[Tomgs]

One other note it takes years for climate control facilities to have any effect. On good and mild planets I have seen them turn to Optimal after 6 to 10 years but unpleasatnt worlds in that time haven't even changed to mild. I am using a nature shrine in my current game (It has the same effects as the climate control and the Urban pacification center systemwide) I am 10 years into the game and none of my unpleasant worlds have gotten better at all.
Atmosphere modification facilities on the other hand work pretty fast 2-3 years. So conditions are probably on a 100 point scale since 30 points doesn't even change its state.
I believe conditions go Deadly, Harsh (only asteroids or planets damaged by events or war), Unpleasant (Why would a homeworld be unpleasant and other worlds in the galaxy have better conditions than your homeworld? Maybe pollution?), Mild, Good, and Optimal.