Whichever wall model is adopted, our central thesis is that it should recover the macro-scopic contact angle(s) for droplets of given liquids on the substrates of interest, and at the same time it should minimally perturb the liquid structure on length scales beyond the immediate vicinity of the wall. The reasoning behind the first requirement is that in the absence of directly measured surface energies, contact angles stand in for the wettability of the substrate. For example, in saying that a surface is hydrophilic or hydrophobic one is really making a statement about the contact angle of a droplet of water on that surface (whilst the present work does not cover vapor-liquid interfaces, the methods we develop should be equally applicable). For the second requirement, we note that if a coarse-grained DPD water bead represents several actual water molecules, structure on the bead length scale induced by the wall (e. g. oscillations in the bead density) should be minimised. This latter requirement involves an inevitable trade off in being able to set surface energies arbitrarily, but as a design criterion it can be used to narrow the choice of wall interaction potentials as described below, and take advantage of a built-in degree of freedom since in determining contact angles it is only the difference in surface energies, γ s1 -γ s2 , that is relevant for the Young equation and the de Gennes spreading parameter. In this article we outline the chemically-specific DPD model that we use as a basis, and describe the wall model that we use. We then introduce the methodology for calculating the surface energies from our DPD simulations such that the Young equation is automatically satisfied. Next, we validate this against direct numerical simulations of oil droplets on surfaces, using dodecane in water at 25 ℃ as our model. Finally, we consider the complementary case of a water droplet in oil, and show that our methodology can reproduce the case of a water droplet in dodecane on a surface-adsorbed monolayer on silica.