A Methodology to Qualitatively Select Upcycled Building Materials from Urban and Industrial Waste

: The rising concern about climate change and other challenges faced by the planet led society to look for different design solutions and approaches towards a more balanced relationship between the built and natural environment. The circular economy is an effective alternative to the linear economic model inspired by natural metabolisms and the circular use of resources. This research explores how innovative strategies can be integrated for evaluating local urban and industrial wastes into sustainable building materials. A literature review is conducted focusing on circular design strategies, re-use, recycle, and waste transformation processes. Then, a methodology for the selection of upcycled and re-used building materials is developed based on Ashby’s method. A total of thirty-ﬁve types of partition walls, which include plastic, wood, paper, steel, aluminium, and agricultural wastes, are evaluated using a multi-criteria decision aid (M-MACBETH). Among these solutions, ten types of walls show high-performance thermal and sound isolation, fourteen types are effective for coating, and two exhibit structural reliability. Regardless of their functional limitations, the proposed solutions based on waste materials bear great potential within the construction industry.


Introduction
The Circular Economy (CE) has gained political and scientific significance in recent years as an alternative to the current mainstream industrial capitalism economic model [1].CE is deemed an effective method to address social, economic, and ecological issues of the contemporary age and thus achieve the United Nations' Sustainable Development Goals (SDGs) [2].
The relationship between Planet Earth and the Global Economy will be truly sustainable when the supply of resources and the assimilation of waste considers the environmental limits of the planet [3].World organisations estimate that production and consumption patterns exceed over 75% of the biocapacity [4].While 92 billion tons of raw materials were extracted, 36 billion tons of waste were produced and collected in 2017, as stated in the Circularity Gap Report.Only 4.2% of these materials were reintroduced into the world economy [1].These values reflect biodiversity loss, natural resources degradation, and the economic inefficiency of linear systems.
The extraction of virgin resources is predicted to double in the next thirty years [1] due to the growth and consumption patterns of the population.This trend will lead to a rupture in the supply chain and the volatility of trade prices, especially in the EU, where the industry is highly dependent on international markets.On the other hand, the amount of unrecovered waste illustrates lost economic opportunities in the order of USD 1000 billion per year [5].The construction sector represents 10% of the European Union's (EU) GDP [6], accounts for the most significant consumption of virgin resources [7] and produces one-third of all generated waste [8].The scientific community calls for a systemic change addressing the entire life cycle of buildings and the construction value chain based on energy efficiency, bio-efficiency, and material efficiency [9].
In this broader context, new strategies have been developed in the last few years, including bioclimatic architecture, disassembly construction techniques, and sustainable materials evaluation [10].However, less importance has been given to the cascade recovery or the creative valuation of waste and by-products from other industries in the construction sector.Open-circuit resource management and industrial symbiosis represent effective methods to avoid loss of material and product value towards an overall economic and social stability.The main challenge presents offering construction solutions that are more flexible and cost-effective than traditional construction techniques.This is particularly important within European real estate markets when raw material stocks are falling, and the global materials supply chain is under pressure [11].
Advanced materials and techniques based on re-use/recycling are emerging on the current market, while designers need to identify the most viable solutions for each specific context.Various tools, e.g., building environmental product declaration (EPDs) and product certification schemes, provide standardised information about the environmental performance of products and materials essential to decision-making [12].Many scholars have developed sustainable assessment criteria for selecting building materials [13,14] and evaluation criteria in line with the Circular Economy principles [15].However, the literature does not yet support the selection of recycled and re-used materials derived from urban and industrial wastes.
Innovative strategies for converting local urban and industrial wastes into building materials and systems are discussed in this study.Our main purpose is to develop a methodology to guide designers' decision-making on upcycled and re-used building materials selection.The proposed methodology is based on the Ashby method followed by multi-criteria analysis in the software M-MACBETH (Measuring Attractiveness by a Categorical-Based Evaluation Technique) [16,17].M-MACBETH can handle multiple results generated from qualitative expert judgments.In our case study, thirty-five construction solutions from post-consumer waste and by-products (plastic, wood, paper, steel, aluminium, and agricultural waste) are analysed and then tested and ranked in a case study in Lisbon (Portugal).This study aims to address the following questions: − How to compare a set of upcycled and re-used materials derived from local urban and industrial wastes?− How efficient are these building systems based on urban and industrial wastes?
The first section of the work presents a literature review on design strategies for the circular management of regional material flows in the construction sector.The second section identifies re-use and recycle typologies and waste transformation processes.The third section introduces a methodology for selecting upcycling materials and construction systems according to CE principles.This methodology is applied to evaluate thirty-five case studies.Finally, the results are discussed based on the sample analysis.

