This paper presents an analysis of the dynamic thermal characteristics of lightweight building elements (LBEs) with a forced ventilated cavity and radiation barriers. A two-dimensional numerical model was used for the analysis, which was verified with an analytical method and outdoor experiments. The influence of the temperature boundary conditions at the cavity inlet and along the ambient surface of the cavity on the dynamic thermal characteristics of the LBEs was analyzed separately. The influence of the LBE width, the cavity width, the specific air flow rate and the cavity surface emissivities was also demonstrated. Multi-parametric equations were derived for predicting the heat flux amplitude and the decrement factor along the length of the LBE. (C) 2005 Elsevier B.V. All rights reserved.