Comparison of the energy terms in the heat-loss function (Eq. (32)) along the magnetic field line for the reference model. Only a region around the cold thread, the PCTR, and the beginning of the coronal part is displayed. Only half the domain with s ≥ 0 is displayed due to the symmetry of the profiles. In the coronal part, the ambipolar heating is set to a nonzero but negligible value for numerical stability reasons.