Shehu (2021) claimed that shelter is a human right and humans deserve a secure and comfortable home. Idowu, Danlami and Ohadugha (2022) believe that shelters and other facilities - electricity, toilets, water, security, health services, and recreational-are primary facilities in an IDP camp. The government, NGOs and international organisations consciously seek to provide shelter for IDPs, which is either low quality or inadequate (Earle et al., 2020; Schimmel, 2022). To solve this problem, we need to construct IDP camps with SBM (Burns et al., 2018). Charlesworth and Fien (2020) highlighted that adequate shelters should cater to all displaced people, such as children, youths, teenagers, adults, the elderly, and pregnant and breastfeeding mothers. IDP camps consist of housing units with convenience, kitchens and living quarters (Seenapatabendige and De Silva, 2023). Resettlement camps should meet the UNHCR standard of approximately 20,000 IDPs (Szilágyi, 2021).

Khoshnava et al. (2020) explained that SBMs containing non-harmful chemicals can improve human health and Indoor Air Quality (IAQ). SBMs are organic, safe, reusable, and sustainable composite materials that enhance quality of life. SBMs can lower harmful environmental and human health effects (Wu et al., 2022). SBMs are non-toxic, renewable, eco-friendly materials that improve human health/wellbeing quality. Using hybrid SBMs can improve human health in and outdoors (Islam et al., 2022; Mehrizi et al., 2023). It can reduce VOC effects on human health by about one-third, according to the life cycle inventory using SimaPro software (McArthur and Powell, 2020; Al-Mudhaffer, Saleh and Kadhum, 2022). Li et al. (2023) agreed that SBMs for reclaimed decking and roofing withstand the elements and require less management. Sustainable building residents experience significant health improvement, stress levels and overall quality of life due to improved interior design features such as lighting, thermal conditions, ergonomic features and air quality. Similarly, using water-saving plumbing equipment minimises water waste, eases shared water supply burden and permits water recycling and alternative water source use. SBMs improve urban biodiversity and protect the ecosystem (Pearlmutter et al., 2020). SBM designs and technologies reduce construction, demolition waste and carbon emissions. From an economic perspective, SBMs save 30 per cent on energy consumption, cost, energy and water efficiency (Elshoubaky et al., 2023). Improved thermal and visual comfort in sustainable buildings can enhance human productivity levels and reduce absenteeism (Elnaklah, Walker and Natarajan, 2021; Durdyev et al., 2022). Visual comfort in a building space is associated with illuminance distribution, which affects psychosocial wellbeing and productivity (Day et al., 2019; Tabadkani et al., 2021). SBMs reduce consumption and maximise resources utilised efficiency (Ogunmakinde, Egbelakin and Sher, 2022). SBM application in new construction can reduce buildings’ environmental impacts (Andersen, Ravn and Ryberg, 2022).

Adeniyi et al. (2021) explained that SBMs are recommended for low-cost building construction because they are cost-effective, readily available, adaptable, energy efficient, reduce waste and CO₂ emissions, enhance community economy, impact psychosocial wellbeing/health, promote culture and are harmless to the environment. SBMs are fast-growing renewable resources in foundations, flooring, roofing, wall cladding, windows, and door construction. SBMs are readily available with a low carbon footprint that has a positive health impact on the IDPs. We use SBMs such as recycled paper, glass, plastic, sandbags, bottles and metal to reduce waste land pollution and conserve natural resources. SBMs are durable materials and reduce environmental pollution. SBMs reflect the culture of the IDPs, making them happy, comfortable and homely.

This study is about SBMs for IDP facilities and their Impact on IDPs’ Health/Wellbeing. The users are displaced men, women and children. Therefore, the research design is a case study of three existing IDP Camps in Nigeria. The investigators sourced the data using questionnaires, an IDI) guide, Focused Group Discussions (FGD) and an observation schedule from three case studies. The investigators used an observation schedule to collect the health/wellbeing components of SBMs in the selected IDP camps. The respondents during interviews (IDI and FGD) were the camp manager, volunteer teacher, architect, Material/health experts and IDPs. The researchers analyse the impact of IDP camp SBMs on residents’ health/wellbeing using interviews and questionnaire data. According to George and Adelaja (2022), there are 3.2 million IDPs in Nigeria. However, the total population of IDPs covers three case studies in Nigeria, which is 180,492.

