Phased optimization of classroom units for low-carbon sustainability and occupant health

The escalating severity of environmental issues has rendered energy conservation and carbon reduction in the construction industry an urgent priority. Educational buildings represent a significant category of public structures, with their energy consumption and carbon emissions exhibiting a persistent upward trend. Moreover, as adolescents spend over half of their walking time in schools, particularly in classrooms, the environmental conditions within these spaces critically determine their health outcomes. Existing research on school energy-saving technologies mainly addresses operational carbon emissions, often neglecting the growing importance of embodied carbon. Concurrently, the mismatch between adult-derived environmental assessment criteria and adolescents’ sensory responses underscores the necessity for age-specific evaluation frameworks. In addition, current optimization frameworks predominantly employ single-phase analytical approaches, failing to reconcile phase-dependent parameter constraints across architectural workflows, from architectural form in conceptual design to envelope and component detailing in technical design. In response to these challenges, this study constructs a phased multi-objective optimization framework, including architectural form, envelope, and component optimizations, for ten major types of classroom units with NSGA-II (Non-dominated Sorting Genetic Algorithm II) algorithms. This framework aims to balance energy, carbon, and health objectives in educational buildings, featuring a workflow that aligns with the architectural design stages. By integrating adolescent-centered Indoor Environmental Quality (IEQ) standards, 18 preferred technologies were identified and evaluated using multi-criteria comprehensive evaluation encompassing life-cycle carbon emissions, health performance, and economic efficiency. This approach resulted in improvements of 11.1 % in carbon reduction and 7.2 % in health performance for classrooms compared to the baseline building.