Environmental Sustainability in Hotels: A Review of the Relevance and Contributions of Assessment Tools and Techniques

Abstract

The hospitality industry is a major segment of tourism, which is, in turn, a main economic contributor for many destinations. Sustainable tourism practices are promoted worldwide by international organizations like the United Nations World Tourism Organisation (UNWTO) to assist different countries. Various frameworks such as the Global Reporting Initiative (GRI), the Sustainable Development Goals (SDGs), United Nations Global Compact (UNGC), and environmental indices and management systems such as ISO 14001 are common assessment tools for environmental sustainability. This research reviews the relevance of incorporating environmental and socio-economic factors within hotel operations that may lead to improved transparency and operational effectiveness while guaranteeing adherence to sustainability within the hotel business. Accordingly, a systematic review of environmental sustainability assessments in hotels was carried out. A comprehensive analysis of research articles published between January 2000 and January 2023 by reputed databases ranging from Google Scholar, Scopus, and others, were used to conduct the literature review. A total of 38 papers were examined adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards, and it is worth noting that a significant increase in interest emerged in 2018, especially in Europe and Asia. The review reiterated the relevance and need to use relevant assessment methods and tools that aid in implementing sustainable development strategies to promote tourism-dependent economies, which can serve as a guiding note for varied tourism destinations. It additionally provides valuable knowledge for future directions, whilst improving research methods and incorporating innovative technologies. These advancements are essential as they may guide policy decisions to protect the environment within the hospitality industry.

1. Introduction

Globally, the tourism sector is known to be both a direct and indirect economic remunerator; nonetheless, it remains a fact that the adverse social and cultural impacts of this sector cannot be ignored. The tourism sector, as defended by (Sohn et al. 2021), has significantly enhanced local economies and communities both directly and indirectly by generating employment opportunities, improving sales in the business sector, and increasing foreign exchange revenue, among others. The prosperity and longevity of hospitality companies depend on the preservation of the scenic and cultural elements that entice visitors to an area. If it is not handled, there will be innumerable consequences. Even with some difficulties, tourism is still one of the fastest growing sectors in the world (Sohn et al. 2021). Paradoxically, major economic sectors like the tourism sector, which have economic benefits, also hold severe negative socio-cultural and environmental effects.

All stakeholders, including the government and communities, have a role to play in achieving the optimal performance and sustainability of the tourism industry (Achmad et al. 2023) and should aim to set sustainability targets and goals while ensuring that the right measurement strategies such as the use of sustainability indicators are being adopted for ensuring a more sustainable tourism sector (Miller and Torres-Delgado 2023) Sustainability indicators help destinations use available data as a guide during the preparation of policies, strategies, and other development forecasts for the tourism sector (Font et al. 2023). The work of (UNWTO 2023) points out that it is crucial to assist and support developed and developing tourism destinations in adopting sustainable tourism practices as the challenges of the international markets keep growing. Similarly, despite the global tourism and hospitality sector witnessing exponential growth over the years, it is worth highlighting the ongoing challenges posed in this sector. Major consumption categories within hotels are reported in research to account for 21% of all tourism’s ecological footprint, with an additional predicted increase to 25% by 2035. Another important challenge of the tourism sector lies with tourist places that were severely impacted by the pandemic. Despite the fact that they are making significant progress toward recovery, it remains imperative for them to perceive obstacles as possibilities for constructive transformation and to transition tourism into a more sustainable form (World Economic Forum 2023).

In modern tourism destinations, irrespective of their success in terms of reputation and revenue generation, the reality behind the specificity of island destinations cannot be ignored. The tourist and hospitality sector has faced challenges, and concerns about sustainability have grown across all disciplines (Sulphey and Faisal 2021; Makoondlall-Chadee et al. 2021). An analysis of current tourist trends and future perspectives is crucial to ensure that the continuing socio-economic changes and the values associated with the Great Reset are well understood and evaluated (Glebova and Perić 2023).

For a coherent and sound management of tourism activities and services, different sets of criteria and indicators have been devised. “Indicators are used for monitoring the tourism system; measure and analyse alterations and likely impacts on the tourism dynamics while enhancing the target placed for achieving sustainable tourism,” (Ali and Frew 2013). The utilization of sustainable indicators within the tourist sector serves the objective of facilitating the industry’s sustainable and enduring growth, while concurrently ensuring the fulfillment of the social, environmental, cultural, and economic requirements of pertinent stakeholders. An impact analysis and an evaluation of the execution of action plans within the tourism sector are additional methods for assessing the industry. Furthermore, concerns for the adoption of sustainable indicators within the tourism industry emerge from a lack of careful monitoring of tourism destinations, specifically within natural areas (Reihanian et al. 2012). Due to insufficient data about the social and environmental impacts of tourism to better preserve the attractiveness of destinations, sustainability indicators have been viewed as a valuable tool.

Environmental sustainability is becoming a crucial concern in sustainable development, particularly in hotel businesses, which are renowned for their substantial use of resources. The provision of services to guests, which encompasses accommodation, necessitates significant amounts of resources such as water, electricity, and materials, resulting in considerable waste and the release of greenhouse gas emissions (Gössling et al. 2015; Iddawala et al. 2024; Gunduz Songur et al. 2023; Khatter 2023). Understanding the relevance and contributions of using the right assessment tools and methods allows tourism stakeholders to comprehend, elucidate, depict, and visualize the process and trajectory of contemporary changes in the tourist sector, pinpointing potential areas for future investigation and advancement (Makoondlall-Chadee et al. 2021).

Hotels have a significant impact since they consume a large amount of energy for heating, cooling, and lighting, as well as water for guest services and maintaining gardens. Recent research suggests that hotels contribute to around 1% of worldwide carbon emissions, highlighting the pressing necessity for implementing sustainable measures (UNEP 2022). In addition to solid trash, hotels also produce wastewater and pollutants that have a detrimental impact on the environment (Gössling and Reinhold 2024; Manoharan et al. 2024; Makoondlall-Chadee and Bokhoree 2024).

As an example, hotels located on island states encounter distinct difficulties as a result of their reliance on tourism, restricted availability of natural resources, vulnerability to climate change, and requirement for effective waste management practices that promote sustainability. The Caribbean Hotel Energy Efficiency and Renewable Energy Action (CHENACT) project revealed that implementing energy efficiency measures in Caribbean hotels can lead to a significant reduction of up to 30% in energy consumption (Inter-American Development Bank 2020). Moreover, the use of water conservation technologies is crucial, for instance, in island regions that experience water scarcity (Inter-American Development Bank 2020; World Bank 2021; United Nations World Water Assessment Programme 2022). It is crucial to tackle these difficulties in order to ensure the long-term growth and success of the hospitality business in these regions (Gössling and Reinhold 2024).

The increase in consumer expectations for sustainable hotel activities is motivated by the escalating environmental concerns (Manoharan et al. 2024; Makoondlall-Chadee and Bokhoree 2024; Inter-American Development Bank 2020; World Bank 2021; United Nations World Water Assessment Programme 2022; Jones et al. 2014). The combination of this transition, along with heightened regulatory examination and laws related to climate change, has motivated hotels to embrace more environmentally friendly practices (Rob Van Tulder et al. 2021). The escalating occurrence of climate-induced catastrophes such as hurricanes and floods, which directly impact regions reliant on tourism underscores the urgency for prompt intervention (Intergovernmental Panel on Climate Change 2023). Hotels are currently prioritizing the reduction of carbon emissions, the use of renewable energy sources, and the enhancement of water management (UNEP 2022; United Nations World Water Assessment Programme 2022). Studies indicate that there is an increasing customer demand for hotels that are environmentally friendly (Manoharan et al. 2024; WTO 2022; Sustainable Hospitality Alliance 2023; Reem et al. 2022). As a result, hotels around the world are placing a high importance on environmental sustainability.

