This chapter is primarily a preparation for the study of the total variation flow. This is due to the fact that in order for the 1-Cheeger energy to be lower semicontinuous, it needs to be defined on the space of functions of bounded variation and not on the Sobolev space with exponent equal to one. Thus, we need to extend parts of the linear differential structure to the BV case, and to this end, we will require that we can approximate BV functions with Lipschitz functions in a suitable way. Our strategy will be to present a metric version of the Anzellotti pairings between a vector field with integrable divergence and a BV function due to Anzellotti and prove a generalised integration by parts formula. To be precise, we will prove the existence of two such pairings, separately for the case of the whole space and for a bounded domain with a sufficiently regular boundary. They are defined slightly differently, in particular, in the second case, the Gauss-Green formula takes into account the boundary effects.