Design Strategies for Circular Management of Material Flows
A circular building is designed, constructed, managed, and constructed following the CE principles [9].It can be adapted to the needs of users and the environment and function as a bank, or reservoir, where materials are identified, temporarily stored and released at the end of their life.As a result, this process leads to an optimisation of the entire value chain with new ownership and business models [18].
This life cycle approach requires a transdisciplinary view and multiple-scale approach, the analysis of the connections between construction products, the built environment, and urban features, as well as the coordination of multiple stakeholders such as product manufacturers, service providers, and demolition/disassembly companies [19].Due to this complexity, adopting systems thinking (i.e., understanding what the relationship of each part to the whole is and the relationship of the whole to each part in a system) facilitates the collaborative network in the value chain, where the architect assumes a central role [9,20].Pomponi et al. (2017) propose CE strategies in the built environment through a system perspective that considers three following levels: macro-(national level, cities, general industry structure); meso (regional level/buildings/eco-industrial parks); micro-(product level, building components) [9].However, this systematisation does not present a complete building analysis and understanding.
Buildings are long-lived entities, often interpreted as large static units but result as sets of various artefacts, each with its specific life cycle, grouped to respond to a series of requirements and constraints [21].Consequently, buildings are not efficiently managed through their lifecycles as single manufactured products [6].Indeed, the diachronic analysis of buildings reveals that they encompass a set of dynamic systems that can partially update themselves according to users' needs without becoming obsolete [22].This phenomenon occurs because a building includes shearing layers (Site, Structure, Skin, Services, Stuff) responsible for its primary functions.Some of these systems can accommodate faster changes without compromising other systems being initially conceived as functional independent [23].
Designing a building in multi-layers may help approach each system according to specific rules and strategies [24].Their independence allows a quick dismantling at the end of building life.However, a building transformation capacity depends not only on functional aspects but also on technical and physical ones.A façade may have a longer lifetime than the systems and components, and these may be incorporated in different technical or biological cycles [25].Thus, their subcomponents and materials also require functional, technical, and physical independence allowing necessary transformations at the component and material levels.Within this perspective, the Hierarchy of Material Levels define the buildings as hierarchical system sets for building primary functions [21].These systems, in turn, are composed of components, elements, and materials [26].
The compression of the buildings as a small piece of a city's metabolism, a living system composed of a series of logically and hierarchically assembled elements, helps organise circular design principles in a top-down approach and then achieve better management and a "wholly independent" and "exchangeable" design.
Regarding the Hierarchy of Material Levels, circular strategies are related to specific scales of intervention (Figure 1).Four design strategies that contribute to narrowing and slowing down regional material flows are identified in the literature [24,27,28]: (a) Design with local resources: analyses material flows in the geographic, economic, and social contexts of the city, affecting the choice of elements and materials.(b) Design for adaptability (DfA): evaluates the correlations between the building and their systems and Design for disassembly (DfD): assesses relationships between elements, components, and systems.(c) Design with sustainable materials focuses on materials and elements.

Design with Local Resources
As stated by Walker et al., the preliminary step in the design of a low environmental impact building is the inventory of locally available materials [29].The use of local building materials reduces transport cost and impacts, supports regional development, and facilitates sustainable circular business models.The Living Building Challenge program defines as a requirement in the certificates of the building that at least 75% of the budget for building materials should come from within a 5000 km radius of the building site, of which 30% should be sourced within 1000 km and 20% within 500 km [30].The LEED v4 in Material and Resource credits include the location valuation factor, which states that Products and Materials should be extracted, manufactured, and purchased within 160 km from the site location of the project [31].
SuperRuse Studios has pioneered the online platform Harvest map, an inventory of local used materials and their location, encouraging designers to explore resources and potential-used building products locally available [24].Similarly, REPAiR project, and the REFLOW project, among others, introduce the Activity-based Spatial Flow Analysis (AS-MFA) [32].This methodology connects the spatial, material, and social analyses relating to material flows and stocks from waste production.It determines the qualitative and quantitative waste flow specifications in content, space, and time.It also addresses the relations between managers and consumers, allowing the identification of extracted and manufactured resources, possible exchanges of by-products and wastes between industries (industrial symbiosis) and re-used recycling strategies [32].

Design for Adaptability (DfA)
The Design for Adaptability (DfA) defines the need to conceive the buildings as adaptable living systems.They should be resilient and respond to multiple demands of the environment and the users [33].The valuable life ends with its inability to accommodate changes [28].Thus, the obsolescence of the building results from an incompatibility between demands and the capacity for transformation [33].Considering the functional and social perspectives, there are three types of stakeholders: Society, Owners, and Users.Furthermore, when considering the capacity, influenced by technical and physical characteristics, Location, Building, Systems, and Components should be considered [34].Schmidt III et al. propose a method for assessing structures according to six types of change, driven

Design with Local Resources
As stated by Walker et al., the preliminary step in the design of a low environmental impact building is the inventory of locally available materials [29].The use of local building materials reduces transport cost and impacts, supports regional development, and facilitates sustainable circular business models.The Living Building Challenge program defines as a requirement in the certificates of the building that at least 75% of the budget for building materials should come from within a 5000 km radius of the building site, of which 30% should be sourced within 1000 km and 20% within 500 km [30].The LEED v4 in Material and Resource credits include the location valuation factor, which states that Products and Materials should be extracted, manufactured, and purchased within 160 km from the site location of the project [31].
SuperRuse Studios has pioneered the online platform Harvest map, an inventory of local used materials and their location, encouraging designers to explore resources and potential-used building products locally available [24].Similarly, REPAiR project, and the REFLOW project, among others, introduce the Activity-based Spatial Flow Analysis (AS-MFA) [32].This methodology connects the spatial, material, and social analyses relating to material flows and stocks from waste production.It determines the qualitative and quantitative waste flow specifications in content, space, and time.It also addresses the relations between managers and consumers, allowing the identification of extracted and manufactured resources, possible exchanges of by-products and wastes between industries (industrial symbiosis) and re-used recycling strategies [32].

Design for Adaptability (DfA)
The Design for Adaptability (DfA) defines the need to conceive the buildings as adaptable living systems.They should be resilient and respond to multiple demands of the environment and the users [33].The valuable life ends with its inability to accommodate changes [28].Thus, the obsolescence of the building results from an incompatibility between demands and the capacity for transformation [33].Considering the functional and social perspectives, there are three types of stakeholders: Society, Owners, and Users.Furthermore, when considering the capacity, influenced by technical and physical characteristics, Location, Building, Systems, and Components should be considered [34].Schmidt III et al. propose a method for assessing structures according to six types of change, driven by the real estate market, performance, use, location, size, and space [33].Other academics, e.g., Geraedts, developed key performance indicators for designers to assess the adaptive capacity of buildings [34].

