Science mapping on the Environmental Footprint: A scientometric analysis-based review

Ecological Indicators 106 (2019) 105543

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Science mapping on the Environmental Footprint: A scientometric analysisbased review

T

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Sara Martineza,b, , Maria del Mar Delgadoc, Ruben Martinez Marina, Sergio Alvareza a

Department of Land Morphology and Engineering, Universidad Politécnica de Madrid, Madrid, Spain Department of Natural Systems and Resources, Universidad Politécnica de Madrid, Madrid, Spain c INIA, Environmental Department, Ctra. La Coruña Km. 7,5, 28040 Madrid, Spain b

A R T I C LE I N FO

A B S T R A C T

Keywords: Life-Cycle Assessment Product Environmental Footprint Organization Environmental Footprint Scientometric analysis Literature review VOSViewer

Over these past years, the degradation of the environment has led to an increasing awareness of human impacts on nature. This review adopts the bibliometric and scientometric analysis method to materialize the perception of the increasing interest in the Environmental Footprint domain and, more specifically, in the Environmental Footprint and Life-Cycle Assessment research area. Data retrieved from the Web of Science and mapped with the VOSViewer have been used to evaluate the evolutionary trend and current status of two datasets, the Environmental Footprint dataset and the Environmental Footprint and Life-Cycle Assessment dataset. The findings aimed at providing valuable information related to these fields, such as (1) the characterization of publications, (2) most relevant references cited, (3) most influential keywords in the research topics, (4) major journal sources and (5) main countries active in this particular research field. In addition, new emerging trends, such as the Product Environmental Footprint and the Organization Environmental Footprint were spotted in the analysis. A qualitative discussion is provided identifying main research areas and further research directions. This review may help practitioners and researchers by providing a better understanding of the current state of the Environmental Footprint research field and serve as a starting point for future studies.

1. Introduction Since the publication of the planetary boundaries by Rockström et al. (2009) evidencing that humans are the main precursors of environmental transformations, an increasing awareness of human impacts on nature has emerged. In this context, special attention has been directed towards the shifting to sustainable use of natural resources and to more efficient production and consumption patterns (Roy and Singh, 2017). In order to quantify the environmental performance of products and services, different environmental indicators known as footprints have been developed to assess the human pressures on nature. Among the footprint family, the ecological, carbon and water footprints are the most extended (Galli et al., 2012). However, most of the footprints provide a limited set of environmental aspects and do not provide all the potentially environmental consequences (Alvarez et al., 2016). In light of this limitation, the concept of Environmental Footprint (EF) was adopted as a multi-criteria indicator considering several impacts on the environment (European Commission, 2018; Martinez et al., 2018a). The most widely accepted approach to obtain the EF is the Life-

Cycle Assessment (LCA), which includes all of the impacts generated throughout the supply chain (Guinée et al., 2002). This provides a more complete picture of the environmental performance and avoids burdenshifting between stages, impact categories and countries (European Commission, 2012a,b). Based on this life-cycle thinking, several accounting methods for quantifying the environmental performance of products and services were developed. The main quantifying methods are the ISO 14044 (2006), ISO/TS 14,067 (2013), ISO 14,025 (2006), ISO 14,020 (2000) (ISO, 2018), the Ecological Footprint (Ecological Footprint Standards, 2009), BPX 30-323-0 (ADEME, 2011), PAS 2050 (2011) and the Greenhouse Gas Protocol (Bhatia et al., 2011). Several studies have been carried out analyzing the environmental effects of products (Kjaer et al., 2015; Soode-Schimonsky et al., 2017) and sectors (Martinez et al., 2018c; Neppach et al., 2017). However, the proliferation of LCA standards has led to great discrepancies in the assumptions, methodological choices, and results among the environmental studies (Gazbour et al., 2018). In light of the disparity of environmental standards, the European Commission (EC) put forward an initiative to harmonize the application

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Corresponding author at: Department of Land Morphology and Engineering, Universidad Politécnica de Madrid, Madrid, Spain (S. Martinez). E-mail addresses: [email protected] (S. Martinez), [email protected] (M.d.M. Delgado), [email protected] (R. Martinez Marin), [email protected] (S. Alvarez). https://doi.org/10.1016/j.ecolind.2019.105543 Received 5 January 2019; Received in revised form 26 June 2019; Accepted 2 July 2019 1470-160X/ © 2019 Elsevier Ltd. All rights reserved.

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methodology followed consists of a bibliometric search, a scientometric analysis, and an overall qualitative discussion (Jin et al., 2018). Bibliometric analysis has been applied by authors to evaluate environmental related areas (Albort-Morant et al., 2017) and in particular, footprint indicators (Zhang et al., 2017). Furthermore, the scientometric analysis is considered as an appropriate method to conduct reviews evaluating research development and performance of authors, countries, institutions, journals, etc. in a certain research domain (Konur, 2012). Combining both approaches provides the capturing and mapping of structural patterns highlighting research hotspots of the studied scientific area (Olawumi and Chan, 2018).

of the LCA on green products and services (European Commission, 2013, 2012a,b). This objective was established within the framework of the “Roadmap to a Resource Efficient Europe”, which aimed at transitioning to a sustainable economy and decouple economic growth from resource use and its environmental impact (European Commission, 2011), and it was materialized in the EF as a tool to promote consistency and comparability when assessing the environmental performance (European Commission, 2012a,b). The EC’s Joint Research Centre in cooperation with the Directorate General for Environment, proposed the Product Environmental Footprint (PEF) and the Organization Environmental Footprint (OEF) as two methods to “assess, display and benchmark the environmental performance of products, services and companies based on a comprehensive assessment of environmental impacts over the life-cycle” (European Commission, 2012a,b). The PEF and the OEF take existing and recognized guides as a basis to describe product and corporate environmental accounting methods (European Commission, 2013, 2012a,b). In addition, technical guidance concerning the development of PEF and OEF studies are also provided by the Product Environmental Footprint Category Rules (PEFCRs) and the Organization Environmental Footprint Category Rules (OEFCRs) to achieve consistency and comparability (European Commission, 2013, 2012a,b). Unless specified in these guidance documents and PEF and OEF guides, both Environmental Footprints consider 14 mid-point impact categories: ozone depletion, human toxicitycancer effects, human toxicity-non-cancer effects, ecotoxicity freshwater, particulate matter, photochemical ozone formation, climate change, ionizing radiation, marine eutrophication, terrestrial eutrophication, freshwater eutrophication, water depletion, mineral depletion, land use and acidification. In the context of increasing interest in sustainable production and consumption, the Environmental Footprint concept has gained special attention. To date, little research has been conducted analyzing the current state of the Environmental Footprint literature and its trends observed in past years. The purpose of this paper is to provide a scientometric analysis-based review revealing the insights and evolutionary progress of the Environmental Footprint domain. In order to provide a more comprehensive review approach, a general overview of the evolution of the EF publications from 1992 to 2018 is presented. In addition, as the LCA is the most accepted tool to conduct the EF studies, a more in-depth investigation of the bibliographic characteristics and co-occurrence of the research regarding the EF applying LCA is included. Finally, a qualitative discussion of the EF, and EF and LCA establishes the up-to-date status of these promising research fields.

