The Effect of Environmentally Sustainable Practices on Customer Citizenship Behavior in Eco-Friendly Hotels: Does the Green Perceived Value Matter?

: In the green marketing literature, environmentally sustainable practices (ESPs), green perceived value (GPV), as well as customer citizenship behavior (CCB) have not received signiﬁcant attention, particularly in the hotel industry context. The current study aims to examine the effect of ESPs on CCB in a sample of ﬁve-star eco-friendly hotels in Egypt. Furthermore, it attempts to identify the potential mediating role of GPV in the relationship between ESPs and CCB and to examine the extent to which GPV directly affects CCB. To achieve the study aim, a self-administrated questionnaire was developed and directed to a convenience sample of ﬁve-star eco-friendly hotel guests. A structural equation model (SEM) was applied to 374 forms from guests of the surveyed hotels. The ﬁndings of the study reveal that ESPs signiﬁcantly and positively affect GPV and CCB. The GPV has a positive and signiﬁcant effect on CCB. The GPV partially mediates the relationship between ESPs and CCB. These ﬁndings emphasized that environmentally sustainable hotel properties are rewarded by customers in the form of CCBs (i.e., feedback, helping others, advocacy, and tolerance) directly and indirectly (through GPV). Upon this, some practical implications have been suggested to improve managers’ understanding in order to enable them to better manage their ESPs and to achieve positive and optimum outcomes.


Introduction
Undoubtedly, sustainability is one of the single most significant global issues the world faces [1]. Sustainability has been a focus since the early 1970s when environmental concerns and overexploitation were raised for the first time [2]. However, the concept of sustainability was formally recognized during the Earth Summit in Rio De Janeiro, Brazil, in 1992. During this summit, 178 countries decided to work within an environmentally sound framework to mitigate the negative effects of businesses on nature [3]. In the hospitality industry context, sustainability was introduced at later stages, as initially, this industry was considered harmless to the environment [4].
However, among the major sectors of the hospitality industry, the hotel sector creates more negative environmental impacts than is commonly perceived [5]. In their daily operations, hotels consume huge resources, which negatively affect the ecosystem. Hotels rely heavily on water, energy, and nondurable goods and produce significant CO 2 emissions [5][6][7]. As a result, it is essential to design and implement ESPs in hotels to reduce their negative impacts on the environment. ESPs have been characterized as activities adopted by companies aimed at reducing or eliminating their environmentally negative impacts [8].
Due to increasing consumer awareness of a deteriorating environment and concerns for environmental sustainability, eco-friendly products such as eco-friendly hotels are becoming increasingly popular [9,10]. Notably, several alternative terms have been used to describe eco-friendly hotels in the hospitality industry. Some of the common terms that have been used include green hotels [11,12], environment-friendly hotels [13], and sustainable hotels [14,15]. According to the green hotel association [16] (p. 1), green or eco-friendly hotels are defined as "environmentally friendly properties whose managers are eager to institute programs that save water, save energy, and reduce solid waste-while, at the same time, saving money-to help protect both the earth and the environment". Furthermore, Manaktola and Jauhar [17] (p. 365) described an eco-friendly hotel as "a less environmentally damaging property that has made a commitment to various ecologically sound practices such as saving water, saving energy, and reducing solid waste". In addition, Mohd Suki, and Mohd Suki [18] (pp. 103-104) defined eco-friendly hotels as "hotels that are nature-oriented, environmentally focused, and environment-friendly (i.e., eco-friendly) in use of energy, water, and materials that do not exacerbate impacts on the earth and environment." According to Chan [19], an essential component of becoming an eco-friendly hotel is implementing an environmental management system that meets international standards and extends throughout the hotel, as well as between the hotel and its guests, local community, and suppliers.
Previous studies have investigated the positive relationships between ESPs (green practices) and customers' attitudes and behaviors in the hospitality industry. In the Indian lodging industry, Manaktola and Jauhari [17] examined the factors affecting customers' attitudes and behaviors towards green hotel practices and analyzed their impacts on customers' intentions to pay. Yu et al. [20] investigated the effect of green experience on customer satisfaction in green hotels. Others have examined the impact of green awards and certifications on customers' perceived value and their green behavioral intentions [21]. Han [22] reviewed the theories, concepts, and latest research on the linkage between environmental sustainability and consumer behavior. Green hotel practices as predictors to generate a positive hotel image, guest trust, and satisfaction have also been investigated by Moise et al. [23].
