This thesis explores using multi-scale topology optimization (TO) by utilizing inverse homogenization to automate the adjustment of each unit-cell's geometry and placement in a lattice structure within a pressure vessel (the design domain) to achieve desired structural properties. The aim is to find the optimal material distribution within the design domain as well as desired material properties at each discretized element and use machine learning (ML) to map microstructures with corresponding prescribed effective properties. Effective properties are obtained through homogenization, where microscopic properties are upscaled to macroscopic ones. The symmetry group of a unit-cell's elasticity tensor can be utilized for stiffness directional tunability, i.e., to tune the cell's performance in different load directions.  A few geometrical variations of a chosen unit-cell were homogenized to build an effective anisotropic elastic material model by obtaining their effective elasticity. The symmetry group and the stiffness directionality of the cells’ effective elasticity tensors were identified. This was done using both the pattern of the matrix representation of the effective elasticity tensor and the roots of the monoclinic distance function. A cell library of symmetry-preserving variations with a corresponding material property space was created, displaying the achievable properties within the library. Two ML models were implemented to map material properties to appropriate cells. A TO algorithm was also implemented to produce an optimal material distribution within a design domain of a pressure vessel in 2D to maximize stiffness. However, the TO algorithm to obtain desired material properties for each element in the domain was not realized within the time frame of this thesis.  The cells were successfully homogenized. The effective elasticity tensor of the chosen cell was found to belong to the cubic symmetry group in its natural coordinate system. The results suggest that the symmetry group of an elasticity tensor retrieved through numerical experiments can be identified using the monoclinic distance function. If near-zero minima are present, they can be utilized to find the natural coordinate system. The cubic symmetry allowed the cell library's material property space to be spanned by only three elastic constants, derived from the elasticity matrix. The orthotropic symmetry group can enable a greater directional tunability and design flexibility than the cubic one. However, materials exhibiting cubic symmetry can be described by fewer material properties, limiting the property space, which could make the multi-scale TO less complex. The ML models successfully predicted the cell parameters for given elastic constants with satisfactory results. The TO algorithm was successfully implemented. Two different boundary condition cases were used – fixing the domain’s corner nodes and fixing the middle element’s nodes. The latter was found to produce more sensible results. The formation of a cylindrical outer shape could be distinguished in the produced material design, which was deemed reasonable since cylindrical pressure vessels are consistent with engineering practice due to their inherent ability to evenly distribute load. The TO algorithm must be extended to include the elastic constants as design variables to enable the multi-scale TO.

A new paradigm is slowly making its way into society, affecting our material practice as designers. Materials selection in design and product development has for a long time been dominated by a purely technical approach, mainly focusing on properties and performance. With the increasing evidence of climate change, waste and pollution, environmental effects, we are slowly realizing that unsustainable consumption of materials is no longer an alternative. Previous studies of material practices, both within design educations and the design profession, has primarily dealt with the development of material related methods. This thesis has focused on gaining an in-depth understanding of material practices within design processes, in order to develop a pedagogical framework that facilitates the development of reflective material practices in design education. There are four primary aims of the research presented in this licentiate thesis: (1) ascertain obstacles in the traditional ways of teaching materials to design students, (2) to bridge the differences in language, research culture and pedagogic approaches in design education, (3) to investigate current professional material practices in industrial design, and (4) to develop a new material framework for teaching reflective material practices for design students. During the project, the material framework has been tested and evaluated in two mandatory material courses with first and second year bachelor students from Product Design education over a period of four academic years. A comparative case study was conducted with five design consultancies. The qualitative interviews were transcribed and analysed using category zooming. The outcomes of this research are: (1) a new pedagogic framework for teaching materials to Product Design students in higher education, and (2) insights into professional practices of selecting and designing with materials. The pedagogic model A Material Framework for Product Design is designed to facilitate the development of reflective material practices in design education. The Framework consist of four levels: (1) a pedagogical foundation based on Experiential Learning theory that provide a framework for how to approach teaching and learning, (2) designing and structuring learning activities, (3) creating learning environments that facilitate learning activities, and (4) defining learning objectives, assessment of learning outcomes and detecting signs of learning. The main insights from the study of professional practices suggest: (1) that risk management has a major influence on the material selection process, (2) that negotiations of project boundaries in the ‘fuzzy’ pre-design phase has crucial influence on the risk management aspect of the material criteria activities, and (3) a lack of awareness, that design briefs usually outline material criteria expressed as sensorial characteristics, which are later translated by engineering into final material criteria used for the material selection process. The findings implies that design students would benefit from developing reflective material practices in design education.