Sampling techniques for collecting data are limited to analysing the entire population (Taherdoost, 2016; Noor, Tajik and Golzar, 2022). The suitable sampling technique for this study is mixed (probability and non-probability) method sampling, is a multistage (stratified, purposive and random sampling methods). The stratified sampling method involves the states that have registered IDP camps in Nigeria-Lagos in the south-west zone, Abuja in the north-central zone and Borno in the northeast zone. A purposive sampling includes a male child, male adult, male teenager, male youth, widower, female child, female adult, female teenager, female youth, widow, orphans, pregnant women and elderly persons in the camps. Simple random sampling involves selecting IDPs as questionnaire respondents without bias (Roberton et al., 2017). Uakarn et al. (2021) stated that Yamane developed the formula to determine the sample size for an identified population.

The formula is n = N/1 + N (e)^2 (1)

Where N = population size, n = required sample size and

e = level of precision (0.05 for 5% of true value).

The total population of IDPs in Lagos, Abuja and Borno, Nigeria is 180,492. The study sample size for IDPs is determined using this formula:

n = 180,492/1 + 180,492 (0.05) ^2 (2)

Then n = 180,492/452.23,

Therefore n = 399.11.

The investigators gave about 399 IDP questionnaires to fill out.

The unit of data collection is IDPs, which are male (children, teenagers, youth, adults and widowers), female (children, teenagers, youth, adults and widows) orphans, pregnant women and elderly persons. Data collection instruments for this research are an IDI guide for architects, material/health experts, and IDP camp operators, questionnaires for the IDPs, and an observation guide to identify architectural features in the selected IDP camps. The investigators extracted data from field observations, a checklist, a survey questionnaire, and an IDI and FGD guide. The authors distributed three hundred and ninety-nine (399) questionnaires among the IDPs within the selected case studies, as presented in Table 1. Out of 399 questionnaires distributed, the researchers retrieved 335. The authors used a semi-structured questionnaire to analyse the impact of SBM on displaced persons’ health/wellbeing. The breakdown of the number of questionnaires administered and the responses are in Table 2. These questionnaires were deliberately to be completed by IDPs. To gather information on SBMs and their impacts on the IDPs’ health/wellbeing. To analyse the SBMs’ impact on IDPs’ health/wellbeing, the investigators conducted a survey using a semi-structured questionnaire. Four (4) research assistants (two co-authors and two M.Sc. students of Architecture) undertook the data gathering exercise for four months–morning and evening, during the weekend-Fridays - Sundays for 8 weeks (from March 3 to 5 May 2023).

According to Table 2, Igando Emergency Relief/Resettlement Camp (IERC), Lagos, had an 80% response rate; New Kuchingoro IDP Camp (NKC), Abuja, returned 86% of the questionnaires completed. African Mission Global IDP Camp (AMGC), Borno, had a 79% response rate. Therefore, sample collection details for analysis revealed 399 samples were collected, and 335 were submitted/received for analysis across the study area. However, the accepted level or success rate was 84%, inferring there was 16% rejection.

The investigators analysed the qualitative data derived through IDIs, FGDs and observation guides using content analysis and Max QDA (Qualitative Data Analysis). We presented the result using a descriptive approach using tables. They also analysed the quantitative data from survey questionnaires using IBM SPSS v26 and presented the findings using tables, graphs, and figures. The investigators transcribed the interviews and coded the direct quotes under the objectives themes-assessed the SBMs used to design IDP facilities in the three case studies, ascertained the health/wellbeing components of SBMs and analysed the impact of SBMs on IDPs’ health/wellbeing. The researchers stored the data in a data bank and repository for other researchers to access based on request.