The use of sustainability measures in hotels provides numerous advantages. Efficient environmental strategies not only tackle ecological issues but also boost a hotel’s reputation. Hotels that have robust sustainability procedures are able to appeal to travelers who are ecologically sensitive, which, in turn, enhances their marketability (WTO 2022). Furthermore, the adoption of environmentally friendly techniques can result in significant financial savings by enhancing energy efficiency and reducing waste (Sustainable Hospitality Alliance 2023), among others. Research has substantiated that hotels that allocate resources to energy-efficient technologies can decrease operational expenses by as much as 30% (Inter-American Development Bank 2020). In addition, implementing efficient waste management strategies leads to substantial financial savings and positive environmental outcomes (Sustainable Hospitality Alliance 2023). Hence, environmental sustainability is not solely a matter of ethics but also a strategic methodology for achieving long-term commercial prosperity.

Although there is an increasing focus on environmental sustainability in the hotel industry, there are still areas in the existing research where the definition and assessment of sustainability performance are lacking. Prior research has predominantly concentrated on the optimization of water usage, reduction in waste, and conservation of energy. However, there is a dearth of comprehensive comparisons of the primary solutions in these areas (Reem et al. 2022; Khatter 2023). In addition, studies and research are scarce on, for example, reputed tourist destinations, which are often small island nations and encounter distinctive sustainability difficulties due to their insufficient infrastructure and restricted resources (WTO 2022; Selicati and Cardinale 2023).

Sustainability policies and practices are integrated into various hotel activities and operations. Nevertheless, environmental sustainability assessment and the use of relevant assessment tools remain important areas of research interest as this sector requires ongoing evaluation and optimization methods necessary to foster sustainable tourism as a whole (Selicati and Cardinale 2023). Additionally, the use and application of environmental sustainability assessment tools that are known to contribute to overall hotel sustainability set a comprehensive way to measure and also evaluate major hotel operations such as energy and water management and solid and food waste, among others (Segarra-Oña et al. 2024). Environmental assessment tools play a major role in the hotel industry as they facilitate and coordinate the easy integration of sustainable practices into actions. Hence, it was essential to synthesize existing research to offer a robust conceptual framework and assess the effective application of various approaches, leading to a systematic review. A review like this will point out the benefits and drawbacks of the studies that are now available and suggest areas for additional investigation. According to (Rob Van Tulder et al. 2021; Reem et al. 2022), recent studies emphasize the significance of thorough reviews for benchmarking sustainability practices, which are essential for developing models that hotels may use to improve their sustainability and solve environmental concerns (Greenview 2024).

While there is a rapidly increasing interest in researching environmental sustainability in hotels, several research gaps were identified. Firstly, the general problem is the absence of common methods for evaluating sustainability performance to allow for comparison with regional differences and the typology of hotels. Research shows that the majority of the studies are conducted in specific contexts, resulting in the absence of an interdisciplinary framework to make comparisons across the results (Jones et al. 2014). Secondly, it has been observed that the majority of the prior studies have been geared toward the environmental aspect of sustainability, and there is scarce research on the type of configurational integration of the social and economic aspects in sustainability evaluations. For that purpose, there is a requirement for a multi-dimensional perspective that also includes the other two sustainability dimensions for a detailed assessment of the hotel’s performance (Singh et al. 2009). Thirdly, the importance of longitudinal studies that consider the change in the sample hotel’s sustainability performance over time is well explained. The majority of the earlier studies thus offer a cross-sectional view of the practices, without offering a view on the effects of sustainable practices (Styles et al. 2015; Martínez-Martínez et al. 2019). Finally, the literature concerning the use and implementation of emerging technologies/innovation toward the advancement of sustainability in the hotel sector is inadequate. More research should be conducted on the use of current and emerging technologies like blockchain, artificial intelligence, and the IoT to improve sustainability processes and performance (Pirani and Arafat 2014; Poullas and Kakoulli 2023; Khoalenyane and Ajani 2024). As such, the research questions guiding this study are as follows:

• What methodologies, instruments, and indicators are typically utilized to assess environmental sustainability in the hotel sector, and how do these practices vary?
• What is the efficacy of current sustainability assessment tools and techniques in evaluating and quantifying the multiple facets of environmental sustainability performance in hotels?
• What are the principal limitations and constraints in current sustainability assessment approaches for hotels, and which research domains are essential to support hotel practices for enhanced performance?

By addressing the above research questions, this study aimed to conduct a systematic literature review of published research papers on the relevance of applying assessment tools and techniques to promote environmental sustainability in hotels. It will also identify and categorize the various approaches and tools used for environmental sustainability assessment in hotels and discuss the effectiveness and applicability of these assessment methods. Thus, this review contributes the results of an analysis of the current state of environmental sustainability assessment studies conducted on the hotel industry across various destinations to researchers, policymakers, and practitioners by analyzing the application of these approaches across different regions and hotel types. This systematic review aims to illuminate the current research gaps regarding environmental sustainability assessment in the hotel industry and contribute suggestions for enhancing sustainability within this sector. It will also help address the gaps in the literature by identifying and comparing the level of success of various assessment tools and strategies, thereby contributing to the formulation of better ways to assess the efficiency and sustainability of the hotel industry’s environmental management initiatives.

2. Materials and Methods

This section outlines the methodology employed in this research. The systematic literature review (SLR) method has been included and harmonized with the methodologies employed by (Tranfield et al. 2003; Wicher et al. 2019; Bezerra et al. 2020) in conjunction with the PRISMA reporting framework. Systematic literature review (SLR) is a research method that involves gathering and analyzing a comprehensive set of facts and information on a specific topic of interest (Liberati et al. 2009). The SLR facilitates the researcher in conducting a comprehensive, systematic, transparent, unbiased, and replicable search, in contrast to traditional “narrative” reviews that lack thoroughness, rigor, and a framework for interpretation (Tranfield et al. 2003). SLR offers numerous advantages. This systematic review employs the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist as a useful tool for carrying out a systematic review. PRISMA framework makes the review process systematic. This review was conducted in a clear manner, and other researchers can easily conduct the same study if needed (Moher et al. 2015; Page et al. 2021).

These tasks involve establishing specific criteria for what will be included and excluded in the review process, which helps to focus the research and reduce biases. The process involves several stages: the planning phase, the review phase, and the reporting and dissemination phase. Every step is properly conducted in a way that reduces the impact of bias and increases the level of reliability of the results, and all searches were based on the above-mentioned research questions.

2.1. Search Strategy

The first phase is the process of strategically organizing and outlining the review. The process has three distinct stages. Stage 1 involves developing relevant research questions to focus the systematic literature review (SLR) and these have been derived from the literature. Figure 1 presents the flow diagram.

The next step involves performing an exploratory literature search to further narrow down the research focus. The search is performed in an unorganized manner. This step provides an early understanding of the concepts, issues, and keywords related to environmental sustainability assessment tools and methods and how they have been addressed in the literature. At first, guidance was sought from tourism sustainability professionals and other researchers to create the review processes (Tranfield et al. 2003). A process of trial and error was then conducted on the keyword combinations and search strings were then performed.

By systematically addressing these questions, this review contributed to the development of a more standardized and comprehensive framework for environmental sustainability assessment in hotels, fostering improved environmental performance and sustainability within the industry. The review was started by creating the review protocol that includes the purpose, sampling criteria for the inclusion and exclusion, search strategy, and the means of data analysis and synthesis (Bastidas-Orrego et al. 2023).

This protocol was also reviewed by other professionals to enhance its reliability and coverage (Page et al. 2021). In this case, to meet PRISMA’s four-phase flow diagram, the processes of study identification, study screening, study eligibility and inclusion were reported.

• Keywords: “environmental sustainability”, “sustainability assessment”, “hotel industry”, “green hotels”, “sustainable tourism”, “eco-friendly hotels”.
• Search Strings:

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  “(environmental sustainability OR sustainable development) AND (hotels OR hospitality industry)”

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  “(sustainability assessment) AND (hotels OR hospitality)”

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  “(green hotels OR eco-friendly hotels) AND (sustainability practices)”

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  “(sustainable tourism) AND (hotel industry)”

In addition, to further develop potentially relevant sources, cross-reference snowballing was also used, which means examining references of the chosen articles (Greenview 2024). The sources uncovered did not have a regional boundary or temporal restriction; however, to cover modern trends and approaches, priority was given to publications from 2000 to 2023.