Design for Disassembly (DfD)
The Design for Disassembly (DfD) regards the undamaged recovery of materials, components, and systems during and after the building lifetime, which is an effective alternative to building demolition [24,35,36].In DfD, re-used systems have the highest rank and recycle materials the lowest (Figure 2) [36].Thus, the hierarchical model prioritises the recovery (placing it at the highest levels) to preserve the embodied value of systems and components [28].Durmisevic's Transformation Capability scheme introduces the fundamental assumptions for granting dynamic and dismountable structures [21].It is necessary to consider the set of criteria regarding functional, technical, and physical decomposition.The functional decomposition evaluates the logical organisation of elements in an assembly and the functional autonomy of each element.The technical and physical decomposition evaluates the synchronous assembly of systems, the life cycle of components, the design of interfaces, and the connection types [21].ISO 20887 standard on design for deconstruction and adaptability is an international tool to assess deconstruction [37].Furthermore, research projects such as Buildings as Material Banks (BAMB) [38] offer essential support instruments.
Sustainability 2022, 14, x FOR PEER REVIEW 5 of 43 by the real estate market, performance, use, location, size, and space [33].Other academics, e.g., Geraedts, developed key performance indicators for designers to assess the adaptive capacity of buildings [34].

Design for Disassembly (DfD)
The Design for Disassembly (DfD) regards the undamaged recovery of materials, components, and systems during and after the building lifetime, which is an effective alternative to building demolition [24,35,36].In DfD, re-used systems have the highest rank and recycle materials the lowest (Figure 2) [36].Thus, the hierarchical model prioritises the recovery (placing it at the highest levels) to preserve the embodied value of systems and components [28].Durmisevic's Transformation Capability scheme introduces the fundamental assumptions for granting dynamic and dismountable structures [21].It is necessary to consider the set of criteria regarding functional, technical, and physical decomposition.The functional decomposition evaluates the logical organisation of elements in an assembly and the functional autonomy of each element.The technical and physical decomposition evaluates the synchronous assembly of systems, the life cycle of components, the design of interfaces, and the connection types [21].ISO 20887 standard on design for deconstruction and adaptability is an international tool to assess deconstruction [37].Furthermore, research projects such as Buildings as Material Banks (BAMB) [38] offer essential support instruments.

Design with Sustainable Materials
The selection of building materials that comply with sustainability standards reduces construction impacts and ensures that products circulate efficiently on healthy flows [2,39] with low social [40].The CE distinguishes biological and technical materials.The former consists of natural resources free of toxic substances that can be absorbed by the biosphere, e.g., wood or sand [2].The CE model proposes that biological materials can be 'cascaded' through various uses, e.g., solid timber can be transformed into panel products.The latter are manufactured resources that nature cannot assimilate, such as metals and plastics.Technological materials should be retained within industrial loops to ensure they are not discarded in the environment and lost to the economy but re-used and recycled [2].The

Design with Sustainable Materials
The selection of building materials that comply with sustainability standards reduces construction impacts and ensures that products circulate efficiently on healthy flows [2,39] with low social [40].The CE distinguishes biological and technical materials.The former consists of natural resources free of toxic substances that can be absorbed by the biosphere, e.g., wood or sand [2].The CE model proposes that biological materials can be 'cascaded' through various uses, e.g., solid timber can be transformed into panel products.The latter are manufactured resources that nature cannot assimilate, such as metals and plastics.Technological materials should be retained within industrial loops to ensure they are not discarded in the environment and lost to the economy but re-used and recycled [2].The Cradle to Cradle (C2C) Certified TM product has four main categories to assess materials and circular products: the Material Health identifies the chemical ingredients of every material, avoiding chemicals harmful to humans and the environment present on the "Red List"; the Material Re-Use evaluates if the design enables a safe return to nature or industry, and the Renewable Energy and Carbon Management promote renewable energy, and reduced CO 2 emissions; Water Stewardship safeguard clean water resources; and Social Fairness from contributing to equitable society [41].

