An important transformation in architectural wall construction has been made. The mass has been decreased, new materials have been incorporated, and the use of a single element has been substituted by several layers. These modifications have an important impact on the hydrothermal conduction of the walls, and therefore on the amount of energy required to maintain a building's comfort level during its lifetime (energetic effectiveness). An analysis was performed using differently aged schools, houses and buildings in Córdoba, Argentina. The walls were classified and different categories were established based on whether or not single or multiple layers were used and with what materials. The hydrothermal behaviour was assessed using software designed to estimate the transmittance and condensation risk according to the current Argentinean norms which establish the minimum and recommended amount. The current cost was calculated, allowing a comparison of cost – profit. The conclusions indicate a general decrease in the hydrothermal performance of the walls in terms of comfort, increase in energy consumption and a creation of various pathologies which reduce the walls' lifetime. The transformations are not considered as a general system change, but rather as a performance change. In the professional field there is a lack of knowledge about new types of construction, which leads to the frequent selection of alternatives that are far less efficient but just as costly.