The mechanical and optical features of glass have propelled its use as a structural material resulting in a multiplication of its applications especially within the construction and automotive sectors. The tensile strength of glass, however, is limited because of the existence of surface flaws. For this reason, glass is most often heat treated before using it as a structural material. Thermal tempering is the most effective and efficient method to enhance the load bearing capacity and strength of structural glass components. Nonetheless, tempering techniques lead to non-uniform cooling distributions on the surface causing residual stress inhomogeneities, which have a direct impact on the structural and aesthetic features of heat treated components. This work therefore presents a novel cost-effective methodology to address the in-service behaviour of glass components addressing the contribution of the two main aspects in glass strength, namely i) the non-uniform residual stress distribution in the part and ii) the statistic nature of glass strength. The predicted residual stresses came into agreement with both, experimental laboratory results and an industrial case study, where multiple nozzle arrays are employed. Similarly, the probability of fracture of tempered glass parts is evaluated based on annealed glass experimental data. In summary, these results demonstrate that the presented methodology can predict the in-service behaviour of glass components from an early stage of the manufacturing process, namely, the design stage. Thus, this work builds the basis for tailored designs of heat treatment processes to achieve the required tempering state based on ad hoc in-service specifications.