Reabilitação funcional do património industrial edificado com recurso a membranas arquitectónicas: aspectos programáticos, construtivos e económicos

REABILITAÇÃO FUNCIONAL DO PATRIMONIO INDUSTRIAL EDIFICADO COM MEMBRANAS ARQUITETONICAS: ASPETOS PROGRAMATICOS, CONSTRUTIVOS E ECONOMICOS FUNCTIONAL REHABILITATION OF BUILT INDUSTRIAL HERITAGE WITH ARCHITECTURAL MEMBRANES: PROGRAMMATIC, CONSTRUCTIVE AND ECONOMIC ASPECTS Mónica Macieira, researcher1,2; Paulo Mendonça, Associated Professor1; João Miranda Guedes, Associated Professor2 1 Lab2PT, Escola de Arquitetura da Universidade do Minho; 2CONSTRUCT, Faculdade de Engenharia da Universidade do Porto Resumo: No âmbito da utilização de membranas arquitetónicas na reabilitação funcional de edifícios, destacam-se as intervenções sobre o património industrial. No presente estudo são analisados 9 projetos representativos deste tipo de intervenções, de acordo com parâmetros programaticos, construtivos e economicos. Verificou-se que a maioria deste património localiza-se na Europa e foi convertido para atividades culturais ou escritorios. Os resultados desta análise realçam o desempenho adequado das membranas arquitetónicas, como o elevado grau de adaptabilidade/reversibilidade em relação ao edificio pre-existente, permitindo, intervenções ligeiras. Palavras-chave: membranas; reabilitação funcional, edificios industrais. Abstract: In the research framework of the use of architectural membranes on functional buildings rehabilitation, stands out interventions on industrial heritage. In this study 9 representative projects of this intervention’s type are analyzed, according with programmatic, constructive and economic parameters. It was found that most of these buildings are located in Europe and were converted into cultural or office activities. The results of this analysis highlight the adequated performance of architectural membranes, as a high degree of adaptability/reversibility with respect to the pre-existences, allowing, in general, light interventions. Keywords: membranes, functional rehabilitation, industrial buildings. 1. Introduction 1.1. Assumptions for building rehabilitation According to Appleton (2003), building rehabilitation should attempt to meet three basic criteria: reversibility; compatibility and durability. The reversibility intendes to safeguard pre-existances from possible ineffectiveness of adopted solutions, although total reversibility is in most cases impractical. Nevertheless, the intervention proposals must guarantee, at least, the compatibility between what exists and what is proposed, as well as the durability of the adopted solutions. To the notion of technical and material compatibility, Douglas (2006) adds the importance of use compatibility. It is essential that use choice does not be a threat to the constructive and architectural character of the building, but, on the contrary, this same choice should be based on the identified building capabilities to guarantee an optimal appropriation of the space, with minimal intervention and disorder. About use compatibility, industrial building appears to be an example of interest because of their spaces features. It would seems unsustainable the effort, for example, to transform a large and daylight plenty industrial building in a markedly compartmented use, or the reverse. Durability criteria aspires to restrain maintenance needs, and consequent impacts and costs, extending the period for the future next intervention. Equally important as basic premises are the principles of adaptability, repairability/ examination acess and sustainability. Where possible, it is necessary to ensure visual access to essential points of the building to early detect any anomalies or pathologies (related with the importance of diagnosis mentioned by Guedes et al, 2003). On the other hand, it should be given preference to solutions that address the possibility of partial repair instead of their complete replacement. Assuming that the base structure doesn’t present significant damages, intervention’s degree is more associated with architectural decisions (space, function, comfort, etc.) that could impose significative changes/transformations. In these transformations, building technologies and material choice (with respect to its expression, feasibility, etc.) must consider the above mentioned. 