Hello, thanks for trying our game :D.
Yes the building doesn't give itself shade... It's kinda like, if you are the tallest building, you still get the light.
And for the Distiller to works, it needs 12 Darkness.
Putting basic pillar in each 4 sides is not enough, because it's only gives 8 darkness, where each pillar only gives 2 darkness.
You need to upgrade the pillar, so each pillar gives 3 Darkness.