1 Introduction

Without a doubt, universities play a critical role in modern societies in order to solve contemporary social issues and stimulate sustainable ways to preserve natural resources. Universities as organizations can contribute and promote sustainable development through various ways including changes in research orientation, curriculum and operational aspects. More specifically, a common practice of universities is greening their curriculum by introducing sustainability issues into their conventional courses or creating new courses focused on topics regarding sustainable development [1]. They adopt management systems and technologies or practices to improve their environmental footprint and reduce the social impacts within the university campus [2]. In addition, many universities participate in research projects to examine effective and sustainable solutions for society and also they incorporate sustainability-related criteria into their investment decision process [3, 4].

After 2015, the quest for actual improvement in sustainable performance has led many universities to align their sustainability agenda with the sustainable development goals (SDGs) launched by the UN’s Agenda 2030 to promote sustainability [5,6,7]. This implies that universities should manage the requirements of SDGs beyond their institutional boundaries by strengthening their cooperation with governments and other key stakeholders [8]. Universities could work with internal (e.g. faculty, staff and students) and external stakeholders (e.g. local communities, NGOs and government) to promote SDGs [9].

Actually, universities play a central role in changing the current institutions, disseminating knowledge and sharing new ideas with modern society. Therefore, universities need to strengthen the dialogue and cooperation with stakeholders mainly to transfer knowledge about SDGs and sustainability as well as to receive feedback to improve their courses and strategies and thus to reflect the needs of modern societies with regards to sustainability issues. As in any organization, sustainability reporting is a significant communication tool for universities to inform stakeholders appropriately about their sustainability practices and performance, facilitating dialogue [10]. However, sustainability reporting practices of universities have some differences in relation to business community which adopts the standard guidelines prepared by independent international organizations in order to gain their legitimacy and frame a reliable sustainability dialogue framework with stakeholders. To deal with these peculiarities of the universities’ sustainability reporting practices, [11] suggested some tools based on Global Reporting Initiative (GRI) guidelines to assist universities in incorporating experience of GRI guidelines into educational practices and research strategies of universities. To identify the current level of universities sustainability reporting and GRI’s requirements, [12] utilize a content analysis technique based on GRI indicators to examine the sustainability reporting behavior of a sample of universities and identify significant differences in disclosure behavior between different institutional contexts and geographical regions.

Having in mind the significant role of sustainability reports in the accountability of universities, this paper utilizes an evaluation framework to assess the content of sustainability reports published by universities and especially, to evaluate the quality of disclosed information related to the SDGs. The aim is to identify how effective the non-financial reporting practices of universities are in communicating their contribution to sustainability. The suggested framework is based on a set of GRI topics to evaluate each SDG through sustainability reports. A sample of 37 universities’ sustainability reports was used for the purpose of this research which can provide some insights into the universities’ reporting practices which can be the basis for future research.

The remainder of this paper is organized into five sections. In Sect. 2, the theoretical background regarding universities and sustainability as well as universities’ sustainability reporting is presented. In Sect. 3, the evaluation scoring system is discussed and the fourth section presents the results of this study. In Sect. 5, the main contributions of this paper are discussed and the final section draws the main conclusions highlighting possible directions for future research rested on the limitations of this study.

2 Theoretical background

2.1 Universities and sustainable development

During the last decades, sustainable development has been gaining visibility and momentum worldwide from various interested parties. Actually, sustainable development is a normative concept formed by various disciplines such as ecological economics, political ecology, social sciences and natural-based science [13]. To fully comprehend the concept of sustainable development, an analysis of some key milestones is necessary [14]. The first milestone is the definition of sustainable development proposed by the World Commission on Environment and Development (WCED) in its report “Our common Future” which pinpoints that development should “meet the needs of the present without compromising the ability of future generations to meet their own needs” [15]. This definition is mainly associated with the preservation of natural resources and social equity (intergenerational equity). Also, in this report, considerable attention has been given to the role of education in promoting the concept of sustainable development, in creating public awareness and in hel** decision makers shape their agendas for political changes in the future.

