Cavity walls are often proposed in the building envelope design as a solution for improving the thermal comfort of the occupants and reducing the adverse condensation effects on the building fabric. Although the behaviour of a non-ventilated cavity wall is well-known, more studies are required when cavity ventilation is allowed. In order to consistently predict the thermal behaviour of a naturally ventilated cavity wall, a convective model based on the integral equations of motion and enthalpy was developed and applied in the present study. The model is presented as a combination of two limiting cases of a steady laminar flow into the channel gap: fully developed flow and boundary layer flow. Conduction effects across the system are also included through a proper limiting case and then combined with the convective model. In addition a numerical CFD model was developed that provides solution for free convective flow configurations between two parallel conducting vertical walls. For comparison purposes, some test cases were simulated with the two models and a general good agreement was found between results. Finally, the integral model was applied to assess the thermal performance of a ventilated cavity wall for winter and summer conditions. Copyright (C) 2009 John Wiley & Sons, Ltd.