As the climate is changing, it becomes crucial to evaluate buildings ability to maintain safe indoor conditions under future summer. In this article, a methodology is proposed to evaluate different input parameters effects on summer thermal discomfort. Using recomposed future weather files from one regional climate model, sensitivity analyses with the Morris and Sobol are conducted. It points out that the thermal inertia and absorptivity and emissivity coefficients of exterior coatings are the most impactful parameters under future typical summer and future heatwave in Paris in 2050. This analysis is part of a methodology to help designing buildings under climate change. The goal is to provide insights to buildings practitioners to allow them to put in place today mitigation and adaptation strategies to future climate.