Upcycling Waste and By-Products as Construction Materials
Since the European Waste Framework Directive (2008/98/EC) recently replaced by Directive 2018/851/EU-wastes have assumed a prominent role in manufacturing processes [42].The rational use of natural resources as materials, components, and systems has progressively been prioritised.The Communication on resource efficiency opportunities in the building sector (COM (2014) 445 fin.l) and The Circular Economic Action Plan identify product design and product policies as one of the main enablers to implement CE.Furthermore, these long-term targets reduce landfilling and increase recycling and re-use [43,44].
Until the 20th century, many components were customised and designed by architects using local techniques and materials.The secondary materials market was the primary supplier due to the scarcity of resources available.Thus, many buildings were constructed with locally recovered materials, such as medieval constructions where masonry or bricks were employed from Roman ruins [45].Even today, communities and informal settlements in developing countries are built with creative and wise solutions leveraging recycled materials.Throughout the 20th and 21st centuries, several architects have explored re-use and recycling through different creative processes.John Harbraken overcame the design limitation and the original function of products on re-use.Harbraken developed a beer bottle that could be re-used after consumption as an affordable house-building brick [46].Michael Reynolds, back in 1972, built the Thumb House, the first of several homes built on throughout his career.This architect explores a new living concept focused on resource self-sufficiency (e.g., water, and energy) and uses waste from nearby landfills as construction materials [47].Furthermore, research groups such as Vandkunsten Architects [48], Arup-Global Advisory, Design, Planning & Engineering [49], and from the University of Brighton [50] have been working on full-scale prototypes and new practices of flexible building components and materials.
Re-use refers to the repeated use of a product, component, or material for the same or different purpose from its initial use.It includes minor changes that allow it to perform a function, e.g., a wooden structure is refurbished to be used again as a load-bearing structure or a cladding panel [51][52][53].Superuse means recapturing the value of products when they have the lowest possible profit by providing new functions and reintroducing them into new cycles with creative design applications [54].
Recycle is the transformation process of a material so that it can be reintegrated into a new production line as raw material, marking the end of the cycle and the beginning of a new one [51].The main distinction between re-use and recycle is irreversibility: the material does not return to its original form.Recycling can go in two ways: downcycle-the transformation resulting in a material with a lower value; and upcycle transformation into a material with a higher value than the initial one.To name an example, the ferrous blastfurnace slag (Fe-BFS), a by-product generated from siderurgic pyroprocesses to develop active ceramic anodes [55], and the composite material, which has as raw material adhesive and sticker printing waste produced by UPM Biocomposites, Lahti, Finland.The latter was used by Shigeru Ban for the furniture company Arteck Milan in 2007 [56].Downcycle is the most widely used transformation process despite being the least beneficial loop in the waste management hierarchy.Re-use saves 88% of greenhouse gas emissions and optimises several tested environmental indicators compared to recycling [57,58].
Literature review and case study analysis render it possible to identify patterns and distinguish six variants in re-use and upcycle [56,59,60] (Table 1) as described below: (a) Simple Transformation Process: A creative design process that gives new functional value to waste, including little changes such as cutting, polishing, painting, or screwing.
It can be executed on the construction site.The Resource Rows Apartments from Compenhaga Lendeger Group project is a remarkable example of creative re-use.The architects have developed an innovative system for re-using brick walls which involve cutting the walls into sections to deliver panels fitted into a steel structure and design different façade compositions [61].(b) Design Transformation Process: The products never become waste, i.e., after their useful life, they are continuously re-used while maintaining their shape, properties, and composition over their life cycle, except for their function that can change drastically [52].(c) Densification Transformation Process: Regards the compaction process of waste.In some specific cases, e.g., with some agricultural waste, the compression activates a specific potential that releases a natural glue under pressure.It can be an asset to produce straw panels, columns, or beams [56].This process requires advanced industrial equipment or more rudimentary systems to compress the waste [56].(d) Cultivation Transformation Process: The metabolism of cultivated materials enables natural recycle to be carried out locally with basic production techniques.Typically, they absorb carbon dioxide during growth, require controlled humid environments, and feed on other waste or materials.The growth process is halted when the material reaches the required density and strength [59].The material developed by the University of Cape Town in 2018 is a relevant example of this process.Human urine was used to craft building blocks through microbial carbonate precipitation [62].(e) Reconfiguration Transformation Process: Involves grinding, sewing, gluing, and changing the original form of the material.This process combines organic components, inorganic, or mineral adhesives; and can alter the material's density and aesthetic qualities by changing the size of each piece, the grinding, and the resins.It requires specific production processes and industrial equipment, which consume energy and release carbon dioxide.It cannot be executed in the proximity of the construction sites [56].(f) Molecular Transformation Process: Involves the change of the molecular state of the waste.The process requires high-tech procedures involving, e.g., liquefaction or gasification of the original material.A relevant example regards the organic waste into bioethanol [56].This process is carried out in specialised factories.

A Methodological Framework for Evaluating Re-Used and Upcycled Building Materials
This research proposes a methodology for selecting re-used and upcycled building materials and systems from post-consumer waste and by-products.The methodology is applied to internal partition walls.It is based on the Ashby material selection approach [39]: selecting materials involves seeking the best match between design requirements and the material properties.Ashby's method is based on four steps and shown in Figure 3.

Translation of Functional Requirements
The functional performance defines the required level of material efficiency for each building component.Strength, deformability, and durability are fundamental parameters, especially in load-bearing elements [67].The components of the façade system are waterproofing, hygrothermal properties, and so on.Table 2 shows the performance level of each criterion that are listed below:

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Mechanical Resistance Capacity defines the material behaviour subjected to mechanical stress.It refers to the ability to withstand an applied force without failing or excessive deformation.

•
Thermal performance measures thermal properties (conductivity, specific heat) that ensure thermal comfort and building energy efficiency.

•
Acoustic performance is the ability of a material to absorb or insulate sound.

•
Water-resistance represents the ability of a material to maintain its properties when exposed to water.If a material absorbs water, it expands, thermal conductivity increases, and strength and durability are compromised.

•
Fire Resistance characterises the behaviour of a material when exposed to fire, such as the release of toxic gases and emission.The classification of the material fire resistance is fundamental to guarantee the safety of the occupants in case of fire.

•
Durability is the ability of a material to resist the combined action of physical, chemical, and biological factors.If the material is durable, it will have a longer service life and low maintenance.

•
Sensory Properties identifies those sensory properties significant in finishing materials: texture, brightness, transparency, and odour.1.
The translation of requirements defines the function of the material, the requirements necessary to achieve it, and identifies the non-negotiable ones.

2.
The screening process involves the elimination of materials unable to meet the performance requirements.Each material is sorted considering its ability to meet the established requirements.

3.
The rank process involves the evaluation of each material after the 2nd phase, with criteria of excellence.4.
The outcome of the steps is a ranked shortlist of candidates that meet the constraints and exhibit high scores.It is then necessary to collect the information, e.g., from handbooks, supplier datasheets, websites of environmental agencies, and other reliable sources.
In the first phase, to assess the sustainability and functionality of different solutions, it was necessary to synthesise the principles of the circular economy into performance requirements and criteria according to the function in the building.
Given the existence of multiple and heterogeneous criteria, the Multi-Criteria Decision Analysis (MCDA) is used to develop the screening process.The Macbeth (Measuring attractiveness by a Categorical-Based Evaluation Technique) method is adopted in this research for its ability to incorporate many preferences built through pairwise comparison judgments.It is a participative process based on an additive aggregation approach.It allows one to structure the problem and rank the options, considering qualitative indicators, performance levels, and different criteria weights [16,17].
After defining criteria and performance levels, a panel of experts (in this case, architects and civil engineers) judge the performance requirements for each sub-component of the wall.Then, they define the difference of attractiveness between the performance levels of each criterion and between different criteria.This set of criteria-wise is numerically ranked in terms of attractiveness.Then, all options (construction solutions) are classified according to the defined performance levels, and the software, through weighted average, delivers the ranking of all the options on a 0/100 scale.
In the following sections, we adopt these integrated methods (Ashby and Macbeth) to evaluate the performance of internal partition walls, using Lisbon as a case study.According to the concept of "shearing layers", partition walls are part of the Space Plan, with a life expectancy from 3 to 30 years [23].Given its short life expectancy, the partition walls can be upgraded or replaced frequently.These systems require lower structural and weather resistance constraints than other building systems.

