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the design projectToward
Toward the design project
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- K. Kurokawa -
(1) B. Addis (2006), Building with reclaimed components and materials, Earthscan, UK
(2) V.W.Y. Tam (2008), Economic comparison of concrete recycling: A case study approach, Resour. Conserv. Recycl. 52 (5), 821–828, http://dx. doi. org/10.1016/j.resconrec.2007.12.001 (3) P. Crowther (1999), Design for disassembly to extend life and increase sustainability, in 8th international Conference on Durability of Building Materials and Components. Service Life and Asset Management, Institute for Research in construction, Vancouver
(4) S. Huuhka, T. Kaasalainen, J.H. Hakanen, J. Lahdensivu (2015), Reusing concrete panels from buildings for building : Potential in Finnish 1970s mass housing in Resources, Conservation Recycling”, 101, 105–121, 10.1016/j. resconrec.2015.05.017
(5) M. Stacey (2011), Concrete: a studio design guide. RIBA, London (6) A. Glias, (2013) The ‘Donor Skelet Designing with reused structural concrete elements, Master Thesis in TUDelft University The project has the aim to give a contribution on the research toward circular construction systems with the development of an innovative construction and fnancial method. This new method has the goal to foster the concepts of affordability, convertibility, better liveability and sustainability in order to provide an alternative for the construction of our future homes and cities with economic and environmental benefts to builders, occupants, and communities. We do believe in fact in the possibility for Circular Economy to be the key factor to face effectively the current housing crisis and the environmental issue.
The potentialities of concrete in Design for Disassembly: a promising challenge
Concrete has several characteristics, such as durability, mechanical and fre resistance, global availability, variety of type and form, and fexibility in design and application, that give it signifcant potential for disassembly and reuse. Today, it is one of the materials mostly used in the construction sector. Its linear production, though, counting on the use of more than 10 billion tons of sand and natural rocks a year, considerably contributes to degradation of natural habitat and to the generation of solid waste pollution (1). In this regard, according to Tam (2) around 50% of the total amount of waste generated from demolition and construction (about 5.5 billion tons) are concrete waste.
The shift toward an alternative cyclic model in the production of concrete building elements would therefore result not just in a huge saving in terms of energy needed to materials manufacturing, but also in the avoidance of the associated CO2 emissions, solid wastes, and dust pollutants resulted from the demolition processes (3). Converting concrete production from linear to circular models implies though the rethinking of traditional building systems based on the use of wet joints made of Portland cement. It requires new ways of designing concrete structures in view of disassembly and further components’ reuse and adaptation, where elements such as wall panels, roof slabs, and even columns and beams can be disassembled without material loss or pollution to be reused in extending existing building or in the production of new ones, without any loss of value.
In most cases, in fact, concrete elements can be reused with no need for remanufacturing, as it can serve longer periods than its expected operative life. Several experimental projects has recently shown and proven its efectiveness, with huge economic savings. Te Kummatti housing estate rehabilitation project, for instance, developed in Raahe (Finland, 2008) in 2008, resulted in 36% savings in construction costs (4) Te design of a new housing project in Mehrow, near Berlin, witnessed another successful experience. Te project included reuse of precast concrete elements, taken from unwanted buildings that have been constructed using Plattenbau construction technique. Te project also resulted in 30% reduction in cost (5) Still in Germany, in 2001, the federal ministry of transport, building and housing fostered the creation of a research project called Recycling prefabricated building component for future generations with the aim to test the potential of dismantling and designing a house using reused components. Te research actually showed how the total building costs when using reused building elements were 26% less than using new ones (6).
Nowadays the topic of circular building system, generally related to timber technologies,
gains momentum also for concrete structures and fnd the interest of the architecture sector, as well as of industry. In this regard, Peikko, a Finnish company born in 1965 that deals with technology concerning building concrete elements, is now paving the way toward the creation of innovative solutions for the production of bolted concrete structures.
Tese solutions were initially invented out of necessity. As cold weather in Finland didn’t allow for traditional casted connections, they needed to fnd alternative mechanical solutions. It turned out that this type of joints were also avoiding long drying times and making the building easier and faster to assemble, (and thus disassemble). Many of these solutions are currently in used, even though they’re fnally cast in cement in order to prevent drew loosening. Nevertheless, the use of dissolvable binders could easily solved this problem, making bolted concrete structures completely reversible.
Double Skin Facade: a tool of circularity that belongs to urbanity
The building skin is an architectural element which can offer excellent potential for disassembly. Over the years, the element of building skin has progressively gain momentum in view of sustainability as a mediator between the inside and outside environment, controlling the fow of heat, light, noise, information and other media. It is the primary subsystem through which prevailing external conditions can be infuenced and regulated to meet the comfort requirements of the user inside the building (7). Like skin and human clothes, this raiment, too, fulfls the tasks demanded of it by perfoming a number of functions made possible by means of the appropriate design and construction.
