Sustainability Trends in Humanitarian Architecture Research: A Bibliometric Analysis

Abstract

Despite the increasing need for Post-Disaster and Post-Conflict (PDPC) sheltering, and the rising number of humanitarian architects, there is a vague understanding of how “sustainable” shelters in PDPC situations are being addressed in the literature. Therefore, this paper aims at mapping and analyzing the current status and development trends in research that associates sustainability and shelters in PDPC situations during the past four decades (1982–2022) using a bibliometric analysis. This was fulfilled using VOSviewer to identify and visualize literature development trends, active journals, productive authors, contributing countries, influential institutions, and keyword networks. The findings identified four phases of the development process: no recognition (1982–2002), initiation (2003–2012), rapid growth (2013–2017), and accelerated growth (2018–2022). In terms of publications, the “International Journal of Disaster Risk Reduction” and “Sustainability” are the key journals publishing in the field, whereas Gibson and Habert are the most publishing authors. The United States of America was found to be the leading country in the research field, albeit Université de Montréal in Canada was the most active in terms of institutions. The study suggests the promotion of social and economic standards in addition to the environmental while developing sustainable shelter solutions. It also advises shelter professionals from both public and private sectors to improve their collaborations with all related stakeholders.

1. Introduction

The presence of many influential books and scholarly works examining the sustainability concept led to its inclusion in various contexts. In architecture and the built environment context, the drivers of sustainability have been embodied within its system from ancient times. Generally, most ancient civilizations employed local materials and construction methods that were representative of their culture and traditions [1].

Up until the 20th century, the importance of environmental considerations in architecture had steadily diminished, owing to the industrial revolution and what accompanied it with new heating and cooling technologies in building construction [2]. In the 1990s, industrial sectors, including the construction industry, began to acknowledge the environmental effects of their actions. Haapio and Viitaniemi [3] stated that the necessity for a sustainability assessment in the built environment sector has prompted the development of techniques and technologies for over a decade, specifically in institutional, commercial, and residential buildings. However, little is known about sustainable considerations in the field of humanitarian architecture.

Indeed, both sustainability and safety are considered the footing criteria for shelter design. However, in post-disaster and post-conflict (PDPC) situations, priority is given to providing acceptable levels of safety, security, protection, and community health in the initial stages of disasters and conflicts [4], leading to overriding the aspects of sustainability when designing PDPC shelters. Additionally, the considerable number of the affected population and the crisis intensity provided a degree of leniency in considering the environment while designing PDPC shelters [5]. Despite shelter-providing agencies and scholars’ efforts to provide durable shelter solutions, they rarely consider social and cultural factors, thermal, auditory, and visual performance [6]. Consequently, the lack of sustainable considerations would cause natural disasters in the long term [7].

A relatively small body of academic literature investigates sustainability in PDPC architectural systems. However, various review papers on PDPC have been published to synthesize the existing knowledge by highlighting sustainability issues in the research field. For example, Albadra et al. [8] reviewed the literature on post-disaster relief shelters to describe the academic activity and highlight the academic trends in the past forty years. They indicated that only nine out of sixty academic publications on emergency and temporary shelter designs discussed sustainability and life cycle analysis. However, in the former study, the lack of a defined review process and inclusion and exclusion standards for the included records prevented it from being definitive. Similarly, Bashawri et al. [9], who reviewed disaster relief (DR) shelters, showed that guidelines for DR Shelters do not sufficiently address several design aspects to make them more sustainable and inclusive in various locations and settings. This went along with what Alshawawreh et al. [5] argued about, which was the need for more attention in the humanitarian sector to cope with the latest sustainable methods that are used in other reference systems.

The inconsistency of studies that tackle sustainability issues in PDPC sheltering situations refers mainly to the normative nature of the concept. This inconsistency is employed in sustainable shelter literature, which, in turn, formed the essence of this study through three main aspects, as explained below and analyzed in Figure 1.

Firstly, most of the studies that examined the sustainability in the built environment utilized its three pillars for assessment: environmental, economic, and social [10,11,12,13]. In the context of PDPC reconstruction, for instance, Escamilla et al. [14] introduced a life cycle cost and life cycle cost assessment for 20 identified transitional shelters to develop a strategy for post-disaster reconstruction in terms of choosing global and local materials. Similarly, Alshawawreh et al. [5] compared “existing solutions” and “novel designs” for PDPC through sustainability assessment using its three pillars. However, the former study assessed sustainability using three categories, environmental impact, cost assessment, and technical performance, whereas the latter assessed them using environmental, economic, and social parameters. According to Mateus and Bragança [15], despite the importance of the environmental impact of a building, it can only be deemed sustainable after considering its economic, social, and cultural aspects.

Secondly, within the scope of sustainable solutions and approaches, the Shelter Cluster introduced the “A shelter is more than a roof” approach using seven key sustainability solutions: housing and land property, site and settlement planning, owner-driven methods and community participation, local building structure, building back safer, protection mainstreaming, and gender [16]. These solutions clarify that the correlation between sustainability and shelters is not only associated with the building structure, which is environmentally friendly, socially appropriate, and economically affordable but also associated with the right to adequate housing, the core aim of shelter existence. UNHCR and UN-Habitat [17] (p. 8) stated: “The right to adequate housing does not just mean that the structure of the house itself must be adequate. There must also be sustainable and non-discriminatory access to facilities essential for health, security, comfort, and nutrition”. Indirectly, the report also signified the importance of considering the accessibility for disabled people and ensuring a “gendered-sensitive” dimension regarding shelter construction as additional drivers for proposing sustainable shelter solutions. However, in both documents, the humanitarian–social dimension was highlighted, which is considered one of the main pillars of sustainability.

Thirdly, and within a similar discourse, a significant sustainability tool for post-disaster reconstruction called Quantifying Sustainability in the Aftermath of Natural Disasters (QSAND) has been developed by Building Research Establishment (B.R.E. Global) on behalf of the International Federation of Red Cross and Red Crescent Societies (IFRC) [18]. QSAND is considered a self-assessment tool to inform sustainable relief, recovery, and reconstruction approaches. The tool comprises eight categories for assessing sustainability in the built environment: shelter and community, settlement, material and waste, energy, water and sanitation, cross-cutting issues of resilience, livelihood, and participation, and the natural environment [19]. Using resilience to reflect upon sustainability aspects is also demonstrated in Zapata and Muñoz’s [10] work on sustainability meanings. Their work provided a set of four meanings to sustainability; (1) sustainability as a set of social–environmental criteria guiding human actions, (2) sustainability as environmental, social, and economic purposes, goals, or values, (3) sustainability as an object that certain human actions intend to reach, such as a behavior of a particular system, resilience, or adaptive capacity, and (4) sustainability as an approach to studying the social, economic, and environmental variables that are imposed in a system.

The aforementioned literature shows that although there are several approaches to assessing the sustainability of shelters in PDPC situations, these approaches are not unified. They differ in terms of aspects they employ to assess sustainability, the inclusion of some of these aspects in research while neglecting others, and/or not presenting these aspects from a sustainability perspective. These differences are probably the main reason behind the lack of literature on the topic. Therefore, this paper will characterize different aspects of sustainability utilized in PDPC-sheltering situations: (1) studies that make a sustainability assessment in PDPC shelters, such as [5,14]; (2) studies that examine sustainable access to livelihood and services for PDPC communities, such as [20,21]; and (3) studies that address cross-cutting issues embodied within sustainability concepts such as the resilience and adaptive capacity of the shelter, such as [10].

Based on the above, the authors developed a research map that adopted certain aspects related to examining sustainability in PDPC sheltering, as shown in Figure 1. It is worth mentioning that the 1st and 3rd set of aspects were adopted from Zapata and Muñoz’s [10] 4th and 3rd meanings of sustainability, as they were the most relevant to assessing sustainability in architectural systems, whereas the 2nd set of aspects were adopted from QSAND’s [19] sustainability assessment tool and the UNHCR and UN-Habitat’s [17] report. This paper aims at providing an overview of the literature on sustainability in PDPC sheltering situations in the past four decades using bibliometric analysis, which provides resources for evaluating the results of several publications [22]. To fulfil this aim, specific objectives are presented: (1) track the temporal development of PDPC shelters and sustainability research, (2) highlight hotspot topics of PDPC shelters and sustainability aspects in the current situations, and (3) navigate how sustainability is being addressed in PDPC contexts. The results of this paper will direct interested scholars to essential resources, journals, and publications that can act as points of reference for a deeper comprehension of the research field. It will also guide representatives of existing approaches and tools for better sustainable shelter responses in PDPC situations.

