Vernacular architecture is characterised by embodying and expressing a plurality of factors - geographic, climatic, economic and cultural - of the places in which it is located. In its long evolution, and inserted in a context of scarcity, a range of pragmatic strategies and building techniques of adaptation to the surrounding environment were developed. These strategies/materials are usually simple, low-tech and have a low potential environmental impact. From a sustainability point of view, several studies highlight them as having the potential to reduce the environmental impacts of buildings.
In Portugal, there are many expressions of vernacular architecture, whose specificities are an identity factor of several regions. However, there is a lack of quantitative studies on the thermal and environmental performance of vernacular buildings and materials in the Portuguese context. In this sense, this research work presents a qualitative and quantitative study of i) climate-responsive strategies; ii) the thermal performance and comfort conditions of different Portuguese vernacular buildings throughout the different seasons; and iii) the environmental performance of vernacular materials. The research focused on the study of three case studies, with specific features and located in three different zones of mainland Portugal. The thermal performance and comfort conditions of the case studies were evaluated through in situ monitoring of hygrothermal parameters, surveys on occupants’ thermal sensation, and the data analysed according to an adaptive model of comfort. To compare the influence of some strategies on the annual energy demand for heating and cooling, simulations under dynamic conditions for different scenarios were carried out. In the case of vernacular materials, although these are seen as ecological, the quantitative studies available are scarce and that allow establishing an equative comparison with conventional materials. Thus, the life cycle assessment of two earthen materials, rammed earth and compressed earth blocks (CEBs), was carried out and based on specific life cycle inventory values obtained from a producer company, following the guidance provided by the standard EN15804.
From the results, in general, it was found that the case studies have shown a good thermal performance by passive means alone and that the occupants feel comfortable, except during winter when there was a need to use heating systems. In the case of materials, in a cradle-to-gate analysis of different walls, the use of earthen building elements can result in reducing the potential environmental impacts by about 50%, when compared to the use of conventional ones. Additionally, earthen materials have the advantage that they can be recycled/reused in a closed-loop approach.