Good indoor air quality (IAQ) is critically important for many as- pects of our lives, including as we’ve found recently in reducing the transmission of airborne diseases such as COVID-19. Deliv- ering good IAQ poses several challenges to organisations: it can require changes in working practices, be bounded by infrastructure capabilities such as buildings and their heating and ventilation sys- tems, and result in substantial energy usage. In this study we have conducted a preliminary investigation measuring IAQ in a typical ‘science lab’ classroom, and engaging with stakeholders to jointly explore these data. Our mixed methods approach uncovers an in- door air quality ‘trilemma’, which relates air quality, energy usage, and stakeholder practices that can be mediated by, and understood as, a site for potentially impactful future HCI designs.