We show that a structural energy difference, ΔE, must include explicit symmetry-breaking changes of the electronic structure due to temperature-induced configurational excitations, and why ΔE at T=0 K is not necessarily relevant to thermodynamic and mechanical modeling. In Ni3V, we calculate a tenfold decrease of ΔE between D022 and L12 structures from T=0 K to states of order relevant to experiment. ΔE calculated directly from states with short-range order (8 meV) or with low partial order (7–12 meV) agree with high-T experiment (10 meV).