2.2. Inclusion and Exclusion Criteria

The third phase involves conducting a thorough examination of the search. Criteria for inclusion and exclusion were established to define the parameters for the review. Inclusion criteria refer to the specific qualities of the publications that are relevant and will be examined for the study. Exclusion criteria, on the other hand, are the components that are judged to be unneeded and will not be included in this research (Bezerra et al. 2020). Moreover, there were no major limitations regarding the geographical region, publications, or the type of study, whether it was quantitative or qualitative. However, the search was limited to the titles of the articles and abstracts to prevent the results from exceeding the screen’s capacity. To ensure the relevance and quality of the studies included in this review, specific inclusion and exclusion criteria were established:

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Inclusion Criteria:

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Studies published between 2000 and 2023.

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Peer-reviewed journal articles, review papers, book chapters, and conference papers.

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Articles written in English.

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Studies focusing on environmental sustainability assessment in the hotel industry.

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Research employing quantitative, qualitative, or mixed-method approaches.

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Exclusion Criteria:

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Duplicate studies.

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Non-English articles.

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Studies focusing on sustainability practices outside the hotel industry.

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Gray literature, such as reports, theses, and dissertations that have not undergone peer review.

The initial search yielded a total of 4367 articles. After removing duplicates, 1128 articles remained. A preliminary screening of titles and abstracts further reduced this number to 188 articles. These articles underwent a full-text review applying the inclusion and exclusion criteria, resulting in a final sample of 38 studies relevant to this systematic review.

2.3. PRISMA Flow Diagram for Study Selection

The PRISMA flow diagram was applied thoroughly for the planning, conducting the review, and reporting. As mentioned in Section 2.1, search strategy, key terms, and search strings, as mentioned above, were used. Different search string combinations were used to ensure that most of the papers relevant to environmental assessment tools and methods in the literature were covered. A total of 4367 papers were acquired. However, since search strings can contain similar key terms and are used on the same set of articles with similar inclusion criteria, it is quite likely that duplicates may occur. Hence, Microsoft Excel was employed to eradicate duplicates, leading to a total of 1128 papers.

• Identification

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Records identified through database searching: 4367

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Additional records identified through other sources: 50

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Total records after duplicates removed: 1128

During the second stage, an initial analysis was conducted to exclude items that did not align with the topic. The titles, keywords, and abstracts were examined thoroughly to ensure that no pertinent papers were overlooked. A comprehensive textual analysis was not conducted due to time limitations.

• Screening

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Records screened: 1128

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Records excluded based on title and abstract: 940

The third stage entails a subsequent session of reading. The abstract, introduction, background of study, and methodology sections of the 188 papers were carefully examined and assessed in a comprehensive manner (Bezerra et al. 2020; Morioka and Carvalho 2016).

• Eligibility

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Full-text articles assessed for eligibility: 188

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Full-text articles excluded, with reasons: 150

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Not relevant to environmental sustainability in hotels: 90

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Insufficient methodological detail: 30

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Non-English language: 20

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Duplicate records: 10

The four and final step involved performing a comprehensive review of the 38 final sample papers. The individual contribution of each paper was assessed and combined. The emphasis was placed on the ability of each chosen paper to address the study issues as stated before.

• Included

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Studies included in qualitative synthesis: 38

However, the content analysis focused deeper on environmental assessment tools and techniques. The interpretative approach was adopted because it is considered to be more appropriate to draw insight from studies (Pranugrahaning et al. 2021). The Excel spreadsheet was further refined according to research questions and filled in when each article was evaluated. This process helps provide a good descriptive analysis of the selected sample papers. The PRISMA diagram below summarizes all of the information as shared above while highlighting the process required.

2.4. Data Extraction and Synthesis

Data extraction was conducted systematically using a pre-defined extraction form to ensure consistency and comprehensiveness. The following information was extracted from each study:

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Bibliographic Details: Authors, publication year, journal name.

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Study Characteristics: Objectives, methodology, sample size, geographic location.

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Assessment Approaches: Specific sustainability assessment methods and tools used.

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Key Findings: Main results and conclusions of the study.

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Sustainability Dimensions: Environmental, social, economic, and other relevant dimensions assessed.

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Techniques Used: Analytical techniques and models employed in the assessment.

The obtained data were analyzed in accordance with the narrative synthesis approach, during which results of the conducted studies are summarized and interpreted. To achieve this synthesis, the investigation revolved around the research queries in order to offer a clear map of the existing state of environmental sustainability in hotels. An analysis of variance (ANOVA), which is a statistical method, expands upon the t-test by enabling simultaneous comparisons across many groups. This method was employed in this work as it aids the systematic assessment of environmental sustainability assessments in hotels to evaluate the presence of statistically significant variations in such practices across different hotel categories or areas. The authors in (Field 2013; Cohen 1988; Tabachnick et al. 2013) argue that examining the causes of variability in the data is crucial for comprehending whether the observed differences are attributable to random chance or possess statistical significance.

t-test was also used as this allowed the researcher to pinpoint observed differences in environmental assessment practices and determine their significance. This led to better interpretation of how different types of hotels were applying varied assessment tools and methods toward assessing their environmental performance (Field 2013). Furthermore, the utilization of the t-test is advantageous and valuable in generating evidence-based suggestions for enhancing operational procedures within the hotel industry (Cohen 1988).

Chi-square test, normally used for categorical data to test distributions or related relationships, was considered in this study to check for the statistical significance and relationship between the variables used in the study. Correlational analysis was also performed to determine the correlation between the study variables Descriptive analysis was used to determine the trends and patterns of the study variables.

2.5. Validity of Findings

The validity of findings of the studies was evaluated based on specific criteria required for providing methodological credibility to the review (Liberati et al. 2009). Recent studies, such as those by (Moher et al. 2015; Rossi-Semerano et al. 2023) emphasize the importance of rigorous methodological standards in systematic reviews to ensure credibility and reproducibility. In this way, the process applied in the review will enable a more comprehensive and credible evaluation of the state of practices in environmental sustainability assessment in the hotel industry.

The data extracted from the studies was then narratively synthesized, which entails a review and analysis of the findings within the studies. This synthesis reflected the research questions and offered an outline of the state of the investigation concerning environmental sustainability assessments in hotels (Akel and Noyan 2024). Trend analysis used descriptive statistics, while other analyses incorporated theme analysis to identify commonalities and gaps in the literature (Tranfield et al. 2003; Na et al. 2016). To minimize the risk of bias and increase the credibility of the research results, the methodological quality of the included studies was evaluated based on predefined criteria (Higgins et al. 2019).

3. Literature Analytics and Advances

Environmental sustainability concepts within the hospitality sector have emerged and developed over the last few decades. The hotel industry within the broader hospitality sector became aware of the environmental implications of its operations in the early 1990s, in line with the global awareness of environmentalism and sustainable development (Bohdanowicz 2005; Ko and Yuan 2019). The 1992 central event in Rio de Janeiro, commonly known as the Earth Summit, helped catalyze the focus on sustainability, including in the hospitality industry.

During the 1990s and early 2000s, the concepts introduced were fairly simple and comprised recycling programs, energy-efficient practices, and water-efficient measures in hotel operations and the hospitality industry (Kirk 1995; Legrand et al. 2016). These actions were often uncoordinated and lacked a holistic strategy. However, as environmental degradation became a more pressing issue, the industry developed more comprehensive framework strategies, such as Environmental Management Systems (EMSs). The Green Globe, introduced in 1994, provided a model for hotels to measure and enhance their environmental performance.

