Are 3D heat transfer formulations with short time step and sun patch evolution necessary for building simulation?

A numerical model is developed to accurately simulate the transient thermal behaviour of rooms with sun-facing windows, with the use of a refined spatial and temporal discretization. For each node, the energy balance equations are developed based on a consideration of radiation, convection, air enthalpy and three-dimensional heat conduction. As buildings are exposed to rapid climatic variations (particularly incident solar radiation), we have added the different environmental conditions at short time-steps. The simulation considers the projection of solar radiation through a window onto interior walls, referred to as a sun patch. Therefore conduction transfer is treated in three dimensions. The indoor air temperature, the temperature of the cells in the walls and the surface temperatures are calculated at each time step using a variable-step Ordinary Differential Equation (ODE) solver.  
Results from this model are compared to well-known simulation tools using one-dimensional heat conduction without a sun patch.