Warehouses are an integral part of any Covenant base. Supplies are ferried to these buildings (and subsequently, the player) by Supply Ships. All Warehouses can be upgraded to Blessed Warehouses. Blessed Warehouses are simply Warehouses that increase your resource replenishment, compared to the efficiency of a normal Warehouse. BWH's are 40% more productive than WH's, individually.
WH's decrease in unit productivity with the more you build. With one WH producing 10 points per second, your unit WH productivity would be 10. If you expand from there to two WH's, the two WH's would produce 18.2 points per second, making the unit WH productivity 9.1. If you expand from two to five WH's, you would have an overall production rate of 36.4 points per second, with unit WH productivity being 7.28. Now while it is good to increase your amount of production, building too many WH's eventually becomes inefficient, as they will pay for themselves more slowly, with the more you build.
BWH's follow a similar trend, in that they lose unit production with the more you build, but they still give better output, and the output they give out is still relative to how many you have. In terms of efficiency, BWH's equate to WH's as follows:
|Blessed Warehouse to Warehouse Conversion|
|2 BWH's||Is equal to||3 WH's|
|3 BWH's||Is equal to||5 WH's|
|5 BWH's||Is equal to||9 WH's|
|7 BWH's||Is equal to||14 WH's|
As you may have noticed, it is generally most economical to start upgrading from WH's to BWH's at seven total WH's.