Exploring attitudes towards extending lifecycle of wood products by cascading: a case study in Bosnia and Herzegovina, Croatia, Serbia, and Slovenia

ABSTRACT This study explores attitudes toward sustainable-timber resource management and climate-change mitigation by extending the life cycles of wood products and their cascading in Central and Southeastern Europe. A comprehensive survey involving the general public and professional organizations in Bosnia and Herzegovina, Croatia, Serbia, and Slovenia, reveals significant support for wood product reuse in construction, emphasizing ecological aspects and sustainability. Despite doubts about wood product quality, motivation for reuse remains high. Challenges, including limited availability and cost, are acknowledged. Reusing and recycling wood products at the end of their life cycle can extend the life of the wood resource and reduce carbon emissions. Cascading is a promising way to combat climate change and prolong the life cycle of wood products. This study highlights the potential of cascading wood use, underscores the necessity to improve the quantification of wood usage through material intensity analysis of buildings, and emphasizes the requirement for more comprehensive education and explanations to promote sustainable practices.


Introduction
Establishing a circular economy that optimizes material resource efficiency and reduces waste generation is crucial for a sustainable and environmentally conscious society.The forest and wood-based sectors are central to the bioeconomy, providing material, bioenergy, and environmental services.The construction industry, which consumes 40% globally of all materials used by humanity, faces a particular challenge in improving resource efficiency (European Commission 2011, Ruuska andHakkinen 2014).Therefore, promoting reuse and recycling can increase resource efficiency and mitigate climate change through cascading.Current practices often lead to waste generation, but gradually, more efficient methods have been discovered (Müller 2006, Höglmeier et al. 2013, Sáez and Osmani 2019, Nasiri et al. 2021, Niu et al. 2021).Reuse and recycling promote resource efficiency and mitigate climate change through cascading (European Commission 2014, 2016, Husgafvel et al. 2018, Thonemann and Schumann 2018).

Cascading use of wood for sustainability
Cascading is a systematic methodology that sequentially uses materials to extract maximum utility and value.This process efficiently manages wood resources by optimizing their value and minimizing waste throughout each product lifecycle stage (Figure 1).
The European green deal (EGD 2019) policy framework emphasizes the cascading use of wood and circularity concepts.The New EU Forest Strategy for 2030 (2021) follows these principles.It prioritizes using, reusing, and recycling all wood-based products, promoting their prolonged use in the economy for multiple purposes.Wood recycling and reuse are vital for sustainable construction practices and reducing greenhouse gas emissions.Cascading can be used to maximize carbon storage potential of wood by prioritizing its use for high-value products like furniture and construction materials before using it for lower-value applications such as energy production.This approach can also reduce the demand for nonrenewable resources like concrete and steel.Additionally, wood products can be recycled and repurposed at the end of their life cycle, which helps extend their usability and minimizes carbon emissions from harvesting and processing.
Nevertheless, the waste hierarchy in the forest -products industry needs improvement in maximizing the carbon storage potential of wooden materials, althrough studies on the cascading of structural timber components or furniture have been conducted Still, sexceptions include investigations on the cascading of wood from demolished buildings and the viability of using furniture waste as a feedstock for 3-D (2020) successfully produced three-layer medium density fiberboard (MDF) panels from hammer-milled surface-laminated MDF and showed that the substitution of >20% recycled fiber results in panels with improved properties in terms of formaldehyde emission and thickness swelling; Sakaguchi et al.
(2017) investigated the potential for cascading wood from demolished buildings to explore cascading flows and enhancement of cascading potential and concluded that cascading depends mainly on the primary design, which affect the demolition process.In the furniture industry, Pringle et al. (2018) showed the opportunity of using furniture waste as a feedstock for 3-D printer filament to produce furniture components, and Jaramillo et al. (2018) conducted research on the recycling and reuse of cardboard tubes as an input material for outdoor furniture.
Global trends in timber production depend on a large number of factors.However, several factors like forest area and forest utilization rate dominate timber production and market in individual countries and globally.Table 1 provides an overview of the main characteristics of forests and government statistics for the forest-products industry in Croatia, Bosnia and Herzegovina, Serbia, and Slovenia Table 2 shows the critical differences in wood-based constructions across these countries.
Individual companies, regional industry associations, national (mainly in Western Europe) and international organizations implement activities to promote the use of wood: e.g.ProHolz in Austria, Danish Wood Information Council, Swedish Wood in Sweden, Comité National pour le Dévelopment du Bois (CNDB) in France, Promo legno in Italy, Lignum in Switzerland.Nordic Timber Council (NTC) was one of the leading organizations in this endeavor and closed its operation in 2006.It initiated the "Building Europe" campaign to enhance the use of wood in construction.It circulated the "Building Europe -European Wood Magazine" in France, Germany, The Netherlands, The UK, Finland, Sweden, and Norway to inspire and educate architects to use and work with wood.NTC also set up the "Environment Communication Platform" to promote the environmental advantages of wood.CEI-Bois is implementing several action plans to achieve the vision of making wood one of the leading construction materials in Europe.Specific actions focus on standardization, Eurocodes, knowledge base, education and training, construction process, and new markets.Organizations promoting wood at the national level in Bosnia and Herzegovina, Croatia, Serbia, and Slovenia presented in Table 2. Attitudes towards timber construction vary between those countries, even though timber construction offers competitive solutions for more sustainable construction, and iincreasing the use of renewable materials, mainly wood, in buildings could make construction more sustainable and a part of the bioeconomy (Riala and Ilola 2014).In all countries, there are considerable activities, initiatives, and legalization supporting timber constructions concerning current European regulations with an emphasis on using wood as a sustainable architectural construction material for the future.

