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TOWARDS GREEN INDUSTRIAL BUILDING CONSTRUCTION SUSTAINABLE ENGINEERING OF BUILDINGS

E. Durmisevic

e.durmisevic@tudelft.nl TU Delft, Faculty of Architecture, P.O. BOX 5043, 2600 CR Delft, The Netherlands

ABSTRACT Conventional buildings are designed as static and finished products although they are almost daily subject to transformation. Increase of the dynamics of societies caused by increased mobility, economic growth, life stile changes, results into growing number of changes within the built environment. (SEV 2006) Consequently this requires even greater material and energy consumption and waste production. However developers and real estate managers warn that existing building structures are not suitable for the changing demands of the modern society. This is why more than 60% of yearly building production in the Netherlands involves partial and total demolition of existing structures and their replacement by the new once. Resent estimations indicate that existing building account for 2/5 of the worlds annual energy use, one half of its waste stream and 40% of materials entering the global economy. The World Resource Institute projects 300% rise in material use as world population increases over 50 years. At the same time excavation of row materials is becoming difficult and more expensive. Governments introduce a tax on use of row materials. Landfill sites are filling up forcing landfill tax to increase and making the waste management exceptionally expensive. The physical impact of increasing building mass and its frequent transformations become undeniable in 21 century and is forcing building industry to rethink its construction methods. One can argue that existing structures and construction methods are in large part responsible for the increase of the total life cycle costs of the building, material and energy use and waste production. If building practice does not evolve towards building methods that stimulate reuse and recycling of building and its products (by high disassembly potential of its parts) the burden of demolition activities will continue to have negative impact on economic, social and environmental systems. In other words the gap between conventional construction methods and the key principles of sustainable engineering (such as; adapt to the users needs, reduce costs, conceive natural resources, save energy, reduce waste etc.) would increase considerably. This paper will discuss a new design & construction approach that can bridge a gap between growing construction activity and efficient material use. Keywords: Design for disassembly, sustainable engineering, flexibility 1. INTRODUCTION The way in which building parts are put together has a great effect on whether or not a part of the building or the whole building is recycled after its service life. This is

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independent of whether its materials were wisely selected or not. In other words, the building process which represents the way building parts are put together, determines the potential of buildings and its components to extend their life cycle by reuse, reconfiguration and recycling. Ultimately this contributes to the reduction of waste, and energy and materials use. Demolition in general can be defined as the process whereby the building is broken up, with little or no attempt to recover any of the constituent parts for reuse. Most buildings are designed for such end-of-life scenario. This means that different functions and materials comprising a building system are integrated in one closed and dependent structure that does not allow alterations and disassembly. The inability to remove and exchange building systems and their components results not only in significant energy consumption and increased waste production, but also in the lack of spatial adaptability and technical serviceability of the building. Such approach to building integration ignores the fact that building components and systems have different degrees of durability. While the structure of the building may have the service life of up to 75 years, the cladding of the building may only last 20 years. Similarly, services may only be adequate for 15 years, and the interior fit-out may be changed as frequently as every three years. Nevertheless, it is often the case that parts with short durability are fixed in permanently, preventing easy disassembly. Therefore, at the end of components or building service life there is usually little option but for demolition, with associated waste disposal. If we recognise the potential of disassembly, it is possible to divert the flow of materials from disposal and save bought materials and energy embodied in them by avoiding the demolition process. 2. DISASSEMBLY AS A KEY TO THE CYCLIC MATERIAL FLOW As already discussed in the previous paragraph, material flow in the building industry has a dominant linear direction in which material systems are running down. Such material flow is often defined as a once-through linear system passing from raw materials extraction, through materials processing, assembly, use, and finally to demolition.(Figure 1) Such systems recognise one end-of-life scenario, waste disposal.

Figure1: Once-through linear system of material flow However the ideal use of materials and resources available for processes in building industry would be one that is similar to the cyclic material flow (Figure 2). A number of examples from other industries indicate that if the act of demolition is replaced with disassembly, conventional material flow can be diverted towards reuse,

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reconfiguration and recycling of materials and components. This suggests a more cyclic life cycle model, one that provides transformation and adds value to materials during different stages of product life cycles. (Figure 2).

