you're right about the thulium archive, that's fairly weak. 

i disagree with everything else you wrote, though.

solar plants are hardly useless. they are at the same tech level as the mega factory. a solar plant adjacent to 3 manufacturing buildings is on par with a mega factory and much cheaper to build (45 points vs. 30+45+67 points over 3 turns). 

fusion plants are really good. with only one adjacent mfg building they are already better than the manufacturing plant at the same tech level. with 3 or more adjacent buildings they are superior to the industrial sector (final tier). and much cheaper to build than the equivalent factory.

research boosters are a bit weaker, but still worthwhile with 2 or more adjacenct res buildings.

not sure about the durantium refinery. last time i played it had a +4 total production bonus, but maybe that was changed once again recently. with the +4 bonus it was definitely worth it. using some adjacency to other mfg buildings, you basically get a slightly weaker factory that makes the whole economy of the planet better by a large factor. +4 total is like a +40% to everything for some small-ish new colony and still easily a +20% (or more) bonus for a mature planet with a population of 20 billion. not bad at all. 

I believe the new formula for population / production breaks even at around 15 pop - so in fact a planet with 20 pop will be better off than it was before. Also remember that the +2 (previously +4) from durantium is also subject to all multipliers (so becomes +2.5 with 100% approval I believe) and then gets the benefit of all factory / colony / relic multipliers on top.

It was quite a hard nerf though from +4 down to +2 and 1 less adjacency benefit too I think. It is borderline value now while it remains at a 150 build cost - certainly not worth an early build option as you can build 5 basic factories for the same cost.

ok i'll try to clarify the system a bit for you

the adjecncy bonus is the the number shown on the building - basic labs and factories usually have a +1 research resp. a +1 manufacturing bonus. that means if you put 2 factories next to each other, they both get +1. that bonus works in multiple directions - if you build a third factory adjacent to the other 2 (i.e. the 3 hexagons form a triangle), each of the 3 factories now gets a +2 bonus. 

once per colony builings work exactly the same way, but they usually have a higher adjacency bonus since they are supposed to be something special. if you put a solar plant next to a factory, the factory gives a +1 to the plant and the plant gives a +2 to the factory.

the power plant does NOT give its bonus to all buildings on the planet. 

each level of adjecency is worth 5%. i.e. 2 basic factories next to each other have a native manufacturing bonus of 50% (25% each) and as a reward for placing them next to each other, you get a 10% manufacturing bonus ( 1 adjacency) on top of that. if we examine our "3 basic factories in a triangle" example, you'll notice that 3 factories getting a +2 bonus is actually the equivalent of 30% mfg bonus, so by cleverly placing them in a triangle, the 3 factories give you more manufacturing than 4 factories in random tiles with no adjacency.

in short -placement does matter, since without grouping the buildings, you don't get the adjacency bonus, so the planet will have a lower output compared to the same planet with "correct" building placement.

since the bonus of the spammable standard labs/factories is always +1 (or 5%), the adjacency bonus is (relatively) more powerful in the early game and loses some of its importance as the game progresses. for example - 2 basic factories with the bonus give you 60% manufacturing instead of 50%, but two industrial sectors (the highest upgrade of the factory) next to each other give you 160% bonus rather than 150% bonus, whiich is a lot less dramatic. it's still a free 10% bonus, so you might as well pick it up.

i guess that's all there is to it, really. but feel free to ask if something is still confuding

I don't know that the OP is saying they are lame...

I think the capitals are generally worth it, but they are a bit expensive early on.

I disagree. This entire post is off-base.

The colony-unique buildings don't need to be "better" than the regular building if you're only making 1 of that type of building.

Who says it should be that way? You? You who?

The design is extremely apparent: the colony-unique buildings are obviously intended to be strong when you rack up adjacency bonuses. They are weak when you don't ... ok?

You have a problem with the Thulium Data Archive? I can see that as somewhat legit -- almost all the strategic-resource-required buildings are rather meh. By the time you get the resource to spend on the build, and find a good place for the building, you've already exceeded the tech level where those buildings are strong. The only one that remains relevant is the Elerium Defense Shield, since few buildings give high adj bonus to Mil (and you want to stack that Shrinker, amirite??).

However, I still used a Thulium Data Archive for its >1 adj bonus to enhance my Galaxy-unique research building. Levels on that grant the %mod to all my planets, so every level I can get on it is valuable.

That rare case aside, the strategic resource buildings = shrug, don't care. Could definitely use tuning upwards, but not a big a deal.

On the Manufacturing side, the Fusion Power Plant is highly competitive against the regular building -- IIRC if you get two adjacencies with manufacturing buildings, it is more efficient per tile than the regular building at its tier. The Solar Plant is almost good enough (IIRC it takes like 3 adj tiles).

The last Quantum Power Plant is actually better than a single regular manufacturing building. IIRC it's 100% to the regular building's 75%, before you start talking adj bonuses. I actually think the QPP is overpowered and the base value should be nerfed to 75% or possibly lower (70%?), with its adj bonus dropped to 3 and the regular manufacturing building bumped up a notch (perhaps to 80% or 85%).