SBMs are produced and used to minimise, maintain or improve the quality of life and built environment impact (Sahlol et al., 2021). These materials can protect the built environment by reducing the building’s carbon footprint. SBMs promote a cleaner Earth and a future of sustainability while being aesthetically appealing and efficient (Bungau et al., 2022). SBMs are from low environmental impact/renewable resources, are life-cycle durable, have a manufactured/used smaller footprint and have easy end-of-life break (Shayegan, Bahri and Haghighat, 2022). Some can be human-made materials designed to preserve natural resources and are made from renewable resources to meet supply and demand. We use SBMs in the sustainable construction and design of healthy camp environments for IDPs already facing all kinds of psychosocial stresses and depression. For this study, the investigators assessed SBMs used to design IDP facilities in the three case studies in Nigeria. Examples of SBMs used across the three geopolitical - South-West (Igando Emergency Relief/Resettlement Camp-IERC, Lagos), North-Central (New Kuchingoro IDP Camp-NKC, Abuja) and North-East (African Mission Global IDP Camp-AMGC, Borno) to design IDP facilities are in Table 4. The common SBMs used across the three case studies buildings are wood and corrugated zinc roofing sheets. However, from the literature, twenty (20) SBMs were identified for a sustainable future as follows:

1. Bamboo is an SBM that is a renewable, flexible and versatile type of grass with strength similar to wood (Xu et al., 2022). Bamboo application in construction projects includes supporting concrete, scaffolding, roofing and building other structures. 2. Recycled plastic is a renewable resource used as plastic sheets, bricks and lumber. 3. Laminated timber is prefabricated timber with a higher strength and water resistance, potentially replacing steel and concrete (Giordano, Derikvand and Fink, 2023). It has a lower carbon footprint than steel and concrete, supports beams and columns, and is used in roofing and flooring (Chai et al., 2022).

4. Stone is an SBM that occurs naturally on the earth with no factory production and low CO2 emissions, and it is for home furnishings, such as titles and countertops. Stone is durable, low maintenance, versatile and produces little waste when used in construction projects (Kerr et al., 2022). 5. Cob is a mud mixture made from natural materials such as soil, straw, sand and lime (Yemesegen and Memari, 2023). Cobs are for residential building construction or as a replacement for concrete structures. Cobs are inexpensive and produce less CO2 than concrete. 6. Cork is a renewable, recyclable resource and an eco-friendly replacement for traditional insulation. It is SBM for insulating homes and other buildings (Ata-Ali et al., 2021). 7. Adobe is a SBM from the earth and takes less energy to produce (Olacia et al., 2020). It is a clay and straw mixture to make bricks for homes and other structures. 8. Reclaimed wood is restored waste wood during a deconstruction project. Reclaimed wood is used to furnish and decorate new projects and deconstruct lumber from older structures while preserving its integrity and natural beauty (Asa et al., 2022). 9. Precast concrete is a factory with low CO₂ emissions. It is made in exact measurements and shipped to the construction site for bridges, foundations, parking garages, and sometimes entire buildings. 10. Mycelium is an organic and renewable resource with thin fibres from fungi that run underneath the ground as roots. When harvested and dried, mycelium becomes a durable, water, mould and fire-resistant building material that can combine with sawdust and demolition waste to create bricks for building structures (Al-Qahtani, Koç and Isaifan, 2023; Muiruri et al., 2023). 11. Sheep’s wool is a renewable, non-toxic, mould-resistant and natural resource harvested from animals to insulate buildings (Mann et al., 2023). 12. Pollution-absorbing brick is a double-layered brick with porous blocks that allow air through as it filters out pollutant particles. It neutralises CO₂ emissions. Pollution-absorbing bricks are SBM and an air-filtering alternative to earth bricks (Mogas-Soldevila, 2023). 13. 3D-printed concrete is a more sustainable and viable alternative to concrete. It involves using 3D printing for the production of sustainable concrete. 3D-printed concrete allows contractors to digitally design any shape and use concrete to print it (Jipa and Dillenburger, 2022). 14. Cordwood is an SBM that uses stacked short logs (firewood) with Cob or mortar in between to build a wall. The cordwood technique is used in homes and provides a rural finish to the structure. Cordwood offers natural insulation and saves energy and money (Švajlenka and Kozlovská, 2021). 15. Rubber tyres are recycled SBM with durability, flexibility and insulation properties. Sustainability-focused homes (Earthship homes) use recycled tyres filled with sandbags as insulation. Rubber masonry block production uses recycled tyres (Karimi et al., 2023). 16. Newspaper wood is recycled paper waste turned into wood via innovation and advanced technology for construction projects, such as furniture and home décor (Abd El-Sayed, El-Sakhawy and El-Sakhawy, 2020). 17. Plant-based polyurethane rigid foam is an improved eco-friendly insulator used in homes and commercial buildings. It uses a mixture of bamboo, hemp and kelp as wall insulation, furniture and surfboards (de Oliveira et al., 2022). 18. Straw Bales are a renewable resource used as insulation. It is a SBM used for construction in several centuries. Straw bales, when protected from moisture, can last for years as insulation (Koh and Kraniotis, 2020). 19. Recycled glass is SBM used as a mixture in construction projects to imitate natural aggregates such as sand, gravel and crushed stone. It is also used by cement makers in their mixture (Nedeljković et al., 2021). 20. Recycled steel is a renewable SBM that has an unlimited life cycle and can retain its quality and durability. When used as a building framework and structural support, less energy consumption and reduced the project’s carbon footprint (Kim and Kim, 2020).

