There are two "currencies" in Space Engineers (and ironically I'm not talking about the actual currency of SE cash) - materials from which you build things and PCU points of which you are allotted a certain limit on the server. When a player starts, they are concerned with materials, because that's what you need to build things, and some materials are more rare than others. Once you get to where I'm at in the game, materials are abundant but PCU becomes a concern, because you can't mine these - there's a fixed limit.
What I need is PCU, so this means decommissioning existing assets. Originally I was just going to scrap my entire base on earth, but it dawned on me that I just need to "sell the car, and some furniture" to free up the PCU for my new starship. I had a very lovely and nostalgic rocket parked in my silo, but I never use it anymore, and it tied up over 1300 PCU. So reluctantly I deleted it. Then came the base, which I wanted to keep, but I needed to trim down to free up PCU. The irony is that often something that costs a lot of PCU doesn't use a lot of materials, and vice-versa. For example, heavy armor blocks require LOTS of steel plates and cobalt rebar, but each block only costs 1 PCU. A functioning door, on the other hand, costs over 100 PCU. I'm told this is because anything that has moving parts (like a door) has a much higher PCU number. The purpose of PCU is to make sure players don't overload the server. For example, if I could set up 1000 doors in a row and set them on a timer to open and close every second, that would be a big performance hit on the server, whereas a wall block just sits there and does nothing - no logic, no animation, just simple geometry to render.
So I went and switched out a bunch of doors for open passageways, removed a bunch of internal defense turrets, swapped out fancy control centers for simple button panels, and I even removed my windmill to rely on nuclear power alone (so much for green energy). I still have all the essentials I need in an emergency base - a refinery, assembler, cryopod, medical bay, lots of supplies and tools - everything I would need to rebuild my rocket if for some reason I would lose all my space assets. This is highly unlikely, however, especially once I build my second starship, so for now my earth base will be my "summer home" for when I'm exploring the planet, which I still like to do.
View attachment 204382 View attachment 204381
I must admit the PCU limit is probably my least favorite part of playing online. Keen servers seem especially stingy when it comes to this. On the other hand, it does force me to be more clever in my builds. 