Objective and scope
Based on the literature review and experts' opinions, there is a lack of knowledge and different attitudes among the EU countries toward sustainability practices in the forest product industry, and there is a need to quantify it.
The first objective of this study was to investigate and quantify by surveying the attitudes of public and professional organizations towards prolonging the life cycles of wood products to combat climate change through cascading in Bosnia and Herzegovina, Croatia, Serbia, and Slovenia.The focus was to learn more about the potential of reusing wood products, doubts about their durability, and motivation to reuse wood from current buildings, especially as a structural material for new buildings, as well as the importance of ecological, technical, and economic aspects.The second objective is to show the potential of cascading use of wood products based on the comparative survey results.The study will also outline recommendations for more comprehensive education and explain why promoting sustainable practices in the wood products and building construction industry is essential.This study is the foundation for the continuous, separate case studies on wood cascading for other countries' construction and furniture industries.

Methods
The survey questionnaire utilized in this study was developed by an international group of professionals specializing in wood science.Based on the research objectives, a The first survey was aimed at the general public, while the second survey included wood-related professional associations.The first survey, aimed at the general public, used a nonprobability sampling technique, specifically the so-called snowball system.Snowball sampling is a recognized method for recruiting study participants, and it was chosen because of its cost-effectiveness, low-cost data conversion, and ability to collect data over a large geographic area (Dillman 2000, Nederifar et al. 2017, Berndt 2020).The electronic questionnaire, created using '1ka', a free web survey software developed by the Center for Social Informatics at the Faculty of Social Sciences of the University of Ljubljana, was distributed through e-mails and social networks, with university students acting as the first disseminators of the survey.The survey was conducted from late November 2022 to mid-February 2023 and yielded 97 valid responses from Slovenia, 80 from Serbia, 262 from Croatia, and 110 from Bosnia and Herzegovina.
To obtain valuable insights from professional associations, the survey was expanded to representatives of professional associations from each country.Four associations from Bosnia and Herzegovina (Wood cluster "furniture & wood", Foreign trade chamber of Bosnia and Herzegovina, WMTA Banja Luka, Chamber of Economy of the Federation of Bosnia and Herzegovina), 5 associations from Slovenia (The Chamber of Commerce and Industry of Slovenia, The Chamber of Craft and Small Business of Slovenia, Slovenian Forestry Institute, Wood Industry Cluster, ZAPS Chamber of Architects), 6 associations from Croatia (Croatian Forest Institute, Pannonian Wood Competence Center, Wood Technology Engineer Association, Competence Center Ltd. for Research and Development, Wood Cluster Slavonian Oak, Ministry of Agriculture), and 2 associations from Serbia (Chamber of Commerce and Industry of Serbia and Forest Directorate of the Ministry of Agriculture, Forestry and Water Management) were involved.The second survey of professional associations took place from May 29 to July 31, 2023.
The questionnaire (Table 3) consisted of four parts: (1) A general questionnaire that reflected the profile of the respondents who participated in the survey: gender, age, and education.(2) Questions about the potential of wood products reuse.
(3) Questions related to doubts, motivation, and potential to use and reuse wood products.(4) Initiatives and proposals for higher value through reusing or recycling of wood.
Statistical software JASP (Version 0.16.4,JASP Team, 2023) was used for data analysis.Descriptive statistics, such as frequency counts and percentages, were obtained and presented in bar graphs.Pearson's chi-square test for cross-tabulation frequencies was used to assess differences between countries and groups of respondents.The correlation between two ordinal variables was measured by the Spearman rank correlation coefficient, a nonparametric measure of dependence.The statistical significance level was set at p < 0.05.The following abbreviations were used in all bar charts (Figures 2-8): ALLthe data for all four countries combined, SVN -Slovenia, CRO -Croatia, BIH -Bosnia and Herzegovina and SRB -Serbia.

