⁴Note that the symbols k and c in Eq. (272) have a different meaning than in Eq. (271). The reason is that the nonlinear model for moisture transport described in Section 2.4 traditionally uses c for permeability and Eq. (272) should be obtained as a special case of Eq. (275). On the other hand, the heat conduction model from Section 2.1 was implemented earlier and the input parameters are directly called k and c, so changing this notation now could lead to confusion for some older input files.