French architects are making more and more use of the 'Trombe wall' in their design of private housing construction. They are convinced of the thermal efficiency provided by this type of wall, and are now questioning its economic viability. The aim of this study is to attempt to provide an answer to this question using several case examples taking into account the evolution of such factors as energy cost and inflation in medium sized countries such as France. The conclusion drawn from this study are not simple and raise many other questions by considering the numerous parameters involved in the evaluation.