Let me see if I got this right- I should not decommission the first set of buildings, instead I just upgrade it to avail the discount?
Essentially. Even in a case where you don't get the discount (for instance upgrading invention matrixes or perhaps industrial sectors to discovery spheres, which actually cost less and therefore don't give you the discount as they don't cost 50+ more), you still have the building in question helping to build the upgrade, which is a good thing.
If I may take an opportunity to ask yet another question,sir- I saw a screenshot somewhere where taxation of 49% brought in 42 bc, but the production capacity was set to 100% ,costing merely 4 bc.(military at 60%, social and research at 20% each) Is it so because the factories and labs were low in number, thus costing only a wee bit to work ?
This is one planet (the homeworld), with no other planets colonized yet, with 20% of 24rp (civilization capital) going to research spending (4.8, becomes 4 when truncated). The planet is not building a ship (hence the military at 60% is not being charged), and nothing is in the social queue, either (and therefore the social at 20% is not being charged).