I made a quick pass over it, just on the preview to give you an idea how you can improve it. [But perhaps you just want to leave it as is for now and come back to it in ~3 years. Redoing old work, you really realize how much you improved]
- the light in p192c comes more from the south than from above. (And I see now, I forgot that yellow thing on the roof). I also made the main roof darker, but since it's a different material, that was more of an intuitive choice than following rules - I just think it looks better.
- your shadows are a bit spongy, as if the sunlight was diffused on a cloudy day. I removed them and placed standard shadows instead.
- I also put the loading bay in shadows. I guess one could argue that there is artificial lighting, but shadows like that help to bring the shape out.
- outlines are not a bad thing. You started with vehicles, where there is not enough space for them, but on a large building, you can use them. Especially that little stairway with the door needs better readability.
- you can use anti-aliasing on outlines. Setting a pixel of darker color helps to reduce the 'stairway' effect. I did the same for the markings on the ground, same as on the road. (I was lazy and just used 50% opacity. It's usually better to use but one color for that, since that allows for easier changes later on)
- the ventilation system is clearly not pixeled and really blurry. Also, why would there be windows for fans?
I didn't show that, but you could have a drop shadow for the building, even if it's allready all the way on the right edge. To do that, place the shadow as a frontimage with offset. You can just use the standard shadow (in the same directory as the wastebins)
