REFURBISHMENT OF TRADITIONAL BUILDINGS: A LESSON FROM THE PAST?
ALPINE
Daria Petucco1, 1
Università Iuav di Venezia, ArTec - Archivio delle Tecniche e dei materiali per l’architettura e il disegno industriale, Dorsoduro 2196, 30123 Venezia, dariapetucco@gmail.com
ABSTRACT Traditional alpine buildings can still convey, despite hundreds of years, a wide range of meanings. In their position, orientation, form, in the selection of local materials, in their construction technology and in the possibility to be easily repaired they seem to show something that could be called ante-litteram sustainability. Their refurbishment on one side it is a way to transmit and propose again this teaching; on the other, by giving to these buildings a new function in a social and economical changed context, it asks the fulfilment of new requirements. This practically means a building adaptation to new performances and accordingly the introduction in the building site of different materials than the original stone and wood. The paper will present and analyse the refurbishment of two case studies located in Selva di Cadore (BL), as regards in particular the issue of building materials and their environmental sustainability. Case studies analysis will be based on building elements, requirements needed, original materials and materials used in the refurbishment. Starting from the principles that generated and maintained these original buildings and with the support of literature on sustainability, the paper will identify some criteria in the selection of building materials in the refurbishment of traditional alpine buildings.
Parole chiave/Key-words: refurbishment, alpine buildings, materials
Introduction Building refurbishment seems to be a key topic in the building sector a. Among other, two main aspects support this thesis. The first aspect aims to avoid new land use, in order to prevent and mitigate the environmental consequences of soil sealing. The second one considers the amount of existing buildings and the necessity to improve their energy performance. In Italy, giving an example, existing buildings consume the 39,5% of total final energy consumption (source: Ministero dello Sviluppo Economico). Of these buildings stock, the 59% is built before 1971 (source: Istat e Agenzia del Territorio), which means before any regulations in favour of energy savingb. If this observation can be applied to buildings in general, the refurbishment of traditional alpine buildings adds other challenges. Among the many, a first one regards the cultural significance of these buildings. They represent the technical answer of groups of people toward a particular environment and its specific resources. The abandon of these buildings is also a loss of material culture. Another element in favour of their refurbishment extends the view to a regional scale. If on one side the depopulation of mountainous areas is evident, on the other it is possible to identify some counter-trends, as for example those called “amenity migrants�, people that decide to live and work in places with high environmental qualities (Dematteis, 2011). Today, mountains can be seen as places in which shapes a new model of sustainable developmentc. In this scenario, the refurbishment of traditional buildings not only avoids new land use, but it also can foster the development of local short supply change, as regard building materials and technical know-how. Finally, considering the tourist attractiveness of alpine territories, the refurbishment of traditional building is indicated as a way to develop the idea of sustainable tourism, as declared by the Alpine Conventiond. However, the refurbishment of these buildings takes place in a totally different context (social, economic) than the context that produced them. As consequence, in most of the cases the function of building is converted from rural to residential. A refurbished traditional alpine building needs thus to satisfy some requirements, as concern e.g. energy, safety, usability. Different materials get into the building site, in order to answer to these requirements. Original buildings were built mainly with stone and wood, found on site. Their refurbishment needs other materials and extends the map of the materials procurement. In this scenario, the environmental sustainability of the process of refurbishment and in particular of building materials - are factors that need to be taken into account. Handbooks on the refurbishment of traditional alpine buildingse suggest to use local materials; unfortunately, this suggestion can't always be followed. The research on this theme - nearly new in the sector of building refurbishment focusing on the specific point of view of building materials (i.e. their origin,
procurement, composition, installation, recyclability), it is a way to analyse some trends and identify possible operative criteria. Description of method The paper addresses the issue of the refurbishment of traditional alpine buildings through the analysis of two case studies. Building 1 and Building 2 (henceforth B.1 and B.2) are both located in an alpine area (Selva di Cadore, BL) and they are built with pre-industrial building techniques. The informations about B.1 and B.2 which support this paper come mainly from direct interviews with the architects and from the materials (pictures, drawings, reports) they providedf. The analysis presented in this paper is divided in three main parts. The first part aims to briefly describe B.1 and B.2 before the refurbishment, to identify the main features of the two buildings. These aspects are: location, year of construction, building typology, original function and building materials. Table 1 summarizes this