Barriers to the Effective Selection of Sustainable Materials for Residential Building Projects: A Qualitative Study

Abstract

Although sustainability in Tanzania’s construction sector has been explored in areas such as energy efficiency and green building practices, little attention has been given to understanding the specific barriers to the selection of SBMs in residential projects. This study fills that gap by identifying and analyzing the critical barriers hindering the effective selection of SBMs in Tanzania’s residential construction sector. Through qualitative interviews with experts from regulatory bodies, public developers, and academic researchers, this research provides a comprehensive examination of these barriers. Using Atlas.ti 23 software for a qualitative data analysis, six key categories of barriers were identified: (1) Regulatory and Policy Barriers, (2) Financial Barriers, (3) Knowledge and Awareness Barriers, (4) Technical Barriers, (5) Market and Supply Chain Issues, and (6) Cultural and Social Barriers. Among these, lack of awareness and limited knowledge emerged as particularly significant, alongside regulatory and policy barriers, in hindering the effective selection of SBMs. This study’s novelty lies in its focus on the Tanzanian context, depth of the analysis of the unique challenges, and categorization of the barriers. The findings underscore the need for targeted policy interventions, particularly in raising awareness, offering financial incentives, and establishing comprehensive regulatory frameworks. Furthermore, this study presents a graphical representation to illustrate the categories and constructs of these barriers, adding a visual dimension to the understanding of the issues. Future research should expand the scope to include private developers and material suppliers, whose roles are critical in enhancing the availability and adoption of SBMs in Tanzania’s construction industry.

1. Introduction

Globally, the construction industry stands as one of the leading carbon-emitting sectors [1], significantly contributing to greenhouse gas emissions and resource consumption. Buildings account for around 30% of global energy consumption, having a substantial impact on global energy use and the greenhouse effect [2]. The operational phase of buildings, responsible for maintaining internal conditions, contributes the most to energy emissions, emphasizing the need to improve energy efficiency [2]. In addition to energy concerns, the construction industry has a substantial impact on the natural environment, economy, and society, directly and indirectly affecting environmental sustainability [3].

Traditional building practices, characterized by the use of conventional materials, hugely affect environmental balance, leading to significant resource depletion and waste generation [4]. In response, modern construction practices are increasingly focused on sustainability, aiming to reduce both the input of raw materials and the output of waste by closing resource loops [5]. A critical component of this approach is the utilization of SBMs, which are known for their recyclability and minimal environmental footprint [6]. SBMs, known for their recyclability and minimal environmental footprint, offer a pathway to sustainable construction practices [7]. However, despite the evident benefits of SBMs, their widespread adoption in building projects remains limited, particularly in developing countries [8].

The transition to SBMs is impeded by various factors, including persistent traditional building practices, limited awareness, and a lack of understanding of sustainable construction principles [9,10]. In Tanzania, a developing country in East Africa, the green building agenda faces numerous challenges, including an underdeveloped theoretical and contextual understanding of the factors driving green building adoption [11]. Although Tanzania’s 2003 construction policy acknowledges certain barriers—such as entrenched traditional practices, limited awareness, and a lack of technical skills—it lacks a clear definition of green buildings and seldom enforces sustainable practices [12].

These challenges similarly affect the adoption and use of SBMs, which are integral to green building projects. The preference for conventional, Western-made materials—often perceived as indicators of wealth and modernization—further reduces the uptake of locally sourced sustainable materials [13]. The situation in Tanzania mirrors that of many other developing countries, where the upfront costs of sustainable building materials are seen as prohibitive, thus hindering the integration of sustainable construction practices. As noted by [14], in addition to general challenges associated with sustainable design, issues such as poverty, resistance to change, weak governance, and environmental degradation further obstruct the development of sustainable housing in Africa.

Although prior studies have explored various aspects of sustainability in Tanzania’s construction sector, particularly energy efficiency and green building practices, a significant gap persists in understanding the specific barriers to the selection of SBMs in residential projects. Despite the growing awareness of sustainability’s importance, the utilization of SBMs in Tanzania’s construction sector remains limited. The key obstacles—ranging from economic and market constraints to cultural and knowledge-based factors—are not well documented or analyzed in the existing literature. This study seeks to identify, categorize, and analyze these barriers, offering insights into how they impede the adoption of SBMs, particularly in a developing country context.

Understanding these barriers within the context of Tanzania’s construction industry is crucial for stakeholders to devise strategies to mitigate their impacts and promote the adoption of green building practices and SBMs. Consequently, this study is driven by the following research questions:

• What are the key barriers to the effective selection and use of SBMs in residential projects in Tanzania?
• How would you rate the significance in terms of impact of these barriers?
• What are the possible solutions to these barriers?

Through in-depth interviews with experts from regulatory bodies, academic researchers, and public developers, this study seeks to provide a comprehensive overview of these barriers. Ultimately, the findings will help enhance awareness, propose actionable policy recommendations, and contribute to the growing body of knowledge on sustainable construction in developing countries, particularly Tanzania.

2. Literature Review

2.1. Critical Barriers to the Selection of SBMs

With growing concerns over environmental degradation and climate change, there has been increasing focus on how new structures are commissioned and built, particularly regarding their energy use and resource consumption [15]. Similarly, the usage of building materials has a significant environmental impact, primarily due to the extensive reliance on non-renewable resources, which may deprive future generations of these resources [16]. As a result, the use of SBMs has emerged as an important strategy within the construction industry as the sustainability imperative continues to gain momentum [17].

