With increasing urbanization, population growth, and rising living standards, sustainability—regarding energy use, buildings, and the environment—is becoming more widely discussed [1]. In an era of tremendous changes in the scale of society and technology, sustainability can help restore important local resources as well as preserve traditional identities [2]. Furthermore, the main purpose of sustainability is to harness the environmental potential to provide comfort to residents ^[3][4][3,4]. However, environmental issues are not specific to individual countries, and finding sustainable solutions for existing buildings remains challenging in terms of energy efficiency ^[5][6][5,6]. The previous literature reveals that academics agree that vernacular architecture, as a product of adaptation to local conditions, connects the past and is a testimony of cultural identity. Through the use of vernacular materials and available resources, sustainability for the environment can be achieved [7]. Thus, vernacular architecture may represent a means of addressing the challenges of urban development. Research confirms that vernacular architecture is an important architectural heritage ^[8][9][8,9], the result of human behaviour, and the best example of harmonious coexistence between architecture and the natural environment. It reflects people’s traditions, culture, needs, and future expectations [10]. According to studies, vernacular architecture is unique to each region of the world and is substantially influenced by the local climate [11]. Each style may be individual, but the key element is the architecture and the life scenes that take place within it [12]. Vernacular architecture reflects the unique cultural and landscape elements of the area and represents a locally adapted approach to building materials [13]. Understandably, it is the outcome of historical optimisation as a structure that uses readily available materials and well-known construction methods to offer comfort in the local climate [14]. The study of vernacular architecture is not only the intellectual domain of architecture; it also covers sociology, economics, the environment, and cultural studies, which evolve sequentially over time. However, dramatic socio-political events around the world can also have an impact on the development of vernacular architecture [15]. Thus, there is a growing awareness that the life history of vernacular architecture can tell the story of a city’s rapid development and the enormous changes that affect the social and urban fabric [16]. The study of vernacular architecture is therefore a significant research topic.

The desire to modernise has led to a massive urban renaissance, including “megacities” [16]. Experts continue to debate the complex and successful blending of urbanisation trends and vernacular architecture [17]. Given the current challenges of global warming, climate change, and energy reduction, some scholars have started to conduct research on maintaining indoor thermal environments [18] as well as topics related to building energy consumption [19]. Studies have shown that the retrofitting of modern cooling solutions (e.g., electric air conditioning units) constitutes the most common form of retrofitting of traditional houses by a considerable margin [16]. Researchers generally agree that most modern buildings require high energy consumption to maintain indoor temperatures, while vernacular architecture, characterised by accumulated experience, is well adapted to the climate, environment, and social culture ^[18][20][18,20]. Therefore, vernacular building space is a key element in regulating the thermal environment of buildings and the thermal adaptation of residents [21]. Although many scholars have explored the perspective of indoor comfort, few studies have applied these results. In addition, some urban policymakers ignore existing problems and opt to demolish vernacular architectures or replicate and rebuild them, making it difficult to ensure sustainable urban development and collaborative governance ^[22][23][22,23]. Furthermore, this also severs the continuity between architectural history and urban life and blurs the connections between them, a contradiction leading to identity crisis in many contemporary cities. Urban renewal in different urban and rural spaces has also weakened heritage properties and increased the energy burden of buildings [24]. Therefore, the study of local climate and traditional construction materials can facilitate their integration or transformation using modern technologies and values; this can lead to proposals for new models of sustainable development ^[1][10][25][1,10,25]. Due to the inherent vulnerability of vernacular architecture, there is also a research gap to be filled in terms of seismic risk assessment and building conservation ^[26][27][26,27]. In recent years, it has been shown that in the era of high-performance architecture, a combination of traditional materials and modern technologies should be sought in order to fulfil the technical potential of buildings [28]. Countries such as Palestine and China have many vernacular courtyard construction techniques. These not only harmonise with the climatic environment but are also supported by strong religious and spiritual beliefs ^[4][29][4,29]. Some scholars have adopted a qualitative interpretive approach to the solution of vernacular architecture [3], but few studies have yet focused on the cultural and heritage narratives embedded behind the architecture. Traditional regional culture and historical memory are slowly disappearing, and there is great scope for the resilience of vernacular architecture and cultural landscapes in the current context of climate change [13]. Based on the present challenges, architectural practitioners and researchers still need to reflect on this shift towards culture and heritage [30]. Nevertheless, many historical experiences have yet to be grasped and applied to modern architecture. Vernacular heritage is important because of its connection to local culture; for instance, the use and shaping of space, traditional techniques, and material practices [9].