The second milestone was the United Nations Conference on Environment & Development (UNCED) and Agenda 21 which defined that sustainable development promotes simultaneously economic development, environmental protection and social equity. Agenda 21 highlights the role of universities in cooperating with NGOs and industries in order to educate people and strengthen their awareness of environmental issues (chapter 36). The latest crucial step in the evolution of the concept of sustainability was the UN’s Agenda 2030 for sustainable development which broadened the content of sustainable development by defining 17 SDGs [6]. There are various networks and associations which have been developed to introduce principles of sustainable development into higher education with several universities around the world adopting the principles of sustainable development into their research projects, curriculum and organizational operations and practices to improve their environmental performance [16]. In particular, as part of their sustainability action plan, universities devote their efforts to green their curriculum by introducing sustainability principles into the courses of all educational cycles [17, 18] suggested certain ways to green a university’s syllabus by focusing on three aspects such as subject analysis (e.g. reformation of the current subjects by incorporating sustainability issues), syllabus analysis (e.g. introduction of new courses in existing syllabus) and institutional cooperation (e.g. participation in networks to promote sustainable development).

Moreover, many universities change their research orientation in order to promote sustainable development issues. Actually, university research projects could be a good mechanism to promote valuable sustainable development principles for modern societies. This priority was highlighted at the World Conference about ‘‘Declaration on Science and the Use of Scientific Knowledge’’ where the role of science was defined as “the service of humanity as a whole, and should contribute to providing everyone with a deeper under-standing of nature and society, a better quality of life and a sustainable and healthy environment for present and future generations” ([19], Annex I-p.1). In alignment with the definition of sustainable development presented in the [15, 20] suggested that the universities’ sustainability research meet the needs of the current generation ensuring that future generations are able to meet their own.

Furthermore, sustainability is also a core element embedded in university campus operations. Many universities have adopted certain environmental practices and management systems to reduce their negative impacts (externalities) on the natural environment and society [21, 22]. In this context, many universities have made an effort to measure their carbon footprint and adopt zero carbon practices [23,24,25].

Seeking to eliminate the direct and indirect adverse impacts of their operations on sustainable development, many universities decide to introduce environmental and socially responsible criteria in their procurement procedures or investment decisions [4, 26]. Such criteria help universities to avoid cooperations with firms or other stakeholders where their activities are not in line with their universities’ sustainable strategies and polices. In this context, [27] identified that the green purchasing of universities could promote solar photovoltaic energy [28] found that the public Spanish universities have introduced green criteria into university procurement procedures and they have also organized media programs to diffuse environmental knowledge to strengthen the environmental awareness of citizens.

2.2 Universities and SDGs

The introduction of the UN’s 2030 Agenda for sustainable development marked the beginning of a new era for sustainability where all organizations and human activities should be in line with the requirements of the17 SDGs associated with social issues (e.g. no poverty (SDG1) and zero hunger (SDG2), good health and well-being (SDG3), gender equality and reduced inequality (SDG5 and 10)), environmental issues (e.g. climate action (SDG13), life below water and on land (SDG14 and 15), sustainable cities and communities (SDG11)) and economic-related issues (e.g. decent work and economic growth (SDG8), responsible consumption and production(SDG12)). In this new realm of sustainability, universities have integrated SDGs into all aspects of their operations [8]. Also, the promotion of SDGs among universities, is supported by several university movements such as, the Principles of Responsible Management Education (PRME) initiative and the Sustainable Development Solutions Network (SDSN) as well as collaborations with governmental bodies and communities. The literature provides studies which examine how universities deal with the SDGs and according to [5], these studies can be classified into four categories: governance, education learning, social leadership and research.

More specifically, there are studies which analyze what strategies and actions are implemented by universities in order to strengthen their accountability level regarding SDGs and also the means of introducing principles at an organization level. In this regard, [29] analyze the corporate social responsibility and SDGs strategy of Italian universities. They identified that such issues are not well addressed and thus universities should show a stronger commitment to SDGs and sustainability [30] identified that many universities have adopted various campus operations to deal with energy issues either by strengthening the knowledge and awareness of students or by implementing energy systems and renewable energy systems to eliminate energy consumption. Similarly, many universities seem to put SDG 15 (i.e. life on land) at the center of their sustainability strategy by promoting practices which improve existing green areas/spaces on campus and also create new ones [31].

