to emulate diffused shadows from the skylight.
Select the front viewport. On the create command, open the photometric light set.
Click and drag the "mr sky portal" from the object type group to the front viewport, to create it. (Fig.11)
The next step is to place this "mr sky portal" light close to one of the windows (move+ rotate)and change some of its core parameters.
Prior to start selecting and moving lights, it's worth enabling the lights "selection filter" from the main toolbar, to facilitate light selections.
Move/rotate and place the "mr sky portal" close to the left window.
Increase its width/length dimensions to fit the window's size.
Since this "mr sky portal" is being created mainly to emulate the diffused shadows, decrease its multiplier value to about 0.5.
Also, change its filter color to match the skylight.
Enable the "use existing skylight" function to closely match the skylight color.
Change the shadow samples to 32, to reduce the noise/speckles caused by its shadows in the scene (note that the value of 32 will increase the rendering time slightly however, since the sky portal multiplier value is low, it may balance things).
"Copy instance" the "mr sky portal" from the left window, to the right window.
Finally, just copy and move the third and last "mr sky portal". Place it behind the front window and match its dimensions. The renders should now look much better. (Fig.12a and Fig.12b)
With most lights added it is now the appropriate time to add a nice environment image to the background.
A bitmap will be used in conjunction with the current environment's "mr physical sky" shader.
This shader is very good in capturing the true essence of the daylight position.
For example, if the daylight position is low, the "mr physical sky" will add the burnt yellow rim light around the bitmap pixels...which is a very distinctive of the sunset lighting condition.
Open the "material editor "(M) and the "environment and effects" dialog(8).
Drag and drop the "mr physical sky" toggle onto a slot in the "material editor" dialog.
Accept the "instance copy" method. (Fig.13)
Its parameters should load up.