Despite the well-recognized benefits of SBMs, various barriers hinder their widespread adoption. These barriers are not only prevalent in developed countries but are often more pronounced in developing regions due to additional economic, technical, and regulatory challenges. One of the most significant barriers to SBM selection is the cost. According to [18], SBMs often have higher upfront costs compared to conventional materials, which serves as a major deterrent, particularly for builders and developers operating under tight budgets. Ref. [19] argues that the higher initial investment required for SBMs is a critical obstacle, especially in competitive markets where immediate financial returns are prioritized over long-term sustainability.

Another crucial barrier is the lack of awareness and knowledge regarding SBMs. Many stakeholders, including developers, contractors, and clients, are either unaware of the availability of sustainable materials or do not fully comprehend their benefits [20]. This knowledge gap frequently results in a preference for conventional materials, which are more familiar and commonly used. Ref. [21] highlights that this lack of awareness prevents stakeholders from making informed, sustainability-oriented decisions, representing a significant hurdle to SBM adoption.

Technical and performance uncertainties also contribute to the reluctance to use SBMs. Concerns about the durability, reliability, and overall performance of sustainable materials create hesitation among stakeholders [22]. These materials are sometimes perceived as untested or experimental, leading to resistance, particularly in high-stakes, large-scale projects. Ref. [23] underscores that such technical uncertainties are a critical barrier to SBM adoption, especially where risk aversion is high.

Furthermore, supply chain limitations complicate the adoption of SBMs in many regions. Underdeveloped supply chains often lead to inconsistent availability and logistical difficulties [18,24], making it challenging for builders to source the necessary materials in the required quantities. Ref. [25] observes that the limited availability of SBMs is particularly problematic in developing countries, where local production is frequently insufficient.

Regulatory and policy barriers also play a pivotal role. In many regions, building codes and regulations do not adequately support or encourage the use of sustainable materials [22,26]. Without supportive policies or incentives, SBMs struggle to compete with conventional materials, which are often cheaper and more readily available. Ref. [21] points out that the absence of strong regulatory frameworks significantly slows the transition to sustainable construction practices.

In developing countries, these barriers are exacerbated by economic constraints, limited knowledge, and a lack of strong policies and building codes. The economic challenges are more severe in these regions, where the higher upfront costs of SBMs represent a greater obstacle due to their lower levels of economic development [27,28]. The builders and developers in such regions are more likely to prioritize immediate cost savings over long-term sustainability. Ref. [29] emphasizes that financial barriers are particularly challenging in developing countries, where resources are limited. Ref. [30] indicates that when stakeholders—such as architects, engineers, builders, and clients—are not adequately informed about the benefits, availability, and applications of SBMs, they tend to rely on conventional materials that they are more familiar with.

The lack of local production further impedes SBM adoption in developing nations. Many SBMs are not produced locally, leading to a reliance on expensive imports. Ref. [31] points out that this dependence on external sources increases costs and creates logistical hurdles, making it even harder for sustainable materials to gain traction. In countries like Burkina Faso, for instance, local stakeholders have had to develop their own supply chains for green building materials, often at significant expense [31].

Finally, cultural and market preferences in developing countries often favor conventional materials and traditional construction methods [32]. Ref. [26] argues that these preferences are deeply rooted in cultural norms and the existing market structure, posing additional barriers to the acceptance of SBMs. Similarly, ref. [33] notes that entrenched preferences for conventional materials remain a significant obstacle, particularly in the regions where sustainable alternatives are not yet widely recognized or trusted.

Despite the increasing awareness of the need for sustainable construction in developing nations, substantial barriers remain, preventing this “new style” of architectural practice from becoming the norm [17].

Table 1. Barriers to selection of SBMs (Authors).

S/N	Barriers	Key Reference
B1	Lack of awareness and knowledge among stakeholders	[30,34,35]
B2	Lack of an exemplar project	[34]
B3	Shortage of skills and labor	[34,36]
B4	Lack of comprehensive tools/data to compare different material alternatives	[20,37]
B5	Perception of higher cost being incurred	[18,27,28,38]
B6	Perception that sustainable materials are low in quality	[13,39]
B7	Perception of poor aesthetics	[26,32]
B8	Fear of change from conventional practices	[13,40]
B9	Lack of government policies promoting the use of sustainable materials	[17,30]
B10	Limited availability and accessibility of SBMs	[17,24,31]
B11	Possible project delays	[17,40]
B12	Uncertainty in liability of final work	[30,40]
B13	Fear of maintenance issues	[10,20]
B14	Lack of integration in academic curriculum	[27,41]
B15	Market demand/low value	[30,31,41,42,43]

presents a summary of the major barriers affecting the selection of sustainable building materials in developing countries, as identified in previous studies.

Developing countries are striving to promote the development of green buildings despite the challenges such as rapid urbanization and the growing environmental concerns. It is suggested that these barriers can be addressed through a strategic and collaborative approach by stakeholders, which would enhance the incorporation of SBMs in future projects and include the retrofitting of existing buildings to meet green standards [44].