Furthermore, as for teaching programs, universities introduce various models to align curricula with the SDGs principles, use new learning methods regarding SDGs and develop teaching staff and students’ awareness of SDGs [32, 33]. By conducting a survey, [34] identified that 55 faculty members, who participated in the survey, had tried to align the objectives of their courses with SDGs.

Today, universities are regarded as one of the main determinants which can have a strong effect on the engagement of local communities and regions in the sustainable development and the accomplishment of SDGs. The success of universities in motivating local communities to embrace SDGs is linked with the effectiveness of university's management models and the field of study [35]. Some scholars highlight the institutional character of universities which is very important to inform local communities of the importance of SDGs [8] which can be further supported by a strong partnership between universities with local organizations so as to promote SDGs as well as to create effective mechanisms to gather appropriate and accurate information regarding the needs of local communities in relation to SDGs [32].

The literature demonstrates various factors which could affect the stance of universities towards SDG disclosures such as the size, the age of the university and the focus of SDGs [36], and also factors that affect the efforts of universities to promote SDGs such as, government’ funding for universities, infrastructure and research, the universities social media engagement and their degree of extroversion on a global level [37].

2.3 Universities and sustainability reporting

Organizations have developed sustainability reporting practices to increase their accountability regarding sustainability issues by offering appropriate information to all interested parties about their sustainability management system and performance. This type of information is also necessary for various groups of stakeholders to make safer and more correct decisions by avoiding potential risks associated with sustainability issues [38, 39].

In general, the literature has shown both mandatory and voluntary factors which lead organizations to adopt sustainability reporting practices and disclose relevant information [40]. For example, for-profit companies have to disclose non-financial information (such as environmental, social and governance (ESG)) since the banking and financial sector require such information before lending to companies (European Directive 95/2014 and Taxonomy regulation). However, although there is not a clear regulatory regime for not-for-profit organizations concerning sustainability disclosures, these organizations have developed voluntarily mechanisms to prepare standalone sustainability reports. Sustainability reporting practices have also been adopted by universities which have included them in their sustainability policy aiming to inform their stakeholder groups about their sustainability actions as well as to encourage stakeholder groups to adopt sustainability initiatives.

In view of the importance of sustainability disclosures, various international organizations, such as the GRI, Sustainability Accounting Standard Boards (SASBs) and Integrated Reports (IR), have created guidelines and frameworks to address issues in relation to non-financial reporting procedures in order to assist organizations in preparing and disclosing sustainability information [9, 41, 42]. Specifically, GRI’s guidelines are a popular framework [43] many universities have adopted them to gather, prepare and disclose sustainability information [44]. According to [44], European universities seem to be more familiar with the GRI standards than universities from other continents. In this ranking, North America’s universities were in second place and Latin America’s universities ranked third, while universities from Asia and Oceania had the lowest adoption level. By using GRI standard, [45] have developed a framework with 56 indicators in order to investigate the content of a sample of sustainability reports published by 25 Canadian universities. The findings indicate that the majority of universities have a similar approach with the for-profit-organization in terms of the disclosure topics (e.g. eco-efficiency and green architecture) providing less information regarding research and teaching issues. In contrast, [46] showed that universities disclose less information about sustainability performance than information regarding programs to educate students on sustainability issues. Based on a weight factor rating system, [47] identified that the majority of the examined universities disclose information for all aspects of sustainability such as economy, environment and society. In particular, they identified that the highest scores were given to direct and indirect emissions, labor practices and decent work as well as to economic performance.

By analyzing sustainability reporting of 12 universities from different European countries, [48] identified that more emphasis has been placed on environmental issues (e.g. material use and recycling, energy and water consumption, and emissions), while for social issues the focus is on the labor practices and decent work category. In addition, the low level of disclosure can be improved by taking advantage of the best practices and experience from the business community [48, 49] have identified that few Turkish universities have published sustainability reports due to various internal or external factors such as low stakeholders’ pressures, scarcity of financial capital and lack of skilled employments [50]. examined a sample of Australian and Austrian universities and they identified that most emphasis has been placed on economic results and less on environmental and social activities. Similarly, [51] conducted a content analysis on 23 US universities’ sustainability reports and they found a low disclosure level regarding social and economic information and a higher disclosure level and interest in environmental issues mainly because of the government’s financial support for university environmental projects.

