Optimal conditions

AFAIK, optimal is the best, theres no improving on it. All I really know it affects is population reproduction though.

Assuming that SEV implemented it the same way as SEIV did, Conditions are defined internally as a numerical value. The labels shown represent a range for that value, and "Optimal" is the top segment of the range. So, yes, there are "degrees" of Optimal, but without knowing the exact formula for detemining growth rate, I couldn't say whether the climate control facility would make a significant difference.

"Good morning, Pooh Bear," said Eeyore gloomily. "If it /is/ a good morning," he said. "Which I doubt," said he.

You get a message at the beginning of the turn when a facility is unable to improve any further. At that point I remove the facility and add something else in its place.