Thermal performance of a novel modular frame-shear wall for ultra-low-energy buildings: Experimental assessment, parametric analysis, and building-load implications

This study evaluates the thermal performance of a novel modular frame-shear wall for ultra-low-energy prefabricated buildings. Four full-scale wall specimens were tested using guarded-hot-box (GHB) and heat-flow-meter (HFM) methods, and a three-dimensional steady-state heat-transfer model was established in COMSOL Multiphysics. Replacing plastic-coated steel-rod connectors with glass-fiber-reinforced polymer (GFRP) connectors reduced the measured flat-wall thermal transmittance by 13.1–15.2%. Among the investigated junctions, the interior-wall-to-exterior-wall junction exhibited the largest linear thermal transmittance. The numerical predictions differed from the experimental results by 1.5–12.0%, depending on the measurement method and specimen. Parametric analyses were conducted for four insulation materials and total insulation thicknesses ranging from 130 to 300 mm. For the adopted unit reference geometry, the calculated thickness thresholds corresponding to a unit-geometry thermal-transmittance index U∗ of 0.15 W m −2 K −1 were 220.9, 233.4, 242.0, and 251.7 mm for polyurethane, graphite-enhanced expanded polystyrene, rock wool, and foam glass, respectively. The corresponding practical design thicknesses were rounded upward to 230, 240, 250, and 260 mm. In the reference-building sensitivity analysis, the optimized wall inputs reduced the COP-adjusted annual total end-use load intensity by 5.5–5.8%. The results demonstrate the coupled effects of connector material, junction geometry, insulation conductivity, and insulation thickness on the thermal performance of the proposed wall system.