2. Adopted methodology The research has been focused on possibilities that architectural membrane technologies could improve in relation with functional retrofitting of industrial heritage buildings. This study started from the analysis of 60 representative examples, from which 9 were focused on retrofitting of industrial buildings (representing 15%); they were analysed according to parameters shown on Table 1. Thus, selected projects have been grouped and compared. Table 1. Main parameters in study. Programmatic Constructive Economics • Use/ function; • Building typology; • Type of rehabilitation intervention; • Type of use • Type of membrane; • Type of anchoring; • Auxiliary reinforcements; • Self weight; • Fire resistance; • Type of pre-existing building’s structure; • Type of load transmission from membrane to existing structure; • Membrane’s span. • Global cost (material+ installation) • Total cost of intervention • Financing Source 3. Analysis of main parameters in study 3.1. Programmatic Parameters The third analysis criteria regards building program, type of use (permanent or temporary) and type of rehabilitation intervention; important data to evaluate the trend application of these solutions. In It was found that membrane materials have had a significant application in buildings with non-residential category. It was found that 67% of all 60 membrane interventions correspond to use conversions of non-residential buildings. These use conversions occur mainly in buildings with industrial original use (31%) (Figure 1). Figure 1. Use conversion of non-residential buildings analysed: inicial use (inner circle) e final use (exterior crcle). Most part of buildings with industrial use that were interventioned with membranes suffer use convertions (67%) (Figure 2). Among these, 33% were converted into cultural use and offices (Figure 3). One possible interpretation is that frequent amplitude and flexibility spatial features of industrial interior space, combined with a generous natural lighting, make these buildings strong candidates to accommodate special programs or for collective use; which otherwise would be more dependent on new constructions. Figure 2. Existence of use convertion in the analysed projects. Figure 3. Final use of the analysed industrial buildings, with use conversion. As any other buildingit, isn’t possible to understand industrial buildings without knowing the program to which it responds. Regarding industrial program, generally, perhaps the main requirement is its fast and constant redefinition requirements. Independently of symbolic and representative character that industrial building can take, from a certain point, it is first of all a functional shelter. Its appearance, shape and implantation depends on functional and economic factors that derive from evolution stage of a particular industry in a given place and time. In this sense, the resultant architectural features may or may not be a direct consequence, in stylistic and aesthetic sense of the function that it hosts. It is first of all the result of different functional type’s relationship that the building can establish with their industrial occupants. In this line of thought, Cartier (2002) proposes a comparative approach, rather than trying to establish a chronological categorization, aesthetics, or by industry type. Then are identified 5% 13% 5% Industrial; 31% 4% 13% 4% 4% 9% 4% 4% 4% Cultural; 45% 4% 3% Offices; 31% 14% 3% Library Religious Cultural Industrial Warehouse Defense Cave Commercial Offices Educational Accomodation Health Sports with conversi on 67% without conversi on 33% Cultural 33% Residential [PERCENT AGEM] Offices [PERCENT AGEM] Accomodat ion [PERCENT AGEM] some typologies industrial buildings: minimum shelter, neutral envelope, envelope, tailored envelope and building machine. It was found that most rehabilitation projects under study focus on neutral envelope typology (45%) (Table 2). Neutral envelope is defined a building typology whose relationship with its host function it’s relatively indifferent. This doesn’t mean that industrial use does not impose certain conditions to the space, but these are guaranteed by excess in the form of a neutral box, capable of host the said industry as adapt later to another. These buildings have high ceilings, where cames out its large vertical windows and/or roof with skylights to ensure uniform natural lighting. Appear associated with emerge and development of new industrial materials - such as iron, glass and later reinforced concrete - whose features allow to perform larger spans without structural walls. Table 2. Rehabilitation projects with membranes according to the industrial buildings typology. Industrial buildings typology* Rehabilitation projects with membranes [%] Neutral envelope 45% Minimum shelter 33% Tailored envelope 11% Building machine 11% * Difined by Cartier (2002). The membrane’s average durability contrasts with the high durability of the physical structure of industrial buildings, but it keeps up with the relative short/medium use period of the new programms/requirements that determine the functional rehabilitation of these areas. It’s found that the interventions