Thesis

Modelling the life cycle performance of Portuguese vernacular buildings: assessment and contribution for sustainable construction

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Abstract

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.

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... Life cycle stages framework for building materials[18,28]. ...
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Global environmental awareness pushes the building sector to achieve carbon neutrality and find low embodied impact solutions. The European Union has set a 2050 goal and is regulating the whole carbon life cycle (embodied and operational) as part of the Energy Performance of Buildings Directive (EPBD). In this scope, low-tech geo-bio-based materials can have an important role in reducing the embodied environmental impacts and carbon in buildings. Due to their low processing production, these materials fit in a circular approach since they can be easily recycled or returned to the natural environment at a minimal environmental cost. However, the lack of quantitative data on the life cycle environmental performance of some non-conventional techniques can hinder their use since professionals cannot compare the benefits of such versus conventional practice and comply with future EPBD requirements. This paper aims to contribute to the topic by presenting results on the life cycle environmental performance of earthen materials and bio-based insulation products versus conventional solutions based on data from Environmental Product Declarations or studies following the EN15804 standard. The results show that earthen materials can reduce the potential environmental impacts by about 50% versus conventional mansory walls. At the same time, bio-based insulation solutions offer the advantage of lowering operational carbon emissions and stocking carbon (e.g. straw has a Global Warming Potential performance about three times better than Expanded Polystyrene). The benefits of using earthen and bio-based materials are also discussed for the different building life-cycle stages, focusing on the possibility of reusing/recycling these materials in a closed-loop approach.
... Similarly, ´part 13´ of the Recovery and Resilience Plan covers energy efficiency and focuses on engineering and material solutions. Simultaneously, there is a wide range of bioclimatic solutions present in vernacular architecture in Portugal (Fernandes, 2020), that in the last decades have been neglected. ...
... Similarly, ´part 13´ of the Recovery and Resilience Plan covers energy efficiency and focuses on engineering and material solutions. Simultaneously, there is a wide range of bioclimatic solutions present in vernacular architecture in Portugal (Fernandes, 2020), that in the last decades have been neglected. ...
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