Vernacular architecture is characterized by a type of formal expression, which has been developed in response to a number of factors -geographic, climatic and economic -characterizing the local area or region. Despite the fact that Portugal is a small country, there are many different architectural approaches and a range of techniques have been employed in different regions to mitigate the effects of climate. These vernacular approaches have the potential for further development and could be adapted in response to contemporary needs. In this paper, a range of different passive solar techniques used in Portuguese vernacular architecture to provide comfort is presented. The specific focus is on the effectiveness of passive cooling strategies (namely, high thermal inertia, use of light colours and courtyards), and the findings of a case study in which the thermal performance during the summer of a vernacular residential building located in the south of Portugal are presented.

Keywords:Vernacular architecture Life-cycle assessment Environmental impacts Rammed earth Compressed earth block (CEB) Earthen architecture a b s t r a c tIn the Portuguese context, the life cycle assessment of building materials is still in its infancy. So far, there is only a small number of Environmental Product Declarations (EPDs) available, all target for industriallybased materials. Although vernacular earthen materials are seen as ecological materials, with low potential environmental impacts, there are no studies that allow to quantitatively compare these materials with conventional ones, according to the applicable standards. In the case of Portugal, there are no EPDs or studies for these materials and the studies available worldwide are hard to compare, since they not follow the same life-cycle assessment methodology. This paper aims at contributing to a better understanding about the environmental performance of earthen materials by presenting results from the life cycle assessment of Compressed Earth Blocks (CEBs) and Rammed earth, based on specific life cycle inventory values obtained from a producer company, following the guidance provided by the standard EN15804. Among other conclusions, results show that CEB and Rammed earth have a total Embodied Energy of 3.94 MJ/block and 596 MJ/1 m 3 and a Global Warming Potential of 0.39 kg CO 2 eq/block and 47.5 kg CO 2 eq./1 m 3 , respectively. In a cradle-to-gate analysis of different walls, the use of earthen building elements can result in reducing the potential environmental impacts in about 50%, when compared to the use of conventional ones. Additionally, the advantages of using earthen materials are also discussed for the different building life-cycle stages, focusing on the possibility to recycle these materials in a closed-loop approach.

Solar passive strategies that have been developed in vernacular architecture from different regions are a response to specific climate effects. These strategies are usually simple, low-tech and have low potential environmental impact. For this reason, several studies highlight them as having potential to reduce the demands of non-renewable energy for buildings operation. In this paper, the climatic contrast between northern and southern parts of mainland Portugal is presented, namely the regions of Beira Alta and Alentejo. Additionally, it discusses the contribution of different climate-responsive strategies developed in vernacular architecture from both regions to assure thermal comfort conditions. In Beira Alta, the use of glazed balconies as a strategy to capture solar gains is usual, while in Alentejo the focus is on passive cooling strategies. To understand the effectiveness of these strategies, thermal performances and comfort conditions of two case studies were evaluated based on the adaptive comfort model. Field tests included measurement of hygrothermal parameters and surveys on occupants' thermal sensation. From the results, it has been found that the case studies have shown a good thermal performance by passive means alone and that the occupants feel comfortable, except during winter where there is the need to use simple heating systems. OPEN ACCESSBuildings 2015, 5 1243

In Portugal, there is a lack of quantitative studies on the thermal performance of earthen buildings. This paper aims at contributing to this research context by studying site-specific strategies, and the thermal performance and comfort conditions of a rammed earth building located in southern Portugal. The study is based on objective and subjective assessments and consists of assessing the hygrothermal conditions, thermal comfort levels and analysing the occupants' perception regarding thermal sensation. The results showed that the strategies used are closely related to local conditions, mitigating the effects of high summer temperatures and ensuring a good summer thermal performance by passive means alone. During the summer monitoring, results showed that the building stayed most of the time (80%) in Category I (high level of expectation) and the remaining time in Category II, according to the classification method defined by the standard EN15251. During the winter period, the building had the worst performance, being necessary a heating system to guarantee comfort conditions. Additionally, the results showed that the good thermal performance of the case study depended more on the high thermal inertia than on the U-value of the envelope. Limitations and advantages of the use of earthen construction elements are discussed.

Vernacular architecture embodies a plurality of constraints from places where it belongs, in which the use of local materials and techniques is one of the main features. When compared with industrially-produced materials, vernacular materials have low environmental impacts, being an alternative for sustainable construction. The increasing use of new industrially-produced and standardized materials led to the homogenization of the different used construction approaches, and spawned a universal architecture that in many cases is out of the environment context and is very dependent on energy and other resources. This paper addresses the relation between Portuguese vernacular architecture and locally sourced materials, relating them with the territory lithology, agricultural crops and the climate. To assess the contribution of these materials for sustainability, a comparison with industrial materials at level of environmental indicators was established. This paper highlights the advantages of using local materials and techniques as a factor of local socio-economic development.