The increasing risk of overheating in buildings, reinforced by global warming, necessitates advanced modeling techniques to realistically assess and mitigate this hazard. This chapter covers critical modeling aspects for evaluating the overheating risk in buildings, underscoring that simulation is indispensable for an accurate evaluation. Initial discussions focus on the sources of error in thermal modeling and the vital steps for plausibility checks and validation of simulation outcomes. Quality criteria for selecting appropriate software tools are then outlined, ensuring the reliability and accuracy of simulations. Subsequently, the chapter explores simulation aspects of thermal protection measures during summer. These include modeling solar heat gain, thermal inertia, solving the 1-D heat transfer equation, and incorporating latent heat storage with phase change materials. Strategies such as enhanced thermal mass and various ventilation schemes, including increased day and night, are analyzed for their effectiveness in reducing overheating. Additional considerations involve the simulation of glazing systems, including solar transmittance, secondary heat flux, and the performance of shading systems.