Although numerous studies have examined the relationship between ESPs and customer behavioral intentions, customer citizenship behavior (CCB) has not received significant attention in the green marketing literature [24]. Interest in the realm of customer citizenship behavior has increased in recent years [25]. Typically, CCB is viewed as voluntary and social efforts preformed by the customer and is valued by the company [26]. In previous literature, CCB was also known as "customer voluntary performance and customer extra-role behaviors" [27][28][29]. CCB highlighted the customer's non-purchasing behavior [25]. Accordingly, these behaviors encompass extra-role behaviors that customers voluntarily provide in terms of information, ideas, and physical cooperation during or after the service delivery [30].
To fill this gap in the hospitality academic literature, the current study aims to examine the effect of environmentally sustainable practices on customer citizenship behavior in a sample of five-star eco-friendly hotels in Egypt. Furthermore, this is to identify the potential mediating role of GPV in the relationship between ESPs and CCB. In addition, this is to examine to what extent GPV directly affects CCB.
This study effectively contributes to the literature on green marketing in various ways. First, the study improves the understanding of the direct and indirect impacts of ESPs on CCB. Second, the study contributes to an identification of the direct impact of ESPs on GPV, as a new concept, in the hotel industry. Third, the findings of the study could help hospitality scholars in exploring the factors influencing customer voluntary positive behavior (i.e., CCB), which is considered a basis for further studies aiming to examine the justifications for improving customer perceived value and to enhance their CCB in the green hospitality industry context.

Environmentally Sustainable Practices (ESPs) in the Hotel Industry
In recent years, one of the most serious changes we are experiencing is climate change. In response to climate change and environmental degradation, it has become imperative for industries, particularly the hotel industry, to implement environmentally sustainable practices (ESPs) [31]. ESPs have been identified as essential measures designed to enable organizations to achieve their environmental management goals [32]. Furthermore, Giordino and Crocco [33] mention that ESPs are practices employed by entities to maintain the qualities of the natural resources utilized during business processes. These practices are also known as green practices, defined as "a value-added business strategy that benefits a hospitality operation that engages in environmental protection initiatives" [34] (p. 721).
Kasim [5] mentioned that hotels are huge consumers of natural resources. Hotels, particularly luxury ones, are water-intensive businesses that use large amounts of water primarily for leisure purposes. In the hotel industry, consumption of water varies depending on the size and capacity of the hotel, the occupancy percentage, and the type of facilities and services provided [35]. Similarly, huge amounts of energy is used where hotels consumed huge amounts of energy for lighting, heating, and cooling systems daily (24-h) [36]. Hotels typically rely on the burning of fossil fuels to power them, which contributes to climate change, particularly global warming [37]. Moreover, by generating substantial amounts of solid and wet waste, the hotel industry is considered a major source of greenhouse gas emissions [5,36].
Over the last few years, hoteliers have been encouraged to become more environmentally friendly by means of a variety of forces, such as increasing the demand of consumers for green products and services, increasing interest in sustainable development principles, increasing environmental regulation, management commitment to environmental sustainability, as well as increasing customer satisfaction [19,38,39]. In response to these forces, as well as the growing environmental awareness among hotel consumers, more hotels have developed ESPs to improve their image, in order to help them in achieving a competitive advantage and to increase their market share [32]. According to Morelli [40] (p. 6), environmental sustainability has been defined as "meeting the resource and services needs of current and future generations without compromising the health of the ecosystems that provide them, and more specifically, as a condition of balance, resilience, and interconnectedness that allows human society to satisfy its needs while neither exceeding the capacity of its supporting ecosystems to continue to regenerate the services necessary to meet those needs nor by our actions diminishing biological diversity".
ESPs in the hotel industry are mainly focused on three areas: energy conservation, water conservation, and waste management and reduction [20]. The main practices implemented by hotels to save energy include installing energy-efficient light bulbs and appliances, installing automated motion sensors in low-traffic areas, using renewable energy systems like solar and wind energy, installation of triple-glazed windows or reflective glass, and the utilization of digital thermostats in guestrooms [7,40]. Regarding water conservation, the most commonly adopted practices were installing high-efficiency devices like low-flow toilets and showerheads, establishing programs designed to reuse linen and towels, the use of infrared-activated faucets, fixing leaks in bathrooms and toilets, recycling greywater, and keeping track of the consumption of water in each department [36,41]. Concerning waste management and reductions, hotels were committed to using refillable amenity dispensers (i.e., shampoo and soap dispensers), placing recycling-colored bins, purchasing recycled-content products, composting organic kitchen waste, purchasing raw materials in bulk containers, and adopting a donation program for charities [42][43][44][45].
Recently, ESPs have been expanded by hoteliers to include green purchasing (i.e., purchasing green cleaners and ingredients, and locally produced items), environmentally responsible sourcing (i.e., environmentally responsible suppliers), green construction, indoor air quality, green transportation, and noise control [23]. Abdou et al. [46] concluded that eco-friendly hotels play an important role in achieving environmentally related sustainable development goals (SDGs), particularly five-green star ones. In addition to previous practices, five-green star hotels have become more committed to applying continuous training for hotel staff in order to increase environmental awareness, and informing guest regarding the good environmental practices implemented, and encouraging guests to participate in reducing the hotel's environmental impacts.
To identify the importance of adopting ESPs in the hospitality industry, numerous studies have addressed the benefits that hospitality properties would achieve through the implementation of these practices. These benefits are classified into two categories: financial and non-financial [47]. Financial benefits include a reduction in operational costs, revenue generation, and hotel profit maximization. However, non-financial benefits include improving the hotel's image to the existing and potential guests, providing a safe and healthy environment for guests and employees, enhancing customer and employee satisfaction and loyalty, improving the relationship between the hotel and the local communities, contributing to environmental protection, improving environmental performance, and gaining a competitive marketing advantage over competitors [35,[48][49][50].

Customer Citizenship Behavior (CCB)
A variety of conceptualizations and definitions of CCB have been identified. For example, Bettencourt [51] (p. 384) defined customer citizenship behavior as "helpful, discretionary behaviors of customers that support the ability of the firm to deliver service quality". However, Groth [30] (p. 11) defined it as "voluntary and discretionary behaviors that are not required for the successful production and/or delivery of the service but that, in the aggregate, help the service organization overall". Bove et al. [52] (p. 699) defined it as "the voluntary behaviors outside of the customer's required role for service delivery, which aim to provide help and assistance, and are conducive to effective organizational functioning".
Various dimensions of CCB have been identified through theoretical and empirical investigation. Bettencourt [51] outlined three generic dimensions of CCB: loyalty, participation, and cooperation. In a later study, Groth [30] identified three different aspects, including making recommendations, helping other customers, and providing feedback. Considering a wider range of behavioral elements, Bove et al. [52] proposed seven conceptually distinct types of CCB. However, Di et al. [53] revealed that CCB is composed of four dimensions (namely, altruism, civic virtue, conscientiousness, and courtesy). Additionally, Yi and Gong [54] categorized CCB into four dimensions, namely, feedback, tolerance, advocacy, and helping. Feedback included "solicited and unsolicited information that customers provide to the employee, which helps employees and the firm to improve the service creation process in the long run" [54] (p. 1280). Meanwhile, advocacy involves introducing the business, the employee, or both to family and friends through positive word-of-mouth. In CCB, helping refers to voluntarily assisting other customers (i.e., assisting and supporting other customers as well as giving them advice, expertise, and companionship). Furthermore, tolerance was defined as "customer willingness to be patient when the service delivery does not meet the customer's expectations of adequate service, as in the case of delays or equipment shortages" [54] (p. 1280).
Generally, empirical investigations on ESPs as a predictor of CCB in the tourism and hospitality industry are scarce. In the airline context, Hwang and Lyu [61] concluded that consumer attitudes toward ESPs positively affect CCB (feedback and advocacy behaviors). In the green restaurant context, Hwang and Lee [62] indicated that CCB is positively associated with customers' public self-awareness. A study conducted by Thai and Nguyen [63] aims to examine the effect of green hotel practices (GHPs) on CCB and emphasized that CCB is positively affected by GHPs. In the non-tourism and hospitality context, van Tonder et al. [24] revealed that favorable green attitudes have a positive and significant impact on green feedback and advocacy behaviors (for USA participants) and only on green feedback behavior, without advocacy, for South Korean participants. From previous evidence, this can be assumed.