2.1. Bibliometric analysis For bibliometric analysis, the bibliometric search of the literature was performed in the Web of Science from Thomson Reuters, as it is a well-recognized database and provides high-quality records (CañasGuerrero et al., 2013). Two datasets were downloaded: (1) EF dataset and (2) EF and LCA dataset. For the EF dataset the following parameters were used for data retrieving: Topics = “environmental footprint” Timespan = “All year” Database = Science Citation Index Expanded (SCI-E) Environmental Footprint and LCA dataset parameters: Topics = “environmental footprint” AND “life-cycle assessment” Timespan = “All year” Database = Science Citation Index Expanded (SCI-E) Altogether, 1199 original documents were part of the literature set for the EF dataset and 273 publications for the EF and LCA dataset. Each publication included data related to the title, authors, publication year, keywords, countries/territories, institutions, journals, citations, Web of Science categories, pages, and other parameters. 2.2. Science mapping The mapping was conducted using VOSViewer. VOSViewer is a textmining tool developed by van Eck and Waltman (2010), and it is particularly useful for visualizing large networks. It allows a comprehensive bibliometric analysis, as it includes special text mining features, cooccurrence, and co-citation analysis. In addition, it was adopted for this review because of its intuitive data visualization providing distancebased nodes representing the relatedness. In this review, the following steps were carried out using the VOSViewer: (1) Loading of the datasets obtained from the Web of Science, (2) visualization, computation, and analysis of co-citations and (3) visualization, computation and analysis of co-occurrence of keywords, journals and countries.

2. Methodology This review adopts a science mapping approach to evaluate the research outputs in the field of the EF and more specifically, in the literature related to the EF applying the LCA (Table 1). The Table 1 Bibliometric and Scientometric analysis of the Environmental Footprint dataset and Environmental Footprint and Life-Cycle Assessment dataset. Literature datasets

Bibliometric and Scientometric Analysis

Environmental Footprint dataset

Characterization of publications Co-citation Co-occurrence of keywords

Environmental Footprint and Life-Cycle Assessment dataset

Characterization of publications Co-citation Co-occurrence of keywords Co-occurrence of publication sources Co-occurrence of countries

2.3. Qualitative discussion A qualitative discussion is provided following the bibliographic analysis and science mapping to evaluate the situation of the ongoing research areas included in this study. In particular, special attention has been paid to the significance of the current status of the EF, and EF and LCA research. In addition, the main research areas and future research paths have been identified. 3. Results 3.1. Overview of the Environmental Footprint The literature data retrieved from the Web of Science in relation to 2

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identify the most influential publications in relation to a certain research area (Trujillo and Long, 2018). Fig. 3 displays the publications of the EF field which exhibit the highest citations and link strength. The documents which have the highest influence are the ISO 14044 and ISO 14040. This is explained because both scientific standards are wellknown and widely applied documents which serve as guidance for the evaluation of the environmental performance of products and organizations (Pryshlakivsky and Searcy, 2013). ISO 14040 reports the principals and framework of the LCA and ISO 14044 provides general requirements and guidelines of environmental management also related to LCA (ISO 14040, 2006; ISO 14044, 2006). Other relevant documents highlighted in the document co-citation network are the publications of Finkbeiner (2014) and Galatola and Pant (2014), which refer to the viability of the Product Environmental Footprint method, and the research papers of Čuček et al. (2012), Godfray et al. (2010) and Rockström et al. (2009) which deal with environmental issues, such as sustainability, food security and environmental planetary boundaries. Additionally, the co-occurrence of keywords within the publications is also a key analysis to highlight the main research areas. Fig. 4 is a representation of the main topics depicted within the selected field. It uses sizes and distance of nodes and interconnecting lines to show the most frequently studied keywords. The selected terms and their quantitative measurements are summarized in Table 3. Among the different indices presented in Table 3, it has to be highlighted the total link strength, which indicates the strength of the relationship between different items. The higher the value of total link strength, the stronger the relationship between the keywords (Eck and Waltman, 2017). In this study, sustainability and life-cycle assessment have the highest values of total link strength and occurrence. This means these keywords are the most inter-related keywords and have the highest degree of frequency within the literature analyzed. On the other hand, when focusing on the influence of the keyword in the research literature, attention has to be directed towards average normalized citation index, which represents the normalized number of citations and it is calculated by dividing the total number of citations of different document sources by the average number of citations published per year (Jin et al., 2019). In this case, the words green-house gas emissions and climate-change show the highest average citations and average normalized citation. The text mining process also allows for the categorization of the keywords into different clusters. Each cluster groups keywords that most frequently co-occur and the visualization of these clusters is carried out using different node colors. In this case, five clusters were identified. Keywords promoting sustainability are classified in cluster 1. This cluster, represented in red, contains words such as efficiency, energy, performance, management, model, system, water, agriculture, sustainability, and environment. Cluster 2 (green) refers to research studies related to the EF. Biomass, design, emissions, and optimization are the terms conforming this cluster. Cluster 3, represented in blue, consists of keywords related to green-house gas emissions (carbon footprint, climate-change, environmental impacts, green-house emissions, and impact). Cluster 4 (yellow) is associated with policy actions. The keywords are Environmental Footprint, consumption, energy efficiency and framework. Finally, cluster 5 (purple) contains methodology keywords, such as LCA, impact assessment, Life-Cycle Assessment, and Product Environmental Footprint.

Fig. 1. Number of publications per year in the Environmental Footprint field from 1992 to 2018.

Fig. 2. Number of citations per year in the Environmental Footprint field from 1992 to 2018.

the EF consisted of 1199 records providing information regarding title, authors, type of publication, journal, country and institution, citations, references, keywords and other data. Fig. 1 shows the number of publications of the EF per year. Since the first document published in 1992, the results show an increasing number of documents over the years, reinforcing the fact of the raising awareness among the scientific community. A positive trend is also observed in the number of citations per year until 2011 (Fig. 2). From 2011, there is an irregular trend in the number of citations, with a peak in 2011 with 3915 citations and a negative tendency from 2015 to 2018. The 1199 documents in the EF area were categorized into eight document types. Articles constituted the main source with 778 (64.93%), followed by proceeding papers with 256 (21.36%), reviews with much less, 100 (8.35%), book chapters with 39 (3.23%), editorial materials with 16 (1.34%) and the rest of document types (meeting abstracts, letters and news items) accounted for 10 (0.79%). An overview of the EF is shown in Table 2. As observed with the total number of publications, the total number of authors increased from 1992 to 2018. The total average of authors during this period was 225 and the average per publication was 3.2. On the other hand, it is seen a slight fluctuation of the length of the publications, being the average number of pages per publication 8.6 pages. Although the number of times cited also varied slightly, in general, a rising trend is observed (Fig. 2). The total number of times cited was 17,175 and the average per document 19.9. By analyzing the characteristics of the EF publication outputs, it can be concluded that a growth trend is observed in the EF research field over these years. Co-citation analysis has been demonstrated to be a useful tool to