Recent studies have shown a continued evolution in the industry’s sustainability practices. For instance, (Han et al. 2018; Astawa et al. 2019) highlight the increasing integration of advanced technologies and data analytics to optimize energy and water use. Furthermore, (Global Sustainable Tourism Council 2021) reports that more hotels are now adopting comprehensive sustainability certifications and frameworks to address broader environmental and social issues (Rodríguez-García et al. 2023). These developments underscore the industry’s growing commitment to sustainability and the need for ongoing research and innovation.

The twentieth century, particularly the later part, and the twenty-first century saw the integration of environmental sustainability into the hotel industry to a greater extent. The expansion of the United Nations’ Sustainable Development Goals (SDGs) platform in 2015 also contributed to the industry’s preparation for the proposed government-implemented sustainable targets (Rodríguez-García et al. 2023). Scientific and technological developments and consumers’ sensitivity toward environmental problems have prompted organizations like the hotel industry to seek change through the adoption of measures like renewable energy systems, waste conversion technologies, and complete sustainability management systems (Leonidou et al. 2013; Melissen et al. 2016).

3.1. Environmental Sustainability: The Key Concepts and Definitions

To effectively discuss environmental sustainability in hotels, it is essential to define key concepts and terms related to sustainability assessment:

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Environmental Sustainability: Practices that ensure the long-term health of the environment by conserving natural resources, reducing pollution, and promoting ecological balance (Brundtland Commission 1987; Singh 2024).

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Sustainability Assessment: The process of evaluating the environmental, social, and economic impacts of a hotel’s operations to determine its sustainability performance (Singh et al. 2009; Singh 2024; Fischer et al. 2024).

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Green Certifications: Certifications such as Green Globe, LEED (Leadership in Energy and Environmental Design), and Earth Check that provide third-party validation of a hotel’s environmental performance and commitment to sustainable practices (Chan and Hawkins 2010; Dijk et al. 2017; Becken 2013; Suárez-Cebador et al. 2018).

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Energy Management: Practices aimed at reducing energy consumption and enhancing energy efficiency through technologies such as smart thermostats, energy-efficient lighting, and renewable energy sources (Becken 2013; Suárez-Cebador et al. 2018).

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Waste Management: Strategies to minimize waste generation and enhance waste recycling and disposal processes within hotel operations (Pirani and Arafat 2014).

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Water Conservation: Measures to reduce water usage and promote efficient water management in hotel facilities, including low-flow fixtures, graywater systems, and water recycling (Styles et al. 2015).

3.2. Emergence and Application of Environmental Sustainability and Assessments Tools and Techniques in Hotels

Various studies exist that cover the aspect of environmental sustainability and its practice in the hotel business. Initial studies enlightened scholars on the factors that encourage or hinder sustainable practices (Kirk 1995), and it was stated by (Adams et al. 2022) that regulatory pressures, cost reduction, and the corporate entity’s image are key factors that can influence hotels to implement environmental initiatives. Research by (Hsiao et al. 2014; Pontes 2023) support these findings, showing that regulatory compliance and cost savings are significant motivators for hotels to adopt green practices.

Other works focused on specific aspects of sustainability and their efficiency (Higgins et al. 2019; Bohdanowicz 2005) conducted extensive research on high-energy and water conservation practices in European hotels, discovering many potential cost-saving measures and environmental improvements. Similarly, a study by (Gunduz Songur et al. 2023; Jones et al. 2014; Dijk et al. 2017) confirmed that energy and water conservation are still critical areas for sustainability in hotels. The effects of green certifications on the performance of the hotel industry were studied by (Dijk et al. 2017), and it was found that certified hotels engaged in superior environmental management and increased marketability. More recent studies by (Krstinić Nižić and Matoš 2018; Singh et al. 2023) also found that green certifications significantly enhance a hotel’s market position and operational performance.

Increased research focus has now been directed toward determining the global sustainability performance of hotels using total value assessment instruments. For example, (Leonidou et al. 2013, Shaikh and Bhautik 2022) analyzed the environmental, social, and economic aspects of sustainability in Mediterranean hotels and obtained a comprehensive picture of the sustainability index of the hotels. Additionally, recent studies by (Astawa et al. 2019; Wang et al. 2024) highlight the importance of integrating social and economic dimensions into sustainability assessments in the hospitality industry. The use of modern technologies like renewable energy sources and waste conversion technologies was studied by (Poullas and Kakoulli 2023; Becken 2013) thereby supporting the efficient standards of sustainability performance. A recent review by (Madanaguli et al. 2023) further emphasizes the role of innovative technologies in improving sustainability practices in the hospitality sector.

4. Descriptive Analysis

The overall systematic approach adopted for this review intended to offer a reliable and comprehensive assessment of the practices concerning environmental sustainability assessment in the context of the hotel industry. Using the process of narrative thematic analysis within a systematic literature review allowed, as described by (Yuzhen et al. 2023; Wszendybył-Skulska and Panasiuk 2024) the identification, coding, and synthesis of themes derived from the chosen research. This methodology offers a systematic yet adaptable framework for comprehending qualitative data, enabling the acquisition of significant insights pertaining to intricate research inquiries.

4.1. Emergence of Environmental Assessment Tools and Techniques in Hotels

The review identified several approaches and tools used for environmental sustainability assessment in hotels. Hotel classification has traditionally been a main component valued by potential guests, investors, and other stakeholders capable of influencing hotel selection. As the global market evolved and various challenges emerged, it is now becoming more relevant and important for hotel organizations to adopt an integrated approach toward sustainability. In addition to having good ratings and classifications, their approaches need to encompass quality management and proper evaluation of the environmental and ecological contributions of the hotels (Wszendybył-Skulska and Panasiuk 2024). Such advancement will allow for a comprehensive understanding of the varied criteria related to environmental management and sustainability. Given the lack of compulsory or globally required environmentally sustainable criteria, several approaches and methodologies are reported as being used by varied hotel organizations (Johnson 2010; Smith 2020). They are categorized namely into five main types: developed conceptual directions, standards and measures, management models, index models, and evaluation/selection models.

• Established Guidelines:

The existing body of literature demonstrates that guidelines can be categorized into three distinct types: reporting guidelines, principle guidelines, and indicator guidelines. At the reporting guideline level, four tools were identified, namely GRI, IIRC, NVG, and EUNFRD. Others such as the Global Reporting Initiative (GRI) and the International Integrated Reporting Council (IIRC) are more commonly used in the hotel sector. Of the three standards, the GRI standards are the most popular, featuring the most elaborate global reporting guidelines, especially for the hotel industry (Siew 2015a; Siew 2015b; Le et al. 2023). The IIRC is specifically concerned with integrated reporting, which involves the provision of a well-coordinated report that blends both financial and non-financial information about an organization’s sustainability performance.

2

Normative Frameworks:

Normative frameworks offer defined criteria for assessment and possess a more limited scope compared to theoretical frameworks. Such frameworks as asserted by (Morioka and Carvalho 2016) facilitate corporations in their endeavors to enhance transparency and information sharing. Additionally, they can serve as a voluntary collection of non-binding principles that the private sector can utilize to facilitate the conversion of their corporate plan into a sustainable one (Rahdari and Rostamy 2015). In this category, some tools include the United Nations Global Compact (UNGC) and the Sustainable Development Goals (SDGs). The UNGC is a portfolio of the ten principles concerning human rights, labor, the environment, and anti-corruption that offers direction to the hotels on the achievement of further sustainable development (Panth et al. 2015).

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Management Systems:

Sustainability management systems encompass administrative tactics employed to establish, arrange, assess, and disseminate sustainability information, while also delineating procedures and frameworks (Rahdari and Rostamy 2015). Furthermore, these are commonly known as standards and the formal documents are frequently offered as a means of evaluating corporate sustainability performance, encompassing particular requirements or qualities (Panth et al. 2015). The primary purpose of these guidelines is to mitigate the adverse consequences associated with corporate operations. Environmental management is one of the many tools that has attracted recognition in the hotel industry; this includes EMS ISO 14001 and the EMAS. ISO 14001 offers the guidelines on environmental management standards while EMAS offers a higher standard regarding reporting to the public (Bohdanowicz 2005; United Nations Global Compact 2021). Additionally, they have been created and very widely applied in the hotel and tourism sector to establish standards for the application of environmental management practices. They assist hotel enterprises in mitigating their adverse environmental effects. The EMAS system, in contrast to the ISO 14000 series, mandates that organizations must publicly disseminate their environmental reports (Özçelik et al. 2015).

