| Are you sure you get partial credit when replacing one type of building with a different type? I have never noticed this happening. |
I just checked it out in the game. I first verified that basic factory (50SP) upgraded to factory (75SP) within two weeks at 15SP per week, so that checks out.
I then checked basic factory (50SP) upgraded to basic lab (40SP) this claimed to take 4 weeks (should be 3 at most?). Just building a basic lab on a free tile was also 4 weeks. I then checked out extreme stadium (250SP) which took 16 weeks to upgrade from basic factory and 20 weeks to build on a free tile.
To me it looks like if the building your upgrading to, is cheaper than the building that's already there, then you don't save anything over building on a free tile, but if the building you're upgrading to is more expensive it actually looks like you get full credit.
There also seems to be discrepency in number of weeks to complete reported in the planet screen and the number of weeks to complete in the colony list of the civilization manager screen. The civilization manager colony list appears to be correct. (This has been discussed in other threads). If you use this, the difference in upgrade vs. buy is 3 weeks which at 15SP's per week is at least 45SP's. Since the basic factory is 50SP's it looks as if you're getting pretty much full credit for upgrading a lower cost building for a higher cost building.
You can verify this in-game yourself in a similar manner. You can get the costs of the buildings from your PlanetImprovements.xml file in the GalCiv2\Data\English directory.
