We present a predictive model for the heats of sublimation of the condensed phases of energetic materials that combine the empirical relations of Politzer with first-principles density-functional calculations of the electronic properties of the molecular surfaces. The distinct features of our methodology are the use of numerical pseudo-atomic orbitals for the quantum mechanical calculation of the electronic charge density, as well as an improved technique for the molecular surface area determination. As applications, we used our model to predict heats of sublimation of energetic molecules CL-20, HMX, RDX, TNT, FOX-7, TATB, and LLM-105, with the Politzer parameters fit based on a set of eight nitro-aromatic molecules. In comparison with conventional quantum chemistry calculations, our approach is tremendously less computationally demanding, yet it still demonstrates competitive accuracy and predictive power.