Sustainable and Affordable Prefabricated Construction: Developing a Natural, Recycled, and Recyclable Mobile Home

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Article Sustainable and Affordable Prefabricated Construction: Developing a Natural, Recycled, and Recyclable Mobile Home

Carlo Berizzi 1,* , Salvatore Nirta 1 , Gaia Nerea Terlicher 1,* and Luca Trabattoni 2

1 Department of Civil Engineering and Architecture, University of Pavia, 27100 Pavia, Italy; [email protected] 2 Department of Architecture and Urban Planning, Opole University of Technology, 45-758 Opole, Poland; [email protected] * Correspondence: [email protected] (C.B.); [email protected] (G.N.T.)

Abstract: Outdoor tourism is a form of outdoor holiday that is growing rapidly today, and that stands out from other forms of tourism for its immediate relationship with the landscape which becomes for the tourist the main attraction of the holiday intended as a break from ordinary urban life. Outdoor tourism today represents a growing percentage in the tourism sector, in which mobile homes are the real players. Despite the considerable use of this product in open-air accommodations located in relevant landscapes, there is still no sensitivity in the constructive approach and in the choice of materials in terms of sustainability. In the open-air tourism sector, the lack of ecological sensitivity results from two levels of application: one regarding the whole settlement and the public spaces of outdoor accommodations and one regarding the mobile unit from the design to the production

process. This paper will provide some practical strategies to introduce the ecological theme in the mobile home for the tourism sector. The research aims to analyze the production system of mobile

Citation: Berizzi, C.; Nirta, S.; homes in order to introduce alternative materials within the existing assembly line. The research Terlicher, G.N.; Trabattoni, L. demonstrates the possibility of a product being sustainable both economically and environmentally, Sustainable and Affordable healthy, and well-integrated with landscape by adopting an approach that makes it possible to use Prefabricated Construction: the same assembly line currently in use. Developing a Natural, Recycled, and Recyclable Mobile Home. Keywords: sustainability; outdoor tourism; mobile home; ecology; prototype Sustainability 2021, 13, 8296. https://doi.org/10.3390/su13158296

Academic Editor: Antonio Caggiano 1. Introduction The global impact of the entire construction sector today is estimated at around 30% [1]. Received: 17 June 2021 This impact is due not only to the energy and consumption cost of CO related to handling Accepted: 19 July 2021 2 Published: 25 July 2021 and transportation, but also to the enormous consumption of material, often not renewable. Furthermore, the construction industry is responsible for over 30% of global greenhouse gas

Publisher’s Note: MDPI stays neutral emissions (GHGE) and 36% of global waste production that can be quantified as 3.8 billion with regard to jurisdictional claims in per year [1]. published maps and institutional affil- It is not only the construction system that includes building is responsible for nega- iations. tively affecting the environment, but also the process of demolition which generates waste that cannot be reused. Nevertheless, the most used materials in construction are cement and concrete, which in terms of carbon dioxide emissions and depletion of fossil energy resources represent the worst materials [2]. It is obvious today that the building sector is the cause of a high percentage of GHGE Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. in the world; thus by working in a more conscious way, it can play an important role in This article is an open access article sustainable development. The sector can contribute promoting sustainable architecture, distributed under the terms and which means using materials that are environmentally friendly, in which the purpose of conditions of the Creative Commons architecture is to reduce irreversible impacts on the environment and human health [3]. Attribution (CC BY) license (https:// According to the International Resource Panel, by using “material efficiency strate- creativecommons.org/licenses/by/ gies”, such as the use of alternative and recycling materials, it will be possible to reduce 4.0/). emissions from material cycle of residential buildings in the G7 states by 80% in 2050

Sustainability 2021, 13, 8296. https://doi.org/10.3390/su13158296 https://www.mdpi.com/journal/sustainability Sustainability 2021, 13, 8296 2 of 16

(United Nations Environment Programme (UNEP) 2019) [4]. Even the 2019 Global Status Report for Buildings and Construction promotes the reduction of demolition and the development of a circular economy in the building sector in order to reduce emissions that have increased from 2017 to 2018 [5]. The use of alternative materials, such as natural, recycled, and recyclable materials, represents the new frontier for the building sector to contribute significantly to sustainability. Using recycled and recyclable materials means selecting them according to their life cycle, preventing the exploitation of resources and reducing the production of waste generating a “closed circulation of components” [3]. Recycling and reusing strategies can avoid producing more energy for new buildings’ construction by earning energy from existing building materials [6]. In this way, waste material becomes a resource contributing to a good circular economy practice in which the concept is to work on the building sector such as nature does: using natural materials and recycling materials in a cyclic optic that does not know the meaning of waste [7]. The conscious use of materials in construction is also one of the prerogatives of the 2030 Agenda for Sustainable Development which aims to make human settlements sustainable by guaranteeing sustainable production and consumption models, trying to protect and promote sustainable use of the terrestrial ecosystem. Using sustainable materials means using resources consciously, and positively affecting, as the report “Our Common Future” states, the world’s balance by providing natural environmental, economic, and social benefits [8]. Natural, recycled, and recyclable materials can all be considered eco-friendly even if they are of different origin and nature: naturals derive directly from raw materials which of course do not cause CO2 emissions and add to air pollution, consequently creating a healthy environment for humans; recycled materials derive from waste materials reducing them and can be natural or artificial; recyclable materials provide an opportunity for the future and can include natural or artificial materials that can be reused again in another process. One of the most spectacular forms of the present is tourism, which is a mirror of contemporary society [9]. Sustainability in the field of tourism finds an immediate comparison with outdoor tourism where there is a strong relationship with nature and the surrounding landscape. However, the reflection on sustainability in this field needs to be analyzed on different levels including taking into account the sustainability value of the individual accommodation unit. The placement of accommodation facilities in particularly sensitive areas of the territory and of particular landscape interest requires greater sensitivity to sustainability issues both in terms of composition at an architectural level and in a technical key through the use of properly selected materials with respect to the environment. Thus, the need for improvement on a sustainable level does not only concern ordinary buildings today. The theme of outdoor tourism still has deep gaps and it needs more sensitivity in terms of ecology. In Italy alone, there are more than 2600 outdoor accommodations and that can accommodate together up to 1,000,000 tourists at the same time, considering that the arrivals in the outdoor accommodations have increased by about 15% since 2010 [10]. The number of tourists in Italy was more than 131,000,000 in 2019, of which more than 10,000,000 were arrivals in outdoor accommodations [9]. These numbers combined with a failed sustainability approach have a strong environmental and landscape impact. Within these structures, mobile homes represent the real actors of these contexts, being the most widespread typology, thus defining their landscape. The production of mobile homes operates independently of the context in which they are placed, creating environmental disconnections in which, at most, “façade operations” are activated which do not solve the environmental problem. Mobile homes are housing units on wheels for seasonal occupation produced on an industrial level and placed within the outdoor accommodation facilities. They have a usual dimension of 8 × 4 m, can accommodate up to six people, and consist of a kitchen-living room, bedrooms, and toilet and are usually connected to a veranda. They are designed to be easily transported usually by truck or by tow. The main characteristic of Sustainability 2021, 13, 8296 3 of 16