As regards the factors which influence the quality of universities’ sustainability disclosures, previous research has highlighted the previous innovation experience of universities, the political context and parameters related to the operation of universities [52] explained the corporate sustainability strategies of German universities based on the theories of stakeholders, legitimacy, and neo-Institutionalism. Examining a sample of 32 universities from various continents, [53] show that their sustainability reporting behavior is affected by both external and internal stakeholders. Additionally, they identify that sampled universities have a low level of disclosures concerning material aspects and also adopt a superficial way to reach the materiality principle [54] identifies that universities upgrade sustainability management and reporting practices in order to increase their accountability level and improve their sustainability performance. Also, it is stressed that universities should prepare their own sustainability reporting guidelines due to the fact that the guidelines for for-profit organizations are not appropriate for the needs of universities [54].

Considering the dynamic and complex nature of the sustainability concept which is constantly evolving and the importance of sustainability reports, which serve as an informative tool for understanding the sustainability contribution of universities, there is a constant need for a systematic examination and evaluation of universities sustainability reports. The outcomes of such studies will not only show the evolution of universities’ non-financial reporting approach but also areas for potential enhancement in order to completely fulfill their informative objective. With this respect, this paper offers further evidence for the non-financial disclosures of universities in relation to the new directions of sustainability shaped by the 2030 Agenda for sustainable development. It highlights how universities present their actions and performance in relation to the different SDGs.

3 Methodological approach

The methodological approach for the evaluation of university sustainable reporting practices is a synthesis of diverse components (i.e. concepts, frameworks and tools) which have already been suggested and effectively used in the field of sustainable development in general, and non-financial reporting practices of organizations in particular. Basically, the architecture of the proposed methodological approach consists of two main components (see Fig. 1). The first one focuses on the reporting framework which defines the sustainability topics which should be covered by universities’ sustainability reports and the second part is related to the configuration of an evaluation system which enables the assessment of the quality of sustainability reports. The next sections thoroughly explain the logic of the proposed methodological approach and the role of each component.

Fig. 1
figure 1

Flowchart of the methodological approach

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3.1 Reporting framework

The reporting framework is placed at the center of the suggested methodological approach. It specifies a set of issues associated with the universities’ contributions towards sustainable development and consequently they constitute reporting topics for which relative information should be disclosed in sustainability reports published by universities to inform interested parties about their sustainability management practices and performance.

As sustainability is a manifold concept which is constantly evolving [55], the main concern during the design process was that the reporting framework has to embrace up-to-date sustainability aspects or topics in line with the latest directions in the sustainability concept. In this context, the 2030 Agenda for Sustainable Development is one of the latest breakthroughs in the sustainable development, which directs and coordinates the global actions to achieve a specific set of 17 SDGs [56, 57]. Actually, there are already efforts to help organizations to embrace SDGs in their non- financial reporting practices [58, 59]. These initiatives offer guidance and a set of reporting topics per SDG through which organizations can organize their reporting processes and prepare their sustainability reports.

For this reason, the 2030 Agenda was selected for the foundation of the proposed reporting framework, defining the main sustainability issues for which universities should provide information and data in their sustainability reports. Τable 1 details the sustainability issues (SI) each corresponds to a particular SDG suggested by 2030 Agenda, and the sustainability topics used for the evaluation of each SI. As can be seen, the reporting framework consists of 207 sustainability topics grouped into 17 sustainability issues (i.e. SDGs). It is important to be mentioned that all sustainability topics have been developed by the Global Reporting Initiative (GRI) [60] which is a well-known and leading organization in the field of non-financial reporting, and an increasing number of firms are adopting its sustainability reporting guidelines [42]. The latest version of its sustainability reporting guidelines is the GRI standards which are periodically revised to keep up with the latest changes in the sustainability field. More specifically, GRI standards provide a set of topic disclosures which provide firms with explicit instructions on how to disclose sustainability information. For instance, according to the disclosure topic “406–1: Incidents of discrimination and corrective actions taken” an organization which wants to disclose such information should refer, among other things, to the number of discrimination incidents and how the organization deals with such incidents [61].