aspects, implemented with some data about the refurbishment. The second part, which is the most substantial, presents the work of refurbishment of B.1 and B.2. A general description of the refurbishment of the buildings introduces the chapter: type of intervention, protection, function and a brief description of the construction process. After this, B.1 and B.2 are figuratively broken into different parts (supporting structure, envelopes, internal and external partitions) and their related elements, following the UNI 8290-1:1981g approach. This allows to identify common and recurring elements in traditional alpine buildings and to describe them homogeneously and transferable for future researches. For each elements so catalogued, the functional requirements of final user are identified (safety, comfort, usability, appearance, management, integrability and environmental protection, as defined by UNI 8289)h which are needed in the building reuse. It is thus given a short description of the interventions which are necessary to fulfil the requirements. All this steps are aimed at the comparison between the original materials of building elements and the materials needed in the refurbishment. The analysis of materials is divided in: recovered materials from original building (e.g. larch wood beam); recovered materials from other buildings (e.g. larch wood beam from a disassembled building); “new” materials but similar to the original (e.g. new larch solid wood beam); “new” materials but different to the original (e.g. steel beam or glued laminated timber). All this process is deeply described in Tab.2 (for B.1) and Tab.3 (for B.2). The third part tries to identify some features, criticality and trends in the refurbishment of traditional alpine buildings, starting from the analysis above. The paper does not intend to be exhaustive about the whole work of refurbishment (e.g. plants are not considered in this work). Its aim is rather to highlight the
connection between the refurbishment of traditional alpine buildings (new function, new requirements) and the resources needed (materials). Case studies descriptions B.1 is located in the hamlet of L'Andria. The building type can be referred to the ladin bi-parted (casa ladina bipartita), that encompasses two function - the rural and the residential - under the same roof. The functional division is marked vertically, by means of two different building materials: stone walls for the residential part and the stable; a wood structure for the barni. On the ground floor, there are a kitchen, a room named stua (a wood-paneled room with a heating device, which is connected and stoked by a fireplace in the kitchen), a storeroom and a stable. On the first floor there are two bedrooms and the northern one leads to a tool shed, located in the back. Next to this residential function, empathized by a change of materials - from stone to wood - , there are a barn and a palanzin which is an outdoor balcony used for drying the broad beans. On the upper floor there is an attic which is used as depot. B.2 is located in the small hamlet of Marin. On a stone wall basement, which hosts a stable, rises a braced column wood structure (a crociera)j, which is used as barn in the main floor and as depot in the loft. The barn has an external balcony, also built with wood. On the west and south side of the building there are two added wooden tool sheds. The building is entirely dedicated to rural functions. The main features of the two case studies are summarized in the following table.
Tab.1 - Main features of Building 1 and Building 2.
Case studies refurbishments The refurbishment of B.1 and B.2 shows different approaches and solutions. This reinforced a largely shared thesis: each building has to be considered as uniquek. If it is recommend to identify common strategies and orientations in the refurbishment (as regards e.g. materials and techniques), the uniqueness of each building acts like the first and inescapable factor. Both buildings have thus gone through a long process of physical, technical and historical analysis, as first approach and tool to the designl. Firstly, the work of refurbishment faces the challenge to revive a building in a completely different context from its original one. This regards, e.g. the function (from rural to residential), the way of life and comfort level of new inhabitants (e.g. installation of plants, durability of materials), the legislative framework (e.g. energy, seismic) and, of course, the availability of specific building materials and techniques. The analysis of the two case studies intends to give a brief description of their refurbishment, followed by tables which focus on the theme of materials supply, referred to the more expressive elements of these buildings. Building 1. The intervention foreseen for B.1 is a “partial building renovation� (ristrutturazione edilizia parziale - tipo 2).m The new function planned for the building it is residential. Considering that part of the building already has this function, the most challenging task is the conversion of the barn into a liveable place. On the ground floor the kitchen and the stua are maintained. The stable and the storeroom are resized and converted into a bathroom and a gym. New underground rooms for technical plants and storage are added on the north-west side of the building. On the second floor, as originally, the stone walls host two bedrooms. The wood barn becomes a living room. A bathroom, an entrance and an utility room are located in the north side. The outdoor balcony maintains its features. Finally, the original attic is converted into a bedroom, a bathroom and a loft. As concerns the stone part of the building the main work is its consolidation: the realization of a new foundation, the protection from water percolation in the northern embankment and the filling of connections between the stones. The thermo-hygrometric behaviour is also taken into account. As the disassembling of the wood frame could compromise its consolidated static behaviour, this structure is just cleaned with a cryogenic process. This is due to the preservation of the particular characteristics of wood joints, which can rotate in to absorb the pressure of hay, snow and wind. In order to answer to static issues, frameworks of glued laminated timber are juxtaposed to the original wood structures. The same principle is adopt to the roof: a new thermal-insulated roof,
