A short term experimental investigation on the thermal inertia: time lag and decrement factor of aerated lightweight concrete (ALC) wall panels is the main purpose of this study. ALC wall panels of different density and different aerial intensity of newspaper sandwiched were produced and erected on a prototype house. All wall panels were installed facing east direction and subjected to natural environment or tested under transient condition. The inner and outer surface temperatures of the wall panels were recorded at 3 min interval, 24 h a day. Time lag and decrement factor were computed from the surface temperatures recorded. The results showed that newspaper sandwiched ALC panel has greater time lag and lower decrement factor compared to ordinary ALC panel. It is found that time lag and decrement factor were influenced by the thermal diffusivity value of the wall panel. The thermal inertia property of the panels was negatively related to its thermal diffusivity. (C) 2011 Elsevier B.V. All rights reserved.