with membranes have increasingly for permanent use (89%). Regarding the degree of interventions it’s found that they are mostly Light (45%) (Table 3). Table 3. Interventions degree of projects analysed. Intervention degree Example Percentage of cases Light P.04. Logan offices 45 % Medium P.08. Frøsilo 33 % Deep P.03. Dresden Train Station 22 % Exceptional - 0 % 3.2. Constructive Parameters Another analysis criteria of selected projects is related with constructive parameters. Depending on improvements to be achieved, it resorts to different solutions that can be characterized by the combination with other materials, components or structures, as follows: second membrane skin system (Mendonça, 2005), by the interior or building exterior, placed in tension and executed on a preexisting support; membrane panel’s system, mounted on another panel (made by other material or substructure); multi-layer system, composed by different materials and technologies, which external layers are membranes with protection and non-structural function (whose intermediate layers aren’t tensioned); double membrane system under pressure (with positive or negative air insufflation). According to the studied proposals, most of them are built with metallic substructures, mainly steel (89%) (Table 4). Table 4. Constructive data of projects in analisis. Constructive parameters Intervention with membranes Preexisting Funcional Rehabilitation projects of industrial heritage buildings with architectural membranes Type of application * Number of membrane layers Type of load transmission from membrane to structure** Substructure material*** Membrane´s self weight [kg/m2] (estimative) Sub-structure´s self weight [kg/m2] (estimative) Membrane type Membrane superficial area [m²] Light transmission [%] Pré existing structure type **** Reinforcement need for preexisting Structure to make the intervention with a membrane? P.01. Salzburg Train Station T 1 PE ME 1,08 1 PTFE 1700 38 ME no P.02. Sakuragicho Train Station T 1 L ME 0,9 1 GF + PTFE 3573 13 ME yes P.03. Dresden Train Station T 1 L ME 1,2 3 GF + PTFE 30 000 13 ME yes P.04. Logan offices T 1 PE PO 0,2 0,8 PVC 1200 50 MI no P.05. Casting house, Landschaftspark P 2 PE ME 1 4 ETFE 580 81 ME no P.06. Eco Membrane T 1 PO ME 0,5 0,5 PVC 1400 85 ME no P.07. Frac Art Centre P 2 PE ME 1 4 ETFE 3362 81 MI no P.08. Frøsilo P 2 PE ME 1 4 ETFE 9800 90 CO no P.09. Mino T 1 PE ME 0,5 0,8 Polyester 80 20 MI no Average T 1 PE ME 1 2 ETFE 5744 55 ME no * Tensioned (T), Pneumatic (P); ** Ponctual (PO), Perimetral (PE), Lineal (L); *** Wood (WO), Metallic (ME), Polymer (PO);**** Concrete (CO), Metallic (ME), Mixed (MI). With respect to the materials adopted, since its birth ETFE foil has been used in most of the studied proposals (34 %) (Table 5), mainly in the last decade. The self-cleaning, durability and high light transmission have favoured the use in many permanent envelopes, breaking the traditional relation between membrane systems and temporary buildings. Most of the building uses where the pneumatic system has been designed are still focused on cultural programs. But in the last decade, the range of uses has been extended to permanent typologies, like covering of courtyards. The lightness of inflated systems, compared with glass, and the improvement of the membrane resistance materials have favoured the international promotion of this technology; in the last decade they have been used in substitution of glass technologies (Gonzales et al, 2012). Other membranes, like PES or fiberglass coated with PTFE, are also used in large surface envelopes, where higher membrane resistance is needed (Table 6). Table 5. Membrane materials adopted in the analysed projects. Membrane material Percentage Ethylene tetrafluoroethylene (ETFE) membrane 34 % Glass fabric coated with polytetrafluoroethylene (PTFE) 22 % Polyvinyl chloride (PVC) 22 % PTFE membrane 11 % Polyester (open wave) membrane 11 % Tensile structures, as that term refers, reach structural capacity through tensile forces for most components, such as cables or membranes (with the exception of rigid limits and structural components subject to compression and bending). According to Lewis (2003) this structure’s type are usually subdivided into: perimetrically tensioned, pneumatic and with prestressing elements (such cable networks and beams). It’s found that most projects under analysis presents perimetrically tensioned structure (67%) and pneumatic (33%) (Table 5). Planning a rehabilitation intervention begins with the analysis of pre-existing; it’s found that type of pre-existing structure isn’t concrete or mixed, but mostly metallic (78%) (Table 7). Also verifies that 78% of pre-existences didn’t need to be structurally reinforced to receiving interventions