In principle and from an economic analysis, the value of conventional heritage lambs depends a) on their uniqueness b) on the value of the artistic attributes given to that heritage asset, c) on their degree of conservation d) on their age. All four aspects have to do with scarcity, since we are talking about unrepeatable, unreformable lambs and therefore with a limited supply. Of all these elements, we could say that only the degree of preservation and the age are relatively *objectivable. It is reasonable to think that of two Roman bridges, with the same artistic characteristics, the one in a better state of preservation will be more valuable. In the same way that two palaces, with the same artistic consideration, the one from the 14th century will be more valuable than the one from the 19th century. The incorporation of time in the economic value means that the older a heritage asset is, the more improbable it will be to find other similar lambs (thus increasing the supply of substitute lambs). In general, in the case of industrial heritage, we can say that the origin of its value, in comparative terms compared to other heritage lambs, cannot be based on these two *objective elements, since its good state of conservation is compensated precisely by its scarce history (in terms of time).