För att möjliggöra en hållbar utveckling skiftar många polymerforskares fokus just nu från att syntetisera polymerer från fossila resurser till att producera biobaserade polymerer från exempelvis träd. Av särskilt intresse är lignin, som utgör ungefär en tredjedel av allt växtmaterial men i nuläget oftast används som bränsle. Många forskare har undersökt de möjligheter som öppnas genom att bryta ner lignin och modifiera molekylerna som fås därigenom, såsom ferulsyra. Denna studie syftade till att modifiera ferulsyra till en styren-lik monomer med en karboxyl-substituent, och att testa vattenbaserad polymerisation av denna monomer.Det första steget i modifiering var dekarboxylering av ferulsyra. Detta utfördes genom upprepningar av tidigare studier där baskatalyserad dekarboxylering utfördes i polära aprotiska lösningsmedel. Efter flera försök hittades en fungerande metod, där trietylamin gav en dekarboxylering med högt utbyte efter tre timmar i dimetylformamid vid 100 °C. Att isolera produkten var också utmanande i början, men en trestegs-extraktion med H2O och Et2O som avslutades med en tvätt av saltvatten gav tillräcklig renhet. En ättiksyra-grupp adderades till fenolen med hjälp av en tvåstegsreaktion som hittades i litteraturen, men inte förrän ett dussin försök till nya metoder med kloroättiksyra gjorts utan framgång. I den fungerande metoden tillsattes en acetatgrupp med metylbromoacetat i återkokande aceton med kaliumkarbonat som bas, innan acetatet demetylerades av litiumhydroxid i en metanol/vattenblandning vid rumstemperatur.Den resulterande monomeren, 4-oxy-ättiksyra-3-methoxy-styren (OAMS), sampolymeriserades med styren, både i bulk- och emulsionspolymerisation. Bulksampolymeren hade en något högre molekylvikt och glastransitionstemperatur än homopolystyren, med en betydligt högre dispersitet. Emulsionspolymerisation var utmanande, eftersom OAMS inte är särskilt löslig i vare sig vatten eller styren, och i slutändan producerades inga tydliga resultat genom dessa försök.  Studiens huvudsakliga slutsats är att även om det är möjligt att syntetisera ren OAMS från ferulsyra, är användbarheten av denna molekyl som monomer i vattenbaserad polymerisering inte övertygande, eftersom den är så pass olöslig om inte bas tillsätts, vilket introducerar risken för hydrolys.Slutligen, även om studien ledde till få säkra slutsatser på grund av flera ofullständiga resultat, uppnåddes huvudsyftet att modifiera ferulsyra och testa polymerisation av den bildade monomeren. / To enable a sustainable development, scientific focus is shifting from synthesizing polymers from fossil-based resources to producing bio-based polymers from for example wood. Of particular interest is lignin, which makes up about a third of plant matter but is nowadays most commonly used as fuel. A great deal of research has explored the possibilities opened up by breaking down lignin and modifying its derived molecules, such as ferulic acid. This study aimed to modify ferulic acid into a styrenic monomer with an acidic substituent, and to investigate the aqueous polymerization of this monomer.The first step of modification was the decarboxylation of ferulic acid. This was attempted through recreations of previous studies where base-catalysed decarboxylation was carried out in aprotic polar solvents. After several trials, a successful procedure was found, where triethylamine gave a high-yield decarboxylation after three hours in dimethylformamide at 100 °C. Isolating the product was also initially challenging, but a three-step extraction with H2O and Et2O finished by a wash of brine gave sufficient purity.Adding an acetic acid-group to the phenol was achieved using a two-step procedure found in literature, but not before trying a dozen novel methods using chloroacetic acid without success. In the working procedure, an acetate group was added using methyl bromoacetate in refluxed acetone with potassium carbonate as base, before demethylating the acetate using lithium hydroxide in a methanol/water mix at room temperature. The resulting monomer, 4-oxy-acetic acid-3-methoxy-styrene (OAMS), was copolymerized with styrene, both in bulk and emulsion radical polymerization. The bulk copolymer displayed a slightly higher molecular weight and glass transition temperature than homopolystyrene, with a significantly higher dispersity. Emulsion polymerization was challenging, as OAMS is not very soluble in either water or styrene, and ultimately, no conclusive results were produced through this route.The study concluded that while it is possible to synthesize pure OAMS from ferulic acid, the degree of usability of this molecule as a monomer in aqueous polymerization is not certain, as it is hardly soluble without the addition of base, which introduces the risk of hydrolysis. Ultimately, although few solid conclusions could be drawn from this study due to several incomplete results, the core objective of modifying ferulic acid and testing polymerization of the resulting monomer was achieved.