mobile home is that they do not need any permanent foundations, therefore they are easily removable. This last feature gives it a privileged position in the current European debate on the issue of land use. In fact, soil sealing is one of the main causes of soil degradation in the European Union, and to this end the European Commission is committed since 2011 to promoting a more sustainable use of land and soil, an objective made explicit with the “Roadmap to a Resource Efficient Europe” in which an increase in net land use equal to zero by 2050 is set as the goal. In these terms, the mobile home product is not permanently connected to the ground, therefore it does not consume soil and it gives rise to reversible settlements. This, connected to the fact that they are industrially produced and therefore with dry assembled materials and to the fact that they are flexible thanks to their transportability, represents a sustainable choice compared to ordinary buildings. The use of sustainable materials is, today, still a distant topic in their application on mobile homes for tourism [11]. At a commercial level, the sustainability of materials is often less important than their availability, their adaptability to the production process, and their evolutionary readjustment. The application of alternative materials in mobile homes can be an opportunity to enhance this product, to create healthy architecture, and to react to contemporaneous problems such as climate change during its production and life cycle, as well as it representing a design opportunity. The use of sustainable building techniques with the use of structures built with ecological materials can drastically reduce the environmental impact of outdoor accommodations, so that they are non-invasive and in harmony with the natural scenario in which they are immersed. Thus, the study started from two research questions: is it possible to build a sustainable mobile home for tourism following the existing assembly line of the industry? Can a sustainable mobile home for tourism be competitive within the existing tourism market? The study will research some practical strategies to introduce sustainable construction in the mobile homes field, which has still not been adopted in this sector. Through the study of a mobile home prototype carried out within the AUDe (Architecture and Urban Design) laboratory of the Department of Civil Engineering and Architecture of the University of Pavia, currently put into production by the Crippacampeggio company (Carate Brianza, Italy), we want with this paper to promote the possibility of introducing alternative materials in an existing industrial chain to realize sustainable products like that of mobile homes.

Productive Process The aim of the research is to analyze an existing industrial assembly line of mobile homes and insert into it alternative materials in order to enhance the product of the mobile home, transforming it into a sustainable industrial product. Thus, the earliest stage of the design process includes analysis of the assembly line, a study that allows, in the following stages, choosing the best eco-friendly materials (materials that are not harmful to the environment) that permit the maintenance of the same processing industrial techniques. The analysis of the productive process was developed studying the productive line of one of the main Italian producers, a seller of Mobile Home Crippacampeggio, for which a prototype was designed that was an improvement in terms of naturality, recyclability, and of being recycled. The industry is located in different locations in northern Italy, one in Pavia where the prototype was developed, and it is the major producer in Italy of mobile homes, also exporting their products, mainly to Croatia where they have other factories. Its production system is based on a fast assembly line permitting them to produce at least 10 mobile homes per day. According to the assembly line, the production of each mobile home is based on phases during which each part of the mobile home is assembled. The assembly line moves from one point to another of the industry during its construction, permitting in a continuous way the work of the workers. Inside the industry, there is a rail path that permits them to push the mobile homes from one point to another according to the needed phase thanks to the presence of wheels under the mobile home. There are nine phases of production: Sustainability 2021, 13, 8296 4 of 16

• Chassis mounting: steel frame located on the base consisting of 2 or 4 wheels that supports the entire mobile home; • Floor formation: includes different panel layers with structural function and insulation as well as the finishing layer; • External walls elevation: includes insulation and the internal finishing layer; • Partitions elevation: panels with their finishing layers; • Ceiling formation: includes external and internal finishing layers and insulation; • Realization of the electrical and water system; • External finishing layer; • Furniture insertion; and • Finishes. Each phase lasts 50 min and one mobile home is ready in 7.5 h, with a total of 75 workers across all the phases. Regarding the production system and the realized product, which is prefabricated, it is obvious that all materials that are used must be dry assembled.

2. Material and Methods 2.1. Current Materials For the analysis phase of the actual production, a basic model of mobile home produced by the industry was selected. The model selected is Evo and presents a simple structure; it is composed by a wooden frame while the rest of the components for the floor and wall system are made of panels that can be easily assembled. The materials used to create the flooring and the walls are all wood, but mainly chipboard with a high percentage of formaldehyde. In particular, the chipboard used for the walls presents good percentages in terms of naturality and for being recyclable (respectively, 70% and 50%) but a low percentage of being recycled, which is only 20%. The finishing internal layer of the walls and ceiling is made of meranti, which belongs to the family of Shorea trees. About 50 species of Shorea are on the IUCN red list as they are endangered. Despite this, these trees are still cut illegally and used, and among the many wood companies, only few have obtained FSC certification, whose wood does not reach the European market. Meranti is configured as a sheet to which is applied a plastic film (kraft paper) to make wood waterproof. This means that the recycling process is impossible to apply due to the inability to decompose the material in its constituent parts. The same problem is faced in the furniture which is composed of chipboard, to which is applied a urea coating which is unsustainable, not natural, and unrecyclable. The materials used for insulation comprise sandwich panels composed by steel sheet and polyurethane, which does not represent the best choice since it is impossible to decompose. Moreover, polyurethane is not natural and is unrecyclable, and even if the steel sheet could be recyclable, it could not be recycled because the remains would be contaminated by the glues and polyurethane. The finishing layer of the floor is composed of linoleum which is not natural; it is realized in PVC, but is very cheap, easy to place and recyclable. The finishing external layer of the roof is made by a waterproof membrane made by PVC, thus 0% natural but 90% recyclable. This first approach represents the starting point for the research, that permitted understanding the logic behind the choice of each material and their characteristics in terms of properties and natural, recycled, and recyclable percentage, useful for the second phase of the research. The economic condition of a company has a very important influence on the sustainability financial statement; the aim of the research was indeed to act according to the model of a sustainable economy, a strategy that undoubtedly encounters limitations due to high costs and availability of materials. In fact, many of the materials, highly performing and sustainable, have a limited production and sometimes their companies do not export the products, thus not allowing their availability outside the country itself. Furthermore, Sustainability 2021, 13, x FOR PEER REVIEW 5 of 17

Sustainability 2021, 13, 8296 5 of 16 performing and sustainable, have a limited production and sometimes their companies do not export the products, thus not allowing their availability outside the country itself. manyFurthermore, of these many materials of these provide materials expert provide users and expert therefore users and have therefore very high have costs, very which high forcosts, a product which for such a product as that of such the mobileas that homeof the ismobile inaccessible home is or inaccessible at least not or reproducible at least not inreproducible a vision of futurein a vision production. of future To production. improve the To mobile improve home the productmobile home in a real product vision in of a productionreal vision (andof production not in a utopian (and not vision), in a utop differentian vision), levels of different sustainability levels haveof sustainability been taken intohave account: been taken environmental into account: (origin environmental of raw materials), (origin economicof raw materials), (economic economic accessibility (eco- andnomic recycled accessibility and recyclable and recycled materials), and recyclable and social materials), (integration and with social landscape (integration and health with guarantee).landscape and health guarantee).