Figure 2: Cyclic material flow This mode of operation has been recognised within product design practises as Design for Environment strategy.(Graedel 1997) These industries recognise different end-of-life cycle scenarios of the product such as: reuse, maintenance, remanufacturing, recycling. These strategies have resulted into a successful business program in companies as Kodak, IBM, Simens, Xerox etc. However the implementation of cyclic material flow to the building design & construction is still far away from happening. Most modern buildings today are made of prefabricated components designed to be mountable. On the other hand, disassembly in the building industry usually involves a few bulldozers and some explosives. In order to increase a building’s potential to be disassembled, first of all we need to change our perception of the building technical composition from being permanent and fixed to being changeable and open. Open structures would allow for modifications according to new requirements and recovery of materials and components for reuse and recycling. Finally, they allow existing and new building stock to serve as primary material sources for new construction, rather than harvesting resources from the natural environment. In order to bring construction industry closer to such end-of-life scenarios, as designers and engineers, we must consider how we can access and replace parts of existing building systems and components, and accordingly, how we can design and integrate such open building systems and components in order to be able to reconfigure or to replace them later on. Design of such transformable and material efficient structures would have environmental, economic and social benefits and can be recognised as the key to sustainable construction in the future. Demolition prevention by design Obviously in order to adopt such a approach our understanding of the performance of the building structure needs to be changed. We need to understand that building can not be observed as a finished product, and that the total life cycle of building and its elements would be much more environmentally and economically efficient if the options for re-placeability and recovery of building parts would be provided for during the design phase. Therefore one of the basic analyses during design is to understand when and where does disassembly takes place in the building. This is extremely

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difficult task since each building represents a system of planes, lines and points broken into number of material levels which again interact with each other on different physical levels, that form ultimately technical composition of the building structure. Such maximal integration of building elements results into building structures that do not support recovery of its materials because: a) almost all elements create dependent relations with surrounding elements,(Figure 3) b) connections between the elements are not designed for disassembly, c) materials are often composites what complicates their recycling process. This dependent integration of components, that is created after the assembly, can be compared with the ‘spaghetti effect’ in a building, a term that was first used in building construction by Van Randen in 1988. (Van Randen 1992) Figure 3 presents the relational diagram of building components within one conventional housing project in the Netherlands. It shows that in order to remove one part great number of relations have to be removed. This is often not possible without demolished.

Figure 3: Relational diagram (left) shows dependencies between components within one housing project in the Netherlands. In order to resolve this effect so that building parts can be disassembled without degrading other parts, different approach to building structuring is needed. In other words a systematisation of the building is needed according to the two main criteria for disassembly: independency and exchangeability of building parts. The question of the building systematisation aiming at improved efficiency of the built environment has been addressed in the past. A well-known approach is the one that addresses the independence and decoupling of the levels of decision making within the built environment. This approach was first recognised in the work of Professor Habraken who introduced the theory of levels of change in 1960’s in his book ‘Supports’. Habraken suggested that the built environment could be divided into three levels of decision making, namely: urban fabric or tissue, base building or support, and fit out or infill, proposing that these three elves should become independent of each other in order to provide changes on infill levels without interrupting other two levels. Later on Duffy and Brand defined 4 and 6 functional levels of a building in order to identify individual building functions with different changing rates such as: site, structure, skin, services, space plan and stuff. However when the issues of material recovery play a role one has to realise that besides different functional changing rates and levels of responsibility, each material

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has different technical changing rates as well. Thus each material within a building has embedded duality in terms of different use and technical life cycle. It is the fixed integration of functions and their materials throughout different levels of technical composition that complicates replacement of parts. Therefore Design for Disassembly has to focus primarily on systematisation of levels of technical composition in order to provide decomposition of the functional and physical building levels. Levels of technical composition are: subcomponents, components, subsystems, systems, building. As illustrated in figure 4, levels of technical composition are multidimensional and can result into X number of independent material levels.