Corrosion fatigue is a common failure mechanism in rock drilling components and many othermechanical parts subjected to cyclic loads in corrosive environments. A crucial part in the design ofsuch components resides in the selection of the right materials for the application, which ideallyinvolves testing and comparison of their performance under working conditions. The present work was performed with the purpose of designing a corrosion-fatigue testing methodthat would allow the designer to compare the performance of different materials exposed to corrosionfatigue, permitting also the comparison with results from dry fatigue testing. The method was designedfor rotating-bending machines. Two different steel grades were used during the work, one throughhardened and one case hardened. The effect of these heat treatments and of shot peening overcorrosion-fatigue behaviour were studied using the proposed method. It was proven that the testing speed has a strong impact on the fatigue life of steel. It was found that,at a fixed stress level, the case hardened and shot peened steel reached 3X10^6 cycles at 2300 rpm,while it failed at only 5X10^5 cycles with a testing speed of 500 rpm. A large beneficial influence of theshot peening was demonstrated. It was also observed that, at fixed testing speed, the shot peening onthe through hardened steel can increase its fatigue strength from 190 MPa to 600 MPa under corrosionfatigue. Many cracks were found at the surface of the shot peened parts, which are arrested near thesurface by the compressive stress layer from the shot peening. It was also found that, for the non-shotpeened parts, case hardening had a slightly higher corrosion-fatigue strength than the throughhardened. This might be a result of the compressive stresses from carburization, or due to the highercore toughness of this steel grade.

En ”lätt-att-rengöra” yta definieras som en yta som stöter bort vatten och smuts. I detta projekt har klarlack med olika sammansättningar studerats i syfte att introducera egenskapen ”lätt-att-rengöra”. För att uppnå denna egenskap måste beläggningen vara superhydrofob och oleofob. Detta innebär att kontaktvinklarna för både vatten (WCA) och dijodmetan (DMCA) måste vara över 150°. En hybrid sol-gel-metod valdes för detta projekt på grund av dess många fördelar som kontroll av ytmorfologi, enkel inkorporering av nanopartiklar och organiska komponenter i nätverket samt förmåga att bilda ett antal kompositioner. Hybrid sol-gelfilmerna, som innehåller både organiska och oorganiska komponenter, ger mekanisk beständighet, flexibilitet och förmåga att härda vid låga temperaturer. De organiska komponenterna fyller porerna i den oorganiska oxidkedjan, vilket gör att det hybridorganiskt-oorganiska materialet når slutlig densitet vid lägre temperatur. Både hydrofoba och hydrofila kiselnanopartiklar studerades för att undersöka vilken av dem som bäst inkorporeras i filmen. Den högsta uppnådda hydrofobiciteten och oleofobiciteten var av ett prov med 133° WCA och 152° DMCA. Provet bestod av en organisk och oorganisk komponent såväl som hydrofoba kiselnanopartiklar. / An easy-to-clean surface is defined as a surface that repels water and dirt. In this project, clearcoats with different composition have been studied in the process of introducing easy-to-clean properties in the coating. To achieve these properties the coating needs to be both superhydrophobic and oleophobic. This means that the contact angles against both water (WCA) and diiodomethane contact angle (DMCA) should be above 150 °. A hybrid sol-gel approach was chosen for this project due to the several advantages it provides such as, control of surface morphology, easy incorporation of nanoparticles and organic components into the network and ability to form a range of compositions. The hybrid sol-gel films, which contain both organic and inorganic components, provide mechanical resistance, flexibility, and ability to cure at low temperatures. The organic compounds fill the pores between the inorganic oxide chain; hence, the hybrid organic-inorganic material reaches final density at lower temperature. Both hydrophobic and hydrophilic silica nanoparticles were studied to analyze which of them would be best incorporated into the film. The highest hydrophobicity and oleophobicity achieved were by a sample with 133° WCA and 152° DMCA. The sample consisted of an organic and inorganic component as well as hydrophobic silica nanoparticles.