Starting from the 80’s, after the oil crisis and the emerging awareness about limited resources, double skin facades especially started to emerge, as a system fexible enough to meet climatic changes for most types of building use, providing at the same time both improved indoor climate and reduced use of energy. Literature documents several defnitions of Double Skin Facade. Harrison and Boake (8) described it as a pair of glass skins separated by an air corridor, that acts as insulation against temperature extremes, winds, and sound and eventually contains sun-shading. Uuttu (9) provides also some informations concerning the width of the cavity: from 20 cm to several meters. In any case, the concept of Double Skin Facade is not new: Saelens, (10) recalls its origin in the description of a mechanically ventilated multiple skin façade made in 1849 by Jean-Baptiste Jobard, at that time director of the industrial Museum in Brussels. He mentions how in winter hot air should be circulated between two glazings, while in summer it should be cold air. More simply even double windows of old palaces and blocks could be considered ancestors of Double Skin Facades.
When designed properly for Design for Disassembly as an independent element this type of technology offers a great amount of advantages in terms of Design for Disassembly and Circular Economy. It is an integrated system, as it can be combined to solar panels and collectors, enabling their relevant contribution to the building’s energy supply: building envelope optimised for energy aspects has a maximised passive capacity and hence represents the foundation for viable energy concepts in the future. Double facades can thus become active multifunctional facades, able
(7)C. Schittich (ed.) (2017), Building skins. New enlarged edition, Birkhauser Edition Detail
(8) K. Harrison, T. Meyer-Boake (2003), The Tectonics of the Environmental Skin, University of Waterloo, School of Architecture http://www.fes.uwaterloo.ca/architecture/ faculty _projects/terri/ds/double.pdf (9) S. Uuttu (2001), Study of Current Structures in Double-Skin Facades, MSc thesis in Structural Engineering and Building Physics. Depart- ment of Civil and Environmental Engineering, Helsinki University of Technology (HUT), Finland, http://www.hut.f/Units/Civil/Steel/SINI2.PDF (10) D. Saelens (2002), Energy Performance Assessments of Single Storey Multiple-Skin Facades, PhD thesis, Laboratory for Building Physics, Department of Civil Engineering, Catholic University of Leuven, Belgium
(11) https://www.tudelft.nl/bk/onderzoek/ projecten/green-building-innovation/ facade-leasing/facade-leasing-pilotproject-at-tu-delft to deliver an ongoing indoor comfort service. Te placement of solar panels and collectors can happen in the way of segregation, when clearly distinguished from the facade, incorporation, when replacing conventional materials, or amalgamation, when they serve also other functions. Notwithstanding, whenever these components are on the exterior layer of the building, maintenance and replacement is easier, even if the use of high technologies could make more difcult a strategy of direct reuse.
This system has lower construction costs compared to solutions that can be provided by the use of electrochromic, thermochromic or photochromic panes, and still effective performance concerning both acoustic and thermal insulation. Due to the additional skin, in fact, the thermal bufer zone formed in-between reduces the heat losses and enables passive solar gains, so that a good design of a double skin facade could even avoid the presence of any type of additional HVAC system, with a consequent radical reduction of energy consumptions.
It has potentially high level of transformability, in terms of technological adaptation. Te external skin can be easily technologically improved through the substitution of the panels it is made of. Tis concept becomes crucial when speaking of adaptive facades. Recognising changes in their environments and load and using past events to improve future performance or maintain serviceability, Adaptive Facades could enable a further improvement of the structural performance of the component over time. Tey could store detailed informations of their operative life and give feedbacks to their producers who could provide further innovations before its reuse.
In this regard, Double Skin Facade enables the avoidance of intrusive events of maintenance: the outer and the inner skin work together in a complementary way but they’re structurally independent. Tis is important in terms of maintenance and Operative Life of the building as it means an incredible saving in terms of energy and costs, from the user point of view, who, in case of external panels substitution, can still live inside his housing unit, as well as for the constructor.
Due to its structural independency, Double Skin Facade permits a high level of construction adaptation. Tis is crucial in terms of adaptation to the existing, as an additional layer applied for retroftting purposes. Accelerating the rate and depth of energy renovations in buildings is in fact one of the biggest challenges currently facing the construction industry in view of circularity. Across Europe buildings constructed between the ‘50s and the ‘70s in fact are reaching the end of their service life and their facades are far below current standard as well, with a particularly high rate of energy consumption (11). In this regard, it’s interesting the project of refurbishment by Lacaton & Vassal on the 530 logements in Bourdeaux, developing exactly this concept.
Double Skin Facade is also a tool of functional fexibility. According to its width, variable thanks to the independency of the external skin, double skin facade could become an expansion of the housing unit, generating a winter garden that at the same time improve the indoor comfort and that could gain a social value when shared. Tis type of space could even brand the housing unit, as an openable bufer between the inside and the outside. Several projects all over the world actually used this as a leading concept of design. Let’s just think, for instance, to the Winter Garden Housing by Atelier Kempe Till, built in Belgium, or to the Milanofori Housing Complex by Open Building Research and Como Arquitectos, where the double skin becomes a bufer between artifcial and nature.