While the first section introduced the topic and the knowledge gap, the rest of this paper is organized in four other sections. Section 2 covers the materials and methods, including the data sources, analysis software, the search criteria, the documents’ selection, and the data analysis tools. Section 3 identifies the results of the analysis, whereas the interpretation of the results is presented in the discussion section (Section 4). Finally, Section 5 presents the conclusion and implications of the study.

2. Materials and Methods

A bibliometric analysis of the literature is used in this study to provide a microscopic overview of the fundamental sustainable PDPC shelter publication features and a comprehensive representation of the research process in the field of shelter analysis. Van Eck and Waltman from Leiden University in the Netherlands created a software program called VOSviewer (v1.6.18) to construct and display econometric networks. This software can create networks for journals, researchers, keywords, and publications while displaying the outcomes using knowledge maps based on co-citation, coupling, and co-authoring links [23]. The use of bibliometric maps, which enables the detailed examination of cognitive structure and its evolution through time in a particular academic topic, is a crucial component of these investigations [24].

In the current research, a process was designed to choose the search keywords, choose the proper database, set the search criteria, choose the analysis software, and analyse the findings. The steps are shown in Figure 2 below and explained further in the following subsections.

2.1. Selection of Database

An online database was used to address the final records to secure the reliability and accuracy of the data source. The study used Scopus database for document selection due to two main reasons: firstly, as the study aims to track the temporal evolution of the research field, Scopus has a broad and diverse coverage of different research fields (over 87+ million records from 1877 onwards) [25]. Secondly, Scopus offers an easy downloading process [26] and diverse search filtration options.

2.2. Identification of Search Keywords

As described in the introduction, the multidisciplinary nature of the sustainability concept led to the use of similar alternative terms that addressed sustainability aspects in PDPC sheltering situations without using the term itself, such as durable, resilient, etc. Therefore, it was crucial to expand the scope of the search to include a larger number of keywords and terms that signify the sustainability concept without contradicting its meaning. The study used the previously explained terminologies in Figure 1, which demonstrated sustainability aspects that exist in PDPC shelter situations.

Additionally, due to the proliferation and the inconsistency in using the term “shelter” in PDPC sheltering situations, the study adopted the IFRC five sheltering definitions emergency shelters, temporary shelters, transitional shelters, progressive shelters, and core shelters, as they consist of organized and more frequently used terminologies [27].

2.3. Search and Selection of Documents Criteria

The selection of records was based on specific criteria. Firstly, the study aims at tracking the development of PDPC shelter research in the past four decades, i.e., 1982–2022; therefore, a total of 365 records were found. This result was based on various research sources to diversify the search options and to conduct an inclusive analysis, such as journal articles, book chapters, and conference records. Secondly, the records selection included only English-written studies to facilitate the authors’ accessibility to all records. Lastly, the search was carried out on document titles, abstracts, and keywords by using a matrix of terminologies between the IFRC shelter types (“emergency shelter”, “temporary shelter”, “transitional shelter”, “progressive shelter”, “core shelter”) and the previously mentioned sustainability aspects, using Boolean logical operators. See details in

Table 1. The used Boolean expression in documenting selection.

	Boolean Logical Expression
1	sustainability OR sustainable	AND	“emergency shelter” OR “temporary shelter” OR “transitional shelter” OR “progressive shelter” OR “core shelter”	AND PUBYEAR > 1981	AND (LIMIT-TO (LANGUAGE, “English”	101
2	access AND (health OR security OR comfort OR nutrition OR energy)					79
3	“sustainability” AND (“assessment” OR “indicator *”					13
4	resilien * OR Adapt * OR mainten *					172
	Total					365

. Please note that the (*) is used to include all word derivations in the search, i.e., access* includes accessibility and accessible.

2.4. Selection of Data Extraction Software

It is now feasible to use software programs to assess vast quantities of scholarly data and execute data expression through the results of data visualization, given the rapid growth of data mining, information analysis, and graphics rendering technology. Bibliometric is a quantitative manuscript examination utilizing statistical research methodologies and mathematics [28].

Two sets of software were employed to facilitate the organization and the analysis of the collected data. Firstly, Microsoft Excel 365 was used to manage data tables and generate figures pertaining to publication trends, citation trends, top authors, most-cited papers, top countries, top institutions, and the research disciplines involved in sustainable sheltering context research. Secondly, VOSviwer software (v1.6.18) was used to perform co-citation, co-country, and co-word analysis and extract authorship, citation, and keyword data [29].