In Table 5, wood containing microfibril and corrugated zinc sheets containing zinc are the commonly used SBMs with health/wellbeing components used across all three selected IDP facilities. Wood regulates and boosts respiratory sensitivities to improve IDP’s sense of wellbeing and enhance recovery. Zinc’s anti-inflammatory properties can relieve health conditions such as acne, rosacea, etc., to improve the health/wellbeing of the IDPs. In FGDs with some IDPs, the findings suggest that, in most cases, the built environment of camp facilities has a significant effect on the health/wellbeing of surveyed IDPs. Eighty-three per cent of them reported that their health/wellbeing is not the same now as before their displacement. They said,

When asked the reason for their improved health/wellbeing. They traced it to the IDP camp environment’s enhanced indoor and outdoor air quality.

SBMs address environmental challenges and promote a more sustainable future for the construction industry. As the global population grows and urbanisation expands, the demand for buildings and infrastructure rises exponentially. However, this rise in construction has a significant effect on the environment - resource depletion, pollution and greenhouse gas emissions. In this context, SBMs offer a solution by reducing the environmental impact on human health/wellbeing while improving building efficiency, durability and healthiness. Therefore, objective three (3) analyses SBM impact, focusing on IDPs’ health/wellbeing benefits across the three selected case studies using semi-structured survey questionnaires distributed in Table 4 and ID1. SBMs impact IDPs’ health/wellbeing in several aspects, such as environmental protection, comfort, improved health, better quality of life, waste minimisation, Noise avoidance and longevity.

The study provides rich insights into SBM and its impact on IDPs’ health/wellbeing in IDP facilities in Nigeria and can explore many new perspectives on IDPs. However, the study has limitations. Firstly, the findings derived from IDIs and FGDs may not be representative of the entire IDP population in Nigeria. Purposive sampling was used in the study, which could introduce selection bias and limit the generalisability of the results. Second, expert experiences due to restrictions could affect the research findings. It can lead to underreporting of SBM and its impact on their health/wellbeing or a skewed representation of their experiences. Third, participants may have difficulty responding well, particularly considering traumatic experiences or if the interviews are conducted immediately after the displacement. It can affect the reliability and validity of the data collected. Finally, the study provides rich insights. However, It can be challenging to quantify and measure the prevalence and magnitude of factors contributing to occupants’ wellbeing in IDP facilities. Therefore, to mitigate these limitations, there is a need for more comprehensive mixed-method research to understand SBMs and their Impact on IDPs’ Health/Wellbeing in IDP Facilities in Nigeria.