2.2. Contextual Challenges

Tanzania faces similar challenges as those described in Section 2.1 like the rest of the developing world, particularly the Sub-Saharan part of Africa. Ref. [45] claim there are no clear government policies and regulations mandating the application of green building practices in building development in Tanzania. This lack of policy support and enforcement regulations can further be explained by the fact that Tanzania relies on adopted foreign building standards and certification systems such as LEED v4.1 and Green Mark 2017 [45], to assess the environmental compliance of construction activities and building materials [11]. UNEP (2009) [46] states that the absence of strong policies and regulatory frameworks is frequently linked to low levels of awareness and knowledge among stakeholders in the construction industry. Ref. [47] found that in regions with robust environmental policies, there is generally a higher awareness and more knowledge about sustainable building materials. The challenge of limited awareness and knowledge of SBMs in Tanzania can further be attributed to the lack of comprehensive tools/data to compare different material alternatives. For instance, the price list of materials, last published by the National Construction Council in 2019 [48], only provides information about conventional materials. This list, which is widely referenced by builders, developers, and policymakers, exclusively features conventional materials, thereby neglecting the growing array of sustainable alternatives. In addition, Ref. [47] noted that without standardized metrics and comparison tools, builders and developers struggle to make informed decisions. By establishing, for instance, a central database that includes SBMs and launching educational initiatives, the NCC can drive the adoption of sustainable practices. This alignment with global trends would not only foster socio-economic development but also ensure environmental sustainability, positioning Tanzania’s construction industry for a competitive future.

3. Methodology

This study adopts a qualitative research design (Figure 1) to investigate the complex barriers hindering the effective selection of SBMs for residential projects in Tanzania. Previous studies, such as [17,30,49], have utilized quantitative and mixed methods; however, a qualitative approach was deemed more appropriate for understanding the multifaceted nature of this issue in the Tanzanian context. As [50] suggests, interviews allow for in-depth exploration of the participants’ perspectives, while [51] emphasize that this method captures the contextual richness of their lived experiences. By focusing on the Tanzanian context, this research aims to uncover the specific barriers faced by stakeholders in adopting SBMs and propose strategies for overcoming them. This study seeks to identify, categorize, and analyze these barriers, offering insights into how they impede the adoption of SBMs in Tanzania.

A purposive sampling strategy was employed to select 16 participants, categorized into three key groups: regulatory bodies, academic researchers, and public developer experts. Three categories of experts were included: (1) Regulatory bodies: Participants were chosen based on their roles in policy enforcement and inspectional compliance related to sustainable construction. They were drawn from the National Environment Management Council (NEMC), the Tanzania Green Building Council (TGBC), and the National Construction Council (NCC); (2) Academic researchers: Participants were selected based on their specialization in sustainability within construction and their contributions to the recent research on sustainable building practices (2015–2023). This criterion ensured that the data obtained reflected the current practices and knowledge-based perspectives; (3) Developers: Public housing developers were selected based on their involvement in green residential projects, ensuring they provided insights into the practical challenges of implementing SBMs in large-scale housing projects. These selection criteria ensured that the participants were knowledgeable and actively involved in the SBM selection process. This approach provided a comprehensive view from regulatory, academic, and practical implementation perspectives [52].

The data were collected through semi-structured interviews, allowing flexibility to explore new areas of inquiry and gather detailed responses. This method, as noted by [53], is particularly useful in qualitative research for capturing the nuanced insights that structured methods may miss. The interviews lasted from 30 to 60 min, and were conducted either in person or through online platforms, depending on participant availability. Each interview was audio-recorded with the consent of the participant, ensuring accuracy during transcription. Pilot interviews were conducted with three participants to test and refine the interview guide, ensuring the questions were clear and elicited relevant information [54]. This process helped refine the questions and allowed for a more effective interview structure moving forward.

Ethical considerations were strictly adhered to in this study. The ethical clearance was granted by the host institution’s research ethics committee [55]. The participants were fully informed of the study’s purpose and their rights, including the option to decline being recorded or to withdraw from the study at any point. Informed consent was obtained from all the participants, and confidentiality was maintained throughout the research process. Sensitive data were handled carefully to avoid any unintentional disclosures of personal or organizational information. To enhance the accuracy and credibility of the collected interview data, each interview transcript was shared with the respective participants for validation. This process, often referred to as respondent validation, allowed the interviewees to review the identified themes, key arguments, and overall interpretations, ensuring that they accurately reflected their perspectives [56,57]. By involving participants in this verification step, this study shifted part of the validation process from the researchers to the respondents themselves, enhancing the overall credibility of the findings [58]. Participants were guided with clear instructions about this process, including examples of the data output they would review, to ensure the accuracy of their feedback and prevent substantial alterations to the original transcript [59]. The feedback received was carefully reviewed and incorporated where relevant, with justifications provided when certain suggestions were not included, ensuring both transparency and the integrity of the original data.

For a data analysis, this study deployed Atlas.ti software, which facilitated the organization and coding of the interview transcripts. The major benefit in using Atlas.ti is that it directs the researcher, through the use of different types of codes that enhance the formulation of categories and themes, thus reducing the time used to analyze the data manually as revealed by [60]. A thematic analysis was used to identify the key themes and barriers related to SBM selection as outlined by [61]. The process included the following: Step 1–Familiarization with the Data: this stage involved reading and re-reading the interview transcripts in order to obtain an overall understanding of the data; Step 2–Generating Initial Codes: This stage involved assigning codes to significant segments of the text. This involved labeling segments of the transcribed data that appeared relevant to the research questions and objectives; Step 3–Creating Categories/Themes: At this stage, codes were grouped into broader themes that represented the data more comprehensively. It involved sorting the different codes into themes and gathering all the data relevant to each potential theme; Step 4–Reviewing Themes: At this step, the themes were reviewed at the level of the coded data and at the level of the entire data set for accuracy purposes. This step involved checking if the themes worked in relation to the coded extracts and the entire data set, generating a thematic map of the analysis; Step 5–Refining Themes: this step dealt with refining each theme to identify the essence of what each theme was about; and Step 6–Writing the Report: this final stage involved writing up the analysis, including the themes and supporting data extracts. This systematic approach ensured that the key themes related to the barriers in SBM selection were rigorously explored and accurately represented [58]. To maintain scientific rigor, a hybrid approach combining a theory-led and data-driven analysis was adopted. This method, as suggested by [58,61], allowed this study to integrate theoretical frameworks while ensuring that the participants’ voices were central to the analysis. It enabled the identification of both the established barriers and context-specific challenges unique to Tanzania, thus providing a comprehensive understanding of the issue.