3.2. Environmental Footprint and Life-Cycle Assessment analysis The general overview of the publications related to the EF has thrown some light to the main topics related to this field. In order to obtain specific information regarding the EF as an indicator to evaluate human impacts, a more in-depth bibliometric and scientometric analysis is carried out. This analysis considers the literature in the research area of the EF and LCA, as this approach has been found to be the main tool to calculate this indicator (Table 3). With respect to the number of publications of the EF applying an 3

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Table 2 Characteristics by year of publications of the Environmental Footprint field from 1992 to 2018. Published Year

Total Publications

Total Authors

AU/TP

Total Pages

PG/TP

Total Times Cited

TC/TP

1992 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

1 1 1 2 4 4 8 4 9 15 27 49 54 62 68 86 103 135 206 210 150

1 4 3 3 12 14 20 7 29 42 98 152 172 227 248 320 387 493 950 856 684

1.0 4.0 3.0 1.5 3.0 3.5 2.5 1.8 3.2 2.8 3.6 3.2 3.2 3.7 3.6 3.7 3.8 3.7 4.6 4.1 4.6

2 22 4 29 34 35 49 22 11 153 219 347 427 562 598 748 953 1337 1899 1970 1493

2.0 22.0 4.0 14.5 8.5 8.8 6.1 5.5 1.2 10.2 8.1 7.2 7.9 9.1 8.8 8.7 9.3 9.9 9.2 9.4 10.0

0 58 1 40 60 14 181 25 51 561 1403 1350 1751 3915 1120 1682 1945 1205 1128 517 168

0 58.0 1.0 20.0 15.0 3.5 22.6 6.3 5.7 37.4 52.0 28.1 32.4 63.1 16.5 19.6 18.9 8.9 5.5 2.5 1.1

AU/TP: Authors per published document; PG/TP: document length per document number; TC/TP: Citations per published document.

community. Following these policy documents, research articles from Finkbeiner (2014) and Galatola and Pant (2014) were found with the highest number of links and were the most co-cited articles (Fig. 6). For the EF and LCA domain, the most frequently used keywords were similar to the wider EF database. These keywords were grouped in four clusters which resembled the five clusters mentioned for the EF analysis (Fig. 7). Cluster 1, represented in red, included keywords referring to policy implementation (breakdown, impact assessment, LCA, policy implementation and Product Environmental Footprint), as it was also seen for the EF co-occurrence analysis. Cluster 2 (carbon footprint, impacts, management, products, and sustainability) is represented in green and it contains words associated with sustainability. Cluster 3 (blue) shows terms (energy, environmental impacts, green-house gas emissions, and systems) related to the sources of environmental impacts. Finally, cluster 4 (yellow) can be identified with the meaning of EF. The keywords in this cluster are emissions, Environmental Footprint, Life-Cycle Assessment, and performance. More details of the highlighted keywords are presented in Table 5. According to the average year in which the documents were published, it is seen that the EF applying the LCA is a topic which burst in 2015 and 2016. Contrary to what it is seen in the EF domain, for the EF and LCA field, the climate change topic has not aroused that much attention and is not included in Table 5 due to its low average normalized citation value of 0.3. In fact, the green-house emissions keyword, which is also related to climate change, presented also a low average normalized citation value. Analyzing the average normalized citation of keywords allows the comparison of their importance in both research areas. In this way, researchers showed a higher interest in the topic of climate change and green-house emissions in the EF field as their average normalized citation values are 78% and 60% higher than the average normalized citation of this keyword in the EF and LCA research field. On the other hand, in the field of EF and LCA, it seems that the study of the EF as an indicator of impact assessment has caught the attention of researchers in recent years. This emerging topic appears to be a direction to follow for future research towards the quantification of environmental impacts to improve products’ and services’ performance. Moreover, Fig. 8 visually represents the main source journals where the EF and LCA documents were published. Ten journals were selected as the most influential sources and their quantitative measurements are summarized in Table 6. The sizes and links of the nodes show the closeness referred to the frequencies that publications from journals cite each other. Various colors are assigned to distinguish between journal

Fig. 3. Environmental Footprint document co-citation network.

LCA approach a total of 273 publications were retrieved from the Web of Science database. Among the type of documents, the articles are the main contributors, followed by proceeding papers and reviews (Fig. 5). The rest of the publications have little contribution. The characteristics of the publications reveal that 2016 was the key year. This year exhibited the highest number of publications, authors and number of pages (Table 4). It has to be noted in 2004 only one document was published, but it was cited 120 times, which shows the great repercussion of this research. Comparing the publication trend with the EF literature, it is seen that the number of documents decreased in 2017. The analysis of the publications that were most co-cited revealed similar findings as with the EF database. Three main clusters have been obtained based on the frequency of co-citation and grouped using different colors. Among these clusters, both ISO documents (14040 and 14044) were the publications with the highest impact in the research

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Fig. 4. Mapping of keywords in the Environmental Footprint domain.

clusters, which define the degree of interrelatedness of mutual citation (Jin et al., 2019). Journals grouped in the same cluster tend to have a higher level of mutual citation. For example, International Journal of Life Cycle Assessment has the highest link strength and it is close-related to Sustainability. However, journals from different clusters could also present a high level of correlation, such as International Journal of Life Cycle Assessment and Journal of Cleaner Production. Additionally, the parameters total link strength, number of articles, and total citations provide insights into the level of productivity. A correlation test using the Pearson product moment correlation coefficient (r) at a confidence level of 95% has been carried out to analyze the existence of correlation between the number of publications and the rest of the indices shown in Table 6. This test revealed a very high correlation between number of publications and total citations (r = 0.90, p < 0.001). There is also a strong-moderate positive correlation between the number of publications and total link strength (r = 0.77, p < 0.001). On the other hand, it is detected a weak positive correlation between the number of publications and average normalized citation (r = 0.13, p = 0.53) and a weak negative correlation between the number of publications and average citations (r = −0.11). Average citation per document and the average normalized citation are parameters expressing the influence of a journal in the research community (Jin et al., 2018). In this sense, highly productive journals do not necessarily mean they have a high significance in the research area. In this study, it is found that International Journal of Life Cycle Assessment and Journal of Cleaner Production are the most productive journals in terms of number of publications and citations. However, in terms of significance, Science of the Total Environment and Resources Conservation and Recycling stand out. A country-based analysis was also performed to observe mutual citations of studies among different countries (Fig. 9). The contribution of each country is reflected in the size and linkages between regions. In this review, both developed countries, i.e. the USA, and developing countries, i.e. India, appear to contribute to this research field. Table 7 shows the great influence of European countries in the research fields of the EF and LCA. As seen in other footprint indicators, European countries have a major presence in environmental studies (Zhang et al., 2017). The USA stands out as a very productive and influential country, as the values of all the parameters are significantly high. Other

Table 3 Co-occurrence of keywords in the Environmental Footprint literature. Keywords

Occurrence

Total Link Strength

Average Year Published

Average Citations

Average Norm. Citationa

Life-Cycle Assessment Sustainability Environmental footprint LCA Energy Emissions Green-house gas emissions Performance Systems Management Carbon footprint Environmental impacts Design Impact assessment Framework Consumption Model Climate-change Optimization Product environmental footprint Impact Environment Efficiency Agriculture Energy efficiency Biomass Water