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Index Systems:

In the field of quantitative analysis, an index is a straightforward metric that is derived by consolidating various indications into a unified measure. The classification of indices can be further divided into two categories: non-integrated indicators, which do not take into account nature-society factors, and integrated indicators, which incorporate several dimensions of sustainability (Ness et al. 2007). The indices includes the Dow Jones Sustainability Index (DJSI) and the FTSE4Good Index, which are often used to measure a hotel’s level of sustainability. These indices measure and rank the firms on the environmental, social, and governance elements to assess the comparative sustainability worth of enterprises (Awalludin and Aripin 2023; SPGlobal 2021).

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Rating/Ranking Systems:

Indices like the Bloomberg ESG Data and the ISS-Oekom Corporate Rating rate the sustainability disclosures and performance of hotels. These systems enable investors and stakeholders to take better decisions in possibilities of a hotel regarding sustainability (Yu et al. 2018).

Hotels have frequently used frameworks and standards like the Global Reporting Initiative (GRI), the Sustainable Development Goals (SDGs), ISO 14001 for Environmental Management Systems (EMSs), and other certifications in their quest for sustainability. Through standardized metrics, GRI, for instance, offers an organized method for reporting environmental, social, and governance (ESG) issues, improving transparency and building stakeholder trust among hotels and other organizations (Pozzobon 2021). However, putting GRI into practice in hotels can be resource-intensive, among other challenges. Adopting SDGs or other normative frameworks provides a thorough worldwide framework that synchronizes hotel operations with general societal objectives, encouraging cooperation and all-encompassing sustainable ways (Alvarez-Risco et al. 2020). However, prioritization and measurement issues may arise when adapting the SDGs to various hotel environments, making successful implementation more difficult (Jones and Comfort 2019). Hotel environmental performance is continuously improved and regulatory compliance is supported by EMS ISO 14001, which guarantees systematic environmental management (Le et al. 2023). However, smaller hotels might be discouraged from obtaining certification due to its cost and complexity, which would restrict its applicability and reach (Le et al. 2023). Environmentally concerned consumers can easily distinguish products and services from one another thanks to ratings and criteria such as Green Key, which also help with operational enhancements and market distinction (ISO 2021). However, obtaining and retaining certifications can be expensive, and there is always a chance of greenwashing, which could damage the legitimacy of sustainability initiatives (ISO 2021).

Several advantages and opportunities have been gained in hotels in developed and small island developing states from the adoption of sustainable guidelines, frameworks, ratings, and/or standards. For instance, when referring to the Sustainable Development Goals (SDGs) and the Global Reporting Initiative (GRI), which are well established in developed nations, it has been reported that they offer a well-structured approach toward improving environmental performance while harmonizing with responsible tourism practices. Adopting environmental approaches and practices, as mentioned above, leads to increased competitiveness between concerned hotels by attracting environmentally conscious investors and consumers (Robin et al. 2017). Through other certifications such as EMS ISO 14001, hotels may safely guarantee compliance and aim to maximize their operational efficiency, as such efforts may lead to cost savings and enhanced processes (ISO 2021). By adopting all of the above, it is important to highlight some related challenges that hotels may face, such as a high upfront expense for implementation and institutional or organizational hurdles during implementation procedures, which may specifically affect smaller hotels from developed countries or even hotels within developing island states.

As small island developing states (SIDSs) are recovering from the pandemic and other potential health-related or environmental challenges, the adoption of proper environmental sustainability approaches and methodologies can only enhance their competitive advantage. SIDSs were among the quickest to recover their visitor numbers post-pandemic despite their insularity and other related challenges, and they welcomed back 36 million foreign visitors in 2023 (+42% from 2022), as reported by (GRI Standards 2016). The hotel sector of SIDSs may greatly benefit from the adoption and proper implementation of the above-mentioned sustainability guidelines, frameworks, and certifications, as they can be viewed as established practices that may alleviate the potential environmental challenges faced by SIDSs while ensuring that they align with global environmental goals and targets.

4.2. Common Environmental Sustainability Assessment Tools and Methods

Environmental sustainability indicators are crucial in the modern hotel sector, as they serve as vital measures to assess and enhance the environmental performance of hospitality establishments. The indicators contain various metrics that evaluate the environmental impact of a hotel. These variables include energy consumption, waste management, water conservation, and emissions reduction (Font and McCabe 2017). The significance, significance, and contributions of environmental sustainability indicators to the hotel business are of utmost importance (Kasim and Goh 2019). They function as essential instruments for quantifying. The aim is to make advancements in achieving sustainability objectives, improving operational effectiveness, cutting expenses, complying with regulatory standards, and meeting the increasing need for eco-friendly accommodation choices among customers (Abdou et al. 2022).

To ensure the long-term sustainability of the tourism business, it is crucial to utilize a variety of tools, instruments, metrics, regulations, and strategies. The categorization of economic, social, and environmental sustainability has been devised to facilitate a more accurate and tangible comprehension and evaluation of these separate dimensions. Researchers have explored various assessment tools to evaluate, enhance, and oversee certain sustainable tourism ideas at tourism destinations. The seven assessment approaches that are often used and acknowledged by (Klein-Vielhauer 2009) are as follows: sustainability indicators, Environmental Impact Assessment, Life Cycle Assessment, Environmental Auditing, Ecological Footprint Analysis, Multi-Criteria Analysis, and Adoptive Environmental Assessment; these are among most the widely used methods within tourism and hospitality. In order to ensure the long-term sustainability of the tourism business, it is crucial to utilize a variety of tools, instruments, metrics, regulations, and strategies. These are essential for the successful implementation of sustainability concepts and principles in tourist practices (Klein-Vielhauer 2009). The delineation between economic, social, and environmental sustainability has been constructed to provide a more accurate and concrete understanding and assessment of these topics. Researchers have explored various assessment tools to evaluate, enhance, and oversee certain sustainable tourism ideas at tourism destinations.

It is argued by (Ness et al. 2007) that indicators are quantitative approaches used to represent many aspects of environmental, social, and economic progress in a specific geographic area. Indicators, sometimes known as indices, are regarded as composite indicators since they have the capacity to integrate multiple aspects of sustainability. The Environmental Sustainability Index (ESI) and the Index of Sustainable Economic Welfare (ISEW) cover a wide range of factors related to the relationship between nature and civilization, and go beyond the limitations of economic assessment. In the past, several tools and indicators were employed to assess the three pillars of sustainability on populations. The Environmental Sustainability Index (ESI), for instance, is a numerical measurement used to assess the level of environmental sustainability. The Environmental Sustainability Index (ESI) is a comprehensive method used to evaluate and compare the degree of environmental sustainability in the hotel business (SEDAC 2023). The Environmental Sustainability Index (ESI) is used as a measure to evaluate a country’s overall progress in the field of environmental sustainability. The Environmental Sustainability Index (ESI) is a comprehensive composite index that evaluates many socio-economic, environmental, and institutional elements that impact and demonstrate the condition of environmental sustainability on a national scale. The Environmental Sustainability Index (ESI) has been universally implemented since 2002, encompassing 142 nations. The assessment and monitoring of progress toward environmental sustainability is conducted using a thorough checklist consisting of sixty-eight indicators.

One commonly used approach to evaluate the potential environmental consequences of tourism industry enhancements is the Environmental Impact Assessment (EIA). The main objective of the EIA is to encourage sustainable development by effectively and carefully utilizing and overseeing resources (Therivel 2010). The Environment Impact Assessment (EIA) technique is highly beneficial in the hotel business, particularly for the purpose of planning new structures or substantial modifications (SEDAC 2023). The EIA attempts to evaluate and analyze auditing procedures in order to analyze the constraints of natural resources and potential negative impacts on society, water, and biodiversity. This evaluation takes into account economic, socio-cultural, environmental, and biophysical considerations.