While this study focused on key stakeholders such as the regulatory bodies, academic researchers, and developers, the perspectives of private developers and material suppliers were beyond its scope. Their exclusion was influenced by the following: the need to focus on the stakeholders directly involved in policy implementation and research, specifically those shaping the regulatory frameworks and academic discourse of the subject matter [62,63], and the fact that the nature of the construction sector in developing countries tends to be more informal than formal, which often results in private developers being less engaged with sustainability concepts [64], while material suppliers simply respond to market preferences rather than actively trying to shape them [65]. Future research could include these groups to provide a more holistic view of the market dynamics influencing SBM adoption.

4. Results and Discussion

4.1. Interviewees’ Demographics

This study engaged 16 experts from academia, developer entities, and regulatory bodies (

Table 2. Interviewees demographics (Authors).

Interviewee Code	Category	Education Level	Involvement in Sustainability Projects	Years of Involvement in Sustainable Practices	Organization Role
INT-A1	Academic Researcher	Ph.D.	Publishes on sustainable construction	Above 10	Lecturer and Researcher
INT-A2	Academic Researcher	Ph.D.	Publishes on sustainable construction	Above 10	Lecturer and Researcher
INT-A3	Academic Researcher	Ph.D.	Publishes on sustainable construction	Above 10	Lecturer and Researcher
INT-A4	Academic Researcher	Ph.D.	Publishes on sustainable construction	Above 10	Lecturer and Researcher
INT-A5	Academic Researcher	Ph.D.	Publishes on sustainable construction	Above 10	Lecturer and Researcher
INT-A6	Academic Researcher	Master’s degree	Publishes on sustainable construction	1–5	Postgraduate researcher
INT-A7	Academic Researcher	Master’s degree	Publishes on sustainable construction	6–10	Lecturer and Researcher
INT-D1	Developer	Bachelor’s degree	Adherence to Environmental Regulations	1–5	Project Manager
INT-D2	Developer	Bachelor’s degree	Alternative Materials Assessment	1–5	Quantity Surveyor
INT-D3	Developer	Bachelor’s degree	Alternative Materials Assessment	1–5	Quantity Surveyor
INT-D4	Developer	Bachelor’s degree	Energy Efficiency Building Design	6–10	Architect
INT-D5	Developer	Master’s degree	Life-Cycle Cost Assessment	1–5	Quantity Surveyor
INT-D6	Developer	Master’s degree	SBM Selection and Green Building Design	Above 10	Architect
INT-R1	Regulatory Body	Bachelors’ degree	Compliance Inspector	1–5	Environmental Engineer
INT-R2	Regulatory Body	Bachelor’s degree	Overseeing Green Agenda Promotion	Above 10	Civil Engineer
INT-R3	Regulatory Body	Master’s degree	Research and Development (R and D)	6–10	Civil Engineer

). Among the academic researchers (n = 7), five held PhDs with over a decade of experience in sustainable building, predominantly serving as senior lecturers in fields related to the built environment. The remaining two academic researchers held master’s degrees, with most (n = 3) possessing 1–5 years of experience in sustainable construction, while one expert had over 10 years. The developer experts (n = 6) were a mix of bachelor’s (n = 4) and master’s (n = 2) degree holders, with most (n = 3) having 1–5 years of experience in sustainable construction, while one had over 10 years. The regulatory body representatives (n = 3) included two with bachelor’s degrees and one with a master’s degree, each with varying levels of experience: one with 1–5 years, another with 6–10 years, and a third with over 10 years of experience. This diversity reinforces this study’s validity since it integrates both theoretical and practical viewpoints, ensuring comprehensive insights into the barriers to sustainable material selection in Tanzania.

Moreover, these interviewees’ demographics ensure that the gathered data reflect a strong theoretical foundation, provide insights into policy enforcement and environmental considerations, and contribute to the practical and on-the-ground experience of Tanzania’s construction sector.

4.2. Identified Key Barriers and Themes Discussion

1. Knowledge and Awareness Barriers: The lack of awareness and limited knowledge about SBMs emerged as a significant barrier and was equally as important as regulatory and policy in hindering the effective selection of SBMs in Tanzania. This barrier’s impact is profound, extending from end users to building professionals, many of whom rated the awareness of SBMs as quite low. The unfamiliarity with sustainable materials goes beyond their benefits and includes a fundamental lack of understanding of what SBMs even entail. Several interviewees attributed this gap to the absence of educational campaigns, the minimal integration of sustainability concepts into academic curricula, and the lack of industry training programs that could promote awareness of SBMs.

One interviewee noted, “Many people still do not fully understand the concept of sustainable materials, including not only regular citizens but also building professionals with university-level construction education and years of experience. There is a need for more educational programs about sustainability in construction within industry organizations” (INT-A2). Similarly, another interviewee highlighted the disconnect between academic research and industry practice: “There is a strong need for an increased Industry-Academia link up because you (researchers) keep producing research works on arising technologies and yet few occasions are arranged to update the industry professionals. Having such opportunities would elaborate the knowledge of professionals about emerging technologies such as the crucial need for utilization of SBMs among others” (INT-A3).

These concerns mirror the findings from other studies in developing countries, which consistently show that insufficient knowledge and awareness are key barriers to adopting sustainable practices. For instance, Ref. [30] highlights that education plays a crucial role in enhancing the awareness of sustainable materials, which, in turn, influences their adoption. Similarly, Ref. [20] underscores that the lack of information about which materials are more sustainable significantly affects the decision-making processes in construction. In the absence of reliable information or expertise, building professionals often default to conventional materials, a practice confirmed by [17].

