This article studies the hygro-thermal behaviour of two traditional underground wine cellars from Morcuera (Soria, Spain). The differences between them are analyzed and our hypothesis is that one of these constructions is better than the other for the ageing of wines. The hypothesis takes into consideration the existence of a temperature difference of over 2 degreesC between them as a basis for reaching the aforementioned conclusion. However, the relative humidity inside both of them is 100%, which could pose problems if the presence of mould is not controlled, This study is based on fieldwork for the inventory and cataloguing of traditional agrarian constructions in the "Tierras Sorianas" area. The objective of this investigation is to highlight some advantages of traditional building techniques over modern construction practices from the energy-saving viewpoint. (C) 2004 Elsevier Ltd. All rights reserved.