2.2.2.2. MethodologyMethodology andand LegislationLegislation ofof ReferenceReference AA mobilemobile homehome modelmodel (EVO)(EVO) waswas selectedselected asas aa referencereference thatthat couldcould representrepresent thethe best-sellingbest-selling product.product. ThisThis productproduct waswas thethe startingstarting pointpoint forfor researchresearchin interms termsof oftechnical technical characteristicscharacteristics andand environmentalenvironmental sustainability.sustainability. AnAn itemizeditemized listlist ofof materialsmaterials ofof allall thethe componentscomponents ofof thethe productproduct waswas obtainedobtained fromfrom thethe company.company. From From this, this, the the incidence incidence of of each each material material was was calculated calculated based based on on its its weight weight inin relationrelation toto thethe totaltotal weightweight of of the the mobile mobile home. home. Systems,Systems, windows,windows, andand allall accessoryaccessory materialsmaterials suchsuch asas bathroombathroom ﬁxtures,fixtures, monitors,monitors, andand bedsbeds werewere notnot takentaken intointo considerationconsideration inin thisthis analysisanalysis becausebecause theythey werewere consideredconsidered unessentialunessential forfor thethe purposepurpose ofof thethe research.research. ConsultingConsulting thethe technicaltechnical datadata sheetssheets ofof thethe producersproducers ofof thethe identiﬁedidentified materials,materials, threethree referencereference characteristics,characteristics, natural,natural, recycled, recycled, and and recyclable, recyclable, were were analyzed. analyzed. BasedBased on the weight weight of of each each material material and and in inrelation relation to its to value its value in the in triad the triadof char- of characteristicsacteristics taken taken into into consideration, consideration, an overall an overall result result for forthe the EVO EVO model model was was obtained obtained by bycalculating calculating the theweighted weighted average, average, resulting resulting in the in following: the following: natural natural materials materials 38%, 38%,recy- recycledcled 10%, 10%, and and recyclable recyclable 82% 82% (Figure (Figure 1). 1).

FigureFigure 1.1. PercentagePercentage ofof thethe EVOEVO model.model.

TheThe mathematicalmathematical formulaformula ofof thethe weightedweightedaverage averagewas wasused usedfor forthe thecalculation: calculation:

x1𝑥·p1∙𝑝+ +𝑥x2·p2∙𝑝+ ...+⋯+𝑥+ xn·pn∙𝑝 p1 +𝑝 p+𝑝2 + ...+⋯+𝑝+ pn

StartingStarting fromfrom thesethese values,values, thethe researchresearch setset thethe goalgoal ofof improvingimproving eacheach ofof themthem andand reachingreaching thethe thresholdthreshold ofof thethe Italian Italian legislation legislation on on CAM CAM [ 12[12]] for for the the recycled recycled percentage. percentage. The legislation imposes compliance with minimum environmental criteria and in The legislation imposes compliance with minimum environmental criteria and in particular the research focused on the construction sector, in which compliance becomes particular the research focused on the construction sector, in which compliance becomes mandatory for the renovation and maintenance of public buildings in Italy, but it can still mandatory for the renovation and maintenance of public buildings in Italy, but it can still be used as a quality reference for any building or product that wants to increase its degree be used as a quality reference for any building or product that wants to increase its degree of sustainability. of sustainability. The minimum thresholds in relation to the percentage of recycled and recyclable present within the product and materials are indicated in the annex dedicated to construction: 50% of the components must be disassembled, of which at least 15% that cannot Sustainability 2021, 13, 8296 6 of 16

be traced back to the supporting structure [13]. In the case of mobile homes, which are developed with dry technology, it is easier to achieve this goal for which a goal of 99% was set starting from a base of 82% (EVO). Instead, 15% of the material by weight of the total must be composed of recycled raw material and among this percentage, 5% must not refer to the load-bearing structure [13]. It is evident that the reference model (10%—percentage of recycled material in the EVO product) is below the expectations required by the legislation. The first goal of the research was to overcome this threshold. The legislation also introduces clear objectives for each type of material used, in this case wood and insulating materials were taken into consideration. The wood must come from sustainably/responsibly managed forests or it must be made from recycled wood or, even better, from both. These characteristics are easily demonstrable through the PEFC and FSC certifications which have been decisive for the choice of wood materials, in the absence of such certifications, materials with certifications of equal importance were chosen [13].

2.3. Process of Selection of the Materials Many factors influenced the choice of the different materials: ecology, industrial assembly line, and mechanical properties. To select the materials, a hierarchy was established in which the priorities linked to their characteristics that could best result a sustainable and eco-friendly final product and guide the choice of the materials were defined. These characteristics are represented by the intrinsic value of the material (natural, recycled, recyclable) [14]; from its availability; from the production costs; and from the cost of sale. A compositional architectural choice was taken into consideration in order to promote the aesthetics of sustainability, capable of promoting an ecological product also on a technical level. The approach consists of the correspondence of the materials with the sustainability parameters that best adapt to the product and the current context: availability, naturalness (a product that is made from materials and ingredients found in nature, with little or no human intervention [15]), recyclability, and origin. Then, the technical characteristics of the materials in relation to the production system were taken into account: lightness, adaptability, fire resistance, and dry modularity. Faced with the selection process, the materials that were selected are: • Wood (birch, conifer and bamboo) • Natural linoleum • Vegetable fiber • Textiles The following text is divided into the components that make up the mobile home, and each component comprises the description of the materials that have been chosen. Furthermore, for each material their certification is made explicit. Each certification is described below: FSC certification [16] guarantees that the entire wood–paper supply chain certified for its standards derives from environmentally friendly, socially useful, and economically sustainable forest management. CATAS CARB certification [17] is a certification regarding formaldehyde emission limits issued in wood-based products. The certification was born exclusively for the state of California; it then extended as a reference to many European companies. PEFC certification [18] is a system of no-profit certification in which every single nation defines the management standards to follow to obtain the certification; it provides a guarantee that the certified wood and arboreal material contained in a product comes from sustainably managed forests.

2.3.1. Flooring System The materials used by the industry for the ﬂooring system are not very sustainable but are good in terms of mechanical characteristics; thus, they have been replaced maintaining Sustainability 2021, 13, x FOR PEER REVIEW 7 of 17

guarantee that the certified wood and arboreal material contained in a product comes from sustainably managed forests.