2.5. Data Analysis

Performance analysis and Science mapping are frequently used to assess the quality of research and show the field’s development, composition, intellectual structure, and activity [30]. For the aim of this research, the performance analysis focuses on the key elements of scientific publications, taking into account activity indicators such as the year of publication, number of documents, academic journals, countries, authors, and universities, as well as other indicators of impact on scientific productivity such as the impact factor of the academic journal [31]. At the same time, science mapping created bibliometric maps to examine the field’s intellectual structure. Hereby, we looked at the co-occurrences of keywords, countries, and authors [32].

3. Results

3.1. Literature Development Trend

As seen in Figure 3, the yearly number of publications related to the research field of sustainability in PDPC context had changed over time. Overall, it can be noted that the development trend in the PDPC sustainable shelter research area can be divided into four main temporal phases. Period I, 1982–2002, where the number of publications was considerably low, meaning that no attention was given to sustainable shelters, whether in disaster or conflict situations. However, the rapid change in period II, 2003–2012, indicates inconsistency of attention given to this area of research, but signifies an increase in attention towards the topic. While period III, 2013–2017, indicates an increased focus on related research and scholarly work that examines relevant topics, the last period, IV, shows a rapid increase between 2018 and 2022, except for 2019. The year with the highest number of publications was 2022, with 54 related publications.

3.2. Keywords Hotness Analysis

3.2.1. Co-Occurrences of Keyword Networks

In order to provide a general understanding of research areas associated with sustainability and PDPC shelters, a keyword analysis was conducted. As shown in Figure 4, there are four main keyword clusters representing different areas of research relevant to sustainability and PDPC, which are cluster 1 (red), cluster 2 (green), cluster 3 (blue), and cluster 4 (yellow).

The first cluster is the largest cluster. This analysis shows that this cluster concentrates on disasters, sustainable development, and housing, including terms such as “disaster management”, “shelter (civil defense)”, “risk assessment”, and “disaster prevention”. It is important to note that the distance between the terms indicates how closely they are linked to each other. Despite having “housing” and “disaster” as keywords with high occurrences in cluster 1, the cluster shows that “sustainable development” is also a dominant node but with stronger links to “architecture”, “structural design”, and “construction”.

The second cluster (green) is focused on two major areas: health and demographic information, such as age and gender. Major nodes dominating the cluster refer to mental health and post-traumatic situations. Related terms in this cluster express social aspects that constitute the sustainability social pillar. The third cluster (blue) represents issues related to disasters and health while having “emergency shelter” as a dominating node. What distinguishes the health-related terms in this cluster compared to the previous one is that they are linked to emergencies and disastrous situations. Proximity and strong linkages between these terms and the term “United States” show that special attention has been paid to health care within natural disaster situations in the United States of America [2]. The final cluster (yellow) has no distinct focus, except for the keyword “floods”, which is relatively associated with the term “risk management”. The top-25 highly occurred terms are presented in Table S1 in the supplementary data.

3.2.2. Evolution of sustainability and PDPC shelter topic

Figure 5 provides an evolution overview of the research terminologies during the years that showed more attention to the related research (the third and fourth phases); 2013–2022. The color of the term highlights the year of publication for the research that has the term. As noticed, it is easy to grasp the keywords that are relatable to the research field, such as “emergency shelter” and “disasters”, which are linked to repetitive sustainability keywords such as “sustainable development”, “energy utilization”, and “costs”. These links are demonstrated in the blue color shades, indicating that such an association started to gain prominence after 2013.

Additionally, the keyword analysis aimed at providing a detailed understanding of how sustainability and PDPC shelter correlations evolved. Accordingly, the forty interval between 1982–2022 was divided into four periods, as mentioned earlier: period I (1982–2002), period II (2003–2012), period III (2013–2017), and period IV (2018–2022). Figure 6 shows a density map of topic evolution in the sustainability research field in PDPC sheltering.

In period I (1982–2002), Figure 6a shows that most of the relatable research publications tackle issues concerning health, community development, demography, and terms related to structure capacity. However, it shows limited keywords, with four fragmented and two connected clusters. The same figure also illustrates that the relatable keywords such as “hazards management” and “community resilience“ are connected terms that illustrate the social and the economic aspects of sustainability, such as “social environment” and “socioeconomic factors”.