The Life Cycle Assessment (LCA) is defined by (Castellani and Sala 2012) as a method employed to examine the comprehensive environmental impacts of a product or service throughout its entire life cycle. Utilizing Life Cycle Assessment (LCA) enables the identification and mitigation of significant trade-offs that may arise between various media and production stages. The Life Cycle Assessment (LCA) is a sequential process that involves process selection, design, and optimization. In order to identify the most suitable process alternative for further process optimization, a Life Cycle Assessment (LCA) is employed to assess the possibilities based on their economic and environmental aspects (Filimonau 2016). Nevertheless, hotel companies seldom employ a Life Cycle Assessment (LCA) to comprehensively review the whole life cycle of their offerings due to the substantial financial implications involved. Due to the extensive range of products, services, processes, and activities required, the execution of the hotel business has proven to be challenging.

Cost–benefit analysis (CBA) is a widely used assessment tool for evaluating and monitoring environmental impacts. This tool facilitates the assessment of whether a decision is both logically possible and economically viable. It also enables the evaluation of costs to gauge and compare the viability of projects or processes being implemented. Cost–benefit analysis is a method used to determine the entire expenses of a project compared to the total benefits it will provide. However, it is important to note that cost–benefit analysis often produces inaccurate results owing to unintentional exclusion of costs or too optimistic predictions (Molina-Azorín et al. 2015).

Cost–benefit analysis (CBA) can be utilized to assess the financial viability of installing solar panels on a hotel’s roof. This involves considering factors such as the initial investment, potential energy savings, and available government incentives. Cost–benefit analysis (CBA) lacks the capability to quantify intangible values, such as societal or environmental advantages, and has other inherent limitations. Moreover, the extent of reliance on the accuracy of cost and benefit predictions significantly impacts the outcome.

The Ecological Footprint Analysis (EFA) is a crucial tool utilized to quantify the ecological impact of hotels on ecosystems and resources. This program enhances knowledge regarding resource utilization and facilitates the identification of potential areas for enhancing resource efficiency (Wackernagel et al. 2014). When performing an Environmental Footprint Analysis (EFA) for the hotel business, it is important to consider the primary areas of consumption, which include food, accommodation, transportation, consumer goods, services, and waste. Ecological footprint calculations are quantified in global acres (or hectares), with each global acre representing one biologically productive acre, as determined by the average productivity of the planet. Environmental Footprint Analysis (EFA) enables the quantification of land and water usage by hotels, facilitating the identification of areas where resource consumption can be minimized (Wackernagel et al. 2014). The Environmental Footprint Analysis (EFA) relies on fundamental metrics that do not comprehensively encompass the intricate ecological impacts and do not directly consider social or economic aspects. The primary objective of this program is to assess the ecological footprint of the hotel.

Different tools and methods were adapted by the chosen studies to evaluate the sustainability criteria in the hotels. These techniques fall into four main categories:

• Criteria Weight Attribution: In (UN Tourism n.d.), the techniques were categorized into three, and out of the eleven studies, Multi-Criteria Decision Analysis (MCDA) dominated the approach. It is helpful in weighting the different aspects of sustainability so that an even scale of measurement is achieved (Singh et al. 2009). Other approaches include DEA, WS, and Entropy.
• Sub-Criteria Grouping: To achieve this, Principal Component Analysis (PCA) and Factor Analysis (FA) are used to organize the sub-criteria in groups with similarities to ease the assessment process. PCA was found to be especially used in six studies in the reduction in the dimensionality of sustainability data (Styles et al. 2015).
• Subjective Judgment Minimization: The subjectivity of the expert assessments is reduced with Fuzzy Logic (FL). This technique was identified in seven studies, and it helps to increase the reliability of sustainability assessment by managing imprecise and uncertain information.
• Dependency Determination: The relation between several sustainability criteria is studied with the help of System Dynamics (SDs) and helps to consider all the interconnections in the sustainability assessments (Becken 2013).
• Environmental Footprint: Carbon Footprint or Ecological Footprint Analysis are other common methodologies employing specific techniques within the discourse surrounding the concept of “carrying capacity.” (Fang et al. 2015; Bastianoni et al. 2020).

Referring to previously discussed environmental tools and approaches and in line with the above-mentioned criteria that are in use within hotels, additional benefits may emerge for hotels worldwide and in SIDSs (Bastianoni et al. 2020). On the whole, several targets and goals may be achieved by adopting environmental approaches and tools. For instance, it sets the ground for hotels to work toward improved environmental performance, increased hotel operations efficiency, and global compliance with international sustainability best practices (Biagetti et al. 2023; Guden et al. 2021). This will not only be a marketing and competitive advantage among eco-aware tourists but also open avenues for more collaboration and investment opportunities, further sustaining the practice of sustainable tourism on islands. Island destinations, for instance, bearing a limited geographical area dependent on natural resources, will heavily benefit from adopting sustainability, which can increase resilience to environmental vulnerabilities and the effects of climate change.

Sustainable practices can be promoted by the implementation of environmental tools and approaches as they will contribute to the further use of renewable energy, waste minimization, and water conservation among others, which can aid SIDSs in preventing environmental degradation and improve their resilience to shocks from the environment, to name a few (Shafiee et al. 2019). The additional benefit of environmental sustainability techniques and practices is that they will aid developing islands in building a strong institutionalization of sustainability by incorporating environmental sustainability within local policy frameworks and regulations, providing an opportunity for proper governance, environmental stewardship, and to meet the overall goal of sustainable development, which remains the priority.

4.3. Environmental Sustainability Assessment: Contributions to the Dimensions of Sustainability

Several studies have predominantly focused on the three main pillars of sustainability: the respective environmental, social, and economic personal factors and regulated business contexts. The environmental dimension was the most frequently assessed dimension, followed by the social dimension and then the economic dimension, with 37, 34, and 31 studies, respectively. As for the assessment of governance and the financials aspects, these were reported less often although they sometimes fell under all-encompassing measurements (Leonidou et al. 2013).

Environmental Dimension: These include energy conservation which is obtaining energy most efficiently and cleanly practicable, water conservation, and waste minimization, which is removing waste in the least amount possible and reducing greenhouse gas emissions (Bohdanowicz 2005).

Social Dimension: This is about the relationship and cohesiveness among all stakeholders of the hotel from human resources, the community, and customers. The social dimension helps showcase the organization’s social responsiveness and effects. The author of (Day 2022) further adds that such practices may foster the goodwill and reputation of the organization while focusing on social aspects of sustainability within its operations. It further aids in welcoming and retaining customers who support socially responsible practices.

Economic Dimension: The adoption of social and environmental sustainability practices not only financially contributes to hotel revenues but it also attracts specific customers willing to pay more to stay in environmentally sustainable hotels (Mallieswari et al. 2023). For instance, paying attention to financial returns such as energy savings, cost reductions from implementing sustainability, and revenue can result in other benefits such as a better organizational image (Aleksandrovna et al. 2021).

4.4. Industry Specific Strategies

Environmental sustainability has been an area of research and planning interest among various sectors, more so within the hotel sector over the years for various reasons. Hotels’ intensive resource consumption, environmental impacts, and carbon emissions can be addressed through the right sustainability approaches and methodologies, leading to an overall lower ecological footprint in the hotel sector (Mensah 2006). Such initiatives will also contribute to the global efforts toward addressing environmental deterioration and climate-related challenges.

The findings from the hotel industry reveal that the implementation of sustainability strategies in the hotel sector differs from one geographical location to another and from one type of hotel to another. Several works used their findings to confirm that European and Asian hotels are more progressive in overall sustainability evaluation compared to hotels located in other regions of the world (Leonidou et al. 2013; Arora and Arora 2019). More comprehensive sustainability solutions are also implemented by luxury hotels due to legal obligations and to meet customers’ expectations for more eco-friendly hotels (Chan and Hawkins 2010).