112

276

2015

10

1.1

122 96

203 161

2014 2015

12 10

0.9 0.8

75 78 54 47

149 146 103 98

2015 2015 2015 2015

11 11 12 21

0.8 0.7 1.1 1.5

50 57 57 35 38

97 97 96 88 86

2015 2014 2014 2015 2015

10 9 9 14 14

0.9 1.1 0.7 1.3 1.2

40 23 30 36 33 30 38 24

74 69 65 64 64 58 58 55

2014 2015 2014 2015 2014 2014 2014 2015

10 9 8 12 13 20 10 11

0.9 0.8 1 1.3 1 1.4 0.9 0.9

26 34 33 24 23 22 34

51 45 44 40 34 33 30

2014 2014 2015 2014 2015 2014 2014

15 16 19 13 11 19 11

1 0.9 1.2 1.3 0.9 1 1.1

a The Average Norm. Citation represents the normalized number of citations of a journal source, article, scholar, a country, or an organization. The calculation consists of dividing the total number of citations by the average number of citations published per year (van Eck and Waltman, 2010). The Average Norm. Citation is also applied in the following tables.

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the EF is an indicator related to improving the quality of nature to guarantee its present and future protection. In addition, the most cited documents are the ISO standards 14040 and 14044, which contextualize the spotted keyword Life-Cycle Assessment. In light of these findings, the initial literature was delimited to analyze the EF applying the LCA approach. The type of publications and the most co-cited documents were the same as with the EF literature. These results suggest that the main environmental accounting method adopted when conducting an LCA to obtain the environmental impacts has been the ISO standard. Moreover, Product Environmental Footprint has been identified as one of the main keywords based on the frequency of co-occurrence in both research fields. The PEF and the OEF are recent initiatives to standardize the quantification of environmental impacts using the LCA approach (Vieira, 2018). Among the literature, the PEF has captured the attention of numerous researchers (Golsteijn et al., 2018; Poolsawad et al., 2017; Wade et al., 2018), in fact, two of the most co-cited documents refer to the implementation of the PEF (Finkbeiner, 2014; Galatola and Pant, 2014). The initiative of the EF, which includes the PEF and the OEF, is quite recent and not as mature as the ISO method. The highest increase in publications regarding the EF area and the EF and LCA area is seen from 2014 to 2017. This period of time coincides with the PEF and OEF pilot phase and explains the growing interest in this field. In addition, the complete overview of the PEF pilot phase is published in the journal source Sustainability, which is one of the most influential sources seen in the EF and LCA field (Bach et al., 2018; Lehmann et al., 2016). Regarding the research sources identified, the top most influential journals are Science of the Total Environment and Resources Conservation and Recycling. This aspect is justified by the aim and scope of both journals, a fact that has been highlighted in other scientometric analyses (Darko et al., 2019; Hosseini et al., 2018). The EF indicator and the scope of the journals in Table 6 have in common the concern towards the environment, making the EF publications and journals fit perfectly. A reason explaining the recent contribution of European countries to the study of the EF and LCA is that PEF and OEF indicators have been proposed by the European Commission (European Commission, 2013, 2012a,b). With regards to the most influential countries identified in the network, it was seen that the strongest links occurred between European countries, highlighting the collaboration between GermanyFrance and Italy-Spain. Other significant links were observed among the pair countries USA-Canada and USA-South Africa. Based on this country analysis, it is concluded that Northern countries are contributing more to the EF, and EF and LCA research than Southern countries, such as India and China. In addition, developing countries

Fig. 5. Distribution of the types of documents the Environmental Footprint and Life-Cycle Assessment field from 2000 to 2018.

countries, such as Greece and Spain, present a low number of publications, meaning they are not as productive as other regions, such as Italy. However, these countries present significant figures of average normalized citation expressing their high influence and mutual citations. In addition, the average year of the documents in these countries is 2017, which means they are playing an active role in the research of the EF and LCA. 4. Qualitative discussion 4.1. Environmental Footprint and LCA research analysis Environmental concern is a topic that has been gaining an increasing interest over the years (Bouscasse et al., 2018). Several studies were presented concerning environmental issues, such as water depletion and green-house gas emissions (Chen et al., 2017; White et al., 2017). Nowadays, the complete picture of the environmental effects is reflected in the study of the Environmental Footprint, which quantifies the impacts generated by human beings’ activities. This review has evidenced an increasing attention towards the Environmental Footprint by stating the exponential growth in the number of publications in this field, from 1 in 1992 to 210 in 2017. Among the scientific community, articles are in general the preferred way of communicating environmental research advances as they are regarded as rich sources of information (Jin et al., 2018). Sustainability and Life-Cycle Assessment have been depicted as key contents in the literature of the EF. These findings are coherent because

Table 4 Characteristics by year of publications of the Environmental Footprint and Life-Cycle Assessment field from 1992 to 2018. Published Year

Total Publications

Total Authors

AU/TP

Total Pages

PG/TP

Total Times Cited

TC/TP

2000 2002 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

1 1 1 1 1 1 3 3 5 11 11 21 25 27 63 50 48

3 3 4 1 3 2 12 10 19 48 48 72 106 98 304 215 228

3.0 3.0 4.0 1.0 3.0 2.0 4.0 3.3 3.8 4.4 4.4 3.4 4.2 3.6 4.8 4.3 4.8

4 7 7 12 10 10 36 22 32 109 83 185 218 265 705 520 527

4.0 7.0 7.0 12.0 10.0 10.0 12.0 7.3 6.4 9.9 7.5 8.8 8.7 9.8 11.2 10.4 11.0

1 4 120 0 0 63 101 157 100 281 201 501 408 225 423 169 59

1.0 4.0 120.0 0 0 63.0 33.7 52.3 20.0 25.5 18.3 23.9 16.3 8.3 6.7 3.4 1.2

AU/TP: Authors per published document; PG/TP: document length per document number; TC/TP: Citations per published document. 6

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Fig. 6. Environmental Footprint and Life-Cycle Assessment document co-citation network.

4.2. Main research areas

were under-represented in this EF, and EF and LCA analysis, an effect also observed in other research fields (Darko et al., 2019; Hosseini et al., 2018). The isolation of these countries from the EF, and EF and LCA core research field could be disadvantageous for the implementation of environmental measures and could also constitute an impediment for global sustainable development (United Nations, 2013). For these reasons, it is required to promote future collaboration, not only between developing countries but also among countries already active in this research network, such as some Mediterranean countries (Spain and Greece) and North American countries (the USA and Canada). These collaborations will benefit knowledge exchange, as well as, facilitate joint research funding programmes.

