The surface of Class I planets consists for more than 95% of ice. This makes them the ideal producer of water. Like Class M planets, they depend on energy.
Worker increase per cycle (3 hours) is a random value between 1.2% and 2.4% plus above-mentioned bonuses when upkeep is met.
If upkeep is not met workers leave.
When population is over 100,000, an overcrowding-effect takes place and growth will slow down with increasing population. For very big planets and starbases there may happen a worker-decrease, even if all upkeep is provided.