Respondent profile of the general public
Approximately 45% of participants in the study identified themselves as female and 55% as male.Slovenia had the lowest percentage of female respondents, with 23%, while Serbia had the highest rate, with 67%.About 55% of respondents were young adults aged 18-24, with the lowest percentage in Bosnia and Herzegovina (26%) and the highest in Serbia (81%).This demographic pattern is attributed to the initiation of data collection by university students.About 20% of the participants are 25-34 years old.The middle-aged groups (35-44 years, 45-54 years, and 55-64 years) accounted for 7-9% of the total participants.Only about 2% of respondents were over the age of 65.The highest level of completed education reported by respondents was primarily high school (35%) or higher education through professional and University programs (31%).This fact reflects the method of data collection.

The potential of engineered wood products (EWPs) reuse
More than 80% of respondents in all countries disagree or strongly disagree that wood products used in building construction are made for one use only (Figure 2).
Professional associations provided similar percentages: 88% in Slovenia, 77% in Croatia, 84% in Bosnia and Herzegovina, and 100% (only two associations participated) in Serbia.
Figure 3 shows the results of respondents being asked to select multiple types of wood products they believed had the highest potential for reuse.Among the respondents, those from Slovenia had the highest percentage of agreement regarding the reuse potential of all wood products.In all surveyed countries, more than the general public, a higher percentage of professional associations agree on the reuse potential of all wood products.Construction elements were identified as having the highest reuse potential overall, followed by doors and wooden facades.
Of others, several respondents mentioned furniture as having a high reuse potential.In addition, various wooden floors, parquets, roof construction, beams, rafters, supporters, and columns were also mentioned.
Respondents were asked how vital ecological, economic, and technological aspects are in reusing wood products (Figure 4).More than 80% of respondents in all countries rated the ecological aspect as somewhat or very important.The percentage of respondents, who rated the ecological aspect as very important varies between countries, ranging from 38% in Bosnia and Herzegovina to 60% in Serbia.
The professional associations rated the ecological aspect even higher; all but one of them rated the ecological aspect as somewhat or very important, and in Croatia, even all six associations rated it as very important.In all countries, the percentage of respondents who rated the ecological aspect as very important is higher than for the economic (28%−33%) or technological aspects (27%−29%).There are statistically significant differences between countries regarding the importance of the economic aspect (χ 2 (12) = 24.645,p = 0.017).Bosnia and Herzegovina stands out, where 59% of respondents rated the economic aspect somewhat important and another 26% very important.Professional associations predominately rated the economic aspect as important or somewhat important, and a lower percentage than the general public rated it as very important.The technological aspect was rated as very or somewhat important by more than 60% of respondents.Again, the percentage was highest in Bosnia and Herzegovina (77%), but  the differences between the countries are insignificant.Bosnia and Herzegovina also stands out among professional associations, where all associations rated this aspect as reasonably important.
Spearman's rank-order coefficient confirms a significantly strong positive correlation between the importance of the economic aspect and the technological aspect (r S (488) = 0.531, p < 0.001) (Figure 5).In contrast, the correlation between the importance of the ecological aspect and the economic aspect (r S (488) = 0.343, p < 0.001) and the ecological aspect and the technological aspect (r S (488) = 0.313, p < 0.001) was moderate.