2.3.1. Flooring System Sustainability 2021, 13, 8296 The materials used by the industry for the flooring system are not very sustainable 7 of 16 but are good in terms of mechanical characteristics; thus, they have been replaced maintaining their characteristics but improving their thermal performance by using a customized sandwich panel suitable for the assembly line. their characteristics but improving their thermal performance by using a customized The flooring system (Figure 2) is composed basically of four elements: two panels sandwich panel suitable for the assembly line. and the insulation panel composing the sandwich panel and the finishing layer. The panel The flooring system (Figure2) is composed basically of four elements: two panels located on the bottom part of the flooring is in close contact with the ground; for that and the insulation panel composing the sandwich panel and the finishing layer. The panel reason, the resistance to humidity is relevant in the choice of the material. The first choice located on the bottom part of the flooring is in close contact with the ground; for that was a panel composed of hemp fibers joined by royal jelly, therefore 100% natural and reason, the resistance to humidity is relevant in the choice of the material. The first choice 100% recyclable.was a This panel Canapalithos composed of 1000 hemp pane fibersl [14] joined (by by CMF royal Greentech, jelly, therefore Cavezzo, 100% Italy) natural and 100% also had excellentrecyclable. water This resistance Canapalithos properties. 1000 Unfortunately, panel [14] (by CMFit was Greentech, not able to Cavezzo, be adopted Italy) also had because it wasexcellent temporarily water resistance removed properties. from commercial Unfortunately, production. it was Thus, not able a tochipboard be adopted because panel (Idrolebit was from temporarily Gruppo Saviola, removed Viadana, from commercial Italy [14]) production. that presents Thus, an a chipboardexcellent re- panel (Idroleb sistance to swellingfrom Gruppo (24 h, less Saviola, than Viadana, 8%) when Italy in contact [14]) that with presents water or an humid excellent contexts resistance was to swelling selected. In addition,(24 h, less the than choice 8%) when led to in this contact material with because water or it humidis made contexts up of 100% was selected.recycled In addition, raw materialsthe which choice are led FSC to this certified, material and because the panel it is made with upits ofcomponents 100% recycled conforms raw materials to which formaldehydeare emissions FSC certified, meeting and thethe panelCATAS with CARB its components requirements. conforms to formaldehyde emissions meeting the CATAS CARB requirements.

26 mm_Wood Staves LUNAWOOD 28 mm_Ventilated Cavity 60 mm_Insulation Panel NATURAFLEX 5 mm_BAMBOO Panel

Figure 2. Details of the flooring system. Figure 2. Details of the flooring system. Above the chipboard panel is placed the insulation panel (Naturatherm by Natu- Above raliaBau,the chipboard Merano, panel Italy is placed [14]), the which insulation is made panel of wood (Naturatherm fiber which by allowsNaturali- it to be easily aBau, Merano,workable Italy [14]), and which high density, is made the of latterwood allowing fiber which it to allows resist crushingit to be easily due towork- the weight on it able and high(crushing density, < 10%the ,latter 200 kPa). allowing The performanceit to resist crushing in terms due of thermal to the insulationweight on isit excellent (λ (crushing < 0.04510%, 200 w/mk) kPa). and The the performance panel is waterproof in terms andof thermal breathable. insulation Compared is excellent to the previous(𝜆 solu- 3 0.045 w/mk)tion, and itthe presents panel is a waterproof greater thermal and breathable. mass (270 kg/m Compared) and to a greaterthe previous thermal solu- mass capacity tion, it presents(2100 a J/kgK).greater Thisthermal combination mass (270 allows kg/m3) better and a insulation greater thermal in the summer,mass capacity the season when (2100 J/kgK).the This product combination is used theallows most. better Finally, insulation the insulation in the summer, components the areseason made when of 80% recycled materials, and the whole raw material is FSC certified. the product is used the most. Finally, the insulation components are made of 80% recycled The finishing layer is composed by a Linoleum roll (Marmoleum Cocoa by Forbo, Baar, materials, and the whole raw material is FSC certified. Switzerland) 2.5 mm thick made up of natural raw materials (over 97%), including recycled The finishing layer is composed by a Linoleum roll (Marmoleum Cocoa by Forbo, cocoa bean shells, a mix of linseed oil, wood flour, and a jute fiber net to reinforce the sheet. Baar, Switzerland) 2.5 mm thick made up of natural raw materials (over 97%), including As an alternative to Marmoleum Cocoa, two other very ecologically and qualitatively valid recycled cocoa bean shells, a mix of linseed oil, wood flour, and a jute fiber net to reinforce materials were selected: Red Clay Hanji, a 100% biodegradable vegetable paper linoleum, the sheet. As an alternative to Marmoleum Cocoa, two other very ecologically and quali- and Reclaimed Barrel Oak, recovered barrel wood planks. Both materials were discarded tatively valid materials were selected: Red Clay Hanji, a 100% biodegradable vegetable due to their difficult availability, being originally from South East Asia and North America. paper linoleum, and Reclaimed Barrel Oak, recovered barrel wood planks. Both materials Improving the flooring system by using sustainable materials made it possible to were discarded due to their difficult availability, being originally from South East Asia obtain a system composed of 100% natural materials, 92% recycled materials, and 100% and North America.recyclable materials.

2.3.2. Perimetral System The entire structure of the mobile home is realized with a wood framework, of which the wood is FSC certified and supplied by Sveza company. Between the wooden pillars is placed the insulation, which is 60 mm thick. In its choice, plastic solutions were discarded, opting instead for a 100% vegetable fiber panel (Naturaflex premium from NaturaliaBau, Merano, Italy). Its composition is 90% recycled fibers from jute bags, 8% reinforcement corn fibers, and 2% soda as flame retardant. The panel presents an excellent thermal performance (λ 0.039 w/mk) and it is appropriate during the summer thanks to its high Sustainability 2021, 13, x FOR PEER REVIEW 8 of 17

Sustainability 2021, 13, x FOR PEER REVIEW 8 of 17

Improving the flooring system by using sustainable materials made it possible to obtain a system composed of 100% natural materials, 92% recycled materials, and 100% re- cyclableImproving materials. the flooring system by using sustainable materials made it possible to obtain a system composed of 100% natural materials, 92% recycled materials, and 100% re- 2.3.2.cyclable Perimetral materials. System The entire structure of the mobile home is realized with a wood framework, of which 2.3.2. Perimetral System the wood is FSC certified and supplied by Sveza company. Between the wooden pillars is placedThe the entireinsulation, structure which of isthe 60 mobile mm thick. home In isits realized choice, withplastic a woodsolutions framework, were discarded, of which optingthe wood instead is FSC for certifieda 100% vegetable and supplied fiber by pa Svezanel (Naturaflex company. premium Between fromthe wooden NaturaliaBau, pillars is Merano,placed theItaly). insulation, Its composition which is 60is 90%mm thick.recycled In its fibers choice, from plastic jute solutionsbags, 8% werereinforcement discarded, cornopting fibers, instead and 2%for asoda 100% as vegetableflame retardant. fiber pa Thenel (Naturaflexpanel presents premium an excellent from NaturaliaBau,thermal per- formanceMerano, (Italy).𝜆 0.039 Its w/mk) composition and it is is appropriate 90% recycled during fibers the from summer jute thanksbags, 8% to itsreinforcement high ther- malcorn mass fibers, capacity and 2% (2350 soda J/kgK) as flame, representing retardant. a The great panel improvement presents an from excellent the prior thermal solution per- whichformance was (in𝜆 EPS. 0.039 w/mk) and it is appropriate during the summer thanks to its high ther- malThe mass inner capacity finishing (2350 layer J/kgK) is, representingrealized with a bamboogreat improvement panels 5 mm from thick the (Figure prior solution 3) or linoleumwhich was (Figure in EPS. 4) 2 mm thick, all supported by a multilayer birch pane, which are the same materialsThe inner chosen finishing for layerthe furniture is realized and with the partition bamboo wallspanels and 5 mm they thick will be(Figure analyzed 3) or furtherlinoleum ahead. (Figure 4) 2 mm thick, all supported by a multilayer birch pane, which are the sameThe materials façade chosenwas realized for the with furniture coniferous and th ewood partition staves walls (Jukola and they 3D willby Lunawood, be analyzed Lahti,further Finland) ahead. which are PEFC certified. The wooden staves are heat-treated at high tem- peraturesThe (betweenfaçade was 190–192 realized °C) throughwith coniferous heat and woodsteam processes,staves (Jukola thus 3Dmaking by Lunawood, the wood resistantLahti, Finland) to unfavorable which are external PEFC climaticcertified. cond Theitions wooden without staves the are addition heat-treated of further at high treat- tem- Sustainability 2021, 13, 8296 8 of 16 mentsperatures based (between on chemical 190–192 substances °C) through such heatas solvents and steam or paints. processes, Each thus stave making is 30 mm the thick wood withresistant rabbet to joints unfavorable making external the application climatic easy cond. Theitions staves without are thescrewed addition to wooden of further batons treat- attachedments based to the on underlying chemical substances wooden structure, such as solvents leaving or an paints. adequate Each air stave chamber is 30 mm 30 mmthick thickwith to rabbet ensurethermal joints ventilation making mass of capacity the the application façade. (2350 The J/kgK), easy pattern. The representing that staves characterizes are screwed a great the improvement to façade wooden has batons been from the prior realizedattached through tosolution the aunderlying numerical which was woodencontrol in EPS. machine structure, giving leaving a 3D an surface. adequate air chamber 30 mm thickThe to perimetralensure ventilationThe system inner ﬁnishingofis 100%the façade. natural, layer The is 8% realizedpattern recyclable, that with characterizes and bamboo 100% panels recycled. the façade 5 mm has thick been (Figure 3) or realized throughlinoleum a numerical (Figure4) control 2 mm thick, machine all supportedgiving a 3D by surface. a multilayer birch pane, which are the The perimetralsame materials system chosen is 100% for natural, the furniture 8% recyclable, and the partitionand 100% walls recycled. and they will be analyzed further ahead.