Figure 4: separation of material levels on all levels of technical composition (from systems to materials)

The concept of transformation and independent material levels is not restricted to one scale. Each level of technical composition can be further divided into sub-levels, which can be recursively composed of additional sub-levels. One can say the greater desire for transformation on building, system, and component level, for the reason of their reconfiguration, reuse and recycling, results in a greater number of independent material levels. It is obvious that if we wont to explore transformation of building and its systems by design for disassembly approach than a fixed number of changing levels become ambiguous. The number of independent material levels (as apart of independent levels of technical composition) is increased with the increase of changing user requirements and the need for separation and recovery of building materials. In that respect, design process in the future will have to focus on finding the write mach between the required use strategy for the whole life cycle of the building and number and hierarchy of material levels that will support this strategy. In other words different use scenarios required by different clients will result into different

Building level

System level

Component level

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number of independent levels of technical composition as well as into different arrangement and hierarchy of material levels. Systematisation of the building according to the criteria of independence and exchangeability of building components can be also seen as a process of emancipation of material levels, that are conventionally part of a fixed structure. To illustrate this we can take an example of typical housing construction in Holland where all building functions are integrated into one fixed material level. Most of these buildings are being demolished at the moment, because they can not be adopted to the new lifestyles and requirements. In order to extend the life cycle of such buildings the structure should become adoptable to a certain extend. For example if the long-term use scenario requires spatial flexibility number of material levels such as sanitary installation level, electricity/data level, partitioning level and fittings should be extracted out of previously mentioned, one material level (represented by fixed mass of materials that should last 75 years. (see figure 5 left) If those four levels are developed as independent subsystems that can be replaced, reused, reconfigured, recycled than these buildings could easily transform to number of different spatial typologies and its parts could be reused in different situations or reconfigured and recycled.

Figure 5: left, housing project in the Netherlands that freezes functional levels into one fixed material level (one material level one spatial system); right, alternative solution where four functional levels have been separated. The project that has provided even greater number of independent material levels for the purpose of greater adaptability to the user needs is the Next 21 Project in Osaka. Independency of the façade, installations, and infill systems were a leading concept in this project. (Figure 6) The functional levels are defined by eleven independent material levels (see Figure 6 left).

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This has been a result of desired use requirements such as having total spatial and functional flexibility in the dwellings. Such strategy required that users are being able to reposition windows, extend apartments, and to access all installations for their maintenance, upgrading and repositioning. The functional decomposition that was needed in order to provide these requirements has resulted into eleven material levels in a form of main systems and eighteen sublevels in a form of independent and exchangeable subsystems and components. (Figure 6 left) This has resulted in the design of an external envelope made up of movable steel frames covered with aluminium strips. The façade system can be reconfigured by moving or adding window or door openings, as well as by integrating the balcony into the dwelling space, or by creating a new balcony.(Figure 6 right)

Figure 6: left, number of independent material levels within Next 21, right transformation of the external envelope (Fukao 1999) Design for better building use performance and material efficiency To summarize design for disassembly addresses a moment of change of the purpose of the building assemblies. It addresses the moment when the rearrangement of materials takes place.(Durmisevic 2006) A good understanding of the requirements that takes into account the long-term purpose of the artefact is crucial in the DfD approach. Scenarios for the use of building and building material in the future have to be defined at the early design stage. This requires additional efforts from bought the client and the design team. Every use scenario for a building or a system results in different technical compositions and different configuration types. It is evident that each use scenario imposes different use life cycle on building components. Add to the fact that building components have different durability, it can be concluded that every use scenario will have different numbers and hierarchies of physical levels, and therefore a different hierarchy of technical systems. The hierarchy and material dependency between physical levels corresponds to a desired transformation strategy. Having this in mind, all building structures could be divided

