**1. Introduction**

Climate change throughout the world has increased concerns about ecological harm. Greenhouse gas emissions from this activity inflict permanent harm. Global advances in energy efficiency have been dropping since 2015 according to IEA2020. A decrease in energy costs arrived with the COVID-19 pandemic, resulting in a reduction in energy intensity improvement in 2020, less than the revised rates for 2018 and 2019. As a consequence of the analytical studies of energy institutions, buildings account for one-third of this consumption. Buildings are also responsible for 40% of direct and indirect emissions of CO2 [1].

The importance of construction in worldwide energy consumption has raised awareness of environmental degradation trends. This rising knowledge has sparked efforts to optimize energy efficiency while minimizing environmental impact. The use of efficient designs reduces the energy consumption of a building during its life cycle and helps solve these challenges by reducing the damage to the environment and human health.

Architects and designers have long been concerned with meeting the challenges of nature and architecture. Owing to advances in technology, nature-based design and construction techniques have led to designs based on biological approaches. These techniques, which appear with various terminologies such as bionics, bio-inspiration, biomimetics, and biomimicry, are mainly based on solving problems by inspiring/learning/developing innovative proposals based on the shape, structure, and systems of nature". It has been also argued that "designers can be inspired by nature in order to tackle building design challenges, and this has led to a connection between architecture and biomimicry" [2].

Biomimicry's goal, developing technical advancements and achieving sustainability, appears to be the best ideas of nature, and it imitates them in design processes to solve

**Citation:** Varshabi, N.; Arslan Selçuk, S.; Mutlu Avinç, G. Biomimicry for Energy-Efficient Building Design: A Bibliometric Analysis. *Biomimetics* **2022**, *7*, 21. https://doi.org/ 10.3390/biomimetics7010021

Academic Editors: Negin Imani and Brenda Vale

Received: 20 December 2021 Accepted: 18 January 2022 Published: 24 January 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

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design problems. There is a rising focus on how organisms adapt to changes in the environment, with the claim that these characteristics might bring new approaches to designing technologies to improve performance [3].

New technologies can improve the energy efficiency of any kind of energy-consuming systems. Likewise, biomimicry is considered an "innovative design strategy for increasing energy-efficient designs" [4], and, thus, energy-efficient built environments. Due to the existence of diverse biological mechanisms, natural processes with low energy consumption can inspire creative solutions for optimal energy consumption. It is also a matter of debate that "bio-inspired design may present the potential for causing a paradigm change in traditional design thinking" [5]. Bio-inspired/bio-informed designs can be solution or problem oriented. In this way, these biological mechanisms are explored for novel approaches. "A problem-based approach to provide a better response to building energy reduction, means that once architects are aware of thermal challenges and want to improve thermal performance using bio-inspired design solutions, their priority is to discover appropriate biological examples" [6].

If scientific analysis studies are conducted conventionally, increasing the number of academic publications may result in various limitations in the research. For this purpose, structuring the analytical research with a new method is helpful when it comes to broadening the area of the investigation. Literature reviews stand out as one of these techniques and play a vital role in bringing together previous studies' results. With these types of studies, the present observation's foundation may be successfully utilized; as a result, the research phase is increased and broadened in light of the evaluations to be made regarding research in the relevant field. One of the review procedures that is widely utilized is "bibliometric analysis". Bibliometric analyses are focused on studying specific aspects of an article's content or publishing and producing different scientific communication conclusions [7].

As research progresses, terms and ideas become broader, more multidisciplinary, and more complex, and, despite this progress, questions remain unanswered. Within this framework, in this study, bibliometric research was conducted, and some aspects are discussed. Firstly, articles from Web of Science were studied in order to identify bibliometric indicators in this research, such as annual publication analysis, research area analysis, Geographical area evaluation, analysis of authorship, analysis of organizations, citation by sources, cooccurrence of keywords, and content analysis of the selected articles. Then, as given in Section 2, data visualization was performed using VOSviewer and SankeyMatic software. In the Section 3, the bibliometric findings are discussed. As an inference, biologically inspired approaches to building energy efficiency have been introduced by highlighting why and how bio-informed knowledge has been transferred.

#### **2. Research and Methodology**

The purpose of this study was to survey publications and research directions in biomimicry and architecture utilizing a scientific literature database and science survey analysis. Bibliometric analysis is an effective method for determining the growth and future possibilities of a study topic. Bibliometric methodologies have been used to investigate the growth of research topics, find relationships between logical progress and modifications to the approach, and identify expanding interdisciplinary alliances. The research methodology provides detailed quantitative and statistical scientific information regarding the processes of making decisions.

Today, detailed analyses can be conducted via numerous online databases such as Web of Science, Scopus, and Google Scholar. Additionally, different software tools such as VOSviewer, Citespace, Bibexcel, Gephi, Pajek, Publish or Perish, Ucinet, and Science of Science (Sci2) provide informative data and visualization [8]. The bibliometric data of the search results made with the relevant keywords in the WoS (Web of Science) database were analyzed and visualized with the VOSviewer and Sankey diagram mapping methods, and the relationships, trends, and collaborations between the subjects were revealed through network maps. In addition to primary databases such as WoS, Scopus, EBSCO, and ProQuest used in bibliometric searches, networks such as Google Scholar, ResearchGate, and Academia are also available. The search results in Google Scholar, despite the variety, are not comprehensive, and the results have a different quality load, so the classification of articles for bibliometric work is the responsibility of the researcher. In Google Scholar, updating information related to articles is not accurate, so a bibliometric review of the articles may not have acceptable results. Classification studies were carried out in this study using the Web of Science, which includes indexes such as Sci, Sci, and A&HCI, where the most recent and qualified publications are published.

The bibliometric analysis in this research is based on two mechanisms of functional analysis and scientific mapping. Scientific mapping is a visual representation of the conceptual, intellectual, and social structures of research fields [7]. In this method, bibliographic data analysis is possible based on the author, document, source, institution, country, and keywords. In this research, the analysis of co-occurring words was used to map the studies, which is a method used to measure the strength of relationships between publications' keywords [9]. By analyzing co-occurring words, keywords related to the subject of the articles were obtained. Performance analysis is a method that measures the number of articles and citations published by authors and institutions in this field. In this study, mapping and performance analysis were used together in an integrative way. Bibliographic data from the Web of Science database were analyzed in VOSviewer and SankeyMATIC software. Figure 1 summarizes the study's methodology.

**Figure 1.** Methodology of the study.

Web of Science is "a website that offers subscription-based access to several databases that contain detailed citation data for a wide range of academic subjects" [10]. With the help of such an advanced tool, it is possible to track ideas and disciplines over time, with over 1.9 billion citations from 171 million records in the database. Users can also obtain all of the data for entries in a certain field of research based on a provided query phrase [10]. Visualization of similarity (VOS) mapping is a topic-based approach that allows for a comprehensive and clear representation of advancing study disciplines. It can also draw clusters and cooperation networks using vortices connected by lines [8]. The Sankey diagram (SankeyMATIC) demonstrates a wide data relation to visualize multifaceted connections. It is a type of diagram used to visualize the quantities and flows of assets in proportion to each other. The width of the lines or nodes in the diagram is used to express the size of the data. In this context, the size of the line or node also expresses the size of the flow amount [11].

Biomimicry is an approach that is widely used in material science, architecture, and engineering, etc. In this work, we integrated the network, group, and bibliometric studies of the scientific literature in the context of biomimicry and building energy efficiency by addressing some questions:

