These buildings appear in The Arks Scenario.
The Seedling Ark is a repository containing seeds of all known plants before the New Ice Age. Should the Ark’s life-support systems fail, all our hopes of a green Earth will die along with the seedlings.
In order to keep the Seedling Ark functioning you need to keep its heat level to at least Chilly. If it drops below that level an icon will appear, showing the health condition of the seedlings and it will start draining. If you manage to raise the heat level back in time then the seedlings will slowly heal back to maximum health. However, if the seedlings health completely depletes then the seedlings will die and the Seedling Ark will be lost permanently.
Heating upgrades can be researched.
It takes quite some time for them to fully freeze, you can turn heaters on when they are about to freeze to save coal.
This scenario was probably inspired by the Svalbard Global Seed Vault or an episode during the Siege of Leningrad, when 28 of the botanists safeguarding the seedbank of the Institute of Plant Industry starved rather than eat the collected seeds.