with architectural membranes. Table 6. Membrane’s intervention –presented on the analysed projects. Table 7. Pré existing structure of the analysed projects. Type of membrane structure Percentage Type of structure Percentage Tensioned 67% Metallic 78% Pneumatic 33% Mixed 11% Concrete 11% It’s found that constructive membrane systems in analysis transmit loads to the preexisting structure by following substructure‘s types: perimetral (67%), lineal (22%) and punctual (11%). Most perimetral substructures are frameworks, frames and rings; while the linear substructures are beams, arches, trusses and vertical elements; regarding punctual substructures, it only regists masts and hooks. A particular aspect of interventions with membrane building technologies is their high adaptability/reversibility to existing constructions. It turns out that membranes (due to its features) presents a solution to functional rehabilitation of industrial spaces because they efficiently adapts to large spans typical of these buildings; registering membrane’s span execution with 26m (in average) ranging between 15 and 50m. In addiction applied membranes presents large surface areas, between 1001-5000 m2 (45%) (Table 8). Table 8. Distribution of superficial area size of membrane applied on projects in study. Area [m²] Size Percentage 0-50 XS 0% 51 - 300 S 11% 301 - 1000 M 11% 1001 - 5000 L 45% 5001 - 20000 XL 22% › 20000 XXL 11% * Considera-se a classificação da area superficial definida por Gonzales et al (2012). 3.2.1. Membranes for metallic elements proteccion Many industrial buindings presents metallic building components, such as roofs - and there are many reasons to choose membrane materials over other roofing materials. Membrane cladding will never rust, in wet climates, or when storing corrosives. For example, an ETFE membrane, due to its properties, can acts as protectors against metals corrosion from sodium c (FRAC art center (ref. P.07) and Dresden Train Station (ref. P.03) are examples of this). In addition to being unsightly, a corroded roof is unsafe and expensive to repair. Even a small amount of corrosion in the roof is enough to let moisture drip into the building, causing more rust and possibly ruining the interior of the building. Any type of metal, even when treated with an anti-corrosion treatment, is susceptible to rust. A current rehabilitation solution consists in adding a membrane liner on the inside or outside of a roof, to keep corrosive agents out of contact with the steel, making it impossible rust starts. 3.2.2. Auxiliary protection uses There are some interesting proposals related with auxiliary uses which have a great potential in the retrofitting projects. They take advantage of the flexibility and lightness of the new structure, in order to create large covered spaces where the retrofitted building is protected during the work. Recently research has been developed by the Airlight Ltd. (Tensairity® systems). These structures can cover large dimensions with the optimization of compression and tension efforts in the inflated beams, helped by auxiliary elements. Also, the easy assembly and removal, have great potential use in future projects. 3.3. Economic Parameters A common recorded aspect of the analysed projects is that they aims to achive a low construction cost and low energy consumption during the use phase. The last parameter in analysis is the economic. Imports to retain that the global cost of membrane solutions depends on design complexity, location and skilled labor cost (Armijos, 2008); average global cost (Table 9) it’s around 199 €/m2 (range from 30 to 400€/m2). Pneumatic membrane building systems have, in average, higher costs (333€/m2) than other membrane systems (133€/m2) possibly due to membranes layers multiplication and air keep pressure devices; despite its spent less substructure. Among the industrial buildings interventions analysis, expansions are those that have, on average, the highest global cost. (400€/m²) and the modifications have the lower global cost (138€/m²); interventions made in old buildings (built before 1960) have, on average, higher global costs (209€/m2). At project ref. P.03. all membrane’s components for attachment were selected regarding cost reduction and ease of installation (Foster, 2016). Table 9. Main parameters for economic analisis of projects in study. Projetos em análise Type of intervention Membrane superficial area [m²] Global cost of membrane * [€/m2] Financing source P.01. Salzburg Train Station renovation 1700 220 Public P.02. Sakuragicho Train Station renovationo 3573 220 Public P.03. Dresden Train Station renovationo 30 000 265 Public P.04. Logan offices alteration 1200 30 Private P.05. Casting house, Landschaftspark alteration 580 300 Regional funding P.06. Eco Membrane alteration 1400 30 Private P.07. Frac Art Centre extention 3362 400 Regional P.08. Frøsilo alteration 9800 300 Private P.09. Mino alteration 80 30 Regional funding Average alteration 5966 199 - * Cost of membrane material + substructure + installation. Decomposition of global cost according with Armijos (2008) assume the follow weights: project (5-15%); substructure production (10-60%); membrane transformation (10-60%); installation (10-30%); equipment (5-10%) and transport (1-5%). 