Doubts and motivation to reuse wood from current buildings
Doubts about the long-term quality of wood products refer to concerns or uncertainties related to the ability of wood products to maintain their structural integrity, durability, and appearance over an extended period.These doubts may arise from inadequate material selection, improper processing or treatment, environmental exposure, or other forms of degradation that may occur over time.
Concern of one professional organization is that, in principle, wood tends to degrade more rapidly than concrete and metal over the years.However, it is feasible to assess the suitability of wooden elements for reuse through appropriate testing.Doubts about the long-term quality of wood products collected by the general public are durability, moisture resistance, wood deterioration earlier than concrete, the influence of weather, inadequate protection, pests, poor technological preparation, aesthetic appearance, the impossibility of restoration, functionality, etc.Most respondents (84% to 91%) have no doubts about the long-term quality of wood products (Figure 6).
However, the share of respondents who feel motivated to reuse wood from existing buildings statistically significantly varies by country (χ 2 (3) = 20.772,p < 0.001) (Figure 7).The range is from the highest, 93%, in Serbia to the lowest, 68%, in Croatia.The percentage of respondents who feel motivated to reuse wood from existing buildings is also statistically significantly different from those who have or do not have doubts about the long-term quality of wood products (χ 2 (1) = 8.295, p = 0.004).Of respondents who have doubts about the longterm quality of wood products, only 60% are motivated to reuse wood, compared to 79% of respondents who have no doubts about the long-term quality of wood products.
All but one of the professional associations (from Slovenia) have no doubts about the long-term quality of wood products and feel motivated to reuse wood from existing buildings.Statistically significant differences between countries exist in the level of agreement with the lack of actors, initiatives, and proposals adding more value by reusing or recycling wood (χ 2 (12) = 287.444,p < 0.001) (Figure 8).In Slovenia, Croatia, and Serbia, more than 70% of respondents agree or strongly agree with this statement, while 87% disagree or strongly disagree in Bosnia and Herzegovina.In Croatia and Bosnia and Herzegovina, all professional associations strongly agreed that there is a lack of actors/stakeholders, initiatives, and proposals for higher value through reusing or recycling wood, while in Serbia, both associations agreed.In Slovenia, the associations' answers varied between strongly agree (1 association), agree (3 associations), neither agree nor disagree (1 association), and disagree (1 associations).
There are statistically significant differences between countries in terms of agreement with the statement that reused wood has a lower value compared to other construction and demolition waste, such as metals and plastics (χ 2 (12) = 27.152,p = 0.007) (Figure 9).
Responses from professional associations in Slovenia ranged from agree to disagree; in Croatia, all but one association either disagreed or strongly disagreed; in Bosnia and Herzegovina, all associations disagree or neither agree nor disagree; and in Serbia, both associations disagree.
The percentage of respondents who agree with the statement "reused wood is less valuable compared to other waste" also differs statistically significantly between those who have doubts about the long-term quality of wood  products and those who do not (χ 2 (4) = 14.113, p = 0.007).While a similar percentage of respondents (13% of those who have no doubts and 15% of those with doubts) strongly disagree with this statement, the main difference is among those who disagree.While only 20% of respondents, who doubt the long-term quality of wood products, disagree with the statement about the lower value of recycled wood, the percentage is much higher among respondents who have no doubts (41%).
Statistically significant differences exist between those who have the motivation to reuse wood and those who do not (χ 2 (4) = 23.772,p < 0.001).Of respondents who are motivated to reuse wood, 57% disagree or strongly disagree with the statement that recycled wood is less valuable compared to other waste, while of respondents who are not motivated, only 34% disagree or strongly disagree with the statement.
Respondents noted that reclaimed wood is reused less than metals or plastics due to limited availability, higher costs, and difficulty to process due to its size, shape, and presence of hardware.Additionally, the durability of reclaimed wood depends on its type and condition, and it may require inspection and testing before use, as well as regulatory limitations and cultural factors.For example, structural wood components from existing constructions can be reused, especially in the prefabricated timber roof trusses connected with metal connectors or mechanical connectors (Tekić et al. 2017).The damage at the end of the elements caused by the nails (Tekić et al. 2019) can be easily removed by shortening the elements.Despite these challenges, reclaimed wood can be a valuable and sustainable resource for those willing to invest the time and effort to repurpose it effectively.
Associations mentioned a lack of awareness that wood could be reused.The size of wooden elements is more difficult to recycle and reuse.Recycled metal and plastic can be turned into a product comparable to its original state, while wood could be recycled or reused mainly into products of lower quality than the original products.
The general public has expressed concerns regarding various aspects: economic considerations, the perceived lack of involvement from decision-makers, the more intricate recycling process for wood, and worries about changes in wood properties over its lifespan.Furthermore, the economic rationale behind recycling was questioned.The prevailing notion that wood is prone to decay contributes to the reluctance of individuals to contemplate its reuse at the end of its lifecycle.Other factors, such as visual appearance, price, and potential loss of quality, were also noted.From an ecological standpoint, it was observed that wood decomposes more readily than metal and plastic.A prevalent belief persists that used wood Figure 8.A lack of actors/stakeholders, initiatives, and proposals for higher value through reusing or recycling wood.Survey question: Do you agree that there is a lack of actors/stakeholders, initiatives, and proposals for higher value through reusing or recycling of wood? Figure 9. Reused wood has a lower value than other construction and demolition waste, such as metals, plastics, etc. Survey question: Do you agree that reused wood has a lower value compared to other construction and demolition waste, such as metals, plastics, etc.?
might not hold the same attributes as new wood, raising uncertainty about its worthiness for reuse.Technologically, it was mentioned that working with new wood is more straightforward than working with used wood.However, from the economic perspective, there exists perception that the utilization of used wood could be more costly compared to using new wood.Facts like refurbishment costs, market demand, quality concerns, ease of use, consumer preferences, consumer preferences and perceived longevity collectively contribute to the economic perception that utilizing used wood could be more costly when compared to using new wood, shaping decisionmaking processes in various industries.