In period II (2003–2012), Figure 6b shows a beginning of connection among relatable keywords but with relatively weak linkages. The term “emergency shelter” is linked to “reconstruction”, “sustainable development”, and “housing”. Period III (2013–2017) in Figure 6c shows a more complex cluster mapping. The terms “emergency shelter”, “disasters”, and “sustainable development” appear to be dominant terms, whereas most other terms are linked to them. Terms that demonstrate environmental sustainability exist in large numbers, such as “energy efficiency” and “solar energy”. Additionally, other terms such as “social support” and “health” exist but with weak linkages to “emergency shelter”. In period IV (2019–2022), Figure 6d witnesses the most diverse keywords that link shelter design, disaster management, and health. See Table S2 in the Supplementary Data for the top 20 keywords in each period, depending on their number of occurrences.

3.3. Source Distribution of Publications

In order to understand where the research on PDPC sustainable sheltering is being published, an analysis of publication resources was established. This analysis will inform scholars and help them in their future journal choices by knowing the most relatable journals to their work with relevant literature. A total of 239 sources resulted in the period between 1982 and 2022.

Table 2. Top 10 active journals in terms of publications related to sustainability in PDPC sheltering.

Source	Documents	Citations *	Impact factor in 2021
International Journal of Disaster Risk Reduction	16	163	4.842
Sustainability (Switzerland)	11	93	3.889
Disasters	9	312	3.311
International Journal of Environmental Research and Public Health	7	75	4.614
Disaster Medicine and Public Health Preparedness	5	32	2.75
IOP conference series: Materials Science And Engineering	5	9	------
Lecture notes in civil engineering	5	2	0.133
PLOS One	5	83	3.752
Safety Science	5	81	6.50
International Journal of Disaster Resilience in the Built Environment	4	14	1.32

* Numbers of citations were updated in February 2023.

shows the top 10 most productive sources in this research field, including journals and conference proceedings. It can be seen that “International Journal of Disaster Risk Reduction” is considered the most productive journal in this field, followed by “Sustainability”, “Disasters”, and then the “International Journal of Environmental Research and Public Health Journal”. Indeed, the impact factor of a journal indicates the journal influence capacity. Although, the highest impact factor is referred to the “Safety Science” journal, as it ranked 9th in the number of produced documents.

3.4. Country and Research Institute Analysis

VOSviewer produces collaboration networks based on analyzing co-author affiliations in the existing publications to indicate the influences and cooperation degrees of the countries and their research institutions. From 1982 to 2022, there were about 68 countries involved in the research of sustainability and PDPC shelters, where only 22 of them contributed to a minimum of five publications. Figure 7 shows that the USA has overtaken other countries as the primary source of related research, followed by the United Kingdom and Japan. However, USA, Australia, India, and Germany account for the highest linkage strengths of 1075, 885, 695, and 635, respectively. It is important to mention that the total linkage strength refers to the strength of a country’s bibliographic coupling links with other countries based on the VOSviewer linkage system.

Based on the bibliographic coupling, Figure 8 illustrates the number of documents, citations, and total link strengths of the publications in the top 10 institutions. From 1982 to 2022, about 730 institutions carried out research on sustainability in PDPC shelters. In terms of the number of published documents, out of the top 10 institutions, Université de Montréal in Canada has the largest number of related produced documents, which is four. The remaining nine institutions have the same number of publications, which is three. Despite the almost equal number of published documents across all 10 institutions, the number of citations and the total link strengths distinguished the organizations’ performance in the researched field. Generally, and surprisingly, the top 10 organizations are mostly located in China, Europe, and the Middle East, whereas none of them are located in the USA. It can be also noted that most of these institutions are either research centers or universities, and most of them are concerned with health or building structures and construction.

3.5. Top Cited Articles and Most Productive Authors

Table 3. The 10 most cited documents.

