This paper presents the findings of a theoretical and experimental investigation of the thermodynamics of an internally-heated control volume (CV), ventilated by natural convection. A simple bench-type experiment has been used to determine the temperature history of the air, in support of a global calculation by numerical methods. Good agreement has been achieved between the experimental results and the mathematical prediction, which has wide ranging applications in practical situations. (c) 2004 Elsevier Ltd. All rights reserved.