When the production cost of any building or unit is reduced, the dust cost for it is reduced by the same amount. But it seems, that the dust cost reduction is bugged. The cost is reduced by an excessive amount, that is quite significant. I made some test and here is the results. It seems that the more Production cost reduction you get, the more extra Dust cost reduction you get either. The precise values can be seen on the table below.







Most of the test were on Normal speed, but I made a quick test on Fast speed just to make sure, and the numbers turned out to be exactly the same. I think the table is pretty much self-explanatory. The only thing I'd like to explain is "Extra (d) cost reduction recalculated". Just in case.



So let's say, that we have a unit, that has basic cost of 100 Dust, and we have 50% Dust cost reduction, so in fact this unit cost for us is 50 Dust. And let's say we get a new technology, that reduces Dust cost for units for another 25%. This new cost reduction is calculated based on a basic value, so with this technology the unit will cost 25 Dust. Thus in fact the cost for the unit has been reduced by 50%, and we can afford 2 units for 50 Dust instead of just 1. This calculations are true for my test results either, only the cost reduction there is much higher, thus turning this small 5% errors into much larger values.



Link to the table with all the formulas.



Save files are attached.