Conclusions
The cascading use of wood in the building or furniture industry represents a sustainable and forward-thinking approach to resource management.It emphasizes the efficient utilization of wood through its lifecycle, from the initial harvesting of timber to its eventual repurposing and recycling.This study quantified the sustainability practices of the forest products industry in Central and Southeastern Europe.The survey assessed the situation and preparedness for circular economy practices in selected countries.By including public (university students) and professional organizations, we enhanced its capacity to yield valuable insights from diverse perspectives.This inclusive approach not only enriched our understanding through the opinions of young adults but also ensured the precision and reliability of the findings through the input of professionals.Survey results indicate that the end-of-life options for wood are still being developed, and many of these processes must be better explained.It showed considerable potential for cascading use of wood, but implementation will take time since the industry does not sufficiently understand the concept or does not have incentives to act.There is a need for a detailed analysis of the material intensity in buildings, with a specific focus on wood.This analysis is crucial for understanding and optimizing wood usage, especially in evolving end-of-life options and the potential for cascading use of wood resources.
The study's findings contribute to the broader understanding and implementation of sustainable timber resource management practices by identifying challenges, proposing solutions, and offering a framework for informed decisionmaking in the industry.Education in this domain is essential, and industry associations are doing an excellent job of moving this agenda forward.Survey results could facilitate decision-making and knowledge transfer by associations and higher education.Our results also aim to provide methodology and guidelines for other regions (countries) to conduct a similar study to map consumer and industry perception.
printer filament, for example Sandin et al. (2014) investigated the recycling of glue-laminated wooden beams by modeling the End-of-Life (EoL) process; Vis et al. (2014) focused on cascading in the wood sector and conducted several case studies, including timber frame construction; Daishi et al. (2017) examined the potential for cascading wood from demolished buildings, the case study in Finland; Sakaguchi et al. (2017) also studied the possibility for cascading wood from demolished buildings and the condition of recovered wood, a case study in Finland; Husgafvel et al. (2018) assessed the potential for cascading recovered solid wood; Hong et al.