which partly rests on the glued laminated timber frameworks, is built over the original one. The refurbishment works try to preserve original materials where feasible (the 70%, as the architect declares) and when this is not possible, they are recycled and reused for other functions (i.e. plaster is shattered as basis for new plaster). The building, thanks to thermal insulation of the shell and the plants efficiency, obtained an “A” building energy rating. Building 2. The intervention allowed for B.2 is also a “partial building renovation” (ristrutturazione edilizia parziale - tipo 1).n Differently from B.1, B.2 faces an additional issue in terms of refurbishment: change the rural function into residential and so adapt the building to a new use that was not foreseen in the original. The task for the architects is to match the residential function, which needs to be included, with the spatial and material features of the original building, in order to respect its nature and transmits its history. Following this idea, two bedrooms - which are more suitable to narrower and enclosed spaces - are located on the ground floor, together with two bathrooms and a technical room on the northern side. On the first floor the volume of the wooden barn is almost entirely transformed into an open space (except form a guest room and a toilet, on the north-west side) which hosts the kitchen, the living and dining room. The loft is arranged as a reading place. The wood structure has been totally disassembled. Each element is thus checked, cleaned and, if necessary, repaired. The main wooden bearing “cage”, (pillar, bracing elements and beams), is replaced with steel elements, due to structuralstatic necessities. The steel structure is integrated with bearing wood beams recovered from the disassembled original structure, from other disassembled buildings or replaced from scratch. The external wooden cladding is maintained. The same approach is used for the floor: original joists are cleaned, resized and integrated with a concrete slab. The roof is instead built with a new wooden structure. As regards the stone wall, it is disassembled. Stones are recycled for the reconstruction of the new wall - with reinforced concrete core - with the same aspect and dimension of the original. Building foundations, that were almost non existent in the original building, are built with reinforced concrete. A retaining wall is realized on the underground northern side of the building, to prevent water percolation and bear the loads. As declared by the architects, the work tries to preserve original materials (the 5060%) and, where possible, to recover wood from other buildings. The building, thanks to thermal insulation of the shell and the plants efficiency obtained a “B” building energy rating.
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Tab.2 - Refurbishment of B.1: elements, requirements and materials analysis.
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Tab.3 - Refurbishment of B.2: elements, requirements and materials analysis. Conclusion As emerges by the analysis of B.1 and B.2, the refurbishment of traditional alpine buildings and their conversion into residential buildings, introduces in the building site a wide range of materials, which can be divided as follows. The first aim of the refurbishment project is to preserve original materials (stone and wood) and their functionality, where possible, and to recover them. Wood is often cleaned and restored. As regard the stone, it is possible to maintain the entire element (the stone wall) or just the single blocks, which can be reused to build a new wall. A second strategy is to re-employ the materials recovered from other buildings. This regards, e.g. wood beams and planks, stone blocks that belonged to buildings in ruins or disassembled. This strategy, which is also suggested by some handbooks on the refurbishment of rural buildingso, has the advantage to reuse existing elements and thus to avoid a significant part of manufacturing process and its related energy consumption. Moreover, the appearance and consistency (e.g. the seasoning of wood) of recovered materials can be more similar to the original one. The integration of the original materials can also be done with “new� materials (in terms of time) but which are similar to the original stone and wood. This happens more often with wood elements, i.e. solid wood beams. In most of the cases, the similarity concerns the appearance, the essence and the manufacturing (i.e. the revived of a traditional processing). As regards material procurement (e.g. the same forest), it is more difficult to fulfil the principle of similarity. The three categories of materials listed so far, include - in most of the cases - stone and wood, namely the original materials of traditional alpine buildings. However, as highlights the analysis of B.1 and B.2, the majority of materials that are employed in the refurbishment, are different from the traditional stone and wood.