In essence, in the suggested methodology the disclosure topics of GRI standards, which serve as sustainability topics, were classified into sustainability issues based on the previous relative methodologies [58, 59]. Also, the suggested classification of sustainability topics has already been used by [62] in order to examine the reporting practices of a sample of Greek firms.

3.2 Evaluation system

The next part of the proposed approach for the assessment of universities’ reporting practices is an evaluation system. Except for the reporting framework, other crucial elements are the analysis of sustainability reports and the classification of the assessed SI into broad sustainability areas (SA). The former is used to codify whether or not a report provides information about each of the suggested sustainability topics and the latter gives a picture of universities’ contributions to specific sustainability areas in accordance with the 2030 Agenda.

As for the analysis of sustainability reports, a binary scale was used to codify the disclosed information. It is based on the scoring techniques which have been broadly used for evaluating the quality of non-financial information disclosed through different means [63,64,65,66,67]. The goal of the suggested binary scale was to record the presence or absence of information regarding a particular sustainability topic in a sustainability report. Thus, for each sustainability topic (0) zero points were assigned when an examined report does not disclose information about a specific sustainability topic and (1) point was assigned when information is provided by a sustainability report for a particular sustainability topic. For example, one of the sustainability topics was 302–1 (see Table 1) which associated with energy consumption within organization, if a report discloses such information 1 point was given otherwise no point was given. Therefore, such codification process provides appropriate feedback for estimating in numeric terms the completeness of a sustainability report in relation to the requirements of the suggested reporting framework. A similar binary scoring scale was used by [68] who examined the environmental disclosures from a sample of Sri Lankan firms using 0–1 scale and a set of environmental topics based on GRI. Also, [69] developed an evaluation tool based on a binary scale and a set of disclosure items to evaluate the corporate social responsibility disclosure of UAE banks.

Table 1 Sustainability issues and topics for the evaluation of universities’ sustainability reports
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Concerning the sustainability area (SA) classification, motivated by the approach presented by the European University Association (EUA) in relation to SDGs [70], four sustainability areas were defined in which the sustainability issues can be classified (Table 2). More specifically, the first sustainability area focuses on “Well-being” (SA1) which consists of seven sustainability issues. Among other things, this area is related to the reduction of poverty and inequality, the promotion of good health and also regional development, which are sustainability aspects where universities can have a strong impact. The “Environment” is the second sustainability area (SA2) which includes four SI associated with the contribution of universities to understand and confront crucial environmental challenges such as the protection of natural ecosystems and climate change. The third sustainability area is the “Economy” (SA3) where universities are able to promote and support sustainable economic growth as well as sustainable production and consumption patterns. The last sustainability area is characterized as “Generic” (SA4) and comprises four sustainability issues, where the contribution of universities in this SA affects the achievement of objectives of the other sustainability areas.

Table 2 Sustainability areas (SA)
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4 Empirical analysis

This section presents the empirical analysis carried out in order to explore the sustainability reporting practices of universities. Particularly, it explains the sample selection process and also the main results from the evaluation of the sampled reports.

4.1 Sample and data selection

As for data collection, a sample of 37 universities from different continents was used for the purpose of the empirical analysis. All the universities selected were found from the GRI’s database where universities had registered their sustainability reports. This database offered free access to sustainability reports and thus it was easy to gather them facilitating the data collection process. In particular, through a search on the GRI’s database, the more recent English-written sustainability report available/registered by each university was downloaded.