Translation of Functional Requirements
The functional performance defines the required level of material efficiency for each building component.Strength, deformability, and durability are fundamental parameters, especially in load-bearing elements [67].The components of the façade system are waterproofing, hygrothermal properties, and so on.Table 2 shows the performance level of each criterion that are listed below:

•
Mechanical Resistance Capacity defines the material behaviour subjected to mechanical stress.It refers to the ability to withstand an applied force without failing or excessive deformation.

•
Thermal performance measures thermal properties (conductivity, specific heat) that ensure thermal comfort and building energy efficiency.

•
Acoustic performance is the ability of a material to absorb or insulate sound.

•
Water-resistance represents the ability of a material to maintain its properties when exposed to water.If a material absorbs water, it expands, thermal conductivity increases, and strength and durability are compromised.

•
Fire Resistance characterises the behaviour of a material when exposed to fire, such as the release of toxic gases and emission.The classification of the material fire resistance is fundamental to guarantee the safety of the occupants in case of fire.

•
Durability is the ability of a material to resist the combined action of physical, chemical, and biological factors.If the material is durable, it will have a longer service life and low maintenance.

•
Sensory Properties identifies those sensory properties significant in finishing materials: texture, brightness, transparency, and odour.The proposed methodology for selecting upcycled and re-used materials is applied to partition walls.The first step regards the identification of those functional parts that allow the components of a partition wall to work properly (Figure 4); the second step regards the translation of functional needs into requirements and constraints (Table 3).
The proposed methodology for selecting upcycled and re-used materials is applied to partition walls.The first step regards the identification of those functional parts that allow the components of a partition wall to work properly (Figure 4); the second step regards the translation of functional needs into requirements and constraints (Table 3).
The requirements and constraints necessary to achieve all functional demands were qualitatively identified according to the need to respond to the functional parameters that were previously defined (Table 3).The requirements and constraints necessary to achieve all functional demands were qualitatively identified according to the need to respond to the functional parameters that were previously defined (Table 3).

Environmental Requirements and Parameters According to CE Principles
Environmental performance requirements are essential for evaluating the potential of re-used and upcycled materials.The following requirements are listed in Table 4:

•
The type of waste identifies the nature of the waste.Post-consumer waste is composed of urban waste, i.e., waste of domestic origin generated during daily activities.Industrial waste or by-products result from advanced production processes or waste from a specific industry, e.g., fly ash from the steel industry or wood scraps.

•
The complexity of the Transformation Process allows sorting by order of complexity of the transformation processes.The more complex the transformation processes are, the more energy, carbon, and labour are required to produce new materials and new building systems.The simplest transformation processes can be executed at a construction site, eliminating the need for production and transport processes, whereas complex processes require a specific production line.

•
The toxic content identifies harmful substances that may compromise human and environmental health.The materials used in the circular building must not contain the substances present in Building Industry Red Lists [68].No prohibited products or materials (e.g., epoxy resin) can be employed.

•
The Potential for Reintegration into the Biological and Technological Cycle allows the identification of the capacity that materials, at the end of the useful life of the building, to be re-used in cascade, eliminated by nature in biological nutrients, or recycled without losing value in technological nutrients [69].Each transformation process is evaluated considering the potential contribution of the building material to a global continuous material flow.

•
The Availability and Local Proximity parameters can be defined at various scales according to the city's political and social geographic context.Three radii of geographical proximity with a centre in Lisbon can be defined for this analysis: High proximity: Radius of 10 km; Medium proximity: 25 km radius; Low proximity: Radius of 40 km radius of the centre of the intervention area (Figure 5).Different types of waste were identified and divided into five groups according to their nature: plastic, paper, wood, steel/aluminium, and agricultural waste.The relevant stages in managing this waste, the actors involved, and the potential places to obtain this waste in Lisbon were also identified within the defined radius.

•
The type of waste identifies the nature of the waste.Post-consumer waste is composed of urban waste, i.e., waste of domestic origin generated during daily activities.Industrial waste or by-products result from advanced production processes or waste from a specific industry, e.g., fly ash from the steel industry or wood scraps.

•
The complexity of the Transformation Process allows sorting by order of complexity of the transformation processes.The more complex the transformation processes are, the more energy, carbon, and labour are required to produce new materials and new building systems.The simplest transformation processes can be executed at a construction site, eliminating the need for production and transport processes, whereas complex processes require a specific production line.

•
The toxic content identifies harmful substances that may compromise human and environmental health.The materials used in the circular building must not contain the substances present in Building Industry Red Lists [68].No prohibited products or materials (e.g., epoxy resin) can be employed.

•
The Potential for Reintegration into the Biological and Technological Cycle allows the identification of the capacity that materials, at the end of the useful life of the building, to be re-used in cascade, eliminated by nature in biological nutrients, or recycled without losing value in technological nutrients [69].Each transformation process is evaluated considering the potential contribution of the building material to a global continuous material flow.