Green Perceived Value (GPV)
With the growing number of value-conscious customers, the importance of perceived value to marketing and other disciplines alike has heightened attention in recent years [21,64]. As stated by Zeithaml al. [65], perceived value is crucial to the success of the customer-provider relationship. In most cases, perceived value is conceptualized from the consumer's point of view [66] and is usually defined as "the consumer's overall assessment of the utility of a product based on perceptions of what is received and what is given" [65] (p. 14). According to Zeithaml [65] (p. 13), the definition of value is classified into four categories as follows: (1) "value is a low price"; (2) "value is whatever I want in the product"; (3) "value is the quality I get for the price I pay"; and (4) "value is what I get for what I give". El-Adly [64] conceptualized customer-perceived value as a multidimensional construct that includes more dimensions than price value (customer value for money), such as self-gratification value, aesthetic value, prestige value, transaction value, quality value, and hedonic value. Moreover, Roh et al. [67] add that the dimensions of perceived value may also include functional, social, conditional, emotional, and epistemic values.
Recently, with the increase in customers' environmental awareness, the concept of GPV has been proposed, which was defined as "a consumer's overall appraisal of the net benefit of a product or service between what is received and what is given based on the consumer's environmental desires, sustainable expectations, and green needs" [68] (p. 505). Furthermore, Han [22] (p. 1029) described it as "consumers' cognitive appraisal of the efficacy of an eco-friendly product/service based on his/her perception of what is obtained and what is sacrificed". The perceived value of green products will increase if the customers perceive more benefits than expenses in the consumption situation (i.e., excellent green product performance) and vice versa [22].
In the hospitality industry context, limited empirical studies have explored the relationship between hotel environmentally sustainable practices and customer perceived value. Han et al. [43] examined the perceptions of green hotels' guests towards water conservation and waste management practices and their impact on perceived hedonic and utilitarian values and concluded that these practices positively affect guests' perceived value. Lee et al. [21] revealed that green certifications and green awards have a significant positive effect on customers' perceived value within the hotel industry. In the non-hospitality context, research suggests that green products have a positive and significant association with perceived value [69]. In the Malaysian hypermarkets, Doszhanov and Ahmad [70] found that GPV was highly significantly and positively correlated with customers' intention to use green products (β = 0.920, p < 0.01). Van Tonder et al. [17] concluded that green feedback and green advocacy behavior are indirectly positively affected by green consumption values (through favorable green attitudes in general). Hence, we imply the following hypothesis: Hypothesis 2 (H2). Environmentally sustainable practices significantly and positively affect green perceived value.
Customer perceived value has significant and notable impacts on consumer postpurchase behavior [68,69,71,72]. Numerous studies have concluded that GPV is one of the key drivers of environmentally sustainable consumer behaviors [15]. Chen and Chang [68] and Cheung et al. [69] indicated that GPV has a direct positive effect on green purchase intentions. In the Malaysian green hotel context, Rasidah et al. [73] concluded that perceived value dimensions (functional, social, emotional, and epistemic values) have played a vital role in determining tourists' behavioral intentions, such as revisit intentions and positive word-of-mouth. Lee et al. [21] found that perceived value significantly contributes to green intentions to return and green intentions to pay premiums. In Australian eco-lodges, Ban et al. [71] found that perceived value indirectly (through satisfaction) affects positively guests' behavioral intentions (such as recommendations to others and positive WoM). Moreover, in the green restaurant industry, Riva et al. [72] concluded that GPV has a significant positive impact on millennials' revisit intentions (β = 0.328, p < 0.01). Roh et al. [67] concluded that consumer attitudes toward organic food are significantly affected by GPV. In the context of customer citizenship behavior, numerous studies conceptualized customer perceived value as a key predictor of customer citizenship behavior, where various scholars have emphasized that perceived value significantly positively affects CCB, i.e., [58,74,75]. A study conducted on bed and breakfast lodgers in Taiwan revealed that customer perceived value positively correlated with customer voluntary performance [27].
From a theoretical perspective, social exchange theory is one of the most important and used theories in social behavior, which contributes to understanding the significance of customer-company interactions in the light of customer citizenship behavior [76]. Homans [77] (p. 606) defined social behavior as "an exchange of goods, material goods but also non-material ones, such as the symbols of approval or prestige. Persons that give much to others try to get much from them, and persons that get much from others are under pressure to give much to them". Blau [78] described the social exchange as a relational exchange that generates an expectation of a future return by one party from another. Meanwhile, Bettencourt [51] (p. 387) referred to social exchange as "voluntary actions of an unspecified nature that extend beyond basic role obligations and suggest a personal commitment to the partner".