The lack of demonstration projects was another factor raised by interviewees, reflecting the concerns voiced in previous studies. One participant emphasized, “Some experts in innovative materials come here seeking collaboration. We agree because our company lacks sufficient expertise in this area and therefore cannot rush to take investment risks… Unfortunately, all of them vanish and never return because they want fast money before providing a working demonstration to the investor that it can really work” (INT-D5). This highlights the need for practical, on-the-ground examples of SBM implementation to inspire confidence among developers and investors.

Moreover, the absence of a centralized database on SBMs, a concern raised by several interviewees, exacerbates this barrier. This finding aligns with [8], who argue that without accessible, standardized information about sustainable materials, designers and builders are left without the tools necessary to make informed decisions. One interviewee noted, “Very few professionals, including yourself, have expressed interest in SBMs. In our regular activities of database development, we are typically influenced by market trends, which tend to focus on conventional materials rather than SBMs” (INT-R3). Similarly, the price list of materials published by the National Construction Council (NCC) was identified as reinforcing the preference for conventional materials, as it only includes traditional options, further neglecting the sustainable alternatives [48].

Lastly, the link between awareness and regulatory frameworks is crucial. In regions with stronger environmental policies, there tends to be a greater awareness of sustainability issues, as noted by [47]. The lack of standardized metrics and comparison tools in Tanzania means that builders and developers struggle to make informed material choices. Addressing this issue would require government intervention, particularly through regulations that promote the inclusion of sustainability in both educational curricula and policy frameworks.

2. Regulatory and Policy Barriers: The absence of supportive policies and enforcement mechanisms emerged as the second most significant barrier to the effective selection of SBMs in Tanzania, closely following the challenge of limited awareness and knowledge. Given the context of a developing country like Tanzania, it is unsurprising that all the participants shared this view. The experts emphasized the need for stronger government intervention, clearer regulations, and more robust enforcement mechanisms to promote sustainable practices. They added that the lack of policy support and regulatory frameworks heavily hinders the effective utilization of SBMs and makes consumers less concerned about the whole concept. The respondents INT-A1, A4, R1, and R2, respectively, are quoted below:

“There are lacks policy provisions from the government to encourage the use of sustainable materials. I see that as the non-motivating factor especially to developers who are primarily concerned with maximizing profits on their investments”.

(INT-A1)

“The current regulations are not robust enough to support sustainable building practices. If serious measures are not put in places by the Government, I don’t see how citizens will have interests in this new trend”.

(INT-R1 and R2)

“We need better policy support and enforcement mechanisms to ensure compliance with sustainability standards in material selection. Otherwise, research work will cumulate with less impact if there is no firm intervention of the legal side”.

(INT-A4)

These findings on regulatory and policy barriers align closely with those of previous studies in other developing countries, such as Burkina Faso and Nigeria. The authors of [31] report that government-related barriers hampering the adoption of SBMs in Burkina Faso include the lack of effective government programs and policies focused on green construction, inadequate tax incentives, and the absence of local green building rating systems. These authors proposed recommendations including adapting international rating systems to local conditions and needs, and exploring new green technologies that could be successfully applied at the local scale to promote green designs and green materials. They also urged the government to develop policies incorporating training and incentives for stakeholders.

In a related study [30], the authors identified the lack of building codes and regulations, insufficient research funding for sustainable materials and technologies, and the absence of a standard green building tool as major barriers to SBM adoption. They highlighted that without effective regulations and funding, the introduction and sustainability of SBMs are inhibited. Additionally, Ref. [9] stressed the importance of a strict adherence to codes and regulations as a measure to improve the use of SBMs in the construction industry. These findings suggest that without comprehensive policy frameworks and enforcement mechanisms, the transition to sustainable building materials will remain a challenge in Tanzania and other developing nations.

3. Financial Barriers: The high costs associated with sustainable materials, largely driven by transportation expenses, additional construction and labor costs, and the need for mass production, emerged as notable financial barriers to the utilization of SBMs in Tanzania. Participants consistently pointed to these challenges, with many linking the cost barriers to the absence of funding options and financial support mechanisms. Suggestions were made that addressing these financial hurdles through governmental or non-governmental subsidies, grants, or incentives, as well as investing in local mass production to reduce transportation costs, could significantly enhance the accessibility of SBMs.

For example, one participant noted, “Sustainable materials are often more expensive, which discourages their use. If maybe we (in Tanzania) could imitate some developed countries on how they encouraged this agenda in its early days through incentives such as tax cuts, I believe this would boost the motivation of the consumers” (INT-A4). Another participant added, “The transportation costs for sustainable materials are very high, which adds to the overall expense. For instance, some Dar Es Salaam residents believe that it would be cheaper to use China’s tiles instead of natural cladding stones from Mbeya due to transport additional costs. You can observe how the increased processing sites of these natural cladding stones in Dar Es Salaam has positively affected their proportional use” (INT-A4). Further emphasizing the need for local production and cost efficiency, another respondent suggested, “In order to meet the growing significance, I think people need to integrate the scaling up of production to bring down the costs of these materials. On the other side, the innovative ways of constructing these materials result in extra labor costs and time. It is important to rely on certain optimization principles such as collaborative purchasing, bulk buying, and effective project management to reduce these extra costs” (INT-A5).