•
The Availability and Local Proximity parameters can be defined at various scales according to the city's political and social geographic context.Three radii of geographical proximity with a centre in Lisbon can be defined for this analysis: High proximity: Radius of 10 km; Medium proximity: 25 km radius; Low proximity: Radius of 40 km radius of the centre of the intervention area (Figure 5).Different types of waste were identified and divided into five groups according to their nature: plastic, paper, wood, steel/aluminium, and agricultural waste.The relevant stages in managing this waste, the actors involved, and the potential places to obtain this waste in Lisbon were also identified within the defined radius.

Weighting of Environmental and Functional Performance Levels
After defining the environmental and functional performance levels, a panel of experts establish the distances between each performance level to obtain overall cardinal values.The experts define the difference in attractiveness between two performance levels by selecting the most appropriate adjective from seven semantic categories defined in the Macbeth method: no, very weak, weak, moderate, strong, very strong, or extreme (Figure 6).For example, the complexity of the difference in attractiveness between Simple Transformation Process (S) and Design Transformation Process (D) ratings is very weak.In contrast, the difference of attractiveness between the Cultivation Transformation Process (C) and Reconfiguration Transformation Process (R) is strong.A similar process is undertaken to define the weights of each criterion for each partition wall component.Then, three design scenarios are defined when the dominant criterion is thermal and acoustic insulation, cladding, and load-bearing materials (Figure 7).

Classification Process
A total of 35 materials are collected in this study comprising materials and construction systems upcycled or re-used from post-consumer and industrial waste.These were divided into five groups: plastic, paper, wood, steel/aluminium, and agricultural waste, (Tables 5-9).

Classification Process
A total of 35 materials are collected in this study comprising materials and construction systems upcycled or re-used from post-consumer and industrial waste.These were divided into five groups: plastic, paper, wood, steel/aluminium, and agricultural waste, (Tables 5-9).To assess Availability and Local Proximity (APL), it is necessary to define the stages of waste flow management, the actors involved, and the potential places to obtain this waste (in Lisbon).Table 10 summarises this process for plastic waste, and Appendix A, Tables A1-A5, includes all tables.It should be emphasised that urban post-consumption waste (bottles, cans, objects, and food) is placed in undifferentiated or recycling containers, collected and sorted by municipal collectors, and forwarded to the respective waste treatment and recovery centres.Therefore, these are the most probable places to obtain urban waste in large quantities.Objects that have a longer useful life (e.g., doors, tables, chairs, kitchen utensils) can be found in second-hand shops, online second-hand sales platforms, and specialised repositories such as the Repositório de Materiais in Portugal [100].Regarding industrial waste, one of the best suppliers is the firm producing waste, thus contractors or building materials companies can establish a beneficial relationship with that industry.

Ranking
The M-Macbeth tool allows one to score each option according to the function of the partition wall component.Figures 8 and 9 show the overall thermometer, which ranks the solutions from the best classification (100) to the worst (0).To screen these results, all combinations characterised by a global weighted score lower than 75 are discarded in the 1st and 2nd scenarios.Given the function of the materials in the 3rd scenario, solutions with score lower than 90 are discarded.The structural support function demands a higher set of requirements, and the analyst considered that only those starting from 90 are adequate to perform it.Ten solutions exhibit the best scoring in the 1st scenario.Among those, four bestscoring solutions stand out: (a) Wood Foam (Score: 89.23/100) was developed by the Fraynhifer Institute for Wood Research in Germany.It is obtained through lignocellulose from the biomass of trees and other woody plants.The strength of this material does not depend on the quality of the wood.The wood can contain sawmill waste, forest trimmings and chips as raw material because the strength of the foam is related to the contact between the cross fibres and not their length or fibre quality.It can be produced with different densities from 40 to 200 kg/m 3 and has thermal conductivity levels comparable to expanded polystyrene, around 0.04 w/km.Being a porous and hygroscopic material, it behaves similar to a sponge in the presence of moisture, yet its volume remains intact.In general, wood foam bears high resistance, low thermal conductivity, and good behaviour with fire; in this sense, it can be applied as thermal insulation in product packaging, furniture, and non-structural panels.Besides being a waste-derived product, it is an effective alternative to foams made from petrochemical products [59,85].Ten solutions exhibit the best scoring in the 1st scenario.Among those, four bestscoring solutions stand out: (a) Wood Foam (Score: 89.23/100) was developed by the Fraynhifer Institute for Wood Research in Germany.It is obtained through lignocellulose from the biomass of trees and other woody plants.The strength of this material does not depend on the quality of the wood.The wood can contain sawmill waste, forest trimmings and chips as raw material because the strength of the foam is related to the contact between the cross fibres and not their length or fibre quality.It can be produced with different densities from 40 to 200 kg/m 3 and has thermal conductivity levels comparable to expanded polystyrene, around 0.04 w/km.Being a porous and hygroscopic material, it behaves similar to a sponge in the presence of moisture, yet its volume remains intact.In general, wood foam bears high resistance, low thermal conductivity, and good behaviour with fire; in this sense, it can be applied as thermal insulation in product packaging, furniture, and non-structural panels.Besides being a wastederived product, it is an effective alternative to foams made from petrochemical products [59,85].
(b) PET wool (Score: 88.58/100) or polyester wool is a thermo-acoustic material constructed from used PET bottle fibres.It is a 100% recyclable material, already marketed by some companies in different thicknesses (300-200 mm).It has a heat transfer coefficient of 0.04 W/mK, is waterproof, and has excellent sound absorption capacity, with no harmful chemicals or binders.It is entirely safe to handle as it is non-combustible [75].(c) Hy-Fi and Mycoform (Score: 83.15/100) are similar materials, being composed of agricultural by-products and mushroom mycelium, which serve as natural digestive glue.This type of cultured material uses the natural growth of fungi as a bio-manufacturing method.The manufacturing process is straightforward; agricultural waste is mixed with water and the living organism (mushroom roots/mycelium).After five days, the mixture can be placed in a closed mould, where it rests for another five to ten days (25-27 • C).The roots and organisms grow and fuse into biomass, giving rise to a solid material subjected to heat (70-90 • C), hot pressed, oven-dried or dried in the open air to dehydrate the material, interrupting the growth process, and neutralising the fungus.Due to its thermal conductivity (0.04-0.18W/mK), Mycelium composites are optimised using straw and hemp fibres (low density), and thus with a reduction of the values to 0.04-0.08W/mK.Mycelium alone can absorb low-frequency sounds (<1500 Hz), outperforming cork [93,94].
In the 2nd scenario, there are fourteen high scoring solutions.Among those, four best-scoring solutions stand out: (a) Polli-Brick (93.99/100) from the Winimiz company are 100% recycled polyethylene terephthalate polymer bottles, designed to be re-used, as a translucent, lightweight after consumption and recyclable material.The design of the bottles is modified in 3D into a modular honeycomb-like shape, resulting in a very sturdy container that is suitable for the construction industry, and was used in the iconic EcoARK building at the 2010 International Flora Expo in Taipei (Taiwan) [71].(b) Vegan house atelier Block Architects and Collage House Facade (91.00).The architects designed the facades of these houses using blinds and doors collected in the proximity of the construction site [82,83].(c) 3D Abwab Pavilion (91.00/100) designed the Lot-el studio in the Maboneng district in South Africa.The building consists of 140 stacked containers connected with a twist lock and welded together.Each residence consists of two (or three) containers [86,87].
In the 3rd scenario, the best-ranking solutions are: A temporary pavilion for Dubai Design District was designed with materials from a local waste management company (Bea'ah).The pavilion was composed of 1100 springs from used mattresses, and the architects chose this residue for its strength, lightness, and silhouette.The springs exhibited the function of an organic (cloud-like) structural mesh that controlled natural light and recreated patterned shadows on the floor.At the end of the exhibition, the pavilion was dismantled, and materials were re-used by the company [88].

