Optimizing multi-layer/multi-physics passive adaptive thermal enclosures for climate-responsive energy regulation: a numerical study

Adaptive facades regulate heat transfer by adjusting their thermal behavior in response to environmental conditions. Passive adaptive systems, including stimuli-responsive thermal storage materials, tunable radiative coatings, and variable-conductivity layers, offer significant potential for material-based thermal regulation. However, their combined potential remains unexplored, as most studies examine individual mechanisms in isolation. As a result, trade-offs among energy savings, material usage, design complexity, and climate responsiveness are often underrepresented, overlooking coupled interactions in multilayer assemblies limiting their effectiveness. This study develops a transient three-dimensional numerical framework coupling heat transfer with multi-objective optimization to evaluate trade-offs between minimizing annual energy consumption and enclosure thickness. Three configurations, semi-static, passive adaptive with realistic limits, and passive adaptive with ideal limits, were evaluated using two heat-storage materials across three climates (Phoenix, Baltimore, Fairbanks) and two applications, benchmarked against a static enclosure. Relative to the static enclosure, passive adaptive configurations reduced annual heat gain and heat loss by: 44.4–81.4% and 47.9–80.1%, under ideal limits, and 19.1–49.1% and 30–70%, under realistic limits. Optimal wall thickness decreased from 16.6 cm to 4–7.1 cm (ideal) and 9.5–10.8 cm (realistic). Near-optimal performance is attained within semi-static and realistic ranges, while ideal-limit configurations define upper bounds for theoretical future development. Results reveal climate-dependent roles: thermal storage is most effective in cold and moderate climates, radiative modulation dominates in hot climates, and tunable conductivity benefits all conditions. The proposed-framework establishes quantitative design guidelines for climate-responsive multilayer material-enabled enclosures, supporting material selection and system design for thermal management.