Denna studie undersöker potentialen för frodvuxen gran (Picea abies) som isoleringsmaterial i historiska byggnader, med syftet att utvärdera sambandet mellan densitet och värmeledningsförmåga. Bakgrunden till studien ligger i behovet av hållbara och effektiva isoleringsmaterial som kan användas för att förbättra energiprestandan i byggnader samtidigt som de bevarar deras historiska karaktär och estetiska värde. Frodvuxen gran har växt snabbt vilket lett till en lägre densitet än lägsta värdet som finns att tillgå i den svenska standarden för olika materials värmeledningsförmågor.  Metodologin innefattade både laboratorieanalyser och fältstudier. I laboratoriedelen användes ett hot-disk instrument för att mäta värmeledningsförmåga sedan beräknades densitet och fuktkvot. Fältstudierna genomfördes för att identifiera praktiska tillämpningar och utmaningar vid användning av frodvuxen gran som konstruktionsmaterial. Dessa studier omfattade inspektioner av byggnader uppförda med frodvuxen gran och intervju med ansvarig för uppförandet av dessa byggnader för att utreda dess potentiella funktion som konstruktionsmaterial.  Huvudresultaten från laboratorieanalyserna visade ett starkt samband mellan densitet och värmeledningsförmåga, vilket indikerar att frodvuxen gran med sin lägre densitet har förbättrade isoleringsegenskaper jämfört med senvuxen gran. Fältstudierna bekräftade att frodvuxen gran kan användas som konstruktionsmaterial i byggnader, men pekade också på dess benägenhet till större rörelser vid uttorkning vilket dock går att räkna på för att undvika att problem uppstår vid torkning.  Slutsatserna visar att frodvuxen gran kan vara ett värdefullt tillskott till befintliga isoleringsmaterial tack vare dess förbättrade isoleringsförmåga. Studien rekommenderar vidare forskning för att undersöka långsiktiga nedbrytningseffekter och materialets fuktegenskaper, vilket är avgörande för dess praktiska användning i byggnader. Vidare bör forskningen även studera frodvuxen grans förmåga som putsbärare, både för ler- och kalkbruk, för att utreda virkets kompatibilitet med dessa material. / This study investigates the potential of fast-grown spruce (Picea abies) as an insulation material in historic buildings, aiming to evaluate the relationship between density and thermal conductivity. The background of the study lies in the need for sustainable and efficient insulation materials that can be used to improve the energy performance of buildings while preserving their historical character and aesthetic value. Fast-grown spruce has a lower density then the lowest available in the Swedish standard for materials heat conductivity.  The methodology included both laboratory analyses and field studies. In the laboratory part, a hot-disk instrument was used to measure thermal conductivity, followed by calculations of density and moisture content. The field studies were conducted to identify practical applications and challenges in using fast-grown spruce as a construction material. These studies involved inspections of buildings constructed with fast-grown spruce and interviews with those responsible for their construction to investigate its potential functionality as a construction material.  The main results from the laboratory analyses showed a strong correlation between density and thermal conductivity, indicating that fast-grown spruce, with its lower density, has improved insulation properties compared to slow-grown spruce. The field studies confirmed that fast-grown spruce can be used as a construction material in buildings, but also pointed out its tendency to exhibit greater movement during drying, which can be accounted for to prevent issues during the drying process.  The conclusions suggest that fast-grown spruce can be a valuable addition to existing insulation materials due to its improved insulation performance. The study recommends further research to examine long-term degradation effects and the material's moisture properties, which are critical for its practical use in buildings. Additionally, further research should investigate the ability of fast-grown spruce to serve as a substrate for plaster, both for clay and lime-based plasters, to determine the wood's compatibility with these materials.

I mitt examensarbete undersöker jag vilken putsmetod som lämpar sig bäst för putsning av infärgat faner utan att infärgat damm fastnar på oönskade områden. Testområdet har varit avgränsat till att undersöka detta problem tillsammans med andra, icke infärgade faner. Frågan är om det finns en metod som på ett effektivt och ergonomiskt sätt garanterar ett bra resultat? Mina tester utgår från om val av material, fiberriktning och snittyta har betydelse för hur det infärgade dammet fastnar på ytan. Min förhoppning är att hantverkare och formgivare ska ta hjälp av denna undersökning för att lättare kunna göra medvetna val där infärgade faner kombineras med andra träslag. Genom intervjuer med andra hantverkare, om deras erfarenheter har ett problemområde kartlagts utifrån vad som är mest relevant för undersökningen. Även litterära studier har gjorts för att bättre förstå träts anatomiska egenskaper. För att uppnå optimala förutsättningar för att infärgat damm inte ska fasta på oönskade områden visar testerna, genom att kombinera infärgat faner med ett bandporigt träslag som har en radiell snittyta tillsammans med en fiberriktning som ligger i samma riktning som putsriktningen, med en putsmetod där direkt sug över putsytan verkar samtidigt som putsningen ger bäst förutsättning för att infärgat damm inte fastnar på oönskade områden.