Keywords are essential in reflecting and defining research contents. Therefore, the analysis of the most relevant keywords has been used to identify the framework of the main research areas in EF studies and in EF and LCA studies (Wuni et al., 2019). The emerging trends and hottopics identified in this study are sustainability, EF applicability, mitigation of environmental impacts, policy implementation and environmental methodologies, Sustainability has caught the attention of scholars in the past years. Since its definition in the Brundtland report (Brundtland, 1987), the topic of sustainability has become commonplace in different sectors, such as in industry (de Oliveira Neto et al., 2019), in tourism (Asmelash and Kumar, 2019), in construction (Bamgbade et al., 2019) and in agriculture (Quintero-Angel and

Fig. 7. Mapping of keywords in the Environmental Footprint and Life-Cycle Assessment domain. 7

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Table 5 Co-occurrence of keywords in the Environmental Footprint and Life-Cycle Assessment literature. Keywords

Occurrence

Total Link Strength

Average Year Published

Average Citations

Average Norm. Citation

Life-Cycle Assessment LCA Sustainability Environmental footprint Energy Carbon footprint Impact assessment Product environmental footprint Emissions Environmental impacts Green-house gas emissions Policy implementation Systems Breakdown Management Impacts Products Performance

112 68 45 40 32 22 21 21 25 23 16 14 21 13 13 15 14 14

235 133 117 94 75 64 61 59 58 58 52 51 43 40 40 38 36 34

2015 2015 2015 2015 2014 2015 2016 2016 2015 2016 2016 2016 2015 2016 2015 2015 2015 2015

10 10 8 11 9 5 10 10 8 9 5 4 11 5 9 8 5 9

0.9 0.8 0.8 1 0.8 0.5 1.1 0.7 0.7 1 0.6 0.7 0.8 0.6 0.9 1.1 0.8 1

2018). Studies concerning the application of organic amendments to substitute synthetic fertilizers have become popular, with an increasing number of studies following this direction (Akdeniz et al., 2006; Carbonell et al., 2011; Fusi et al., 2017; Graham et al., 2017). In addition, the implementation of new models that are more efficient, such as new water and energy systems, can have positive effects on the environment and promote the overall sustainability of agriculture (PARIHAR et al., 2018). Another spotted research area is the definition and the applicability of the EF. In the research fields of the EF, and EF and LCA, many publications include the actual definition of the indicator of the EF as proposed by the European Commission (European Commission, 2018). Additionally, one of the main concern in these research areas is the optimization of the design in biomass processes with the objective of reducing emissions (Stougie et al., 2018). Regarding the topic of mitigation of environmental impacts, it has been highlighted the great contribution of studies related to the carbon footprint in the fields of EF, and EF and LCA. The carbon footprint is one of the main indicators to assess environmental impacts. The first journal publication dates from 1992 and, to date, it is still regarded as a hot topic among the environmental research community worldwide (Caro, 2019). Furthermore, energy systems appear to be one of the main contributors to green-house emissions and it is highly followed by many studies (Kapila et al., 2019). As environmental deterioration is now evident, there is an urgent need to propose and assess the implementation of effective environmental policies (Li et al., 2019). Several countries across the world are focusing their attention on reducing environmental impacts (Liobikienė

Fig. 8. Mapping of journal sources in the Environmental Footprint and LifeCycle Assessment domain.

González-Acevedo, 2018). With respect to the different sectors, it has been documented that in the agriculture sector there is room for improvement by establishing green management practices (Qi et al.,

Table 6 Co-occurrence of journal sources in the Environmental Footprint and Life-Cycle Assessment literature. Journal Source

Number of publications

Total Link Strength

Average Year

Total citations

Average Citations

Average Norm. Citation

International Journal of Life Cycle Assessment Journal of Cleaner Production Sustainability Integrated Environmental assessment and Management Environmental Engineering and Management Journal Resources Conservation and Recycling Science of the Total Environment Journal of Industrial Ecology Journal of Environmental Management Environmnetal Science and Technology

31 52 7 4

33 24 16 12

2015 2016 2015 2015

382 464 59 18

11 10 8 5

1.1 1 0.9 0.6

4

8

2016

14

6

0.7

7 10 9 4 5

7 7 6 4 1

2014 2016 2014 2016 2014

197 44 146 43 181

27 7 16 9 25

1.4 1.5 1.1 1 0.9

8

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Fig. 9. Mapping of countries in the Environmental Footprint and Life-Cycle Assessment domain.

these research fields, there are some knowledge themes that future studies could consider. For example, investigations could be directed towards the development of alternative methods to quantify environmental impacts. In this sense, the input-output analysis has been proposed as a tool to complement the process-based approach to obtain the environmental performance of products and organizations throughout their life cycle (Lutter et al., 2016). Furthermore, special attention has to be drawn in sustainability studies towards social aspects. Recently, the inclusion of the social dimension is gaining importance through the application of the Social Life-Cycle Assessment (S-LCA) in both companies and products throughout their lifespan (Tsalis et al., 2017). Promoting the combination of environmental, economic and social aspects in publications will strengthen the basis of sustainable development (Long and Ji, 2019). Finally, studies assessing novel applications should be encouraged to demonstrate the applicability of environmental indicators. For example, the PEF and OEF have been quantified for some case studies (Cobut et al., 2015; Golsteijn et al., 2018; Martinez et al., 2018b; SoodeSchimonsky et al., 2017), but in order to establish a robust

and Butkus, 2017). In this sense, one of the main targets in Europe’s agenda has been direct towards the transitioning to more sustainable production and consumption by improving energy efficiency and establishing a common framework to assess the impacts known as the Environmental Footprint (European Commission, 2018). The final research area highlighted refers to the methodologies proposed to carry out an impact assessment. There is a consensus among researchers that the Life-Cycle Assessment approach is a valuable tool to obtain the environmental performance of different systems (Esteves et al., 2019; Ingrao et al., 2018). Given the usefulness of the LCA, the environmental standards of ISO 14040 and 14044 are based on this approach (ISO 14040, 2006; ISO 14044, 2006). In addition, with the appearance of the PEF and OEF, the LCA continues to exhibit high presence in literature, as these indicators are also based on a life-cycle perspective (European Commission, 2013, 2012a,b).

4.3. Knowledge gaps and future research This study has shed some light on the main trends in the EF, and EF and LCA research fields. Although much progress has been made in

Table 7 Co-occurrence of countries in the Environmental Footprint and Life-Cycle Assessment literature. Country

Number of publications

Total Link Strength

Average Year

Total citations

Average Citations

Average Norm. Citation

Italy Switzerland Germany USA France England Belgium Spain Sweden Norway Australia South Africa Canada Denmark Greece Scotland Netherlands India China Cyprus

42 17 35 51 26 23 20 13 16 10 15 6 16 10 17 10 12 7 10 5

35 33 32 32 31 28 23 21 21 15 14 14 13 13 12 11 10 5 5 2

2015 2016 2016 2014 2016 2015 2016 2017 2015 2014 2014 2014 2015 2015 2017 2017 2016 2017 2016 2016

251 127 239 1100 239 296 163 54 121 157 230 31 110 160 156 55 67 10 25 43

5 7 6 15 9 12 8 5 8 14 15 5 6 14 10 4 4 4 5 8

0.7 0.8 1.4 1.5 0.8 0.7 0.6 1 1 0.8 0.8 1.2 0.8 1 1.2 1.4 0.8 0.6 0.7 1.4

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methodology, many more assessments have to be performed.