The only part of the building numbers balance that confuses me at the moment is that the research Colony-Unique (Innovation Complex) is so much weaker than the Quantum Power Plant. If you have a single tile for research, the regular building is better. The Innovation Complex is only efficient at something like 3 adjacencies (or when you are specifically pumping another tile up in particular). On the flip side as I already mentioned, the QPP is efficient all by itself. Its adj bonus is also nuts.

your logic is flawed. the Solar plant breaks even at 3 adjacency, not 4. and it doesn't cost "a bit less" - it costs less then one third of a mega factory. and you can build it in one turn, whereas a mega factory takes at least 3 turns to build+upgrade. so even if you use it with only 2 adjacencies, it takes A LONG time for the slightly better output of a mega factory to make up for the extra production and turns you have to invest it. a 5% mfg on an average planet running at 20 base manufacturing is worth 1 point of manufacturing. it takes 97 turns just to earn back the additional building cost of 97 extra manufacturing.

that manufacturing cost consideration is more relevant for planets you colonize after you got to that tech level. if you have to scrap an existing xeno factory to replace it with a solar plant, its less valuable of course. 

the economics of research buildings are a bit different. they unlock later and by that time you probably already built up your core research worlds and invested the time to get them to t3 research academies. so you'd need to scrap an academy to make room for a coordination center. if you still build up more research worlds at this stage, it's worthwhile to include the coordination center in the layout plan. again, one of their main selling points is that they are much cheaper, so if you can terraform a tile that is adjacent to 2-3 existsting research labs, it's still worthwhile to build a coordination center in that new tile rather than building up a new lab from scratch - you get back to 100% research some turns sooner, which makes the coord. center the better deal. it takes extremely long for a +5% or +10% research bonus advantage to catch up to the hundreds of research points you lose because the research world spends 2-3 extra turns dedicating a large% of its base production to building/upgrading rather than researching at 100% 

i agree that the thulium research building could use a buff. i don't even use those on planet layouts with very good potential adjacencies (+4 or more). thulium is relatively rare compared to durantium and the thulium based ship modules are some of the best force multipliers in the game. duranthium on the othre hand is usually the most common resource and only really required for shipbuilding if you go for mass driver weaponry. so a duranthum refinery is a bit more viable. it's somewhat overpriced, though. 2 factories + 1 refinery would be a really nice manufacturing sector for a research planet that will require quite a bit of manufacturing for multiple waves of building upgrades and terraforming expansions. if it didn't cost 5 times as much as a basic factory it would be a viable option. i don't really understand why they nerfed it. it finally seemed worthwhile at +4 total production and +3 adjacency.

I would say the thulium archive is a bit on the weak side. the solar plant I also avoid, just not quite with it.

the capitals are just fine, they are expensive but very powerful.

honestly I think the regular upgrades are some of the weakest. The amount of investment it takes to get to those high end buildings can take 100 turns or more to pay for themselves.

i did a Math check a while back and found it was better to do all the standard terraforms with basic buildings before doing a single upgrade. 

i like to put one next to the hyperion shrinker. before it was changed to "one per colony" you could game that system a bit and surround the shrinker with 5 antimatter plants and an elerium shield. i guess a similar case could be made for galactic wonders that give a faction wide bonus. don't really know if any of them scale with adjacencies the way the shrinker does, though.

aside from that special application, it seems completely useless  

So. I have to renege on my initial comment.

After reading the posts here and working more carefully with the numbers (primarily to balance a mod)... I think the adjacency is working well for manufacturing improvements. I haven't had time to work through the other improvements yet, but I will.

If I did the math right, once you reach the final improvement level (Industrial Sector (IS) & Quantum Power Plant (QPP)) it is always cheaper (in terms of manufacturing cost) and produces more manufacturing to use the QPP, even when adjacent to only 1 IS (a pair of IS has a max manu. of 160 at a total cost of 788 (cumulative costs of all improvements); an IS with a QPP has a max manu. of 215 at a total cost of 657; the maintenance is the same either way). And while more expensive with lower tier manu. improvements, the QPP always results in better output when adjacent to 1 or more manu. improvements.

Also, there are only a few times it is less effective to have a Solar Power Plant (SPP) or Fusion Power Plant (FPP) in adjacency:

Solar Power Plants (SPP): With Industrial Sectors, an SPP is always worse, and with Manufacturing Centers an SPP is always worse except in a full hex configuration. The SPP breaks even at a lower cost in a diamond configuration with Mega Factories, but is worse with Mega Factories in any smaller configuration. The SPP also breaks even when paired with a Xeno Factory, but at a lower cost.

Fusion Power Plants (FPP): The FPP is worse with Industrial Sectors only in triangle and smaller configurations.

Costs:

The costs are higher for configurations that include an SPP or FPP early on, but these are always cheaper starting at Xeno and Mega Factories, respectively.

The QPP is always more expensive until using Industrial Sectors, but the extra manufacturing capacity is substantial (from 55% to 195% more manufacturing depending on the improvements and configuration).

Conclusion:

In the long term, it is worth pursuing the Quantum Power Plant as it always results in higher manufacturing (even when adjacent to only 1 manufacturing improvement) and is ultimately cheaper (assuming you don't destroy a manufacturing improvement to replace it...).

Along the way, Solar Power Plants and Fusion Power Plants are less productive than more advanced manufacturing improvements. So if you can always place a SPP in a diamond configuration with manufacturing improvements, and you research Fusion Power Plants before Manufacturing Centers, you will always have equal or better manufacturing at lower costs (except initially with 3 basic factories and a SPP).

Considering it needs the relatively rare Thulium, the Archive is still distinctly disappointing. Compared to the basic building, it costs 5 times as much manufacturing to build, plus the resource (and so the cost of the starbase). That means 5 times as long to get the thing built, on a research world with low manufacturing potential. The cost quite simply isn't worth it for the tiny, tiny benefit, even if it is mildly better.