Thermal performance evaluation of two types of wall panels under dynamic weather conditions

Thermal performance of two types of wall panels were evaluated under dynamic weather conditions. The thermal performance of wall pane ls (61 x 61 cm) prepared in the laboratory with a 5.0 cm extruded polystyrene (XPS) board sandwiched between two 7.5 cm concrete layers and 5.0 cm layer of foam-mortar containing expanded polystyrene (EPS) beads sandwiched between two 7.5 cm concrete layers were evaluated simultaneously in a specially designed air conditioned test box. The thermal transmittance (U-value) and resistance (R-value) of the two wall samples were determined and compared. The thermal transmittance (air to air) of sandwiched XPS concrete and EPS beads foam-mortar concrete wall panel samples are 0.836 and 2.526 W/m2 K, respectively. The corresponding mean thermal resistance values (surface to surface) of the wall panels are 1.142 and 0.292 m2 K/W, respectively. Thermal performance indicates that the wall panel sample with the XPS insulation board sandwiched between concrete is much more effective than the wall panel sample made of foam-mortar containing EPS beads sandwiched between concrete. The results also indicate that the time lag between the maximum exterior surface temperature and the maximum heat transmission on the interior surface is about 4.5 hours for both samples.