Alvarez, S., Carballo-Penela, A., Mateo-Mantecón, I., Rubio, A., 2016. Strengths-weaknesses-opportunities-threats analysis of carbon footprint indicator and derived recommendations. J. Clean. Prod. 121, 238–247. https://doi.org/10.1016/j.jclepro. 2016.02.028. Asmelash, A.G., Kumar, S., 2019. Assessing progress of tourism sustainability: developing and validating sustainability indicators. Tour. Manage. 71, 67–83. https://doi.org/ 10.1016/j.tourman.2018.09.020. Bach, V., Lehmann, A., Görmer, M., Finkbeiner, M., Bach, V., Lehmann, A., Görmer, M., Finkbeiner, M., 2018. Product Environmental Footprint (PEF) pilot phase—comparability over flexibility? Sustainability 10, 2898. https://doi.org/10.3390/ su10082898. Bamgbade, J.A., Kamaruddeen, A.M., Nawi, M.N.M., Adeleke, A.Q., Salimon, M.G., Ajibike, W.A., 2019. Analysis of some factors driving ecological sustainability in construction firms. J. Clean. Prod. 208, 1537–1545. https://doi.org/10.1016/j. jclepro.2018.10.229. Bhatia, P., Cummis, C., Brown, A., Draucker, L., Rich, D., Lahd, H., Cummins, C., Brown, A., Draucker, L., Rich, D., Lahd, H., 2011. WRI, WBCSD, Product life cycle accounting and reporting standard. World Bus. Council. Sustain. Dev. 1–148. Bouscasse, H., Joly, I., Bonnel, P., 2018. How does environmental concern influence mode choice habits? A mediation analysis. Transp. Res. Part D Transp. Environ. 59, 205–222. https://doi.org/10.1016/j.trd.2018.01.007. Brundtland, G., 1987. Report of the World Commision on Environement and Development: Our Common Future. Oxford Pap. Report of, 400. doi:10.2307/ 2621529. Cañas-Guerrero, I., Mazarrón, F.R., Pou-Merina, A., Calleja-Perucho, C., Díaz-Rubio, G., 2013. Bibliometric analysis of research activity in the “Agronomy” category from the Web of Science, 1997–2011. Eur. J. Agron. 50, 19–28. https://doi.org/10.1016/j.eja. 2013.05.002. Carbonell, G., de Imperial, R.M., Torrijos, M., Delgado, M., Rodriguez, J.A., 2011. Effects of municipal solid waste compost and mineral fertilizer amendments on soil properties and heavy metals distribution in maize plants (Zea mays L.). Chemosphere 85, 1614–1623. https://doi.org/10.1016/j.chemosphere.2011.08.025. Caro, D., 2019. E. In: Fath, B.B.T.-E. (Ed.), Carbon Footprint, second ed. Elsevier, Oxford, pp. 252–257. https://doi.org/10.1016/B978-0-12-409548-9.10752-3. Chen, W., Wu, S., Lei, Y., Li, S., 2017. China’s water footprint by province, and interprovincial transfer of virtual water. Ecol. Indic. 74, 321–333. https://doi.org/10. 1016/j.ecolind.2016.11.037. Cobut, A., Blanchet, P., Beauregard, R.L., Cobut, A., Blanchet, P., Beauregard, R., 2015. The environmental footprint of interior wood doors in non-residential buildings-Part 1: life cycle assessment buildings e part 1: life cycle assessment. J. Clean. Prod. https://doi.org/10.1016/j.jclepro.2015.04.079. Čuček, L., Klemeš, J.J., Kravanja, Z., 2012. A Review of Footprint analysis tools for monitoring impacts on sustainability. J. Clean. Prod. 34, 9–20. https://doi.org/10. 1016/j.jclepro.2012.02.036. Darko, A., Chan, A.P.C., Huo, X., Owusu-Manu, D.-G., 2019. A scientometric analysis and visualization of global green building research. Build. Environ. 149, 501–511. https://doi.org/10.1016/j.buildenv.2018.12.059. de Oliveira Neto, G.C., Ferreira Correia, J.M., Silva, P.C., de Oliveira Sanches, A.G., Lucato, W.C., 2019. Cleaner Production in the textile industry and its relationship to sustainable development goals. J. Clean. Prod. https://doi.org/10.1016/j.jclepro. 2019.04.334. Eck, N.J. Van, Waltman, L., 2017. VOSviewer Manual. Ecological Footprint Standards, 2009. Ecological Footprint Standards 2009 [WWW Document]. accessed 10.10.18. https://www.footprintnetwork.org/content/images/ uploads/Ecological_Footprint_Standards_2009.pdf. Esteves, E.M.M., Herrera, A.M.N., Esteves, V.P.P., Morgado, C., do, R.V., 2019. Life cycle assessment of manure biogas production: a review. J. Clean. Prod. 219, 411–423. https://doi.org/10.1016/j.jclepro.2019.02.091. European commission, 2012. Policy background [WWW Document]. URL http://ec. europa.eu/environment/eussd/smgp/policy_footprint.htm (accessed 12.10.18). European Commission, 2018. Environmental Footprint [WWW Document]. accessed 10.3.17. http://ec.europa.eu/environment/eussd/smgp/policy_footprint.htm. European Commission, 2013. Organisation Environmental Footprint Guide. Eur. Comm. Res. Centre-Institute Environ. Sustain. 56, 216 doi:10.3000/ 19770677.L_2013.124.eng. European Commission, 2012. Product Environmental Footprint (PEF) Guide. European Commission, 2011. Roadmap to a Resource Efficient Europe. Finkbeiner, M., 2014. Product environmental footprint – breakthrough or breakdown for policy implementation of life cycle assessment? Int. J. Life Cycle Assess. 19, 266–271. https://doi.org/10.1007/s11367-013-0678-x. Fusi, A., González-García, S., Moreira, M.T., Fiala, M., Bacenetti, J., 2017. Rice fertilised with urban sewage sludge and possible mitigation strategies: an environmental assessment. J. Clean. Prod. 140, 914–923. https://doi.org/10.1016/j.jclepro.2016.04. 089. Galatola, M., Pant, R., 2014. Reply to the editorial “product environmental footprint – breakthrough or breakdown for policy implementation of life cycle assessment?” Written by Prof. Finkbeiner (Int J Life Cycle Assess 19(2), 266–271). Int. J. Life Cycle Assess. 19, 1356–1360. https://doi.org/10.1007/s11367-014-0740-3. Galli, A., Wiedmann, T., Ercin, E., Knoblauch, D., Ewing, B., Giljum, S., 2012. Integrating ecological, carbon and water footprint into a “footprint family” of indicators: definition and role in tracking human pressure on the planet. Ecol. Indic. 16, 100–112. https://doi.org/10.1016/j.ecolind.2011.06.017. Gazbour, N., Razongles, G., Monnier, E., Joanny, M., Charbuillet, C., Burgun, F., Schaeffer, C., 2018. A path to reduce variability of the environmental footprint results of photovoltaic systems. J. Clean. Prod. 197, 1607–1618. https://doi.org/10.1016/j. jclepro.2018.06.276.