Energy Management: Most hotels in Europe, particularly those in the Mediterranean, have increased the efficient use of energy by adopting renewable energy and energy-efficient products and services (Bohdanowicz 2005), and these may extensively benefit the hotel sector, more so among small island developing states. Recent studies show that these measures significantly contribute to reducing the overall carbon footprint of hotels (World Bank 2021; Jones and Comfort 2019). Through energy management, hotels across various destinations and those within island states can reduce their reliance on fossil fuels and make the shift to more clean sources of energy. Such advancements may also lead to other operational benefits as hotels may face reduced fluctuations attached to supply disruptions such as increases in fuel prices (Krstinić Nižić and Matoš 2018; Biagetti et al. 2023).

Water Conservation: Many hotels in water-scarce areas, especially in the Middle East and North Africa, have developed technological methods and water recycling mechanisms to optimize water use in their accommodation services. These practices not only conserve water but also reduce the environmental footprint associated with water consumption (Arora and Arora 2019; Moise et al. 2021). By adopting environmentally friendly practices such as water conservation programs, hotel establishments can appeal better to eco-conscious guests, thus contributing to their overall sustainability. Given that sustainability is a top priority of many travelers, through the right tools and approaches to contribute to water conservation, hotels can further show their environmental commitment and responsibility, contributing to enhancing reputation and leading to more rooms sold and increased revenue (Batra and Norheim 2022).

Waste Management: The analyzed hotels in Asia, particularly those located in large cities, have implemented complex waste reduction strategies and have begun using waste-to-energy technologies (WTO 2022). This approach not only manages waste more effectively but also reduces greenhouse gas emissions by converting waste into energy (Arora and Arora 2019). Proper waste management programs and initiatives as per (Chandani et al. 2024) contribute to significant benefits in hotels, whether in big cities as researched in Asia or within small island states where there are already waste disposal and storage challenges. Through proper waste management initiatives, hotels within small island developing states may be similar to Asian and European countries, as shown in previous studies, and be able to efficiently manage their wastes, environmental impact, and waste disposal (Calisto et al. 2021). Through the implementation of waste management programs, composting initiatives, and reduced greenhouse gas emissions, hotels may work toward reducing their overall amount of waste to landfills, adopting cleaner environments, devising more sustainable energy production, and developing healthier ecosystems (Chandani et al. 2024).

Environmental Assessment: Environmental assessments are increasingly being used to measure and reduce the overall carbon footprint of hotels. By evaluating their environmental impact, hotels can implement targeted strategies to minimize energy use, manage waste, and conserve water, thereby reducing their overall environmental footprint (Legrand et al. 2016). These assessments are crucial for developing long-term sustainability plans that align with global sustainability goals (Global Sustainable Tourism Council 2021). Through proper environmental assessments, hotels may better understand their resource consumption and related environmental impacts that may contribute to enhanced hotel sustainability (Calisto et al. 2021; Obersteiner et al. 2021). Adopting the right proactive approaches may additionally lead to reduced hotel operational costs overall and minimize the environmental degradation of island states.

5. Discussion

The findings from the reviewed publications emphasize the essential function of rigorous environmental evaluations in promoting sustainability within the hotel sector. By implementing robust and dependable methods and procedures, hotels can markedly improve their environmental performance, comply with regulatory standards, and fulfill the increasing consumer demand for sustainable accommodations. This brings us to our initial research questions: What methodologies, instruments, and indicators are typically utilized to assess environmental sustainability in the hotel sector, and how do these practices vary? Utilizing environmental tools enables hotels to adhere to rules and uphold global standards and best practices. An increasing number of small island governments are implementing legislation and policies to promote renewable energy and reduce carbon emissions (D’Souza 2023). By proactively implementing these steps, hotels may establish themselves as leaders in sustainable tourism, thereby improving their competitiveness in the global market.

This systematic research underscores the increasing significance of environmental sustainability evaluation within the hotel sector. In the last ten years, there has been a notable rise in publications on this subject, indicating that sustainability concerns are increasingly recognized by hotel managers, academics, and governmental bodies (Hsiao et al. 2014; Abdou et al. 2020; Hegedüs et al. 2024). This worldwide issue and cooperative effort to address environmental challenges in the hospitality industry is demonstrated by research undertaken in various geographical areas (Leonidou et al. 2013). Hotels in small island states can alleviate their adverse environmental effects and position themselves as pioneers of sustainable development within their local communities and the global tourist industry.

A crucial aspect is our second study question: How effective are current sustainability assessment tools and techniques in capturing and quantifying the diverse dimensions of environmental sustainability performance in hotels? A significant finding is the diverse array of methodologies and tools employed for sustainability evaluation, encompassing guidelines, standards, norms, management systems, index systems, and rating/ranking systems (Kim et al. 2018). The study predominantly emphasizes environmental factors, which is justifiable considering the direct and palpable effects of hotel operations on the environment. The application and execution of environmental assessment techniques have enhanced the dependability of sustainability evaluations by methodically defining and consolidating diverse criteria and their associated weightings. These techniques are especially pertinent to the triple bottom line framework, which evaluates the environmental, social, and economic dimensions of sustainability.

Furthermore, when analyzing the obstacles hotels encounter in sustainability practices, we can refer to our third research question: What are the principal challenges and constraints in existing sustainability assessment methodologies for hotels, and what research areas are essential to advance these practices for enhanced performance measurement? Hotels can receive numerous advantages by forging partnerships with local providers of renewable energy technologies and services, trash management efforts, or water conservation programs (Pontes 2023). These partnerships may facilitate the establishment of green jobs that enhance local economies while fostering a more sustainable and inclusive tourism sector by diminishing the dependence on conventional tourism revenues.

To maximize the benefits of environmental sustainability accomplishments, all stakeholders in the hotel industry—including governments, private enterprises, international organizations, non-governmental organizations, and local communities—must cooperate to tackle challenges and fully actualize sustainable practices in hotel industries in small island states (Manzardo et al. 2022). The implementation of environmental technologies is especially crucial in island settings, where challenges such as initial investment expenses, insufficient technical expertise, and distinct regulatory frameworks need to be addressed.

In summary, as an indication to further maintain and improve the tourism sector of small island states, hotels can significantly benefit from environmental strategies and methodologies inspired by effective European models. These advantages encompass cost reductions, enhanced market attractiveness, regulatory adherence, and economic diversification, which can jointly foster a more sustainable tourism industry.

5.1. Implications for Practice

The implications of these findings are far-reaching for the management of hotels and policymakers. Consequently, hotel managers that implement the best practices of the assessment tools and techniques highlighted above increase sustainability strategies, encourage the enhancement of organizational procedures, and promote overall marketability. Approaches such as ISO 14001 and GRI standards can be useful as hotels can use them to provide a structured environmental management system, obey legislation, and respond to the demands of guests concerning sustainability (Rodríguez-García et al. 2023).

This review also reveals that the proper implementation and use of environmental sustainability assessment and tools require attention in various aspects such as human capital, access, the affordability of technologies, customer choices and their related consumption patterns and behaviors, and the related national policies and strategies, among others. As supported by (Jones and Comfort 2019), implementing sustainability tools requires relevant expertise. The implementation of environmental sustainability approaches and methodologies often requires investment in advanced technologies. Access to the best technologies known to contribute to an overall positive sustainability agenda can be a barrier to small hotels, both in well-established destinations and, even more so, in small island developing states (SIDSs) (Klein-Vielhauer 2009). Hotel industry stakeholders, as discussed by (SEDAC 2023), are often required to align with national policies and strategies. For instance, regulatory frameworks and institutions need to provide the right incentives and facilitate the implementation of environmentally sustainable practices within the hotel sector. Decision-makers can therefore apply these recommendations when framing legislation and providing incentives that would act as props for sustainable management in the hotel business. Through the promotion and framing of standard working structures, authorities can work toward general positive changes and guarantee that hotels have a positive impact on the conservation of the environment. Furthermore, the rise of the overall approach to policy sustainability assessment regarding social and economic concerns can assist politicians in defining adequate and fair policies concerning sustainable development.