26 mm_Wood Staves LUNAWOOD 28 mm_Ventilated Cavity 26 mm_Wood Staves LUNAWOOD 60 mm_Insulation Panel NATURAFLEX 28 mm_Ventilated Cavity 5 mm_BAMBOO Panel 60 mm_Insulation Panel NATURAFLEX 5 mm_BAMBOO Panel

Figure 3. Detail of the perimetral system with bamboo as inner layer.

Figure 3. Detail of the perimetral system with bamboo as inner layer. Figure 3. Detail of the perimetral system with bamboo as inner layer.

26 mm_Wood Staves LUNAWOOD 28 mm_Ventilated Cavity 26 mm_Wood Staves LUNAWOOD 60 mm_Insulation Panel NATURAFLEX 28 mm_Ventilated Cavity 5 mm_Wood Panel BETULLA 60 mm_Insulation Panel NATURAFLEX 2 mm_Linoleum DESKTOP 5 mm_Wood Panel BETULLA 2 mm_Linoleum DESKTOP

Figure 4. Detail of the perimetral system with natural linoleum as inner layer.

The façade was realized with coniferous wood staves (Jukola 3D by Lunawood, Lahti, Finland) which are PEFC certiﬁed. The wooden staves are heat-treated at high temperatures (between 190–192 ◦C) through heat and steam processes, thus making the wood resistant to unfavorable external climatic conditions without the addition of further treatments based on chemical substances such as solvents or paints. Each stave is 30 mm thick with rabbet joints making the application easy. The staves are screwed to wooden batons attached to the underlying wooden structure, leaving an adequate air chamber 30 mm thick to ensure ventilation of the façade. The pattern that characterizes the façade has been realized through a numerical control machine giving a 3D surface. The perimetral system is 100% natural, 8% recyclable, and 100% recycled.

2.3.3. Roof System To make the roof system perfectly adapted to the assembly line and due to structural and waterprooﬁng necessities, it was not possible to make it completely customized. Nevertheless, for most of the materials, the percentages in terms of naturality, recyclability, and recycled nature of the materials were greatly improved. The roof (Figure5) is composed by an inner ﬁnishing layer made of recycled textile materials—Acoustic Textile Felt—(developed by Really, Copenhagen, Denmark) hooked to multilayer birch panel 6 mm thick. The textile panels are 10 mm thick and 70% made of recycled textiles coming from the world of fashion. The panels can be in cotton or wool and are obtained through different pressing processes making them suitable for acoustic insulation (NCR 0.45). The load-bearing and insulating part of the structure is made up of sandwich panels 50 mm thick (Isodeck by Isopan, Verona, Italy). The panel is made of two metal sheets that protect the insulation panel from water and humidity; the inner layer is Sustainability 2021, 13, x FOR PEER REVIEW 9 of 17

Figure 4. Detail of the perimetral system with natural linoleum as inner layer.

2.3.3. Roof System To make the roof system perfectly adapted to the assembly line and due to structural and waterproofing necessities, it was not possible to make it completely customized. Nev- ertheless, for most of the materials, the percentages in terms of naturality, recyclability, and recycled nature of the materials were greatly improved. The roof (Figure 5) is composed by an inner finishing layer made of recycled textile materials—Acoustic Textile Felt—(developed by Really, Copenhagen, Denmark) hooked to multilayer birch panel 6 mm thick. The textile panels are 10 mm thick and 70% made of recycled textiles coming from the world of fashion. The panels can be in cotton or wool and are obtained through different pressing processes making them suitable for acoustic insulation (NCR 0.45). The load-bearing and insulating part of the structure is made up of sandwich panels 50 mm thick (Isodeck by Isopan, Verona, Italy). The panel is made of two metal sheets that protect the insulation panel from water and humidity; the inner layer is made of rockwool which is 47% composed of recycled materials and 100% recyclable. The whole production process of the insulation panel is LEED certified. A PVC membrane—Alkorbright (by Renolit, Worms, Germany)—supplied in rolls and heat-sealed to the underlying sandwich panel during the laying is applied to the outer layer of the roof to make the mobile home waterproof. Furthermore, thanks to the high Sustainability 2021, 13, 8296solar reflectance of the material, which is on average 90.5%, it protects the mobile home 9 of 16 from solar radiation during summer periods. The roof system is 65% made of natural materials, 33% made of recyclable materials, and 99% comingmade from of rockwool recycled which materials. is 47% composed of recycled materials and 100% recyclable. The whole production process of the insulation panel is LEED certiﬁed.