5. Conclusion This review provides valuable information for researchers and practitioners in the field of the Environmental Footprint. The scientometric analysis and mapping show the status quo and research trend in this domain, with special emphasis on the EF and LCA and the development of the European PEF and OEF. Two datasets were analyzed: (1) EF dataset and (2) EF and LCA dataset. The bibliometric and scientometric analysis of the Environmental Footprint dataset revealed the following conclusions:

• An increasing trend in publications from 1992 to 2018 is observed. • The documents which have the highest influence are the ISO 14044 and ISO 14040. • Keyword analysis and science mapping spotted sustainability and •

Life-Cycle Assessment as the terms with the highest values of total link strength and occurrence and the keywords green-house gas emissions and climate-change as the terms with the highest average citations and average normalized citation. Keywords were grouped in five main clusters, such as sustainability (e.g., performance), research studies related to the EF (e.g., biomass), green-house gas emissions (e.g., carbon footprint), policy actions (e.g., energy efficiency) and the methodological approaches (Life-Cycle Assessment).

The bibliometric and scientometric analysis of the EF and LCA dataset revealed the following conclusions:

• An increasing trend in publications from 2000 to 2016 is observed until 2017. • Both ISO documents (14040 and 14044) are the publications with • • •

the highest impact in the research community, followed by research articles related to the PEF. Four main research areas are identified with the co-occurrence of keywords referring to policy implementation (e.g., impact assessment), sustainability (e.g., carbon footprint), environmental impact sources (e.g., energy) and the definition of the Environmental Footprint (e.g., Life-Cycle Assessment). The most contributing sources of the EF and LCA are International Journal of Life Cycle Assessment, Journal of Cleaner Production and Sustainability. USA and European countries, such as Italy, Germany, and France, are the most active countries in the EF and LCA research field.

It has to be noticed that this study relied upon published literature. Furthermore, this review only studied documents published in English. As an overall, this scientometric analysis-based review provides researchers and practitioners with valuable information based on a comprehensive analysis of the current EF literature and future trends. Acknowledgments This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. References ADEME, 2011. General principles for an environmental communication on mass market products Part 0: General principles and methodological framework 1–38. Akdeniz, H., Yilmaz, I., Bozkurt, M.A., Keskin, B., 2006. The effects of sewage sludge and nitrogen applications on grain sorghum grown (Sorghum vulgare L.) in Van-Turkey. Polish J. Environ. Stud. 15, 19–26. Albort-Morant, G., Henseler, J., Leal-Millán, A., Cepeda-Carrión, G., 2017. Mapping the field: a bibliometric analysis of green innovation. Sustainability 9, 1011. https://doi. org/10.3390/su9061011.

10

Ecological Indicators 106 (2019) 105543

S. Martinez, et al.

scitotenv.2017.10.306. Neppach, S., Nunes, K.R.A., Schebek, L., 2017. Organizational environmental footprint in German construction companies. J. Clean. Prod. 142, 78–86. https://doi.org/10. 1016/j.jclepro.2016.05.065. Olawumi, T.O., Chan, D.W.M., 2018. A scientometric review of global research on sustainability and sustainable development. J. Clean. Prod. 183, 231–250. https://doi. org/10.1016/j.jclepro.2018.02.162. Parihar, C.M., Yadav, M.R., Jat, S.L., Singh, A.K., Kumar, B., Pooniya, V., Pradhan, S., Verma, R.K., Jat, M.L., Jat, R.K., Parihar, M.D., Nayak, H.S., Saharawat, Y.S., 2018. Long-term conservation agriculture and intensified cropping systems: effects on growth, yield, water, and energy-use efficiency of Maize in Northwestern India. Pedosphere 28, 952–963. https://doi.org/10.1016/S1002-0160(17)60468-5. PAS 2050, 2011. Specification for the assessment of the life cycle greenhouse gas emissions of goods and services [WWW Document]. URL http://www.bsigroup.com/en/ Standards-and-Publications/How-we-can-help-you/Professional-Standards-Service/ PAS-2050/ (accessed 10.10.18). Poolsawad, N., Thanungkano, W., Mungkalasiri, J., Wisansuwannakorn, R., Suksatit, P., Jirajariyavech, A., Datchaneekul, K., 2017. Thai national life cycle inventory readiness for product environmental footprint. Int. J. Life Cycle Assess. 22, 1731–1743. https://doi.org/10.1007/s11367-016-1257-8. Pryshlakivsky, J., Searcy, C., 2013. Fifteen years of ISO 14040: a review. J. Clean. Prod. 57, 115–123. https://doi.org/10.1016/j.jclepro.2013.05.038. Qi, X., Fu, Y., Wang, R.Y., Ng, C.N., Dang, H., He, Y., 2018. Improving the sustainability of agricultural land use: an integrated framework for the conflict between food security and environmental deterioration. Appl. Geogr. 90, 214–223. https://doi.org/10. 1016/j.apgeog.2017.12.009. Quintero-Angel, M., González-Acevedo, A., 2018. Tendencies and challenges for the assessment of agricultural sustainability. Agric. Ecosyst. Environ. 254, 273–281. https://doi.org/10.1016/j.agee.2017.11.030. Rockström, J., Steffen, W., Noone, K., Persson, Å., Chapin, F.S., Lambin, E.F., Lenton, T.M., Scheffer, M., Folke, C., Schellnhuber, H.J., Nykvist, B., de Wit, C.A., Hughes, T., van der Leeuw, S., Rodhe, H., Sörlin, S., Snyder, P.K., Costanza, R., Svedin, U., Falkenmark, M., Karlberg, L., Corell, R.W., Fabry, V.J., Hansen, J., Walker, B., Liverman, D., Richardson, K., Crutzen, P., Foley, J.A., 2009. Planetary boundaries: exploring the safe operating space for humanity. Nature 461, 472–475. https://doi. org/10.1038/461472a. Roy, V., Singh, S., 2017. Mapping the business focus in sustainable production and consumption literature: review and research framework. J. Clean. Prod. 150, 224–236. https://doi.org/10.1016/j.jclepro.2017.03.040. Soode-Schimonsky, E., Richter, K., Weber-Blaschke, G., 2017. Product environmental footprint of strawberries: case studies in Estonia and Germany. J. Environ. Manage. 203, 564–577. https://doi.org/10.1016/j.jenvman.2017.03.090. Stougie, L., Tsalidis, G.A., van der Kooi, H.J., Korevaar, G., 2018. Environmental and exergetic sustainability assessment of power generation from biomass. Renew. Energy 128, 520–528. https://doi.org/10.1016/j.renene.2017.06.046. Trujillo, C.M., Long, T.M., 2018. Document co-citation analysis to enhance transdisciplinary research. Sci. Adv. 4, e1701130. https://doi.org/10.1126/sciadv.1701130. Tsalis, T., Avramidou, A., Nikolaou, I.E., 2017. A social LCA framework to assess the corporate social profile of companies: insights from a case study. J. Clean. Prod. 164, 1665–1676. https://doi.org/10.1016/j.jclepro.2017.07.003. United Nations, 2013. World Economic and Social Survey 2013 Sustainable Development Challenges. van Eck, N.J., Waltman, L., 2010. Software survey: VOSviewer, a computer program for bibliometric mapping. Scientometrics 84, 523–538. https://doi.org/10.1007/ s11192-009-0146-3. Vieira, M., 2018. Product environmental footprinting – the new European standard [WWW Document]. URL https://www.pre-sustainability.com/sustainability-consulting/sustainable-innovation/product-environmental-footprinting (accessed 10. 10.18). Wade, A., Stolz, P., Frischknecht, R., Heath, G., Sinha, P., 2018. The Product Environmental Footprint (PEF) of photovoltaic modules—lessons learned from the environmental footprint pilot phase on the way to a single market for green products in the European Union. Prog. Photovolt. Res. Appl. 26, 553–564. https://doi.org/10. 1002/pip.2956. White, D.J., Hubacek, K., Feng, K., Sun, L., Meng, B., 2017. The Water-Energy-Food Nexus in East Asia : a tele-connected value chain analysis using inter-regional input-output analysis. Appl. Energy. https://doi.org/10.1016/j.apenergy.2017.05.159. Wuni, I.Y., Shen, G.Q.P., Osei-Kyei, R., 2019. Scientometric review of global research trends on green buildings in construction journals from 1992 to 2018. Energy Build. 190, 69–85. https://doi.org/10.1016/j.enbuild.2019.02.010. Zhang, Y., Huang, K., Yu, Y., Yang, B., 2017. Mapping of water footprint research: a bibliometric analysis during 2006–2015. J. Clean. Prod. 149, 70–79. https://doi.org/ 10.1016/j.jclepro.2017.02.067.