Moreover, the new upsurge in experimentation of recent years, where boundaries have been tested as well as visual conventions, and a new focus on new materials’ performance
made the topic of building skin particularly fascinating as it has rarely been in the history of architecture. Set into a context, building skin can redefne entire segments of city, drawing more attention than any other building component.
In this framework, the correspondence between external appearance of a building and internal life established by Modernism loose of its signifcance and is questioned with growing intensity. At any rate, how does one maintain the postulate of refecting uses on the outside, when these uses change several times over the life cycle of a modern building? (7)
The design principles
Te project stems from seven main goals whose combination is meant to enable the construction of afordable and circular Social Housing complexes. Having them in mind over the desing phase, they set an operational framework as key-performance indicators enabling an efective circular project based on the use of Design for Disassembly.
How can we achieve all of them and hence provide a reliable construction method for the construction of affordable and circular social housing?
A few exemplar references follow the theoretical explanation of each principle, ofering a precedent to be further developed through the project.
Spatial fexibility Flexibility generally indicates different levels of transformation. When the same building structure, defned by a certain design grid and by a certain amount of structural elements, ofers several diverse indoor arrangements without implying intrusive and heavy construction interventions, it’s possible to speak of spatial fexibility. In literature, Delirious New York by Rem Koolhaas could recall this concept when mentioning the contrast between the rigid urban grid of Manhattan and all the unique episodes it keeps together. Te same rhythm generates diferent and almost infnite outcomes: (Manhattan) is a mountain range of evidence without a manifesto (12).
Replicability A building system is replicable when it can be replicated and adapted to several housing typologies and in different geographical context. In this regard, we could also talk of technical fexibility of the structural system.
Demand adaptability The concept indicates the possibility for the user to adapt his housing unit according to his needs and budget of the moment. In this scenario, over time, the housing complex can potentially grow or shrink, depending on the amount and type of housing demand. Te housing unit thus complete progressively, over a long range of time, opening up a way for low-income groups to access better-quality housing while contributing to building longevity. Tis concept of flling the grid in a free and temporary way is not new. It recalls the ‘60s and ‘70s, instead, with the Plug-In City by Archigram or the Spatial City by Yona Friedman. In both the cases, a versatile and free sub-structure is ruled by a structural, perhaps infnite, grid of pillars and slabs. In the vision of Friedman, this spatial infrastructure shall have been designed for collective use.
Reuse
(12) R. Koolhaas (1978), Delirious New York, Oxford University Press
Modularity permits the potential reuse of components over time without the need of further transformations, at least regarding shape and size. A modular system, combined to a certain level of fexibility, can avoid standardisation and foster instead the simplicity of customisation. In terms of maintenance, modularity permits high levels of adaptation, as components could be easily substituted over time in order to grant high-performances over the whole operative life of the building.
Non-intrusive maintenance The independency of buildings’ system is required in order to facilitate eventual actions of maintenance and substitution over time. Understanding systems and how they are integrated to the rest of the building’s structure is the frst step to enable eventual episodes of self-maintenance, that would imply savings of energy and resources. Te concept recalls the theory of building layers by Steward Brand: if systems are independent, modifcations of one of the systems won’t afect the others. Terefore the building system could easily adapt to eventual maintenance operations, avoiding intrusive procedures, that would cause for the users additional expenses in terms both of costs and energies. Te presence of an exterior independent involucre could conceptually recall the proposal of a geodetic dome over Manhattan of Buckminster Fuller: an ideal way to reduce energy consumptions of the city. Moreover, the independency of the building involucre can ofer the possibility to adapt to the context the building belongs too, in environmental and urban terms, without afecting interiors. Barcelona octagons, with their ordered and clear facades facing the street and their chaotic and diverse interior courtyards, conceptually represent this concept.
Selective sharing Sharing spaces and services is a way to improve affordability and to save money and energy. Nevertheless, the aim of the project is to fnd a balance between the natural needs of both a private and a public life of each user. Rather than forcing, the project shall suggest spontaneous and informal social practices. Te current pandemic of Covid-19 asks a rethinking of the meaning of co-habitation and social housing. In this regard, data suggest that in the years to come shared living will become increasingly attractive to millions of people, as they struggle to fnd adequate and afordable housing in cities. Terefore, there’s the need to rethink common spaces, as into a hierarchy, defned by how many people can ft in.
Urban Branding In terms of circularity, this is an important factor to enhance the concept of vicinity at an urban scale and to give an identity to an entire urban segment. Facade is crucial as it defnes the exterior aspect of a building, in respect to the urbanity it belongs to. A radical, but still efective, example of this is the project called Te Mountain by BIG, an housing complex partially covered by an involucre that literally represents a Mountain. A way to make attractive, or at least to rise curiosity, a peripheral and till that time neglected district of the city. Moreover, as border between private and public life, double skin facade can be perceived as a showcase of its users from the outside, and as a further bufer of division providing more privacy from the inside.
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