A proposal for closing the Reynolds-averaged energy equation is presented at the twoequation level of turbulence modeling. The eddy diffusivity for heat is proposed as a function of the local energy of turbulence, k, and the local temperature time scale, t  , instead of using mixed time scale, m  . The proposed two-equation heat transfer model solves two differential equations, one for the temperature variance, t k , and the other for the temperature time scale, t  . The nearwall limiting behavior of turbulent quantities associated with heat transfer has been captured with the proposed model. Therefore, an additional term is included in the temperature variance equation to improve the prediction of nearwall behavior. Moreover, an exact and noval equation for the temperature time scale, t  , is introduced in this study. The proposed t t k  heat transfer model does not suffer from numerical stiffness problems since natural boundary conditions for the variables t k and t  are used ( t k = t  =0 at y=0). The proposed model is assessed by application to fullydeveloped turbulent channel flows under different wall thermal conditions with different values of Reynolds numbers. The results for all cases examined showed good agreement with those of the direct numerical simulation data.