Energy poverty is a growing multidimensional concern worldwide, with children and young people particularly vulnerable. This age group spends a significant amount of time in both their houses and school buildings. To date, there has been little research on the dual vulnerability to inadequate thermal comfort conditions in these two environments. In Portugal, the exposure to inadequate thermal comfort in school buildings varies due to disparities in renovation efforts. This work aims to assess upper secondary school students' perception of energy poverty at home and thermal comfort inside classrooms. A survey method was employed comparing a sample of students from one renovated and one non-renovated school located in the Lisbon district. Surveys were complemented with interviews and surveys completed by other school stakeholders. The results indicate that between 4.2 and 14 % of students live in permanent discomfort (i.e., uncomfortable both at school and home). Despite the discomfort levels observed in students from the renovated school, it is possible to say that the renovation alleviated levels of discomfort. Students with health conditions and disadvantaged backgrounds were more likely to report discomfort than those who did not. This study raises awareness of an underexplored vulnerable group and provides valuable insights into the issue of energy poverty among young people. It addresses the need to incorporate this age group in energy-related school policies and future renovation programs.