Let the player downgrade buildings

[Phibs]

If possible freely (meaning not incrementally).
It makes little sense forcing the player to pay energy for excess food production on 'full' planets for instance so that he/she ends up demolishing and re-building the structure to the appropriate level.

 

[Sebbychou]

Also allow us to downgrade to the Basic versions even if you've past the disassembled colony ship stage. Sometime a basic Hydro is all we need.