	Title	Authors	Citations *	Source
1	Community Resilience and Volcano Hazard: The Eruption of Tungurahua and Evacuation of the Faldas in Ecuador	Graham A. Tobin, Linda M. Whiteford [33]	153	Disasters
2	Health Effects of Coastal Storms and Flooding in Urban Areas: A Review and Vulnerability Assessment	Kathryn Lane, Kizzy Charles-Guzman [34]	124	Journal of Environmental and Public Health
3	Factors impacting on psychological distress and recovery after the 2004 Niigata–Chuetsu earthquake, Japan: Community-based study	Hideki Kuwabara md, Toshiki Shioiri [35]	80	PCN
4	What are the determinants of post-traumatic stress disorder: age, gender, ethnicity or other? Evidence from 2008 Wenchuan earthquake	P.KunaX, TongbY, Liua [36]	79	Public health
5	Introduction and Executive SummaryCare of the Critically Ill and Injured During Pandemics and Disasters: CHEST Consensus Statement	Michael D. Christian, Asha V. Devereaux [37]	67	CHEST
6	Queer Domicide: LGBT Displacement and Home Loss in Natural Disaster Impact, Response, and Recovery	Andrew Gorman-Murray, Scott McKinnon, Dale Dominey-Howes [38]	63	Home Cultures
7	Katrina Cataclysm: Does Duration of Residency and Prior Experience Affect Impacts, Evacuation, and Adaptation Behavior Among Survivors?	Francis O. Adeola [39]	60	Environment and Behavior
8	Post-Disaster Reconstruction of the Built Environment: Rebuilding for Resilience	Dilanthi Amaratunga, Richard Haigh [40]	54	-----
9	Reuse and recycle potentials of the temporary houses after occupancy: Example of Duzce, Turkey	Hakan Arslan, Nilay Cosgun [41]	53	Energy and Buildings
10	Planning Emergency Shelters for Urban Disaster Resilience: An Integrated Location-Allocation Modeling Approach	Laijun Zhao, Huiyong Li [42]	46	Sustainability (Switzerland)

* Numbers of citations were updated on February 2023.

illustrates the 10 most cited articles among the 365 documents that were analysed. Up until February 2023, the most cited article is the “Community Resilience and Volcano Hazard: The Eruption of Tungurahua and Evacuation of the Faldas in Ecuador” with 153 citations.

Out of the 365 publications that were reviewed, 1092 authors were introduced. The threshold was set to be a minimum number of four documents per author, where 12 authors met the threshold. Figure 9 shows the relation between the top 12 authors with the number of publications and number of citations. In terms of number of published documents, George Gibson is considered the most productive author in the field, with five publications. In contrast, the remaining 11 authors published the same number of publications, which was four. The figure also provided a second indication, which is the number of citations. Guillaume Habert, Edwin Zea Escamilla, and Hua Li are the most cited authors, with 74, 74, and 68 citations, respectively.

The analysis also includes a co-citation analysis. Figure 10 shows four major clusters that can be distinguished according to the authors’ expertise. The cluster in red (1) consists of authors that have mainly worked on environmental and disaster resilience, sustainable architecture, environmental engineering, and energy use in buildings (e.g., Cassidy Johnson, Davied Félix, Tom Corsellis). The blue cluster (2) is the second to dominate the area of influence; most authors’ expertise is in emergency management and preparedness, disaster vulnerability, and urban risk. This cluster is represented by Bijan Khazai, Michael K. Lindell, and Susan L. Cutter. The green cluster (3) consists of authors mainly working on ecological and environmental engineering (e.g., X Chen, and Wei Xu). The yellow cluster (4) has the minimum contribution to diverse expertise; however, the nodes demonstrating the clusters focus on epidemiology, resilience, and community/social issues. This cluster is represented by authors such as Ann S. Masten and Sandro Galea.

4. Discussions

4.1. Temporal Trends

The four periods that mark the development trends in researching the sustainability in PDPC sheltering clarify the increase interest in the topic from 2010 onwards. According to the Timeline of Environmental-Architectural Design Concept, the rapid increase in publications during the previously mentioned period could have been attributed to the increase focus on resilience response and recovery to disaster approaches, which occurred at that time [43].

The temporal evolution of sustainability topics was accompanied by a clear development in themes and topics related to sustainability in PDPC situations. Even though phase I (1982–2002) was limited to a few key themes, it is considered the cornerstone of the field’s knowledge. Having “healthcare” and “diseases” as the central themes in the research field is expected, given the increased number of studies focusing on “healthy housing” over the last two decades [44]. In this context, accessibility to healthcare facilities provided the foundation for sustainable shelters in PDPC situations.