These findings are consistent with those from previous studies [8,11,30,31], which have consistently highlighted financial issues as a prevalent barrier to the selection of SBMs in both developed and developing countries. Key similarities include the high initial costs of sustainable materials, the need for government intervention in the form of financial incentives, the challenge of securing funding options, and the higher costs associated with importing materials. These studies have also emphasized a low market demand and a lack of client knowledge as contributing factors to the slow adoption of SBMs.

However, there are notable distinctions between this study and earlier research. While earlier studies primarily focused on the high costs related to the import of sustainable materials [31], this study specifically identifies the impact of the high transportation costs within Tanzania and suggests increased local production as a practical solution. Additionally, this study proposes cost-optimization strategies, such as collaborative purchasing, bulk buying, and effective project management, which were not explicitly mentioned in the prior studies. These strategies are crucial for reducing the overall costs associated with sustainable materials and making them more affordable in the local market.

4. Technical Barriers: The lack of technical expertise among building professionals in Tanzania has emerged as a notable barrier to the effective selection and use of SBMs. Several participants emphasized that many industry professionals are not sufficiently trained in the use of SBMs, which leads to a reluctance to adopting these materials. Furthermore, the limited availability of skilled local labor to execute sustainable construction practices compounds this issue. In some instances, building owners who have committed to using SBMs become disillusioned due to the poor quality and aesthetics of the completed projects, leaving them hesitant to use SBMs in the future.

One participant shared their experience: “There are concerns about the quality and reliability of some sustainable materials. In one of our mass housing developments in the past, we decided to utilize compressed stabilized earth blocks (CSEB), also known as hydraulically compressed earth blocks (HCEB). In this experience, we were disappointed how some units absorbed moisture, affecting the structures. This issue can likely be attributed to the fact that CSEB requires specialized skills and training, and that was our test project. Consequently, the institution has since been reluctant to take more risks with other housing developments” (INT-D3 and A2). Another respondent remarked, “The lack of technical expertise among construction professionals is a critical barrier; many in the industry are not well-trained in sustainable materials, leading to reluctance in their use” (INT-D1, D4, and D5).

Interestingly, the challenges mentioned in the Tanzanian context stand in contrast to the success stories from other developing countries. For example, the project of the Primary School Tanouan Ibi in Mali [66] offers an impressive counter-example. This school was built by local, newly trained masons using hydraulically compressed earth blocks (HCEB). The outcome of this strategy was a building that performed better in extreme climates, withstanding hot sunlight and heavy rainfall, and providing a more comfortable interior climate than traditional clay buildings. This suggests that the technical barriers in Tanzania could be addressed through improved training programs that empower local workers with the necessary skills to implement SBMs effectively.

The findings of this study also align with those from the previous literature, both in developed and developing nations. For example, a study in Australia revealed that the lack of training or skill development in the use of sustainable materials significantly impedes their usage in building projects [8,67]. Most builders, due to insufficient knowledge and expertise, fail to consider the sustainability requirements of general construction projects. Similarly, Ref. [30] pointed out that while efforts to embrace sustainability are ongoing, the availability of experts on green building (GB) remains limited. The lack of training programs on green building materials (GBMs) and the inadequate understanding of the sustainability concept further exacerbate this challenge.

As a solution, many studies emphasize the importance of referral projects and training programs to equip professionals with the practical skills necessary to handle the unique requirements of SBMs [68]. In Tanzania, similar initiatives, such as demonstration projects and skill development programs, could play a vital role in overcoming the technical barriers to sustainable construction. Expanding training programs to include not only building professionals but also local workers would help mitigate these challenges and enhance the quality and adoption of SBMs in building projects.

5. Market and Supply Chain Issues: Unreliable supply chains are a major concern hindering the effective selection and use of SBMs in Tanzania, as they disrupt construction timelines and budgets. This issue echoes broader industry concerns about the robustness of supply chains for sustainable materials. A key factor contributing to these challenges is the market’s limitations, driven by an insufficient demand and economies of scale. As long as the demand for SBMs remains low, the prices will stay high, and the market’s ability to scale up will be hindered. This, in turn, discourages building professionals from opting for SBMs, as they are less accessible and available in the market.

Several participants highlighted these supply chain issues: “The supply chain for sustainable materials is not well developed, leading to their limited availability. The inconsistency in supply and the lack of an established distribution network affect the reliability of sourcing these materials, further discouraging their use” (INT-A4 and INT-D2). Another respondent pointed out the dominance of the use of raw materials for the construction of conventional materials: “The abundance of raw materials used to manufacture popular conventional materials such as cement, concrete blocks, etc., is another important barrier. So, the consumers are reluctant to embrace new market alternatives while the beneficiaries of the existing supply chain aren’t ready to lose their gains in the trade of conventional materials” (INT-D6 and A7).

These findings align with those from previous studies in developing countries. For instance, Ref. [25] observed that limited access to green building materials and technologies significantly hampers the adoption of green building practices, especially when the materials must be imported. In Burkina Faso, a similar issue was reported, where the lack of access to green building materials led locals to develop their own supply chains rather than relying on external suppliers or the government [31]. In addition, the financial losses associated with shifting toward alternative markets, the well-established and profitable supply chains for conventional materials [33], the lack of policy support and market incentives [69], and the widespread availability of conventional materials at lower costs [70] all serve as barriers that align with the current findings.

To address these challenges, it is essential to incentivize the local production and distribution of SBMs through targeted government policies, such as tax breaks and subsidies. By strengthening the supply chain infrastructure, the market for SBMs can become more consistent and reliable. Furthermore, raising awareness among industry professionals about the benefits and viability of SBMs will encourage a wider adoption, ensuring that these materials become more accessible across Tanzania. This dual approach of market-driven and policy-supported interventions can foster a more sustainable and resilient supply chain for SBMs, improving their adoption in residential building projects.