4. Conclusions The paper summarizes the most relevant trends, according to the study of international proposals, mainly in the last decade, which have been analysed through a broad range of qualitative parameters. In the last decade, architectural membrane proposals associated with retrofitting projects has increased considerably. The improvement of membrane materials and the influence of some mediatic projects have also helped to this development. The higher durability helps to promote the application on permanent buildings; their integration in retrofitting processes can takes also advantage of its lightness and easy maintenance requirements. Because of that, functional retrofitting represents one of the most interesting areas of improvement. References APPLETON, J. Reabilitação de Edifícios Antigos: Patologias e Tecnologias de Intervenção. 1.ª Edição. Lisboa: Edições Orion, 2003. ARMIJOS, S. Fabric Architecture: Creative Resources for Shade, Signage, and Shelter. New York: W.W. Norton & Company, 2008. CARTIER, C. L’héritage industriel, un patrimoine. Besançon: CRDP Franche-Comté, 2002. FOSTER & PARTNERS. «Desden Train Station Redevelopment». 2006 [consult: 14.01.2016]. http://www.fosterandpartners.com/projects/dresden-stationredevelopment. GONZALES, A. et al. The Potencial Use of Pneumatic Envelopes in Existing Buildings Retrofitting. Conference proceedings, PLEA 2012 – 28th Conference, Opportunities, Limits & Needs Towards an environmentally responsible architecture; Lima, Peru; November, 2012. GUEDES, J. et al. Conservação e reforço de estruturas patrimonio. Jornadas Europeias do Patrimonio. Cascais: 19 e 29 Setembro, 2003. LEWIS, W. Tension structures: form and behavior. London: Thomas Telford, 2003. MENDONÇA, P. Habitar Sob uma Segunda Pele, Estratégias para a Redução do Impacto Ambiental de Construções Solares Passivas em Climas Temperados. Ph.D. Thesis in Civil Engineering. Portugal: University of Minho, 2005. Acknowledgments The first author wish to thank FCT (Fundação para a Ciência e Tecnologia – Portugal), MCE (Ministério da Educação e Ciência – Portugal) and ESF (European Social Fund) for supporting the research fellowship with the reference SFRH/BD/104891/2014; and wish to thank to Host institutions - Lab2PT, School of Architecture/ University of Minho, Portugal and CONSTRUCT research center of Faculty of Engineering / University of Porto, Portugal. Mónica Macieira (mr[email protected]) Graduate, M.Sc. in Architecture by School of Architecture of University of Minho. She was involved in the AdJustMEMBRANE research project (2010-2013) and InoblockHouse project (2014) as research fellow. Presently she is developing her Ph.D. studies in construction and technology field. Her major interests are lightweight construction and materials, adaptable/reversible design systems/tecnologies, buildings rehabilitation, sustainability of construction and buildings functional performance. Paulo Mendonça ([email protected]) Graduate in Architecture by FAUP at 1994. He was a JNICT fellowship student in the Textile Engineer Department of the University of Minho, where he obtained the M.Sc. at “Design and Marketing” at 1997. As a PhD fellowship of FCT he got the “Advanced Studies Diploma” in Barcelona on the Technical Superior School of Architecture (ETSAB) and Ph.D in Civil Engineering by the University of Minho, with the thesis: “Living under a second skin”. Associate Professor at School of Architecture of the UM (EAUM) and Coordinator of research group DeTech – Design & Technology of Lab2PT. His main research and teaching subjects includes lightweight and mixed weight buildings, low cost housing, local and global economic asymmetries, low-tech strategies, architectural membranes, energy efficiency, invovation and technology. João Miranda Guedes (jguede[email protected].pt) Graduate, M.Sc. and Ph.D. in civil engineering. His main research interests are oriented to the structural rehabilitation and seismic retrofitting of old constructions. In particular he follows research projects involving experimental testing of masonry and timber structural elements, as well as NDT assessment techniques. He’s membre of the board of directors of the Portuguese Association for the Urban Rehabilitation and Heritage Protection.