Discussion
The overall thermometers allow one to compare the performance of each construction solution under multiple criteria within each design scenario.Solutions derived from paper waste display great limitations, due to poor durability, low mechanical resistance and low water and weather resistance.However, some designers have explored its potential in construction, e.g., The Architect Shigeru Ban, well-known for his innovative approach using unorthodox materials.Ban designs emergency shelters, and other structures that are made from paper tubes.A composite material for the structure and cladding is employed at Arteck Milan in 2007, which contains raw material waste from printing adhesives and stickers produced by the Finnish company UPM.On the other hand, wastepaper sludge, a by-product of recycled paper products, can be incorporated into construction materials [101,102].
The construction solutions with plastic waste can be re-used and recycled.However, several reused options did not fulfil minimal functional requirements.On the other hand, recycling plastic waste to produce new materials such as mortar or concrete has been proven to be effective [101,102].Wood, steel, and aluminium bear huge potential in re-using or recycling processes due to their intrinsic physical and chemical properties, as shown in their scores.
Virgin materials such as potentially harmful glues or resins need to be added during the transformation process to achieve an adequate functional performance, which compromises the circularity and health of the material.
Bio-based materials like Hy-fi, and Mycoform also tend to be less durable than technical materials as they are generally hydrophilic materials and are prone to the action of fungi.They should be kept in dry places or be coated with suitable and healthy materials as a solution.The material is coated with a sunflower varnish in the Sunflower Enterprise.The same phenomenon occurs with fire resistance requirements.Building materials and systems can be optimised through passive fire protection solutions such as healthy paints and coatings, e.g., black acacia tannin resin and modified lignin resin (epoxy-lignin) [68].
Although the use of local secondary materials can substantially reduce the life cycle impact, impact from primary materials (e.g., painting, resin) that need to be added during production can outweigh the benefits from using secondary materials [102].
The harvest map revealed that all waste flows analysed in this work were generated near the intervention area.Society produces waste streams regardless of regional and cultural influences, aside from sunflower and cereal cultivation.
The lack of accurate technical and environmental information regarding waste-derived products and experimental materials precludes a Lifecycle Assessment (LCA) of the selected solutions.This analysis addresses a comprehensive assessment to overcome this limitation.In this study, the environmental and functional performances are taken into account in three design scenarios, distinguished for the criteria weights and the thresholds.
However, the use of a multi-criteria analysis tool presents a limitation.First, the performance of the options is evaluated without considering the interactions between components.Second, a cost-benefit analysis should be addressed in further analyses to validate the effectiveness of each selected solution considering contextual constraints.
The principal drivers for enabling material circularity are cost-effectiveness, technical feasibility, and institutional public support [103].According to [12], some obstacles encountered by companies for producing and re-using secondary materials include a difficult sales process, limited quantities and access, and lack of adequate infrastructure for sorting and collection [104].European and national building codes can promote the use of secondary materials.Additionally, the use of environmental product declarations (EPDs), and inclusion in building certification schemes (e.g., BREEAM, Levels, LEED) can lead to making informed decisions [104].
Re-used and upcycled materials may require substantial transformation processes or require the input of primary materials during the transformation into a condition suitable for being used in the construction sector.To this end, meeting the legislative requirements such as energy efficiency and construction reliability is demanding.
The European Commission has recently updated Building Codes (Eurocodes) to incorporate climate impact requirements (e.g., mandate M/515).Specifications and guidelines for material selection should be improved to reduce uncertainties of the construction contractors, designers, financial investors, and to promote the use of secondary materials rather than primary materials.Taxes on primary materials (e.g., aggregates) applied in most EU Member States and reduced Value Added Tax (VAT) for recycled materials in the Czech Republic [103] are effective measures towards a more sustainable building economy.

