A systematic review of thermal manikins for thermal comfort and IAQ assessment: design trade-offs and a capability-based development framework

The pursuit of energy-efficient, human-centric buildings has intensified the need for reliable assessment of Indoor Environmental Quality (IEQ), particularly thermal comfort and Indoor Air Quality (IAQ). Thermal manikins provide repeatable experimental conditions for investigation of heat transfer and human exposure, yet existing studies employ a wide range of instrument designs, complicating comparison and obscuring the relationship between manikin architecture and application objectives. This review systematically analyses current experimental IEQ studies using thermal manikins, mapping instrument configurations and linking technological choices to research applications in thermal comfort and IAQ. The identified manikins are categorised based on their manufacturers, offering a unique insight into the existing types of manikins, the research groups employing them, and the collaborative linkages among these groups. The review reveals a clear functional separation in manikin designs: humanoid thermal manikins dominate comfort-oriented investigations requiring heat-exchange measurement, whereas simplified heated surrogates prevail in IAQ studies focused on airflow and inhalation exposure. Although current platforms can simulate thermoregulation, breathing, and sweating, these subsystems are rarely combined, and existing designs seldom support simultaneous assessment of comfort and exposure. Based on the identified methodological patterns, a capability-based framework is proposed for the first time, to our knowledge, to define minimum application-level requirements across major IEQ scenarios. Synthesis of the reviewed evidence further demonstrates that manikin development is governed by a trade-off between physiological realism, measurement richness, and scalability, leading to two complementary development pathways: reference-grade humanoid platforms for detailed investigations and simplified mass-deployable surrogates for large-scale exposure studies. The findings indicate that future coupled IEQ evaluation will most effectively be enabled by modular hybrid architectures combining plume-relevant geometries with selective instrumentation.