As a case in point, the direct health impact on displaced people living in shelters, such as ventilation, lighting, and thermal comfort, is considered the motor for assessing the environmental aspects of sustainability in PDPC shelters. This is evidenced by the 1971 booklet that was published by the World Health Organization [45], which presented a list of minimum numeric standards for shelters and camps [45]. This booklet included the 3.5 m² standard for covered shelter space per person that was adopted later by the Sphere handbooks [4,46]. This standard, along with other standards in the booklet, are justified from public health perspective, as the spatial needs of the shelter are being measured in terms of needed air ventilation, neglecting other concerns such as privacy, climate control, or storage of belongings [47].

Additionally, the results showed a strong relation between shelter and health in research, which could be justified as these research publications had reported the shelter conditions and their impact on human health. On the other hand, the analysis showed that persistent attention had been given to the environmental consideration of the shelter following 2013, which, in turn, could lead to a better understanding of the shelters’ impact on human health.

In Phase II (2003–2012), “sustainable development” and “disaster planning management” were the dominating nodes. This was mainly due to the efforts in the 1980s and early 1990s to develop the concept of sustainable development [48]. Additionally, more publications on disaster management were produced after 2003, specifically around mitigation and preparedness in the pre-crisis stages [49]. Mitigations and preparedness include a set of response mechanisms and strategies associated with evacuation, site planning, and the preparations for emergency reception centers and shelters, which are considered a sustainable shelter solution [19,49].

As mentioned earlier, phase III (2013–2017) contained more complex keyword networks and clusters. The clusters give prominence to “disaster management”, “healthcare”, and “sustainable development”, which appeared as core themes in previous periods; these topics continued to develop in the PDPC context. However, “emergency shelter” is considered as the most dominant theme to which all other themes are linked, except for “sustainability”, which does not have strong links with the “emergency shelter” and is far away in terms of distance. This indicates that the connection between sustainability as a term (but not necessarily as a tenor) and emergency shelter, is still underrepresented in the publications of the research field. This is evidenced by the inclusion of new keywords, such as, Environmental Impact Assessment (EIA) and Life Cycle Assessment (LCA), which are considered the main sustainability assessment tools. These tools establish cause-and-effect correlations between the environment and human activity, meaning that the theme accounts for the environmental aspect and ignores the social and economic cause-and-effect relations [40,50].

Lastly, in phase IV (2018–2022), the number of annual published articles had increased remarkably, as shown in Figure 3. A similar emphasis on the dominating nodes was found in comparison to other phases; however, an in-depth analysis was observed in the research field. The “sustainability” and “sustainable development” terms in this phase have stronger links to the scope of shelter design.

4.2. Gaps

The citation analysis shows that the number of citations per author is not the only parameter determining the influence of an element in the analysis. This goes back to the co-citation analysis implemented in this study, which provides an overview of significant elements compared to other elements within the same category (i.e., co-cited authors or co-cited sources). It is essential to clarify that “co-citation is a link between two items that are both cited by the same document” [51] (p. 25). For example, although Guillaume Habert, Edwin Zea Escamilla, and Hua Li are the top cited authors in the research field, the red cluster in the co-citation map illustrated in Figure 10 shows that Cassidy Johnson is identified as the most active author, with 178 links.

Additionally, the co-citation analysis shows that the major existing research mainly focuses on issues related to disaster mitigation, architecture, disaster resilience, environmental equality and inequality, and emergency management. The results indicate that attention to sustainable sheltering has been given to the environmental dimensions of sustainability in sheltering construction, neglecting the social and economic aspects. These findings are consistent with [52], which reported that environmental dimension is one of the core areas of sustainability/sustainable development. It is worth noting that topics relevant to participatory design and environmental equality (relevant to the social aspect of sustainability) took place in the VOSviewer analysis but were not fully represented and had no influence in the research field. This may go back to the fact that these documents were only produced in the last couple of years and have not had their full impact yet in terms of number of citations.

The results also show that USA, China, United Kingdom, Japan, and European countries, such as Italy, are amongst the most productive countries in terms of published documents in the research field. However, when we look at an institutional level, the 10 most productive organizations that are taking the lead in the research field are located in China, Europe, and the Middle East, whereas none of them are located in the USA. Despite the intensity of produced related research in the developed countries, some of the developing countries in the Middle East, such as Egypt and Iraq, also contributed to the research field. Such results indicate that Middle Eastern countries became active in the field due to the refugee influx and displacement movement that happened following the Arab Spring and Syrian conflict [53]. Additionally, although the Central African Republic, Sudan, and Eastern Asia include geographic areas with high displacement rates due to disasters and conflicts [54], none of them appeared in the VOSviewer analysis. Therefore, more scholarly work in the research field should be produced in these countries to inform more realistic, culturally rooted, and appropriate design and planning measures.