26 mm_Wood Staves LUNAWOOD 28 mm_Ventilated Cavity 60 mm_Insulation Panel NATURAFLEX 5 mm_BAMBOO Panel

Figure 5. Detail of the roof system. Figure 5. Detail of the roof system. A PVC membrane—Alkorbright (by Renolit, Worms, Germany)—supplied in rolls 2.3.4. Furnitureand and heat-sealed Partition to Walls the underlying sandwich panel during the laying is applied to the outer For thelayer furniture of the and roof partition to make walls the mobile(Figure home 6) realization, waterproof. the usage Furthermore, of panels thanks (usu- to the high ally chipboard)solar with reflectance a high percentage of the material, of me whichlamine is and on averageplastic contents 90.5%, itwith protects high theemis- mobile home sions of formaldehydefrom solar radiation is common. during Thus, summer the challenge periods. was to use natural materials as much as possibleThe avoiding roof system artificial is 65% and made polluting of natural contents. materials, For the 33% construction made of recyclable of the materials, and 99% coming from recycled materials. internal walls and the furniture, two materials were first selected. One was Really’s Solid Textile Board,2.3.4. a rigid Furniture panel andmade Partition of 70% Wallsrecycled cotton from the fashion supply chain. This 8 mm thick rigid panel is perfectly suitable for the construction of furniture; unfortu- For the furniture and partition walls (Figure6) realization, the usage of panels (usually nately, the price was not comparable with the solution adopted later. chipboard) with a high percentage of melamine and plastic contents with high emissions of formaldehyde is common. Thus, the challenge was to use natural materials as much as possible avoiding artificial and polluting contents. For the construction of the internal walls and the furniture, two materials were first selected. One was Really’s Solid Textile Sustainability 2021, 13, x FOR PEER REVIEW 10 of 17 Board, a rigid panel made of 70% recycled cotton from the fashion supply chain. This 8 mm thick rigid panel is perfectly suitable for the construction of furniture; unfortunately, the price was not comparable with the solution adopted later.

26 mm_Wood Staves LUNAWOOD 28 mm_Ventilated Cavity 60 mm_Insulation Panel NATURAFLEX 5 mm_BAMBOO Panel

Figure 6. Detail of the partition wall.

Figure 6. Detail of theAnother partition option wall. was Organoid, a laminate made of 100% natural and 100% recyclable herbaceous essences. However, the very high price of this material was the decisive factor Another option was Organoid, a laminate made of 100% natural and 100% recyclable in opting for two other solutions. herbaceous essences. However, the very high price of this material was the decisive factor The selection led to a multilayered birch panel being chosen for the structure (supplied in opting forby two Sveza, other Saint solutions. Petersburg, Russia). The ﬁnishing of the panel has a good performance, The selectionallowing led itto to a bemultilayered exposed without birch panel adding being paints chosen or solvents for the structure in some part,(sup- while it has plied by Sveza,been Saint covered Petersburg, in others. Russia). Two different The finishing types of of material the panel were has chosen a good for perfor- the internal lining: mance, allowingbamboo it to panels be exposed (by Moso, without Zwaag, adding The paints Netherlands or solvents [14]) 5in mm some thick part, and while FSC it certiﬁed, and has been coverednatural in linoleumothers. Two 2 mm different thick (Desktop types of seriesmaterial by were Forbo, chosen Baar, Switzerland).for the internal The bamboo lining: bamboopanels panels were (by left Moso, natural; Zwaag, thus, The they Netherlands are 100% recyclable, [14]) 5 mm representing thick and FSC a great cer- alternative tified, and naturalto tropical linoleum woods 2 mm increasingly thick (Desktop scarcely series available by Forbo, and Baar, sustainable. Switzerland). Furthermore, The bamboo bamboo panels were left natural; thus, they are 100% recyclable, representing a great alternative to tropical woods increasingly scarcely available and sustainable. Furthermore, bamboo panels are CO2 neutral and HCHO E1 certified. The linoleum used is completely analogous to the one used for the flooring with the only difference being that the product was specifically realized for the furniture upholstery. The percentage of recycled materials used for furniture and partition walls if compared with EVO was the only one that decreased. This is because more importance was given to the absence of formaldeyde (present in chipboards) than to choosing a natural material as birch is.

3. Results 3.1. Natural, Recycled, and Recyclable Mobile Home In a view of ecological and healthy design, the objective of the research was to improve the industrial product of the mobile home. Three factors referred to materials mainly influenced the research: naturality, to be recycled, and recyclability of the materials. The challenge was to calculate the percentage of the three factors of a standard mobile home and compare it to the new sustainable product in order to understand if it is possible today to introduce innovative and eco-friendly materials in the current assembly line. The percentages were calculated on the volume of each material, which allowed us to also keep in consideration the light materials. First, we calculated the percentage of naturality, been recycled, and recyclability for each component of the mobile home: flooring system, perimetral system, and roof system. The result was that compared to the current mobile home, with the new materials, it is possible to obtain 100% naturality for the flooring and perimetral system and that all the components are 100% recyclable, excluding the roof system, which is 99% recyclable. This means that for most of the components, the percentage doubled. At the end, we compared the percentages of the three factors on the mobile homes in total. The result was that the mobile home actually in production is 38% natural, 10% recycled, and 82% recyclable, while the same mobile home but with eco-friendly materials is 92% natural, 35% recycled, and 100% recyclable (Figures 7 and 8). This means that the sustainable mobile home is a healthy product thanks to its naturality and is built with a future perspective of the closed circulation of its components. Sustainability 2021, 13, 8296 10 of 16

panels are CO2 neutral and HCHO E1 certified. The linoleum used is completely analogous to the one used for the flooring with the only difference being that the product was specifically realized for the furniture upholstery. The percentage of recycled materials used for furniture and partition walls if compared with EVO was the only one that decreased. This is because more importance was given to the absence of formaldeyde (present in chipboards) than to choosing a natural material as birch is.

3. Results 3.1. Natural, Recycled, and Recyclable Mobile Home In a view of ecological and healthy design, the objective of the research was to improve the industrial product of the mobile home. Three factors referred to materials mainly influenced the research: naturality, to be recycled, and recyclability of the materials. The challenge was to calculate the percentage of the three factors of a standard mobile home and compare it to the new sustainable product in order to understand if it is possible today to introduce innovative and eco-friendly materials in the current assembly line. The percentages were calculated on the volume of each material, which allowed us to also keep in consideration the light materials. First, we calculated the percentage of naturality, been recycled, and recyclability for each component of the mobile home: flooring system, perimetral system, and roof system. The result was that compared to the current mobile home, with the new materials, it is possible to obtain 100% naturality for the flooring and perimetral system and that all the components are 100% recyclable, excluding the roof system, which is 99% recyclable. This means that for most of the components, the percentage doubled. At the end, we compared the percentages of the three factors on the mobile homes in total. The result was that the mobile home actually in production is 38% natural, 10% recycled, and 82% recyclable, while the same mobile home but with eco-friendly materials is 92% natural, 35% recycled, and 100% recyclable (Figures7 and8). Sustainability 2021, 13, x FOR PEER REVIEWThis means that the sustainable mobile home is a healthy product thanks to its naturality11 of 17

and is built with a future perspective of the closed circulation of its components.

Figure 7. Percentages of Wonderland. Figure 7. Percentages of Wonderland.

Figure 8. Comparison of the EVO model and Wonderland.