Increasing demand for structural health monitoring in space highlights the need to make the creation of these systems more accessible. This study investigates the potential of additive manufacturing to achieve this goal by characterizing a self-sensing material made of a commercially available 3D-printed continuous carbon fibre filament. The results demonstrate the feasibility of converting the filament into a strain sensor with improved sensitivity compared to conventional foil strain gauges. Mechanical and electromechanical properties of the self-sensing material were characterized, including an ultimate tensile strength of 45.09 ± 3.45 MPa, a failure strain of 38.93 ± 3.41%, and a base resistance of 759.11Ω. The tensile gauge factor was calculated to be 467.06 ± 375.90 within the strain range of 0% to 3.8% with a linearity (R2) of 0.93. For the first time, a systematic literature review compares mechanical and electromechanical properties to enable material selection for mechanical design incorporating self-sensing material. The study highlights that the spread of material properties in a group of materials indicates how well-developed a material is for self-sensing purposes. This study advances our understanding of the feasibility of using additive manufacturing to create self-sensing materials for structural health monitoring systems and opens up new avenues for further research.

With increasing emphasis and regulations on the environmental footprint in industries, the integration of reduced carbon dioxide equivalent (CO2eq) plastic materials is desirable. Fiber-reinforced plastic materials mechanical properties differ with varying fiber orientations. Similarly, the welding line phenomenon, commonly present in more complex injection molded parts, decreases the mechanical performance. This thesis aims to experimentally investigate tensile behavior on reduced CO2eq reinforced plastics in different fiber orientations and weld line configurations.  Ten materials with reduced CO2eq are investigated, the types of materials are as follows: PA6 (Polyamide6), PP (Polypropylene), and PA6/PP blend materials. Both short fiber-reinforced polymers (SFRP) and long fiber-reinforced polymers (LFRP) are investigated. The screening resulted in three selected materials for further investigation: one recycled PA6, one bio-based PA6/PP, and one alternative PP. The further investigation involves tensile testing in the five directions and three weld line configurations with non-standardized geometry specimens punched out from an injection molded plate with controlled fiber orientation. Two types of uniform fiber orientation plates are manufactured for the testing conditions, one with holes for weld line testing and one without for testing of orientation. The evaluated fiber orientations are 0° (fibers parallel to load direction), 22.5°, 45°, 67.5°, and 90° (fibers transverse to load direction). The weld line configuration consists of three consecutive holes with 96.5, 146.5, and 196.5 mm distances from the gating system. Three weld line test specimens are generated from each plate, they are denoted W1, W2, and W3 from their respective distance from the gating system, with W1 being closest to the gate. Optical microscopy of fiber orientation and failure modes for the test specimens are performed to investigate and validate the testing conditions.  Varying fiber orientation was found to greatly affect the stress-strain behavior in all four materials investigated. The tensile strength was reduced from longitudinal to transverse fiber orientation, with the most significant reduction near flow direction. High variations were present for the brittle materials supposedly from their weakness to stress concentrations. Strain tended to increase from the lowest at 0° to the maximum at 45°, from which it again decreased to a mid-value at 90° for all materials. The weld line strength reduced significantly for the brittle materials, whereas the ductile materials experienced a much smaller reduction. The three weld line cases failed at similar stresses, while having different stiffness.

