This chapter presents a comprehensive numerical framework for solving the governing equations of turbulent flow and heat transfer in a curvilinear coordinate system using the finite volume method (FVM). Following the derivation of the generalized transport equation, the discretization procedures for the momentum, turbulence, and thermal energy equations are developed over staggered control volumes. The treatment includes steady-state formulations for velocity and turbulence quantities based on the RNG k–ε model, and transient formulations for convective and conductive heat transfer. Power-law interpolation is employed to handle convection–diffusion coupling, and linearization techniques are applied to source terms to ensure algebraic solvability. The SIMPLE algorithm is adopted for pressure–velocity coupling, and under-relaxation strategies are incorporated for numerical stability. The discretized equations are solved iteratively using the TDMA (Tri-Diagonal Matrix Algorithm). Special attention is given to near-wall modeling via wall function approaches to accurately capture heat and momentum exchange at boundaries. The chapter concludes with the integration of the thermal sub-model, which employs a coupled convective-conductive energy balance for evaluating unsteady heat transfer through building envelopes under diurnal conditions.