3.2. Discussion With tourism being a sort of representation of the contemporary society, there is all the more reason for the sector to be expected to demonstrate sensitivity to issues of ecology and sustainability, in which it can trace the path to conscientious planning. The research outcomes demonstrate the possibility of implementing an existing production system with unexpected results. The fact that the research has constantly confronted itself with an existing reality and has not set itself the goal of overcoming it opens a window for the construction world and in particular for the world of outdoor tourism in which the mobile home product is involved. The result obtained shows that the architectural project can work synergistically and in harmony with the more technical aspect in a sustainable vision without falling into a mere “façade operation”. This means that the use of sustainable materials is not a topic so far from the product of mobile homes. On the contrary, the application of innovative materials can give added value to a product which by its very nature is in a privileged position being mobile and therefore removable architecture. Designing Wonderland, a series of construction systems and materials were evaluated to provide a low environmental impact, constructive simplicity, low costs, and all the characteristics necessary for a replicability of the prototype. The prototype makes use of new sustainable materials that allow a lightweight and easily achievable construction within the assembly line. The natural materials used are intended to promote the integration of the mobile home product with the surrounding environment and an attempt was made to obtain a sustainable structure with a reversible environmental impact. Wonderland embodies the principles and objectives that the Laboratory of the Uni- versity of Pavia, AUDe, and the company Crippacampeggio (Carate Brianza, Italy) set themselves: wellbeing, simplicity, innovation, and sustainability. Sustainability and ecology were one of the main concerns during the development of the project which led to the Sustainability 2021, 13, x FOR PEER REVIEW 11 of 17

Sustainability 2021, 13, 8296 11 of 16

Figure 7. Percentages of Wonderland.

FigureFigure 8.8.Comparison Comparison ofof thethe EVOEVO modelmodel andand Wonderland. Wonderland. 3.2. Discussion 3.2. Discussion With tourism being a sort of representation of the contemporary society, there is all With tourism being a sort of representation of the contemporary society, there is all the more reason for the sector to be expected to demonstrate sensitivity to issues of ecology the more reason for the sector to be expected to demonstrate sensitivity to issues of ecol- and sustainability, in which it can trace the path to conscientious planning. The research ogy and sustainability, in which it can trace the path to conscientious planning. The re- outcomes demonstrate the possibility of implementing an existing production system with search outcomes demonstrate the possibility of implementing an existing production sys- unexpected results. The fact that the research has constantly confronted itself with an tem with unexpected results. The fact that the research has constantly confronted itself existing reality and has not set itself the goal of overcoming it opens a window for the with an existing reality and has not set itself the goal of overcoming it opens a window construction world and in particular for the world of outdoor tourism in which the mobile for the construction world and in particular for the world of outdoor tourism in which the home product is involved. The result obtained shows that the architectural project can mobile home product is involved. The result obtained shows that the architectural project work synergistically and in harmony with the more technical aspect in a sustainable vision withoutcan work falling synergistically into a mere and “façade in harmony operation”. with the This more means technical that theaspect use in of a sustainable sustainable materialsvision without is not falling a topic into so fara mere from “façade the product operation”. of mobile This homes.means that On the the use contrary, of sustain- the applicationable materials of innovativeis not a topic materials so far from can the give product added of value mobile to a homes. product On which the contrary, by its very the natureapplication is in a of privileged innovative position materials being can mobile give added and therefore value to removable a product architecture.which by its very natureDesigning is in a privileged Wonderland, position a series being of construction mobile and systemstherefore and removable materials architecture. were evaluated to provideDesigning a low Wonderland, environmental a impact,series of constructive construction simplicity, systems lowand costs,materials and allwere the evalu- char- acteristicsated to provide necessary a low for environmental a replicability impact, of the prototype.constructive The simplicity, prototype low makes costs, use and of all new the sustainablecharacteristics materials necessary that for allow a replicability a lightweight of the and prototype. easily achievable The prototype construction makes within use of thenew assembly sustainable line. materials The natural that materials allow a usedlightw areeight intended and easily to promote achievable the integration construction of thewithin mobile the homeassembly product line. withThe natural the surrounding materials environmentused are intended and an to attempt promote was the made integra- to obtaintion of a the sustainable mobile home structure product with with a reversible the surrounding environmental environment impact. and an attempt was madeWonderland to obtain a sustainable embodies the structure principles with and a reversible objectives environmental that the Laboratory impact. of the Uni- versityWonderland of Pavia, AUDe, embodies and the the principles company and Crippacampeggio objectives that (Caratethe Laboratory Brianza, of Italy) the Uni- set themselves:versity of Pavia, wellbeing, AUDe, simplicity, and the innovation,company Crippacampeggio and sustainability. (Carate Sustainability Brianza, andItaly) ecol- set ogythemselves: were one wellbeing, of the main simplicity, concerns innovation, during the and development sustainability. of the Sustainability project which and led ecol- to theogy development were one of the of amain highly concerns natural, during recycled, the development and recyclable of mobile the project home which prototype led to forthe outdoor tourism. The intention was to explore the design of the minimum space in an innovative way and to minimize the impact on the environment as much as possible. The prototype of a reversible and recyclable mobile home actually built within an industrialized sector can represent a turning point and the key to a new type of design and construction of this type of product that is more sensitive in ecological terms. This prototype is intended as a demonstration that with a more conscious design, it is possible to innovate a product that is currently highly demanded in the ‘leisure’ sector and that is at the same time respectful of the environment.

4. Conclusions Until now, the mobile home sector for outdoor tourism has neglected sustainable architectural and technical choices and has instead only considered the factor of easy removal as a sufﬁcient feature to make it of low environmental impact; thus in the face of new needs, sustainability is no longer ignorable. Sustainability 2021, 13, x FOR PEER REVIEW 12 of 17

development of a highly natural, recycled, and recyclable mobile home prototype for outdoor tourism. The intention was to explore the design of the minimum space in an innovative way and to minimize the impact on the environment as much as possible. The prototype of a reversible and recyclable mobile home actually built within an industrialized sector can represent a turning point and the key to a new type of design and construction of this type of product that is more sensitive in ecological terms. This prototype is intended as a demonstration that with a more conscious design, it is possible to innovate a product that is currently highly demanded in the ‘leisure’ sector and that is at the same time respectful of the environment.

4. Conclusions Until now, the mobile home sector for outdoor tourism has neglected sustainable ar- Sustainability 2021, 13, 8296 chitectural and technical choices and has instead only considered the factor of easy12 of re- 16 moval as a sufficient feature to make it of low environmental impact; thus in the face of new needs, sustainability is no longer ignorable. TheThe aimaim ofof thethe researchresearch waswas toto transformtransform aa standardstandard mobilemobile homehome intointo anan eco-friendlyeco-friendly productproduct compliant with with new new demands demands in in the the building building field ﬁeld in terms in terms of sustainability of sustainability with- withoutout changing changing the assembly the assembly line lineof the of theindustry industry.. There There were were relevant relevant limitations limitations during during the theresearch research process process such such as the as thecosts costs that that should should not notexceed exceed those those which which the thecompany company cur- currentlyrently incurs incurs for forthe theconstruction construction of a standa of a standardrd mobile mobile home homeand the and construction the construction system systemthat forced that the forced choice the of choice prefab of materials prefab materials that are that dry areassembly. dry assembly. Nevertheless, Nevertheless, a strategy a strategyfor the choice for the of choice the materials of the materials of the mobile of the home mobile sector home (natural, sector recycled, (natural, and recycled, recyclable) and recyclable)was developed was developedthat can be that applied can bein applieda broad inway a broad to the way entire to building the entire sector. building The sector. strat- Theegy strategywas developed was developed in order in to order obtain to obtainmaterials materials for long-term for long-term usage usage in construction in construction rep- representingresenting a good a good practice practice of ofcircular circular economy economy (Figure (Figures 9, 10,9–12 11). and 12).