Conclusions
A sustainable and circular urban metabolism can continuously produce the materials it needs to evolve, without exploiting natural resources.Manufacturers and designers are challenged to create efficient systems where materials exist in various states without ever becoming waste.Design strategies that enable decelerated and narrowed material flows will become a common practice in this industry, as new production processes, new techniques, construction processes, and new architectural languages incorporate upcycling remanufacture and re-use.
Designers play a lead role in innovation and must adopt a systematic approach, understanding building composition, assembly, and disassembly routines and their behaviour over time within different social and environmental contexts.Furthermore, designers and construction companies should perceive how the industry manages building material flows, selects new upcycled and re-used materials, and analyses their transformation processes.Despite rarely being put into practice, cascade recovery and upcycling represent competitive strategies for an effective waste management, since they contribute to the resilience in local value chains, and decreases in import dependence, and close material flows.
In this broad context, thirty-five re-used and upcycled materials (post-consumer waste and by-products from various industrial sectors) were evaluated in this study using a Multi-Criteria Analysis considering indicators related to environmental performance, i.e., (i) complexity of transformation processes; (ii) potential of reintroduction in the biological or technological cycle, (iii) toxic content, and (iv) local availability-and indicators related to functional performance, i.e., (v) mechanical resistance capacity, (vi) thermal performance, (vii) acoustic performance, (viii) water and moisture resistance, fire resistance, and durability.A total of ten study solutions were recognised as suitable for thermal and acoustic isolation, fourteen for coating, and two for structural functions.The analysed materials exhibit good environmental performance.Wood, steel, and aluminium waste materials bear great potential, regardless of their functional limitations, the proposed solutions based on waste materials have great potential within the construction industry.
The territory and cities in particular are digitized, not only in their "static" infrastructure-new and existing buildings through BIM models that contain material and component information-but also the material flows of industries, agriculture and domestic waste.This will open multiple opportunities for the exploration of overlooked resources, allowing more matches between demand and supply.
This study provides a methodology that fits within this scheme, by qualitatively evaluating building materials derived from domestic and industrial wastes through technical and sustainability criteria.Its scope can be extended in future research and adapted to other building components and to infrastructure projects.

Figure 1 .
Figure 1.Relationship between Circular design strategies and the Hierarchy of Material Levels.

Figure 1 .
Figure 1.Relationship between Circular design strategies and the Hierarchy of Material Levels.

Sustainability 2022 , 43 Figure 3 .
Figure 3. Methodology for evaluating building materials based on post-consumer waste and byproducts, as proposed in this research.

Figure 3 .
Figure 3. Methodology for evaluating building materials based on post-consumer waste and byproducts, as proposed in this research.

Figure 4 .
Figure 4. Identification of Partition Wall's main functions.

Figure 4 .
Figure 4. Identification of Partition Wall's main functions.

Sustainability 2022 , 43 Figure 6 .
Figure 6.Macbeth judgment matrices related to the attractiveness difference between the performance levels.Figure 6. Macbeth judgment matrices related to the attractiveness difference between the performance levels.

Figure 6 .
Figure 6.Macbeth judgment matrices related to the attractiveness difference between the performance levels.Figure 6. Macbeth judgment matrices related to the attractiveness difference between the performance levels.

Figure 7 .
Figure 7. Macbeth judgment matrices related to the attractiveness difference between each criterion (three scenario models were developed according to the different components of partition walls).

Figure 7 .
Figure 7. Macbeth judgment matrices related to the attractiveness difference between each criterion (three scenario models were developed according to the different components of partition walls).

Sustainability 2022 ,
14, x FOR PEER REVIEW 24 of 434.4.RankingThe M-Macbeth tool allows one to score each option according to the function of the partition wall component.Figures9 and 10show the overall thermometer, which ranks the solutions from the best classification (100) to the worst (0).To screen these results, all combinations characterised by a global weighted score lower than 75 are discarded in the 1st and 2nd scenarios.Given the function of the materials in the 3rd scenario, solutions with score lower than 90 are discarded.The structural support function demands a higher set of requirements, and the analyst considered that only those starting from 90 are adequate to perform it.

Table 1 .
Overview of practical examples of re-use and upcycle transformation processes.

Table 2 .
Performance levels for each functional criterion.

Table 3 .
Constraints and functions of partition walls.
* It should achieve aesthetic and functional consistency.

Table 3 .
Constraints and functions of partition walls.
* It should achieve aesthetic and functional consistency.

Table 4 .
Performance levels for each criterion based on experts' judgments.

of Waste (Tw) Potential for Reintegration into the Biological and Technological Cycle (CTR) Availability and Local Proximity (PRC)
Environmental Requirements and Parameters According to CE PrinciplesEnvironmental performance requirements are essential for evaluating the potential of re-used and upcycled materials.The following requirements are listed in Table4:

Table 5 .
Performance levels of the materials and construction solutions from plastic waste.

Table 6 .
Performance levels of the materials and construction solutions from paper wastes.

Table 6 .
Performance levels of the materials and construction solutions from paper wastes.

Table 6 .
Performance levels of the materials and construction solutions from paper wastes.

Table 7 .
Performance levels of the materials and construction solutions from wood wastes.

Table 6 .
Performance levels of the materials and construction solutions from paper wastes.

Table 8 .
Performance levels of the materials and construction solutions from steel/aluminium wastes.

Table 6 .
Performance levels of the materials and construction solutions from paper wastes.

Table 9 .
Performance levels of the materials and construction solutions from agriculture waste.

Table 6 .
Performance levels of the materials and construction solutions from paper wastes.

Table 10 .
Stages of the production chain, authors, and places to obtain the plastic waste in Lisbon.

Table A3 .
Relevant stages of the production chain, authors involved, and places to obtain wood waste in Lisbon.