Concerning the above-mentioned factors, there are also customer preferences and behavioral intentions that play a crucial role in the effective assessment of environmental sustainability within a hotel. It is worth highlighting, as described by (Therivel 2010), that expecting the same environmental habits from a customer’s household to a particular hotel setting can be challenging despite the individuals typically being much more involved in environmental practices at home. Along the same thought, it can be said that hotels, despite having a very rigid and well-implemented environmental sustainability plan and agenda, may be influenced by the attitudes and behaviors of their guests.

5.2. Limitations

This systematic review possesses some shortcomings that warrant acknowledgment. The selection of studies from published sources may introduce a possible publishing bias, as studies with favorable outcomes are more likely to be disseminated. This bias may cause an overvaluation of effective sustainability practices, ultimately resulting in inadequate strategy development for hotels. Secondly, the emphasis on publications in English may limit access to significant discoveries from non-English literature, perhaps omitting essential regional insights.

A major limitation confronting hotels in both developed and emerging island nations is the issue of human capital, requiring associated training and development investments. This problem might hinder the fair allocation of human resources, especially in remote island areas where specialized labor may be scarce (Dolnicar et al. 2019). Hotels frequently require significant investments to improve employee competencies, which are crucial for the effective implementation and maintenance of sustainable practices. Smaller enterprises or those with constrained financial resources may perceive these expenses as especially onerous (Jones et al. 2014). The difficulty of obtaining proficient personnel can impede the uniform implementation of sustainability measures, hence impacting the overall efficacy of these programs (Gomathy 2022).

The long-term advantages of sustainable practices are evident; yet, the initial investment expenditures provide a barrier for hotels in competitive markets or those with constrained budgets. This problem is particularly evident in both developed and developing island nations, where the substantial expenses linked to sustainable technology may dissuade hotels from implementing these practices (Onsrud 2019). Thus, the lack of initial investment may hinder overall advancement in sustainability within the hotel industry.

Furthermore, national legislation and policies substantially affect the adoption of sustainable practices, either promoting or hindering their implementation. Inadequate or erratic policies may fail to incentivize hotels to adopt sustainability practices, or, conversely, may dissuade them entirely. The disparity in policy frameworks between developed and developing island nations constitutes a significant research limitation, resulting in varying sustainable practices and hindering the formation of industry-wide standards (Khalil et al. 2022; Floričić 2020).

Promoting pro-environmental behaviors (PEBs) among visitors is a vital focus for hotel operators, as these behaviors correspond with the overarching aim of involving guests in sustainable activities (Rekha 2023). Engaging guests not only improves their entire experience but also cultivates a feeling of environmental responsibility (Kumari et al. 2024). Nonetheless, a difficulty arises as certain guests exhibit environmental awareness, while others may stay apathetic or choose less sustainable alternatives. This inconsistency requires an additional examination of the factors affecting guest behavior to enable effective involvement among all stakeholders, including hotel owners, managers, policymakers, and guests (Steg et al. 2014).

The variability in research methodologies and contexts hinders comparison, complicating the synthesis of data due to differences in geographical regions, hotel brands, and operational sizes. Finally, although existing methodologies have been examined, there is an absence of comprehensive analyses regarding the long-term effects of sustainability initiatives. Subsequent investigations must incorporate longitudinal follow-up studies to acquire more profound insights. Implementing strategies that include multiple languages and exploring under-researched domains could augment the comprehensiveness and applicability of findings in subsequent studies, directly addressing the articulated research goals.

6. Conclusions and Recommendations

Stemming from this research question, this systematic review elicited information on the strategies, instruments, and methods for assessing environmental sustainability through the use of specific methodologies within the hotel business. The analysis of 38 selected studies revealed several key findings:

• Increasing Research Interest: In the last decade, a significant improvement has been realized in the study of environmental sustainability in hotels and this has been precipitated by increasing international consciousness and legislation on this matter.
• Diverse Geographic Coverage: Research areas were dissimilar, and the most common regions were European and Asian. This shows a trend of wanting an upgrade of sustainability practices within the hospitality industry across the world.
• Adoption of Established Frameworks: Two guidelines that were found to be in extensive use for sustainability reporting were the GRI and the ISO 14001, which provided systematic methods for the assessment of sustainability.
• Comprehensive Assessment Techniques: It was observed that other tools such as the Multi-Criteria Decision Analysis (MCDA), Principal Component Analysis (PCA), and Fuzzy Logic were often employed to increase the credibility of sustainability evaluations.

The hotel sector is an essential element of the global economy, serving millions of visitors and business travelers annually while making substantial contributions to employment and GDP in many nations. This article highlights the growing significance of evaluating environmental implications in the hotel industry. By using best practices and standardized metrics, hotels may effectively advance sustainable development. Advanced assessment techniques and methodologies are essential for minimizing pollution, attracting environmentally concerned tourists, enhancing brand image, and reducing operational costs through increased efficiency.

Policymakers are crucial in promoting sustainability projects by enacting precise laws and offering incentives to foster environmentally responsible practices. By establishing rigorous environmental standards and providing financial assistance for sustainable initiatives, governments can promote industry-wide transformation. As the hotel industry expands, incorporating sustainability into development initiatives is crucial for maintaining long-term success and resilience.

This review’s conclusions underscore the necessity for additional studies and practical applications, highlighting the need for a sustainable and resilient hospitality sector. Cooperation among industrial stakeholders, researchers, and policymakers is essential for realizing substantial environmental advantages and fostering sustainable development. The observed limitations—namely, potential publication bias, language barriers, and issues associated with human capital—highlight the need for continued research to formulate more comprehensive methodologies and improve the effectiveness of sustainability assessments in the hotel industry. By mitigating these limitations, future studies can enhance the comprehension of environmental sustainability in the hospitality sector, thereby promoting a more sustainable future.

Based on the gaps identified in the current literature, the following recommendations are proposed for future research:

• Standardization of Methodologies: Further empirical studies should be directed toward the creation and testing of frameworks on sustainability reports with generic tools suitable for different geographical locations and categories of hotels. This would improve the standards of comparability and reliability of the assessments being conducted.
• Integration of Social and Economic Dimensions: Sustainability checks and evaluations are still insufficient, and economic aspects should be included together with social aspects. This would afford an integrated perspective of the firm’s sustainability performance, and realize compatibility, redundancy, or rivalry between sustainability strategies.
• Longitudinal Studies: More studies have to be conducted to examine the changes in the sustainability performance of hotels during different periods. This would provide an understanding of the effects that sustainability endeavors would have in the future and the aspects that would lead to continuity in the advancements.
• Emerging Technologies: Future studies should investigate how new technologies such as blockchain, artificial intelligence, the IoT in the hospitality industry affect the promotion of sustainability practices and their impact. Such advancements offer great opportunities toward enhancing operational efficiency, sound consumption patterns, reduced emissions, and improved data transparency, which are all necessary criteria to foster sustainable hotel management. By studying how the integration of such innovations may render the hotel sector more environmentally sustainable, research can provide valuable findings contributing to practical applications and benefits. These may, in turn, guide hotels in both developed and developing island states toward more effective sustainability strategies
• It can be further recommended that other studies further orient their investigation toward pro-environmental behaviors and use behavioral analysis to gain a deeper understanding of how to effectively promote sustainable habits among hotel guests and personnel. Hotels are reported to be capable of enhancing sustainability by understanding the determinants of eco-friendly behaviors and implementing focused interventions and educational initiatives. This method can facilitate the customization of tactics to diverse cultural and economic situations, hence enhancing their efficacy in both developed and developing island states. By comprehending behavioral patterns, hotels may create more captivating and convincing sustainability programs, thus promoting a more ecologically aware hospitality business (Bohdanowicz et al. 2011).
• Regional and Cultural Variations: Studies that examine regional and cultural variations in sustainability practices and their effectiveness would provide valuable insights for tailoring sustainability initiatives to specific contexts.