Moreover, the results showed that most of the top cited documents are being published in the Disasters journal, despite having International Journal of Disaster Risk Reduction as the most productive journal in the field. It is important to note that the journal impact factor is not being addressed during the analysis, meaning that authors who publish in less influential journals are being addressed equally with authors who publish in journals with higher impact factors. Moreover, it can be noted that the theme dominating the most active journals in the research field is around disaster-related topics; this result indicates that the scope of the research field is limited to the type of topics that the journals produce while ignoring the multidisciplinary nature of sustainability in general.

Additionally, most of the sources in the research field were distributed between journal articles and conference articles. According to Montesi and Owen [55], while conference papers can propose more ideas, journal papers are more influential in knowledge building. Therefore, scholars should approach more journals to establish a robust knowledge bases within sustainability in PDPC shelter related aspects.

5. Conclusions

Previous efforts in reviewing the literature on sustainability in PDPC shelters exist, such as [8,44], but they focus more on shelter design and health issues. The main goals of this study were to present an overview of the research on sustainable shelters in a PDPC context, identify significant sources and authors, clarify the major focus areas, and examine how the field has changed over time. VOSviewer software (v1.6.18) was used to quantitatively analyze and visualize the knowledge map of sustainable sheltering in PDPC situations. A total of 365 publications on sustainability that were published between 1982–2022 were analyzed, including journal articles, conference papers, books, and book chapters.

Four essential phases of development in the research field were found: no recognition (1982–2002), initiation (2003–2012), rapid growth (2013–2017), and accelerated growth (2018–2022). The number of research papers related to sustainability in PDPC shelters had increased steadily after 2010. According to the analysis, the following trends are at the cutting edge of this field of study:

• USA, China, United Kingdom, and Japan dominate the publication production in the researched area as countries;
• The analysis did not find a specific organization that stands out in the field of sustainable PDPC shelters research, but it was found that most of the involved organizations operate in the fields of architecture and civil and environmental engineering;
• Co-authorship Analysis identified 1092 authors who contributed to the literature in the field, of whom 12 had provided at least four papers;
• According to the keyword analysis, most research outputs which were conducted prior to 2012 had concentrated on disaster preparedness, healthcare, and environmental design and management. Studies in recent years begin to address sustainable design and eco-design aspects, but with a higher association with shelter design and planning;
• Generally, the link between the engaged institutions in research is relatively weak. It can be noted that most active institutions were universities and research centers and, therefore, lacked the extensive collaboration with stakeholders, non-governmental organizations, and governmental entities that generate shelter responses.

This research highlighted that sustainability in PDPC shelter studies are neither unified nor diverse. The results from the keyword analysis across all four phases showed that more attention in the scope of shelter sustainability had been given to the connection between shelter and health. Additionally, the analysis of active institutions in the field showed a relation with the health sector.

Therefore, further research should focus on presenting the direct connection between health and shelter from a sustainability perspective using its standards, guidelines, and principles. Additionally, the focus on the environmental aspects was at the expense of socio-economic dimensions; therefore, future studies shall emphasize socio-economic aspects and not to ignore the multi-dimensional notion of sustainability in sheltering design. This way, we can boost the diversification of the research hotspots, provide clear research objectives, and as a result, we will have ground-breaking research findings.

The significance of this research lies in improving the clarity and coherence across various shelter bodies. The results of the bibliometric analysis can be used as a point of reference for the researchers who are interested in exploring diverse knowledge pathways in regard to sustainable sheltering in PDPC situations. The results of the collaboration network analysis showed the need to improve the collaboration between stakeholders, academics, and governmental organizations, as it may foster advanced approaches to sustainability and make the research findings realistic and applicable. For shelter professionals, this paper highlights the gaps in the research field and, therefore, could direct the contributions of architects and planners while developing sustainable shelter agendas.

Finally, several limitations should be addressed in this study. Firstly, the study only included studies published in the Scopus database. Literature that exists in the other databases, such as Web of Science or gray literature, could be combined to conduct a more inclusive analysis and highlight other contributions to the evolution of the research field. Secondly, some publications were related to the research field but did not appear in the search due to the lack of unified shelter terminologies in the field of PDPC situations and, therefore, were not included in the analysis.