The social exchange theory, which was built on reciprocity, stated that people feel obligated to reciprocate when they perceive benefits from others' actions [78,79]. If customers feel obligated to reciprocate an employee's behavior that has benefited them, their reciprocity takes the form of CCB [78]. For example, customers who are satisfied with an organization tend to reciprocate by engaging in citizenship behaviors. Furthermore, Al Halbusi et al. [76] (p. 5) confirmed that "grounding on the social exchange theory, tourists who receive benefits or satisfying service from a relational exchange will likely return the favor to the service providers by engaging in voluntary behaviors, such as recommendations or other supportive actions".
From previous findings, and based on the social exchange theory, it could be assumed that the higher perceived environmentally sustainable practices, the higher the green perceived value, which may ultimately lead to positive effects on customer citizenship behavior. With regards to this, we propose the following hypotheses: Accordingly, the study research model is presented in Figure 1. Accordingly, the study research model is presented in Figure 1.

Measures and Instrument Development
In this study, the self-administrated questionnaire was the main form of data collection. After a comprehensive review of the study literature, a standardized questionnaire was developed by identifying valid and frequently used measures. The questionnaire is composed of four sections. The first section dealt with the participants' demographic data, including gender, age, level of education, and marital status. The second section revealed the perceptions of the investigated participants towards environmentally sustainable practices adopted in the investigated hotels. Respondents were asked to determine to what extent they perceive the ESPs to have been adopted. Environmentally sustainable practices suggested by Bruns-Smith et al. [80], Mensah [50], and Moise et al. [23] were adapted and employed. The scale was composed of nine items (i.e, "The hotel installs energy-efficient light bulbs and appliances in public areas and guest rooms"). The reliability analysis revealed an excellent internal consistency for this scale (α = 0.965). The third and fourth sections revealed green perceived value and customer citizenship behavior respectively.
Regarding green perceived value, a five items scale, based on Cheung et al. [69], was adopted. A sample item is "The hotel's environmental functions provide very good value for you". The scale had good internal consistency (α = 0.949). Furthermore, the four items scale, (i.e., "When I have a useful idea on how to improve service, I let the hotel know"), proposed by Yi and Gong [55] was adapted and used to measure CCB. The internal consistency reliability for the CCB scale was 0.922. The response rate for all measurement items was calculated by using a five-point Likert scale ranging from 1 = strongly disagree, to 5 = strongly agree.

Measures and Instrument Development
In this study, the self-administrated questionnaire was the main form of data collection. After a comprehensive review of the study literature, a standardized questionnaire was developed by identifying valid and frequently used measures. The questionnaire is composed of four sections. The first section dealt with the participants' demographic data, including gender, age, level of education, and marital status. The second section revealed the perceptions of the investigated participants towards environmentally sustainable practices adopted in the investigated hotels. Respondents were asked to determine to what extent they perceive the ESPs to have been adopted. Environmentally sustainable practices suggested by Bruns-Smith et al. [80], Mensah [50], and Moise et al. [23] were adapted and employed. The scale was composed of nine items (i.e, "The hotel installs energy-efficient light bulbs and appliances in public areas and guest rooms"). The reliability analysis revealed an excellent internal consistency for this scale (α = 0.965). The third and fourth sections revealed green perceived value and customer citizenship behavior respectively.
Regarding green perceived value, a five items scale, based on Cheung et al. [69], was adopted. A sample item is "The hotel's environmental functions provide very good value for you". The scale had good internal consistency (α = 0.949). Furthermore, the four items scale, (i.e., "When I have a useful idea on how to improve service, I let the hotel know"), proposed by Yi and Gong [55] was adapted and used to measure CCB. The internal consistency reliability for the CCB scale was 0.922. The response rate for all measurement items was calculated by using a five-point Likert scale ranging from 1 = strongly disagree, to 5 = strongly agree.
