So I was seeing how good/bad Habitats were purely for the purpose of Pop Growth, and they seem to be very good for that.
To compare to other means of Pop Growth, let's take some values:
1 energy credit will be our base so I get (by comparing worker output) roughly:
Food = 0.67 Energy (This is because a Farmer produces 6 while a Technician produces 4.)
Minerals = 1 Energy (Similar as Above.)
Mote/Gas/Crystal = 13 Energy (Just picked base buying from market rate. The worker rate for Refiners is something around 8, but those are really slot intensive.)
Alloy = 4 Energy (The number I get for the production chain if everyone involved were Technicians taking into account consumer good upkeep difference and building upkeep difference and assigning 10 Energy value to rare materials is between ~4.4
Consumer Goods = 2 Energy (Similar as Above.)
With these values, we can compare somewhat the methods of Pop Growth. Luckily, the modifiers are additive so we get a flat number for each % value.
(1) Encourage Planetary Growth = (100 / 0.75 monthly growth) * ( 1000 food / 120 months ) * 0.67 Food/Energy = 741.74 Energy/Pop
(2) Robot Assembly Plant = (100 / 2 monthly growth) * (6 minerals * 1 energy/consumer + 5 energy + 1 Food + 0.5 Consumer Goods)) = 625 Energy/Pop
(3) Gene Clinic = (100 / 0.3 monthly growth) * (2 food + 3 Consumer Goods * 2 energy/consumer + 2 energy) = 3333.33 Energy/Pop
(4) Cyto-Revitalization Center = 4666.67 Energy/Pop
So we get an idea of what a pop costs through these methods… but the primary method I use would be Nutritional Abundance. The output is 0.3 pops per planet per month and the cost 0.25 per pop which means each pop acquired through this is a variable price.
If we have 1 planet and 10 pops, it costs 2.5 food per month for 0.3 pops. At that rate, we get 555.56 Energy a Pop.
This means that a Density > 11 Pops/World makes Robot Assembly Plants more efficient.
> 13 Pops/World makes Encourage Planetary Growth more efficient.
> 60 Pops/World makes Gene Clinic more efficient.
> 84 Pops/World makes Cyto-Revitalization Center more efficient.
Those last two aren't becoming worthwhile anytime until way late.
Anyway, you get the idea how this works. What about Habitats with their large upfront cost and alloy maintenance?
We'll assume that we have the +10% tradition and 2 +10% technologies researched for 3.9 Pop growth per Habitat. If we treat the capital building maintenance as the "cost" of the pop growth and divide the upfront cost over a period of time we get different amounts:
Initial Cost (3000 Alloys) not included:
(100 / 3.9 monthly growth) * (5 alloy * 4 energy/alloy + 5 energy) = 641.03 Energy/Pop
Initial Cost over 100 years:
(100 / 3.9 monthly growth) * (5 alloy * 4 energy/alloy + 5 energy + (3000 alloy * 4 energy/alloy) / 1200 months)) = 897.44 Energy/Pop
Initial Cost over 50 years = 1250 Energy/Pop
Initial Cost over 20 years = 1923.07 Energy/Pop
So compared to Nutritional Plenitude, these numbers are more efficient at:
> 11 Pops/World not including initial cost
> 16 Pops/World dividing initial cost over 100 years
> 22 Pops/World dividing over 50 years
> 34 Pops/World dividing over 20 years
If you ignore the initial build cost, that's about equivalent to the Robot Assembly Plants and better than Encourage Planetary Growth.
If you wanted to treat 1 food as worth 1 energy, that makes the Encourage Planetary Growth cost 1111.11 Energy/Pop and everything else becomes more efficient than Nutritional Plenitude at lower pop densities.
In other words, Habitats are actually pretty good for increasing pop growth with the "planet" itself being treated as a pure side effect. They definitely don't hurt for cheaper research if you were okay with keeping the pop counts low. Slap a fortress on one for an FTL inhibitor might be nice. If for some reason you didn't plan on taking the Ecumenopolis perk, they could be used for Alloy/Consumer Goods production. However, those are so powerful that I don't see any reason why you wouldn't pick up that perk unless it wasn't an option.
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