The majority of the sustainability reports have been prepared by universities from north America (18 reports) and Oceania (10 reports), whereas five and four reports were published by European and Asian universities, respectively. As regards the publication year of the sustainability reports, the analysis covered on an eleven-year reporting period spanning from 2010 to 2020 and most of the reports were published in 2015, 2016 and 2017. Interestingly, owing to the fact that the UN introduced the 2030 Agenda in 2015, sampled reports can be divided into two groups. The first group includes 23 sustainability reports which were prepared in the period 2010–2016, in other words, reports which were published prior to the introduction of the 2030 Agenda for sustainable development. This group also includes reports prepared in 2016 because examined universities might not have had enough time to adjust their reporting practices to the requirements of the 2030 Agenda. The second group consists of 14 reports published after 2016, which means that universities had time to rearrange their reporting strategy in accordance with the requirements and directions of the 2030 Agenda (Table 3).

Table 3 Classification of sustainability reports according to publication year
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4.2 Data analysis and results

Having defined the final set of sustainability reports, the next step was a careful and in-depth examination of the content of the sustainability reports so as to highlight and examine sections of the reports which provide information relevant to the sustainability topics of the reporting framework. More specifically, two experienced reviewers in preparation and analysis of sustainability reports were responsible for the codification process. Each reviewer read the sustainability reports in order to define parts of the reports (e.g. sentences, paragraphs, figures and tables) which provided information relative to the sustainability topics. Next, the two reviewers discussed the results in their analysis to resolve any differences in opinion and reach a consensus. Also, for each report, the suggested binary scale was used to assign a score for each sustainability topic (i.e. 0–1 points, (not disclosed/disclosed) and to create the final dataset appropriate for further quantitative analysis of the sustainability reporting practices of universities.

Having assigned the scores, the analysis concentrated on the evaluation of the SI. For each sustainability issue which refers to a particular SDG, an evaluation score (SISC) was calculated as the quotient of the sum of the scores given to sustainability topics and the maximum number of topics suggested by the reporting framework (Eq. 1)

$${SISC}_{k}=\frac{{\sum }_{1}^{n}ST}{n}$$
(1)

where: SISCk is the evaluation score of a particular sustainability issue k = 1,2,3……17, ST is the score assigned to each sustainability topic proposed for the evaluation of a particular sustainability issue, and n is the number of sustainability topics proposed for each SI.

Thus, the evaluation score (SISC) ranges from (0) zero to one (1). Zero (0) is assigned when a sustainability report does not disclose any information about sustainability topics covered by a particular sustainability issue, (1) one when a sustainability report provides information or data for all topics covered by a particular sustainability issue.

Table 4 details the average SCSI of each sustainability issue achieved by the examined sustainability reports. Generally, universities failed to provide adequate information for the aspects of their sustainability performance and strategy associated with each sustainability issue. Since the SCSI scores are low, the reporting performance of universities cannot be regarded as satisfactory and the sampled universities were not able to inform interested parties about their sustainability footprint. More specifically, only one sustainability issue had an average score which was higher than 0.5 points which was associated with climate change and universities’ actions to handle issues related to climate change and its impacts (SI13: 0.59 points). Moreover, 7 out of 17 sustainability issues had a score between 0.40 to 0.50 points, while SI4 (Quality education) and SI16 (Peace, justice and strong institutions) had a score less than 0.20 points which denote a very poor reporting performance and thus this report is unable to inform stakeholders about these issues.

Table 4 Evaluation scores of sustainability issues (SI)
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Furthermore, to assess whether or not the launch of the 2030 Agenda for sustainability development is a factor which had an impact on the quality of information disclosed for each sustainability issue, independent t-tests were run. For all sustainability issues, the outcomes indicate that there are no statistical differences in the reporting performance, which means that the adoption of the 2030 Agenda did not influence sustainability reporting practices of universities (see p-values column in Table 4).

Next, taking into consideration the number of sustainability issues suggested for each sustainability area (see Table 2), the evaluation scores were calculated for each of the suggested sustainability area (Eq. 2). In practical terms, the SASC is calculated as the sum of the scores of the sustainability issues (i.e. SISC, see Eq. 1) included in each sustainability area divided by the number of them.

$${SASC}_{i}=\frac{{\sum }_{1}^{j}{SISC}_{j}}{j}$$
(2)

where: SASCi is the evaluation score of a particular sustainability area i = 1,2,3 and 4, and j is the number of sustainability issues proposed for each SA.

