Evolution of the various energy components in the HERACLES simulations. We show E_kin+th, which sums the kinetic and thermal (i.e., gas) energy; E_rad,trapped, which is the trapped radiation energy; E_dep,pm, which is the energy deposited by the magnetar; E_rad,losses, which is the radiative energy streaming out through the outer grid boundary; and ΔE, which is defined as E_kin+th + E_rad,trapped + E_rad,losses - E_dep,pm and should be constant. The start of the simulation is 1.15 d in all simulations — any magnetar energy deposited prior to that is not accounted for in the HERACLES simulations.