Some sub-categories can be the following: “innovative” materials (e.g. glued laminated timber, plywood, low emissivity glass); traditional materials but strangers in regards to the building typology considered (e.g. concrete, reinforced concrete, steel, brick); plastics and similar (e.g. polystyrene, polyethylene); composite materials (e.g. carbon fiber). On one side, traditional alpine buildings teach a lesson about the calibrated and contextual use of resources and in particular of the materials. On the other side, their refurbishment should adapt these buildings to different requirements, which of course need to be satisfy through the use of resources and “new” materials: the best example can be that of the insulating materials. The attempt to find a balance between these two aspects it is of course a critical point in the design and realization of a refurbishing. Considering what has emerged in the analysis of two case studies and referring to literature on sustainability in general, as e.g. sustainability rating systemp, it is possible to start to identify some criteria for the refurbishment, which can learn from the lesson that these buildings bring to us. One of these could be the criterion of recovery and reuse. This could not only be a way to preserve and recognize the value of these buildings but also a way to introduce the refurbishment in a concept of circular economy. Secondly, the proximity of materials, which are necessary in the refurbishment, could be another criterion. This aspect was fundamental in the construction of traditional alpine buildings. Today transports represent the 32,9% of total final energy consumption (Source: Ministero dello Sviluppo Economico). Fostering the use of local materials and products (i.e. wood) can be a way to reduce this percentage and also to improve closed loop local economies. Thirdly, another criterion could be the use of materials and systems that could be assembled and disassembled (e.g. dry construction). Traditional alpine buildings have often a “hard” core made of stone and a disassembled wood frame. People could easily repair and replace the elements: some floors were build following this principle, and with the possibility to extract a single deteriorated joist. Moreover, lifestyle and needs of people are changeable. Working on reversibility of material assembly it is therefore a lesson learnt from the past and a sustainable approach. Another criterion could be those of compatibility. Building industries offer a wide range of materials. The choice of a material rather than another should consider firstly the interaction with the original building materials. A last criterion, among the many that could be identified, touches the field of innovation. Material innovation offers products that could in part satisfy the previous listed criteria, but that are also specifically designed for the refurbishing. Thermal-insulated plaster or carbon fiber heating panel (with a millimetre thickness, which heats the room without the necessity of modify the storey height) are some example in these direction. Traditional alpine buildings are a results of continuous and repeated innovations too.
a In 2012 in Italy the only sector with a positive trend was those of refurbishment. (Ance, 2012). b Data are available in the Energy Efficiency Report, November 2011. c “Montagna 2020. Per una crescita intelligente, sostenibile e inclusiva delle zone di montagna”. In www.montagna-europa.it (last accessed 18/04/2013).
d Alpine Convention, Tourism Protocol, 22.12.2005, article 11. e A refurbishment handbooks comparison is made by the author in her ongoing Phd Thesis. f Interviews with the architects of B1 (Arch. Giuliano Giusto) and B2 (Arch. Francesco Loschi from Studio Exit) were conducted by the author in march 2014.
g UNI 8290-1, Residential building. Building elements. Classification and terminology. (Plants are not considered in the analysis).
h UNI 8289, Building - Functional requirements of final user - Classification. i B1 is also quoted in E. Gellner (1988), Architettura rurale nelle dolomiti venete, p.141. j The wood structure system “a corciera” is described by E. Gellner (1981), Architettura anonima ampezzana: nel paesaggio storico di Cortina, pp. 71-72.
k Op.cit. Gellner (1988), p. 225. l The importance of the preliminary analysis is emphasized in all the refurbishment handbooks, analyzed by author in her ongoing Phd Thesis.
m Allegato 1 alle N.T.A. del P.R.G.del Comune di Selva di Cadore, 1992, p.7. n Ibid. p. 9. o Musso S.F., Franco G.(2000), Guida alla manutenzione e al recupero dell'edilizia e dei manufatti rurali, Marsilio, Venezia, p.14.
p As e.g. Leed, Itaca.
Bibliography Ance (2012), Osservatorio Congiunturale sull'industria delle costruzioni. Politecnico di Milano (2011), Energy Efficiency Report, L’Efficienza Energetica in Italia: modelli di business, soluzioni tecnologiche, vincoli e opportunità di sviluppo. Dematteis G. (a cura di) (2011), Montanari per scelta. Indizi di rinascita nella montagna piemontese, FrancoAngeli, Milano. Official Journal of the European Union (2005), Protocol on the implementation of the Alpine Convention of 1991in the field of tourism - Tourism Protocol. UNI 8290-1 + A122:1983, Residential building. Building elements. Classification and terminology UNI 8289, Building. Functional requirements of final user. Classification. Gellner E.(1988), Architettura rurale nelle dolomiti venete, Edizioni Dolomiti, Cortina. Gellner E.(1981), Architettura anonima ampezzana: nel paesaggio storico di Cortina, F. Muzzio & c. editore, Padova,. Musso S.F., Franco G.(2000), Guida alla manutenzione e al recupero dell'edilizia e dei manufatti rurali, Marsilio, Venezia. Leed Italia, Gbc Italia (2011), Green Building. Nuove costruzioni e ristrutturazioni.