Figure 2 shows the average SASC achieved by sampled reports. None of sustainability areas had an evaluation score higher than 0.5 points which denotes the poor ability of sustainability reports to inform interested parties about the defined sustainability areas. Particularly, the findings show that Environment area (SA2), which is associated with environmental issues and challenges, was the area in which examined universities paid more attention to in their sustainability reports (SA2: 0.49 points). As regards the other three examined sustainability areas, the evaluation scores were even lower. The Economic area (SA3) had an average score of 0.38 points, while universities provide similar quality level of information about Well-being (SA1) and Generic (SA4) areas since the average scores assigned to these SAs were 0.31 and 0.30 points, respectively.

Fig. 2
figure 2

Average SASC for each SA

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To better comprehend the reporting behavior of the examined universities in relation to the sustainability areas, the examined sustainability reports were categorized into five different performance groups according to their evaluation scores (Fig. 3). The low evaluation scores of Well-being and Generic (SA1 and SA4, respectively) can be explained by the fact that the overwhelming majority of the sustainability reports (28 and 27 reports respectively) were classified in the two lowest performance group (i.e. 0–0.20 points and 0.21–0.40). For each of these two SAs, five reports had a score which ranged from 0.41–0.60 while, only three reports were classified in the highest group (i.e. 0.81–1.0 points). Furthermore, the difference in the evaluation scores between Environment area (SA2) and the other examined sustainability areas can be partly attributed to the large number of sustainability reports which achieved an evaluation score between 0.41 and 0.60 points (i.e. 19 reports). Also, in contrast to SA1 and SA4, only one report was classified in the lowest group concerning SA2. Finally, the Environment area was the only SA where more than half of the reports had an evaluation score above 0.40 points.

Fig. 3
figure 3

Classification of reports based on SASC

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With respect to the overall quality of the sustainability reports, the overall evaluation score (OVSC) was calculated for each sustainability report and used to categorize the sampled reports in five reporting performance groups (see Table 5, Eq. 3). In more detail, for each report the OVSC was calculated as the sum of the scores achieved by the report for each sustainability area divided by the number of sustainability areas (i.e. four SAs).

Table 5 Overall reporting performance of examined reports
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$$OVSC=\frac{{SASC}_{1}+{SASC}_{2}+{SASC}_{3}+{SASC}_{4}}{4}$$
(3)

As can be seen, eight reports were classified in the lowest performance group (i.e. 0–0.20). As for this performance group, the average evaluation score was 0.17 point with the lowest score being 0.09 points. Most reports (16 out for 37 reports) belong to the second lowest performance group (i.e. 0.21–0.40) having an average evaluation score of 0.30 points. Also, only three reports were assigned a score which was higher than 0.81 points. For this group, the average total evaluation score was 0.87 points and the highest score assigned to a report was 0.96 points which denotes an exceptional reporting performance. Finally, the average total evaluation score was 0.37 points which is obviously a very low reporting performance that underlines the fact that there is plenty of room for improvement in the sustainability reporting practices of the examined universities.

5 Discussion

For modern economies, the concept of sustainable development is definitely the path to viability. The latest directions of sustainability determined by the SDGs specify that both the not-for profit and for-profit organizations have to design specific organizational and production related practices to contribute to economic, environmental and social perspectives of sustainability [71]. In this context and recognizing that universities play a key role in supporting sustainable development, educating citizens in basic human values and principles [72], this paper contributes to the current literature by producing new insights into the universities’ efforts to discuss issues related to their SDGs performance and activities through sustainability reports. \In particular, this study contributes to the literature regarding universities’ sustainability practices. It expands the focus beyond the three-pillar sustainability approach, by investigating universities’ reporting practices on issues and challenges posed by the introduction of the 2030 Agenda for sustainable development [73]. Specifically, previous studies indicated that universities’ sustainability reporting practices mainly focus on the three main perspectives of sustainable development while there is limited focus on SDGs [74,75,76]. Thus, even though the sample of the empirical analysis was small in the current study, it advances knowledge about the commitment and the approach of tertiary education to promoting SDGs.