Sustainability 2021, 13, x FOR PEER REVIEW 13 of 17

FigureFigure 9.9.Incidence Incidence ofof componentscomponents inin EVOEVO model. model.

FigureFigure 10. 10.Incidence Incidence of of components components in in Wonderland. Wonderland.

Figure 11. Percentage for each component in the EVO model.

Figure 12. Percentage for each component in Wonderland.

The research highlights the possibility of a product being sustainable, environmentally friendly, and healthy for humans that, more than others, needs to be integrated with Sustainability 2021, 13, x FOR PEER REVIEW 13 of 17 Sustainability 2021, 13, x FOR PEER REVIEW 13 of 17

Sustainability 2021, 13, 8296 13 of 16

Figure 10. Incidence of components in Wonderland.

Figure 11. Percentage for each component in the EVO model. Figure 11. Percentage for each component in the EVO model.

FigureFigure 12. 12.Percentage Percentage for for each each component component in in Wonderland. Wonderland.

The research highlights the possibility of a product being sustainable, environmentally friendly, and healthy for humans that, more than others, needs to be integrated with nature as it isThe placed research in open highlights air accommodations the possibility which of a areproduct usually being of particular sustainable, beauty environmen- in terms oftally landscape. friendly, and healthy for humans that, more than others, needs to be integrated with The study demonstrates that introducing innovative materials in terms of sustainability is an opportunity that is not so far from our reality. The output of the research was the production through the company Crippacampeggio (Carate Brianza, Italy) of a prototype (Figures 13 and 14) of a 92% natural, 35% recycled, and 100% recyclable mobile home, inserting itself within the production process currently in use by the company without interfering with the current assembly line. Possible developments of the research that is being carried out in the AUDe laboratory have as objectives not only the mobile home product, but the entire process being certified, from production to its use, thus paying attention to every single phase. An example to consider is the certification of the final product through a protocol known worldwide such as LEED. Thus, attention is therefore placed on materials and in particular on their origin, disposal, and recyclability. Furthermore, in the industrial point of view, today, products and wastes are produced simultaneously, where instead it would be necessary to direct the industry sector towards ecology, structuring it to measure the environmental impacts. It is necessary to produce light structures by using recycled/recyclable materials or components, thus improving the environmental performance and reducing the costs in a cyclic view and reducing embodied energy as well as deleting waste [19]. Focusing on reducing embodied Sustainability 2021, 13, 8296 14 of 16

energy, which means consumed energy during extraction, processing of raw materials, transportation, and construction and demolition processes, allows us to reduce the impact on the environment and to design long-lived constructions [20]. It is not only the attention on embodied energy that allows us to plan consciously, but also the search for a NZEB product can have an impactful effect on the environment and on the performance of the building. The use of this type of approach on a product such as that of mobile homes Sustainability 2021, 13, x FOR PEER REVIEW 15 of 17 allows a signiﬁcant reduction in costs due to the maintenance, heating, and cooling of the housing units, especially during the summer, when they are most used.

FigureFigure 13. 13. PlanPlan and and section section of of the the prototype. prototype. Sustainability 2021, 13, 8296 15 of 16 Sustainability 2021, 13, x FOR PEER REVIEW 16 of 17

FigureFigure 14. 14.PicturePicture of the of theprototype prototype in phase in phase of construction. of construction.

Author Contributions: Conceptualization and supervision, C.B. and L.T.; funding acquisition and methodology, C.B.; research on sustainable materi materialsals and technical details, L.T.; investigation and original draft preparation, G.N.T.;G.T.; review review and and editing, editing, G.T. G.N.T. and andS.N. S.N.;; industrial industrial process process and anddata data curation,curation, S.N. S.N. All Allauthors authors discussed discussed the theresults results and and commented commented on the on manuscript. the manuscript. All authors All authors pro- videdprovided critical critical feedback feedback and and helped helped shape shape the the rese researcharch and and the the manuscript. manuscript. All All authors authors have have read andand agreed to the published version of the manuscript. Funding: ThisThis research research was funded by Crippacampeggio.srl. InstitutionalInstitutional Review Review Board Board Statement: NotNot applicable. applicable. InformedInformed Consent Consent Statement: Not applicable. Data Availability Statement: Not applicable applicable. ConflictsConflicts of Interest:Interest: We,We, CarloCarlo Berizzi, Berizzi, Salvatore Salvatore Nirta, Nirta, Gaia Gaia Terlicher, Terlicher, and and Luca Luca Trabattoni, Trabattoni, declare de- clarethat wethat have we have no economic no economic or personal or personal relationships relationships that can that inappropriately can inappropriately influence influence the scientific the sci- entificinput presented.input presented. We declare We thatdeclare we authorizethat we author the publicationize the publication of the scientific of the contributionscientific contribution presented, presented,as well as theas well processing as the processi of personalng of data personal entered data for entered the exclusive for the purposes exclusive of purposes the journal. of the journal. References References 1. Kappenthuler, S.; Seeger, S. From resources to research—A framework for identification and prioritization of materials research 1.for sustainableKappenthuler, construction. S.; Seeger, Mater.S. From Today resources Sustain. to 2019research—A, 7–8, 1–14. framework [CrossRef for] identification and prioritization of materials re- 2. Karim,search M.R.; for Zain, sustainable M.F.; Jamil, construction. M.; Lai, F.C.; Mater. Islam, Today M.N. Sustain Use. of 2019, Wastes 7–8, in 1–14, Construction doi:10.1016/j.mtsust.2019.100009. Industries as an Energy Saving Approach. 2.Energy Karim, Procedia M.R.;2011 Zain,, 12 ,M.F.; 915–917. Jamil, [CrossRef M.; Lai,] F.C.; Islam, M.N. Use of Wastes in Construction Industries as an Energy Saving 3. Charytonowickz,Approach. Energy J.; Skowronski, Procedia 2011, M. 12, Reuse 915–917, of building doi:10.1016/j.egypro.2011.10.120. materials. Procedia Manuf. 2015 , 3, 1633–1637. [CrossRef] 4. 3.Environment Charytonowickz, Programme. J.; Skowronski,Changes in BuildingM. Reuse and Construction of building Have materials. Great Potential Procedia to Slow Manuf. Global Warming2015, 3,. 2020.1633–1637, Avail- abledoi:10.1016/j.promfg.2015.07.456. online: www.unenvironment.org/news-and-stories/story/changes-building-and-construction-have-great-potential-slow- 4.global-warming Environment (accessed Programme. on 122020. March Changes 2020). in Building and Construction Have Great Potential to Slow Global Warming. 2020. Environment Programme. Available online: www.unenvironment.org/news-and-stories/story/changes-building-and-construction-have-great-potential-slow-global-warming. 12 March 2020 (access on 12, March, 2020). Sustainability 2021, 13, 8296 16 of 16

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