Vernacular architecture is closely and traditionally linked to energy efficiency due to its adaptation to climate and location. The main purpose of this paper is to diagnose the hygrothermal behaviour inside the vernacular housings of the Jerte Valley (Valle del Jerte), located in the Spanish Central System mountain range (Sistema Central). This region is widely characterised by a Mediterranean continental mountain climate with medium-sized mountains and presents two distinguished six-month periods: one is warm and dry, whereas the other is cold and rainy. The objective of the aforementioned diagnosis is to promote the preservation of buildings and its energy refurbishment. As a starting point, a study that associates the region's monthly climate data with the thermal comfort has been developed. Afterwards, a regional building type has been defined for further use by an energy simulation program in order to measure the hygrothermal behaviour of the envelope. Finally, these results have been related both to thermal comfort and bioclimatic strategies. The results suggest that, during the warm period, indoor conditions are comfortable without the need for an additional energy supply. Nevertheless, in the cold period, indoor conditions are warmer than outdoor conditions, but an additional external energy supply will be required to achieve the comfort zone. Accordingly, it is determined that the refurbishment solutions used for those constructions must maintain intact the bioclimatic strategies that benefit summer conditions. However, strategies that give rise to winter conditions without changing its summer behaviour must be improved. (C) 2016 Elsevier B.V. All rights reserved.