Introduktion (och mål) – Parisavtalet är en överenskommelse där länder såsom Sverige enats om målet att hålla den globala temperaturökningen under 2 °C och sträva mot att begränsa den till 1,5 °C. För att nå detta mål måste växthusgasutsläppen halveras till 2030 jämfört med 2019. Bygg- och fastighetssektorn står för 22 % av Sveriges totala utsläpp av växthusgaser och genomtänkta materialval är en potentiell åtgärd för att minska dessa utsläpp. Ett material med goda klimategenskaper är en cellulosabaserad isolering såsom hampafiberisolering, Målet med studien var att undersöka om hampafiberisolering kan bli ett etablerat isoleringsmaterial i sandwichpaneler avsedda för lager- och logistikhallar. Metod – Metoden för studien var en fallstudie då fokus låg på en specifik analysenhet. Datainsamlingen skedde genom triangulering där intervjuer och dokumentstudie användes som insamlingstekniker. Sju intervjuer genomfördes med personer representerade av företag i form av fastighetsinvesterare, tillverkare av sandwichpaneler, tillverkare av hampafiberisolering och byggföretag. Utifrån det som framgick i intervjuerna skedde en tematisk analys. Därefter granskades aktuella dokument deduktivt utifrån respondentsvar för att utmana eller styrka dessa teman. Resultat – I studien framgick att det krävs att flera aspekter behöver uppnås för att hampafiberisolering ska kunna användas i sandwichpaneler. Detta var aspekter gällande funktionen på panelen, övriga aspekter och miljöaspekter. Den största fördelen med hampafiberisolering är dess klimatpositiva egenskaper och detta var också anledningen till att isoleringen använts av respondenterna i studien. De nackdelar som framgick i studien var priset, ovana, få referensobjekt och ovissheten gällande fukt. Det framgick att oskadad hampafiberisolering kan återanvändas efter en väggelements livstid genom att den kan användas i sin helhet eller blandas ut till ny isolering. Det finns även möjlighet att skapa biokol av isoleringen med hjälp av förbränningsugnar. Analys – Utgångspunkten för analysen var empirin från intervjuerna, vilket lade grund för en riktad innehållsanalys i aktuella dokument. I analysen sammanfattades och jämfördes empirin från dokumenten med intervjuerna för att styrka och utmana det som framkommit. Det framgick att en del faktorer gick att styrka som krav alternativt trovärdiga konklusioner från respondenter. Andra aspekter gick inte styrka i dokument. Diskussion – Resultatet från intervjuerna och dokumentstudien i studien visar ett stort fokus på miljö. Då datainsamlingen var utformad utifrån frågeställningar hölls studien aktuell till undersökningsområdet. Ett genomtänkt respondenturval bidrog till hög reliabilitet vid datainsamlingen. / Introduction (and aim) – The Paris Agreement is an agreement where countries such as Sweden have agreed on the goal of keeping the global temperature increase below 2°C and striving to limit it to 1.5°C. To achieve this goal, greenhouse gas emissions must be halved by 2030 compared to 2019. The construction and real estate sector accounts for 22% of Sweden's total greenhouse gas emissions, and a potential measure to reduce these emissions are well thought out material choices. A material with good climate properties is cellulose-based insulation such as hemp-fibre insulation. The aim of the study was to investigate whether hemp-fibre insulation can become an established insulation material in sandwich panels intended for warehouse- and logistics properties. Method – The method for the study was a case study as the focus was on a specific unit of analysis. Data collection was conducted through triangulation in which interviews and document studies were used as collection techniques. Seven interviews were conducted with individuals representing companies in the form of property investors, sandwich panel manufacturers, hemp-fibre insulation manufacturers, and construction companies. A thematic analysis was conducted based on the findings from the interviews. Subsequently, current documents were reviewed deductively based on respondents' answers to challenge or support these themes. Results – The study concluded that several aspects need to be achieved for hemp-fibre insulation to be used in sandwich panels. These were aspects concerning the function of the panel, other aspects, and environmental aspects. The biggest advantage of hemp-fibre insulation is its climate-positive attributes, which was also the reason the insulation was used by the respondents in the study. The disadvantages identified in the study were the price, unfamiliarity, few reference projects, and uncertainty regarding moisture. It was noted that undamaged hemp-fibre insulation can be reused after a wall element's lifetime, either in its entirety or mixed into new insulation. There is also the possibility of creating biochar from the insulation using an incinerator. Analysis – The basis for the analysis was the empirical data from the interviews, which formed the foundation for a directed content analysis in the current documents. In the analysis, the empirical data from the documents was summarized and compared with the interviews to support and challenge the findings. It was found that some factors could be supported as requirements or credible conclusions from respondents. Other aspects could not be supported in the documents. Discussion – The results from the interviews and the document study in the study show a strong focus on the environment. Since the data collection was designed based on the research questions, the study remained relevant to the research area. A well-considered selection of respondents contributed to high reliability in the data collection.