2. Publishing Trends and Implications for the Future of Architecture

Trends in the literature indicate that China is one of the most active and influential countries in the field of vernacular architecture, with the highest TPs (n = 311) and 1051 TCs. The emphasis on preserving China’s vernacular heritage has been reflected through a series of policies, such as the development of the “Beautiful Countryside Program” since 2005 [9] and the implementation of the “Rural Revitalisation Strategy”, which is also related to the decline and preservation of vernacular architecture ^[31][103]. Moreover, China has a long cultural history, with its cultural values being carried by the architecture of the traditional vernacular. These have been discussed by many scholars ^[32][104], prompting the publication of relevant research results. Undeniably, China’s architectural heritage is vast, yet the consumption of vernacular heritage in commercialised “reconstruction” has generated new narratives related to the Chinese countryside. This has been demonstrated by studies of vernacular materials and features [25]. Therefore, the establishment of a genealogy of traditional vernacular architecture is conducive to the preservation of this heritage. Thus, it is crucial for the future development of architecture ^[32][104]. At the same time, Italy stands out with a total of 121 publications and 1074 citations. Like China, Italy also has a diverse and wide range of architectural styles and continues to advance on the research path of vernacular architecture.  Similarly, institutions within these countries are influential, such as Xi’an University of Architecture and Technology in China, with a total of 78 publications, and Escola Superior Gallaecia and the University of Minho in Portugal, as well as Islamic Azad University in Iran and Oxford Brookes University in the UK. In addition, among the journals in which the authors publish, Renewable and Sustainable Energy Reviews and Sustainability (Switzerland) are the two most influential, with a total of 282 and 268 citations. It is also evident that Elsevier is the most active publisher in vernacular architecture. In view of the increasing number of publications on vernacular architecture in the last two decades, the 20 most highly cited journals are counted, and a qualitative and systematic analysis can more effectively distil the research contributions of scholars.

3. Status of Vernacular Architecture and Its Resilience

To better answer research question 2, “Which are the most influential countries, institutions, and authors that discuss how vernacular architecture relates to cities?”, this analyses the status of the vernacular architecture field. The results show that vernacular architecture is disappearing, and knowledge about its construction practices is gradually being forgotten [14]. This concern about the disappearance of traditional architecture and the emergence of new architecture is shared by both developed and developing countries. Dramatic changes in traditional cultural landscapes threaten multiple values and identities such as species, habitats, knowledge types, and landscapes [10]. For the performance of vernacular architecture in today’s urbanisation, a large portion of scholars focus on the fields of energy assessment, climatology, and seismology; for example, its utilisation of building materials and techniques available at the time to provide the most comfortable shelter [14]. Others focus on the theoretical perspectives of narratology, architectural heritage preservation, and cultural values, exploring various aspects of the physical and cultural impacts of vernacular architecture itself. Current research has largely established that urbanisation, materials, and land use influence the sustainable production of buildings as well as cities and that there is also a need to address future climate change ^[33][57]. The choice of research methods also varies. Many of the documents in this bibliometric search rely on quantitative analyses, which have the advantage of providing specific scientific contributions to the academic community and reducing the likelihood of bias. Of course, qualitative analysis is more appropriate for these elements regarding architectural values and regional culture, which can provide potential opportunities for vernacular architecture in human well-being and cultural sustainability. Due to the different choices of methods, there are differences in practice. Part of the literature on quantitative methods deals with content such as environmental and energy indicators, which involve practical projects on energy consumption data, carbon emissions, indoor environmental quality indicators, energy challenges, etc. Also, studies addressing thermal comfort, modern design, and building technologies in the context of climate and environmental sustainability are available. Meanwhile, there are case studies for building conservation and restoration, and building seismic performance improvement. Corresponding practice in spatial planning and decision analysis is also included. However, the preservation and cultural transmission of vernacular architecture are equally necessary and urgent. Therefore, vernacular architecture conservation, traditional building materials, technological sustainability, cultural heritage, national decision making, and land strategy are addressed in practice. In terms of cultural identity and sustainability, the presence of vernacular architecture can contribute to social and community cohesion, which can be better expressed through historically documented architectural documents and oral histories. It is undeniable that vernacular architecture is essential for resilience as well as sustainable urbanism to better survive in the twenty-first century ^[33][57]. The validity of the structural style of vernacular architecture can explain its function and principles and adapt to climate and aesthetics that are meaningful for resilience [1]. The findings of this bibliometric analysis can help practitioners in the building industry as well as scholars by providing a systematic reading archive. Thus, their professionalism in the practice of vernacular architecture can be improved in accordance with local policies and technical standards. In summary, considering the status of vernacular architecture today, researchers need to think about climate change in the context of an unpredictable future, especially in the quest for ways in which cities can become more resilient. Not surprisingly, vernacular architecture offers a possibility to complement urban issues.

