Why is Bh6 an inaccuracy?

Hey folks!

In one of my recent OTB games I had the above position and went for Bh6 to: - force the trade of Bishops - prevent h5 as response to h4

The engine likes f3 better and gives a line which dosen't help me understand the reasoning. Could someone please help me out here? I am 1600 FIDE.

Thanks in advance!