Figure 2 .
Figure 2. The potential of EWPs.Survey question: Wood products used in building construction are made for one use only and cannot be reused.

Figure 3 .
Figure3.The highest reuse potential of wood products.Survey question: Which wood products have the highest reuse potential?

Figure 4 .
Figure 4.The importance of (a) ecological, (b) economic, and (c) technological aspects.Survey question: How important are the following aspects when reusing wood products?(a) ecological aspect, (b) economic aspect, and (c) technological aspect.

Figure 5 .
Figure 5. Positive correlation between the importance of the economic and the technological aspect (a), the ecological and the economic aspect (b), and the ecological and the technological aspect (c).

Figure 6 .
Figure6.Doubts about the long-term quality of wood products.Survey question: Do you have doubts about the long-term quality of wood products?

Figure 7 .
Figure 7. Motivation to reuse wood from existing buildings.Survey question: Do you feel motivated to reuse wood from current buildings, especially as structural material?

Table 2 .
Wood-based construction in Bosnia and Herzegovina, Croatia, Serbia, and Slovenia.
Foreign Trade Chamber of BiHassociation for wood industry and forestry, University of Sarajevo, Faculty of Forestry and Mechanical Faculty Faculty of Forestry University of Banja Luka Croatian Chamber of Economy -Association of wood processing industry; Croatian Wood Cluster; Slavonian Oak Wood Cluster; University of Zagreb Faculty of Forestry and Wood Technology Association for forestry, wood processing, furniture and paper industry, Serbian Chamber of Commerce The Furniture and Wood-Processing Industry Association, Wood Industry Cluster, Wood Industry Directorate, The Association of Slovenian Manufacturers of Prefabricated Houses

Table 1 .
Croatia, Bosnia and Herzegovina, Serbia, and Slovenia forest in numbers 2022 and Government statistics 2021 and 2022 for the forest products industry in Croatia, Bosnia and Herzegovina, Serbia, and Slovenia.Italy, D -Germany, A -Austria, CRO -Croatia, SLO -Slovenia, CH -China, BiH -Bosnia and Herzegovina, RF -Russian Federation, F -France, RS -Republic of Serbia, NLthe Netherland questionnaire was developed, addressing the prolonged life cycles of timber-related issues.The questionnaire was implemented in the Central and Southeastern European countries Bosnia and Herzegovina, Croatia, Serbia, and Slovenia.The study methods included two exploratory web-based surveys in English language using the same questionnaire.

Table 3 .
The main content of the survey questionnaire.