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into three groups, such as fixed structures, partially decomposable structures, and totally decomposable structures. The process of transformation from massive to decomposable structures symbolises the process of separation of building functions, according to use strategy, from fixed to fewer dependent conditions. Figure 7 illustrates three different configuration types that match three different long-term use scenarios. Configuration1 addresses flexibility that deals with the inner partitioning of a space, and introduces a floor and wall system that can be reconfigured and replaced. Configuration 2 addresses spatial flexibility that introduces a flexible concept for electrical installations imbedded in movable walls. Configuration 3 addresses a concept for the total flexibility, introducing systems that can be reconfigured and replaced. Configuration 1 Configuration 2 Configuration 3

Figure 7: illustrates three different types of configurations

Taking into account all possible combinations of functions, sub-functions, sub-sub-functions on building, system, component levels it is possible to develop thousands of different configuration types with a building. Therefore the key issue in the design of transformable structures is the definition of the right match between the long-term use strategies and the type of configuration that will support these use strategies. Design protocol Considering the complexity of the design of transformable buildings based on design for disassembly strategy the key issue is to define the boundary conditions within which building and its systems will be developed through the number of optimisation phases. Accordingly design for disassembly can be summarised into the following steps: • Definition of the use performance through specification of long and short-term scenarios; • Functional decomposition followed by the initial specification of material levels; • Definition of a hierarchy of material levels that corresponds to the frequency of change of building components for the purpose of maintenance and functional

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change. If a structure is represented by a closed hierarchical relational diagram, then re-structuring should take place. This can result in the change of material levels, or change of functionality. • Development of a life cycle coordination matrix for the proposed solution that indicates disproportion of use and technical life cycle within chosen materials. At this point designer can optimise the matrix by reducing or extending the technical life cycle by choosing other materials, or by allocating other functions to the existing materials, which are accounted for the great life cycle disproportion. Such optimisation of the life cycle coordination matrix is directly related to the reconfiguration of the structure or functional decomposition. • Outline of the physical integration between parts that have different functional and technical life cycle. This stage deals with the pure physical aspects of relations between two components. • Evaluation of a design solution by use of a knowledge model that can match design solutions with desired performance indicators; (as for example model measuring transformation capacity of the building) 3. CONCLUSIONS Results of many research studies, regarding sustainable construction and disassembly as a key element of sustainable construction, are summarised in reports by CIB deconstruction TG 39 group (Chini 2005) and the US governmental Green Building program (EPA 2005). These indicate that designing transformable buildings with exchangeable and reconfigurable /reusable components, seen from the perspective of 21st century requirements, results in the reduction of construction and demolition (C&D) debris, conservation of landfill space, reduction of the environmental impact of producing new materials, creation of jobs, and reduction of overall building project expenses through avoided purchase/disposal costs. Furthermore, demountable buildings are easier to adapt to new requirements. In short, such an approach to building design has the potential to accomplish benefits such as: -Economic benefits: Reduction in operating costs, Creation, expansion, and shaping of markets for green product and services, Improvement in occupant productivity, Optimisation of life-cycle economic performance -Social benefits: Enhancement of occupant comfort and health, Heightening of aesthetic qualities, Minimizing the strain on local infrastructure, Improvement of overall quality of life -Environmental benefits: Reduction in waste streams, Conservation and restoration of natural resources, Enhancement and protection of biodiversity and ecosystems, Improvement of air and water quality 4. REFERENCES

Abdul Chini [2005], Deconstruction and Material Reuse. International Overview,CIB

Publication Nr. 300, 2005

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Durmisevic E. [2006], Transformable building structures, Design for Disassembly as a way to introduce sustainable engineering to the building design and construction, PhD theses, TU Delft February 2006

EPA [2006]: US Environmental Protection Agency, report http://www.epa.gov Fukao S.[1999], Design drawing of the Next 21, Tokyo University chair of Professor

Fukao Graedel T.E. and Allemby B.R. [1996] , Design for Environment, Prentice Hall SEV Realisatie [2006], Jouke Post, Geert-Jan van den Brand, Henk Bouwmeester, De

kunst van rekbaar vastgoed, Bouwen in een tijd vol veranderingen, Rotterdam 2006 Van Randen [1992], Entangled building, Delft University of Technology