The paper presents the results of an experimental study on ventilated walls with an external clay cladding in a temperate Mediterranean climate. The aim of this work is to assess the actual thermal performance of the ventilated facade with a complete thermo-fluid dynamic analysis. The paper describes the experimental work carried out on walls with different exposure and various heights of the ventilation channel (6 m and 12 m) with controlled internal air temperature. The air velocities, temperatures and heat fluxes in the ventilated facade were monitored and correlations between the thermo-physical parameters were identified. The study showed that, on sunny days, the external surface temperatures, temperatures in the air cavity and air velocity in the gap are considerably higher for the 12 m wall, while during the nighttime lower temperatures are found for the various layers of the wall. The data obtained allowed us to calculate the Reynolds number and to identify the airflow rate in the channel. Correlations were found between the air velocity in the gap, the airflow rate, the Reynolds number and the sun-air temperature. These correlations are useful for modelling ventilated walls, which are generally very complex, with simplified equivalent walls. Finally it was possible to identify the peak temperatures with respect to exposure and thermal lag. The thermo-graphic analysis showed that the behaviour of the walls is almost uniform without thermal bridges. (C) 2011 Elsevier Ltd. All rights reserved.