Godfray, H.C.J., Beddington, J.R., Crute, I.R., Haddad, L., Lawrence, D., Muir, J.F., Pretty, J., Robinson, S., Thomas, S.M., Toulmin, C., 2010. Food security: the challenge of feeding 9 billion people. 812 LP-818. Science (80-) 327. https://doi.org/10.1126/ science.1185383. Golsteijn, L., Lessard, L., Campion, Jean-florent, Capelli, A., D’Enfert, V., King, H., Kremer, J., Krugman, M., Orliac, H., Roullet Furnemont, S., Schuh, W., Stalmans, M., Williams O’Hanlon, N., Coroama, M., 2018. Developing Product Environmental Footprint Category Rules (PEFCR) for shampoos – the basis for comparable life cycle assessments: product environmental footprint category rules for shampoos. Integr. Environ. Assess. Manage. 14. Graham, R.F., Wortman, S.E., Pittelkow, C.M., 2017. In: Comparison of Organic and Integrated Nutrient Management Strategies for Reducing Soil N2O Emissions, https:// doi.org/10.3390/su9040510. Guinée, J., Gorrée, M., Heijungs, R., Huppes, G., Kleijn, R., de Koning, A., Oers, L., Wegener Sleeswijk, A., Suh, S., de Haes, H., Bruijn, H., van Duin, R., Huijbregts, M., 2002. Handbook on LCA, Operational Guide to the ISO Standards. Hosseini, M.R., Martek, I., Zavadskas, E.K., Aibinu, A.A., Arashpour, M., Chileshe, N., 2018. Critical evaluation of off-site construction research: a scientometric analysis. Autom. Constr. 87, 235–247. https://doi.org/10.1016/j.autcon.2017.12.002. Ingrao, C., Messineo, A., Beltramo, R., Yigitcanlar, T., Ioppolo, G., 2018. How can life cycle thinking support sustainability of buildings? Investigating life cycle assessment applications for energy efficiency and environmental performance. J. Clean. Prod. 201, 556–569. https://doi.org/10.1016/j.jclepro.2018.08.080. ISO, 2018. International Organization for Standardization [WWW Document]. accessed 10.10.18. https://www.iso.org/standards.html. ISO 14040, 2006. Environmental management – Life cycle assessment - Principles and framework [WWW Document]. URL https://www.iso.org/standard/37456.html (accessed 12.10.18). ISO 14044, 2006. Environmental management – Life cycle assessment – Requirements and guidelines [WWW Document]. URL https://www.iso.org/standard/38498.html (accessed 10.12.18). Jin, R., Gao, S., Cheshmehzangi, A., Aboagye-Nimo, E., 2018. A holistic review of off-site construction literature published between 2008 and 2018. J. Clean. Prod. 202, 1202–1219. https://doi.org/10.1016/j.jclepro.2018.08.195. Jin, R., Yuan, H., Chen, Q., 2019. Science mapping approach to assisting the review of construction and demolition waste management research published between 2009 and 2018. Resour. Conserv. Recycl. 140, 175–188. https://doi.org/10.1016/j. resconrec.2018.09.029. Kapila, S., Oni, A.O., Gemechu, E.D., Kumar, A., 2019. Development of net energy ratios and life cycle greenhouse gas emissions of large-scale mechanical energy storage systems. Energy 170, 592–603. https://doi.org/10.1016/j.energy.2018.12.183. Kjaer, L.L., Høst-Madsen, N.K., Schmidt, J.H., McAloone, T.C., 2015. Application of environmental input-output analysis for corporate and product environmental footprints-learnings from three cases. Sustain 7, 11438–11461. https://doi.org/10.3390/ su70911438. Konur, O., 2012. The evaluation of the global research on the education: a scientometric approach. Proc. – Soc. Behav. Sci. 47, 1363–1367. https://doi.org/10.1016/j.sbspro. 2012.06.827. Lehmann, A., Bach, V., Finkbeiner, M., 2016. EU product environmental footprint-midterm review of the pilot phase. Sustain 8, 1–13. https://doi.org/10.3390/su8010092. Li, X., Yang, X., Wei, Q., Zhang, B., 2019. Authoritarian environmentalism and environmental policy implementation in China. Resour. Conserv. Recycl. 145, 86–93. https://doi.org/10.1016/j.resconrec.2019.02.011. Liobikienė, G., Butkus, M., 2017. The European Union possibilities to achieve targets of Europe 2020 and Paris agreement climate policy. Renew. Energy 106, 298–309. https://doi.org/10.1016/j.renene.2017.01.036. Long, X., Ji, X., 2019. Economic growth quality, environmental sustainability, and social welfare in China – Provincial assessment based on Genuine Progress Indicator (GPI). Ecol. Econ. 159, 157–176. https://doi.org/10.1016/j.ecolecon.2019.01.002. Lutter, S.P.S., Giljum, S., Wieland, H., Mutel, C., 2016. Spatially explicit assessment of water embodied in European trade : a product-level multi-regional input-output analysis. Glob. Environ. Change 38, 171–182. https://doi.org/10.1016/j.gloenvcha. 2016.03.001. Martinez, S., del Mar Delgado, M., Marin, R.M., Alvarez, S., 2018a. The environmental footprint of an organic peri-urban orchard network. Sci. Total Environ. 636, 569–579. https://doi.org/10.1016/j.scitotenv.2018.04.340. Martinez, S., Delgado, M. del M., Martinez Marin, R., Alvarez, S., 2018b. The Environmental Footprint of the end-of-life phase of a dam through a hybrid-MRIO analysis. Build. Environ. 146, 143–151. https://doi.org/10.1016/j.buildenv.2018.09. 049. Martinez, S., Marchamalo, M., Alvarez, S., 2018c. Organization environmental footprint applying a multi-regional input-output analysis: a case study of a wood parquet company in Spain. Sci. Total Environ. 618, 7–14. https://doi.org/10.1016/j.

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