6. Cultural and Social Barriers: One of the most significant barriers to the effective selection of SBMs in Tanzania is rooted in cultural and social resistance to change. Many stakeholders hold a strong attachment to the conventional materials and construction methods, often perceiving them as symbols of wealth or modernity, particularly when aligned with Western construction standards. This mindset, however, reflects a surprising contradiction, as the local sustainable materials (sometimes labeled as “alternative”) ignored today were once highly valued by African ancestors. These materials were integral to traditional construction practices that were sustainable and well suited to the local environment. Yet, the current resistance to using such materials impedes their adoption in modern building practices.

Several participants highlighted this issue: “There is a cultural resistance to change and a preference for conventional materials, as if we don’t like our local stuff at all. By this, I point to the degree at which these locally sourced materials we ignore today were once preferred by our ancestors. I believe this mentality is often tied to perceptions of wealth and a desire to align with Western construction practices. The mindset that sustainable materials are inferior or less prestigious can be traced back to a colonial legacy where Western methods and materials were promoted as superior. This cultural resistance hampers the progress towards more sustainable building practices, as people are reluctant to shift away from what they have always known and trusted” (INT-A5, D1, and D2).

Additionally, this cultural reluctance is compounded by a lack of community engagement in the decision-making process. When communities are not actively involved or consulted, they may feel disconnected and less likely to support sustainable building materials. As one respondent noted: “In many of our communities, the SBMs are still viewed with skepticism. This doubt is partly due to a lack of familiarity and trust in these new materials, as well as a fear of the unknown. Moreover, there is slow evolution of social attitudes which can be attributed to insufficient community engagement in the decision-making process. So, the communities are less likely to support this trend when they are not actively involved or consulted about the benefits and uses of SBMs” (INT-R2).

These findings align with the previous literature that has noted similar patterns of resistance to change. For instance, Ref. [71] found that stakeholders often resist adopting new sustainable practices due to a lack of trust in unfamiliar materials, which are frequently perceived as inferior to the conventional materials. Ref. [47] also points out that eco-friendly or sustainable materials are often viewed through a lens of historical and cultural bias, particularly in developing regions where traditional methods are deeply rooted and alternative materials are not fully appreciated. This “resistance to change” is a widely recognized barrier across various sectors, with [72] emphasizing that societal resistance to new innovations often stems from a lack of awareness or understanding.

In addition to cultural bias, a lack of participatory approaches exacerbates the resistance to SBMs. Ref. [31] argued that community engagement is essential for the successful implementation of new technologies, including sustainable construction practices. Without it, communities are more likely to resist due to unfamiliarity or a lack of perceived benefits. Similarly, Ref. [8] stressed the need for sustained government intervention and the active involvement of various stakeholders to overcome this reluctance. In contexts where the community is not involved, people often focus on the immediate solutions provided by conventional materials rather than embracing long-term sustainable alternatives.

One positive example that Tanzania could learn from is the Bangre Veenem school complex in Burkina Faso, which successfully relied on locally sourced materials to achieve a sustainable design. As [73] reported, the designer engaged with local traditional authorities before initiating the project to ensure cultural sensitivities were respected, such as avoiding sacred areas. This level of community involvement not only secured the support of the community but also minimized material transportation and leveraged the area’s natural resources. This project highlights the importance of engaging with the local communities in Tanzania to ensure both the social acceptance and sustainability of building projects.

The current study suggests that overcoming cultural and social barriers will require changing the entrenched perceptions of SBMs as inferior or unfamiliar. Engaging communities in the decision-making process and raising awareness about the benefits of SBMs can facilitate broader acceptance. In this way, stakeholders can begin to bridge the gap between traditional practices and sustainable innovations, fostering a more culturally sensitive approach to sustainability in Tanzania’s construction sector.

4.3. Thematic Synthesis

A thematic synthesis offers an effective means of identifying and organizing patterns from qualitative data, particularly when analyzing interviews [74]. In the current study, a thematic synthesis was employed to derive the major constructs underlying the key barriers to sustainable building material (SBM) selection from the interview transcripts. This process allowed for the extraction of the relevant constructs that emerged from the recurring themes across the participants’ perspectives [61]. This approach involves carefully coding data, identifying themes, and synthesizing constructs to provide an interpretive framework [75]. An extension of this process is called “Construct Development”, where emergent themes are refined and structured into broader constructs, reflecting the more specific barriers or enablers [76]. The use of software in this process as described by [77], can facilitate researchers to save time by being able to deal with large amounts of qualitative data, having increased flexibility, and having improved validity and auditability of the qualitative research. As discussed in Section 3 of this study, Atlas.ti was deployed for the analysis task of the data gathered from the interviews.

Following the coding stage, the thematic analysis proceeded with clustering related codes into broader themes. Using Atlas.ti, the codes were grouped into broad categories. This step is crucial in helping researchers review the results in a structured way, as thematic clustering allows for the identification of patterns within the data [78]. Similar to how a cluster analysis provides insights in quantitative studies, thematic clustering in qualitative research provides an avenue for organizing data and ensuring a cross-validation of the findings. The synthesis of major constructs occurred after the thematic clustering. In this step, constructs were developed from the themes by identifying the sub-themes or specific variables contributing to the broader barriers. For instance, the theme “Financial Barriers” was broken down into constructs such as “High initial cost”, “Lack of financial incentives”, and “Unclear return on investment”. This process of construct development involved refining and categorizing the data into manageable units that could explain the complexity of the barriers in a more granular fashion [61]. Each construct represents a distinct aspect of the overarching barriers and reflects the specific challenges identified by the participants. For example, “Lack of enforcement mechanisms” emerged as a key construct under the theme “Regulatory and Policy Barriers”, highlighting the participants’ shared concerns about insufficient regulatory support for sustainable materials.

A critical part of the thematic synthesis involved validating the developed constructs. Similar to how a cluster analysis allows for validation in quantitative studies [79], respondent validation was used in this study to confirm the accuracy of the identified constructs.

The participants were asked to review the synthesized themes and constructs to ensure that they accurately represented their views. This validation process is crucial in enhancing the credibility of the qualitative findings [80]. Through this synthesis, six key categories of barriers were identified, and for each category, multiple constructs were developed (Figure 2). The relative importance of each construct was considered based on how frequently they were referenced in the interviews. For example, constructs such as “Lack of supportive policies” and “Limited awareness and knowledge” were frequently mentioned by participants, suggesting their prominence as barriers to SBM selection.

To provide a holistic overview, a summary of the barriers (

Table 3. Summary of key barriers identified by participants (Authors).

Interviewee Code	Regulatory and Policy Barriers	Financial Barriers	Awareness and Knowledge Barriers	Technical Barriers	Supply Chain and Market Issues	Cultural and Social Barriers
INT-A1	✓	✓	✓
INT-A2	✓	✓	✓	✓
INT-A3	✓	✓	✓
INT-A4	✓	✓	✓		✓
INT-A5	✓	✓	✓			✓
INT-A6			✓
INT-A7	✓	✓	✓	✓	✓	✓
INT-D1	✓	✓	✓	✓		✓
INT-D2	✓	✓	✓	✓	✓	✓
INT-D3	✓	✓	✓	✓
INT-D4	✓	✓	✓	✓
INT-D5	✓	✓	✓	✓	✓
INT-D6	✓				✓
INT-R1	✓		✓
INT-R2	✓		✓			✓
INT-R3			✓		✓	✓

) emphasized by each participant was compiled, offering the reader a clearer understanding of which barriers were more frequently mentioned and highlighting the variations in perspectives among the different stakeholders [81].

4.4. Study Implications

The findings of this study on the barriers to the effective selection of SBMs for residential building projects in Tanzania have several practical implications for policymakers, industry professionals, and researchers. This study underscores the need for targeted policy interventions that address the lack of awareness and financial incentives such as tax cuts, as well as the absence of comprehensive regulatory frameworks promoting sustainable construction practices. By integrating sustainability specifications into building codes and encouraging the use of a centralized database, policymakers can enhance the utilization of SBMs in the construction industry. For industry professionals, understanding the identified barriers—such as the financial, technical, and policy-related obstacles—can lead to more informed decision-making and a greater willingness to incorporate SBMs into building projects. This shift could not only reduce the environmental impact of construction activities but also improve community engagement, ultimately benefiting the corporate clients and the broader economy of Tanzania. Lastly, this study contributes to the global discourse on SBM utilization by expanding the body of knowledge related to the barriers in the context of a developing country like Tanzania.

5. Conclusions

This study identified and analyzed the key barriers to the effective selection of SBMs in residential projects in Tanzania, revealing six major categories of barriers: (1) Regulatory and Policy Barriers, (2) Financial Barriers, (3) Knowledge and Awareness Barriers, (4) Technical Barriers, (5) Market and Supply Chain Issues, and (6) Cultural and Social Barriers. Within each category of barriers, significant factors were critically explored with an emphasis on the cause and the resulting effect on the selection of SBMs.

Lack of awareness and knowledge emerged as the most cited barrier, closely tied with regulatory and policy challenges. These findings emphasize the urgent need for government intervention through clearer regulations, incentives, and enforcement mechanisms that encourage the adoption of SBMs. Beyond policy, educational initiatives and technical training programs for building professionals are critical to overcoming technical barriers and ensuring the proper implementation of sustainable practices. Expanding these programs would address the skills gap and improve the quality and performance of SBMs in local projects.

Additionally, overcoming the financial barriers requires practical strategies such as collaborative purchasing, bulk buying, and scaling up local production to lower costs and increase accessibility. Similarly, enhancing the supply chain infrastructure for sustainable materials is crucial for reducing market and supply chain issues. Incentivizing local production and streamlining distribution networks can stabilize the availability of SBMs and encourage their wider adoption.

On the cultural and social front, stronger community engagement in decision-making processes is essential to reducing resistance to sustainable materials. By involving communities and promoting the benefits of SBMs, social acceptance can be improved, allowing for smoother transitions to more sustainable practices.

Looking ahead, policymakers should focus on integrating sustainability specifications into building codes, creating centralized databases for sustainable materials, and encouraging local manufacturing and distribution. For industry professionals, understanding and addressing these barriers can lead to more informed decision-making, ultimately contributing to environmental sustainability and economic growth.

This study’s findings provide a foundation for further research, particularly in the inclusion of private developers and material suppliers, whose roles are pivotal in driving market demand and the availability of sustainable materials. Learning from international examples, such as the Primary School in Mali and the Bangre Veenem School in Burkina Faso, can offer valuable insights into the successful integration of local sustainable materials in developing countries, and these lessons can be adapted to the Tanzanian context.

Despite achieving the objectives, this study acknowledges some limitations. The interviews were conducted with experts from regulatory bodies, public developers, and academic researchers. Future studies could consider insights from other industry players such as private developers and material suppliers or even employ a different data collection method such as a survey questionnaire and case studies. Second, the categorization of the identified barriers could also affect the generalization of the results because of the context of the analysis. Consequently, further research could focus on other geographical contexts to allow possible comparisons.