HOW THEY WORK
The Mass and Energy values displayed in your interface are really decimal numbers, but they are displayed with the values floored to the nearest whole number. For instance, an interceptor that costs 0.975 mass per second will be displayed as costing 0 mass per second.
When economic production structures are built next to structures that use their resources, they provide an “adjacency bonus”: that structure uses less of those resources. For instance, the factory building that interceptor will use less mass per second to make it if it is built next to mass extractors or mass fabricators, and it will use less energy per second if it is built next to power generators.
Similarly, mass and energy storage buildings provide adjacency bonuses to economic production structures. For instance, mass storage buildings placed next to a mass extractor will actually increase the extractor’s output.
The adjacency bonus is percentage-based and goes by the percentage of the building that is surrounded by bonus-granting buildings. For instance, a T1 power generator will grant a certain adjacency bonus to a factory if all sides of the factory are covered with T1 power generators, and 50% of that adjacency bonus if two sides of the factory are covered with T1 power generators.
You can tell an adjacency bonus is working when a small red line appears between the two buildings. For this to occur, at least 1/2 of the building’s sides must touch each other. (You can’t put a T3 power generator touching one square of a mass extractor and expect it to grant a bonus to the mass extractor’s energy use.)
Adjacency bonuses are still in effect even when the bonus-granting buildings are turned off. (This means you can turn off your fabricators and they will still make adjacent buildings more effective.)
Finally, although not an “adjacency bonus”, rebuilding a structure on its own wreckage will reduce the cost of the structure by 50%.
THE NUMBERS
Remember that all mass producers are also power consumers.
More complete data for non-maximum bonuses can be found in each unit’s section.
All sides have identical adjacency bonuses.
Tech 1 Power Generator
Maximum bonus: 25% less energy spent
Works with: Any power consumer
Hydrocarbon Power Plant
Maximum bonus: 50% less energy spent
Gives bonus to: Any power consumer
Tech 2 Power Generator
Maximum bonus: 50% less energy spent
Gives bonus to: Any power consumer
Tech 3 Power Generator
Maximum bonus: 75% less energy spent
Gives bonus to: Any power consumer
Tech 1 Mass Storage
Maximum bonus: 50% more production
Gives bonus to: Any mass producer
Tech 1 Energy Storage
Maximum bonus: 50% more production
Gives bonus to: Any energy producer
Tech 1 Mass Fabricator
Maximum bonus: 10% less mass spent
Gives bonus to: Any mass consumer
Tech 1 Mass Extractor
Bonus: 2.5% for one extractor
Gives bonus to: Any mass consumer
Tech 2 Mass Extractor
Bonus: 3.75% for one extractor
Gives bonus to: Any mass consumer
Tech 3 Mass Extractor
Bonus: 5% for one extractor
Gives bonus to: Any mass consumer
Tech 3 Mass Fabricator
Bonus: 1.25% for one fabricator
Gives bonus to: Any mass consumer