Even though there are scholars who have made suggestions on how SDG-related practices can be embedded in different dimensions of universities strategies associated with the curriculum, research projects and campus operations [77], there is not much work on how sustainability reporting practices can successfully incorporate 17 SDGs into universities sustainability reports. In this regard, the structure and the components of the suggested methodological approach can facilitate universities in reorganizing their sustainability reporting mechanism in order to gather relevant information and prepare the content of the sustainability reports in a systematic way. Moreover, because the suggested reporting framework is based on previous reporting methodologies developed by well-known international organizations (such as GRI, UN Global Compact, and WBCSD), the content of universities’ reports can successfully meet the latest requirements for sustainability reporting. All disclosure topics are developed by GRI’s latest reporting guideline, which is suitable for both for-profit and non-profit organizations [45]. GRI guidelines and disclosure topics help organizations to disclose information which is useful for various stakeholders as it facilitates their decision process [78]. Hence, the suggested reporting frameworks can provide a valid map which directs the efforts of universities in their sustainability reporting practices.

Apart from the organization of the content of sustainability reports, universities can benefit from the suggested evaluation system because it can be utilized as an internal accounting and measuring system of sustainability reporting performance. Actually, it can be implemented by universities in order to find the weak and strong points of their sustainability reports and consequently estimate the level of improvement in or deterioration of their sustainability reporting practices.

6 Conclusion

This paper suggests a methodological approach for examining the reporting practices of universities in relation to the SDGs introduced by the 2030 Agenda. More specifically, based on previous experience in the analysis of sustainability reports, a methodology was suggested which can be suitable for analyzing the content of sustainability reports in order to estimate the extent to which universities inform interested parties about their management efforts to align their operations with SDGs. For reliability and validity reasons, the suggested evaluation system is based on well-known methodologies for the selection of disclosure topics and a binary scoring system for measuring the SDG disclosures.

Due to sample limitations, the empirical analysis cannot be used for generalization about the quality of universities’ sustainability reports, but the findings of the research reveal some interesting indications for universities’ stance towards SDG reporting disclosures. The analysis of the sampled reports indicated that the coverage of SDGs in sustainability reports was not satisfactory and thus sustainability reports cannot be regarded as an effective tool or mechanism though which universities can disseminate information to interested parties about their sustainability strategy and practices However, three reports were the exception to this rule as they had a high coverage level. As for the sustainability areas, SA2 had the highest evaluation score which indicates that the universities provide more information about the SDGs associated with environmental perspective of their sustainability performance and strategy compared to the other three Sas (i.e. Well-being, Economy, Generic). This means that the universities should reexamine their reporting approach in relation to these sustainability areas. Finally, the analysis of each particular sustainability issue (i.e. SDG level) showed that universities provide more information about climate change (SI13) while, the issues with the lowest coverage level were quality of education (SI4) and peace, justice and strong institutions (SI16). Also, it is worth noting that there was not any sustainability issue where the sampled report has a high level of coverage.

The empirical analysis of this paper reveals some interesting issues which could be further explored. Thus, there are some recommendations which could be good starting points for future research. Due to the small sample examined, this paper is unable to draw firm conclusions about the sustainability information disclosed in universities’ sustainability reports. Hence, further research needs to be carried out utilizing large samples of sustainability reports or other sources of non-financial information, like websites or other reports. Such studies will enrich our understanding of the non-financial reporting practices of universities highlighting new directions for improvements. Additionally, future research should focus on the particular characteristics of universities and their goals as organizations so as to develop new disclosure topics more relevant to universities. A reporting framework adjusted to the needs of universities ensures a high level of transparency and accountability and thus the sustainability reports will be a powerful communication mechanism for universities. To develop an effective reporting framework for universities, the active participation of universities is an important factor since they can provide valuable feedback in order to understand their needs. Although the simplicity of the suggested scoring system facilitates the evaluation of sustainability reports in relation to the coverage level, it is not able to evaluate actual sustainability performance of universities. Thus, future research should develop a scoring system which can record the progress of universities’ sustainability performance.