Energy Measurement in 3 phase ac split into 3 lines
My question is - If I use 3 X single phase energy meters for all three lines, will it give me the total energy consumed in the building as recorded by the 3-phase meter?


Yes.

The sum of the power in the individual phases will equal that in the 3 phase feed.
There may conceivably be some interesting results, such as if a 2 wire connected phase to phase load is used, or several thereof, but the end result should (will) "balance.