Integrated Conservation Strategy of Built Heritage =Estratégia de conservação integrada do património edificado: sistemas construtivos tradicionais e materiais naturais

摘要

The risk of losing ancient construction systems is highly relevant in the whole Mediterranean region, but also in many other countries worldwide. The earthen heritage and the mixed construction systems with timber are decreasing very fast and being identified in lists of risk by UNESCO, ICOMOS and by many researchers all over the world. They represent a cultural value of the societies that is being neglected due to unbalanced development, demolitions, lack of knowledge, and guidelines for conservation, instead of the expected unique reason of decay due to natural agents or ageing. Although some conservation approaches have been successful, the results are still scarce and the mistakes continuously repeated imposing irreversible gaps in reading this relevant heritage, mainly in urban areas. This entails questions about the approach to protection, conservation, and the reasons behind such disseminated failure in these objectives. The earthen architecture shows precisely the difficulties in the establishment of a strategy able to successfully achieve the goal of preserving its cultural value. This needs continuous research and ability to communicate the best conservation strategy as just one of the steps of a balanced framework. This investigation aims to discover reasons for failure of conservation strategies involving the traditional construction systems, valuing the case of adobe architecture; to give significance to traditional construction systems as a cultural value to protect and preserve; to propose conservation research areas necessary in a framework of integrated conservation of built heritage, involving the specific case of adobe buildings. The research methodology of this investigation is based mostly on qualitative methods and a case study about adobe construction system, its evolution since the 19th century until the middle of 20th century, and its interaction with architecture. The case study was used to address the main identified gaps of research needed to proceed with an integrated conservation and protection approach of adobe heritage in Portugal. A combination of sources was used following a multi-method approach: in situ surveys, collection of archive files (drawings, written documents and photos), published literature, published and unpublished reports from international organisations, photographic reports, open interviews, and laboratory tests. The first analyses show evidence of multiple causes of failure for the support of conservation strategies. The most important is the lack of a long-term integrated strategy within a recognized and supported framework. Secondly, the continuity of shortcomings is expressed in inadequate choices at several levels of decision-making, absence of measures of maintenance and conservation. Thirdly, the lack of knowledge about the adobe traditional construction system, its evolution and wide interaction with architecture, the approach to the present standards of comfort, and finally, the problem of waterproof barrier and salt's effects are the main causes of failure in the promotion of adobe conservation strategies. This research recommends the use of the construction system as a cultural value to guarantee the longevity of traditional building heritage, supported by research. It also stresses the importance of understanding the difficulties of application of conservation strategies, looking to a wider international area to better understand the reasons behind causes and eventual successes. It proposes an interpretation of evolution of the adobe construction system and identifies the main defects, both of which should constitute the base of knowledge of any conservation strategy. Finally, considering an integrated framework of conservation strategy, an approach is recommended that integrates key issues of awareness for heritage and research. The specific case study of adobe construction emphasized three main approach areas: the vernacular architecture for public awareness; thermal and comfort issues for protection strategy; and finally, the waterproof barrier with diatomaceous earth, its role in the decrease of salt's effects and as an effective barrier, for the use of research to solve technical problems of earthen construction.