The idea is, simply, that somewhere offsite a number of identical building elements are built.

这个想法很简单，就是在异地的某个地方建造了许多相同的建筑元素。

First and foremost, the use of identical elements, built in a factory system, to construct a larger building lowers cost through economies of scale.

首先，使用相同的元素， 在工厂系统中建造，建造更大的建筑， 通过规模经济降低成本。