4. Lessons from Experience and Sustainable Development

Lessons can be learned from previous studies, allowing people to respond to research question 3, “Which are the most cited publications, and do they address the experiences and lessons learned in vernacular architecture?”. Section 3 provides the answer to RQ 3, and among the 20 highly cited articles listed, the paper Energy retrofits in historic and traditional buildings: A review of problems and methods is the most cited (n = 197). However, this focuses on energy retrofits in historic and traditional buildings in Europe and North America with cold or temperate climates ^[34][72]. Vernacular buildings and regional traditions in other climates still need to be further explored and cultural barriers need to be overcome. A regulatory gap remains in the sustainability aspects of their proposed building retrofit guidelines and decisions. However, China‘s approach to traditional architecture has been characterised by a development strategy that adheres to international conventions while also exploring its own sustainable methods [25]. Similarly, the highly cited (n = 169) article Multiple criteria evaluation of rural building’s regeneration alternatives also discusses the economic benefits and environmental potential of building regeneration in the context of building reuse ^[35][78]. Nevertheless, the conclusion is that the solution is hardly applicable to all subjects in all countries. Thus, these gaps confirm the need for this study. As shown, folk architecture has been optimised through history and is worthy of study in terms of “climate adaptation”, “material technology”, and “comfort”, but traditional intelligence and responsiveness have been gradually lost [14], especially in developing countries. Therefore, the same alarm needs to be sounded from the perspective of human well-being and cultural heritage. Vernacular buildings have evolved from the distant past to become buildings that will house future generations. Understanding them is therefore imperative ^[33][57]. The heritage of values and technical effectiveness of traditional architecture can stimulate the construction of a more sustainable future ^[32][104]. From previous experiences and lessons learned, it can be seen that spaces must be appropriately designed at the micro- and macrolevels, based on the energy required to sustain the environment to meet the modern architectural paradigm to maintain sustainability [1]. Moreover, the evidence shows that the utilisation of renewable resources and energy sources in response to the risk of climate change is also an option for sustainable development [14]. In summary, the indications and the predictions of future research trends can further the research potential of vernacular architecture, providing the possibility of integration between architectural engineering, the humanities, and the social sciences, thus contributing to the diversification and sustainable development of vernacular architecture.

5. Architecture in Cities and the Future of Humankind

The keywords and themes of current global vernacular architecture research are further identified: “Energy and Thermal Comfort”, “National Countermeasures and Seismology”, “Vernacular Architectural Heritage Conservation and Sustainability”, and “Urban and Vernacular Architecture”. The study found that these are the topics and research directions of interest to practitioners and related scholars, covering the fields of engineering and humanities. It is also evident from the analysis of the literature data that, in order to solve the problems of air pollution and energy consumption in contemporary cities, the technologies in vernacular architecture can be utilised [3]. Such traditional techniques can benefit the residential areas of modern cities and efficiently transform the traditional strategies into sustainable and favourable conditions for human survival. Therefore, they must be further considered by both industry practitioners and researchers. However, in the conflict between urbanisation and architectural styles, vernacular architecture must find a new identity in the city as well as in human society [10]. Through the literature, it is evident that vernacular architecture can provide strategies with feasibility for urban development. For instance, vernacular traditional construction strategies have good potential in designing urban areas that, when combined with contemporary design methods, can more effectively satisfy the daily needs of the occupants to provide more sustainable living environments [4]. Modern architecture is more likely to achieve architectural sustainability when following the design principles of vernacular types, whether in terms of ventilation, climate comfort, building materials, or technology. Thus, vernacular architecture can guide the behavioural patterns of the occupants and contribute to the sustainable development of the architecture in cities [6]. In addition, the study of vernacular architecture is intended to facilitate architects becoming more familiar with architecture and urbanisation which, in turn, can enhance the sustainability of the city [1].