To assure that the study instrument measures the constructs that it sets out to measure, the questionnaire's face validity was tested. To evaluate the questionnaire form's content validity, six hospitality academics were asked to provide feedback. Furthermore, thirty tourists participated in a pilot study, who are not included in the study's main sample, in order to examine the feasibility of the questionnaire by testing how comprehensible and appropriate the questionnaire was, as well as whether the questions were well-understood, clearly defined, and consistently presented. Upon the participants' comments, modifications were made to the wordings of some statements (i.e., the hotel offers a linen reuse option to multiple night guests, the hotel uses sensors or timers to save electricity in intermittent use areas, and the hotel educates guests on environmentally friendly practices) and some statements were also re-ordered.

Sampling and Data Collection
As mentioned earlier, the current study aims to examine the effect of ESPs on CCB in a sample of five-star eco-friendly hotels in Egypt. Furthermore, it was designed to identify the potential mediating role of GPV in the relationship between ESPs and CCB. In addition, it was designed to examine the extent to which GPV directly affects CCB. To achieve the study aim, a self-administrated questionnaire was developed and directed to a sample of five-star eco-friendly hotel guests. The study mainly focuses on five-star eco-friendly hotels that are shown to be highly dedicated to adopting and implementing ESPs into their operations, particularly in Egyptian destinations, as mentioned by Abdou et al. [46] According to what was published by the Egyptian Hotel Association [81], the total number of five-star eco-friendly hotels was 32 hotels. Among the 32 five-star eco-friendly hotels, only 12 were willing to participate in the field study. Participation in the survey by the investigated hotels was subject to the conditions of anonymity. The investigated hotels were selected from different destinations (Sharm El-Sheikh, Hurghada, Madinat Makadi, and Marsa Alam). The sample of the study included both local and foreign guests who stayed in the investigated eco-friendly hotels. The study sample was recruited by using the convenience sample method "a type of non-probability sampling, in which people are sampled simply because they are convenient sources of data for researchers" [82]. According to Hall et al. [83], the systematic review of the behavior and attitudes of consumers and producers towards sustainable accommodation has indicated that convenience sampling was the most common sampling method used.
Data were collected by the research team with the assistance of two well-trained university students. Firstly, the potential participants were invited to take part in the field study after their check-out process. Furthermore, participants were informed that participation in the study is voluntary. They were asked to sign a consent form before participating in the study. A short background of the research purpose was given to the investigated participants by the field researchers. A total of 450 questionnaire forms were distributed; only 374 forms, with a response rate of 83.1 percent, were valid for statistical analysis.
Following the recommendation of Hair et al. [84], the appropriate sample size was decided upon. They suggested calculating the appropriate sample size based on the number of investigated variables. The minimum ratio (variable:sample = 1:10) is acceptable. Consequently, the minimum sample size required for this study was 180 participants, where the total variables under investigation were 18 variables. Our study sample size of 374 participants was sufficient.
Due to the study using a self-administrated questionnaire, common method variances (CMV) could be an issue. To reduce the possibility of common method variance (CMV), participants were assured that the collected data would be kept anonymous and confidential and that they would only be used for research purposes. All answers were to be given honestly, with no correct or incorrect responses. Furthermore, a common and simple statistical tool (Harman's single-factor test) was employed to detect CMV [85]. The collection of data lasted almost two months, from December 2021 to February 2022.
Based on the valid responses obtained from the investigated participants (374), nearly two-thirds of the investigated participants (65.2%, N = 244) were males and 34.8% were females. Regarding age, participants with an average age ranging from 30 to 40 represent the higher category (70.9%, N = 265). In terms of participants' educational level, the majority of them (74.3%, N = 278) had a university degree. Regarding their marital status, married participants constituted 61.3% (N = 229).

Data Analysis
The following statistical analysis methods were used to analyze the collected data: descriptive statistics, including frequencies, percentage, mean, and standard deviation were used to identify the participants' demographic data and to describe the participants' perceptions of study constructs' items. A reliability analysis (Cronbach's alpha), as well as a confirmatory factor analysis (CFA), were used to assess the validity and reliability of study items. The common method variance (CMV) was detected using Harman's single factor test. Convergent as well as discriminant validities were verified using composite reliability (CR), the average variance extracted (AVE), and the Maximum Shared Variance (MSV). Furthermore, the Fornell-Larcker criterion was also used to examine discriminant validity. Lastly, structural equation modeling (SEM) with bootstrapping was utilized to determine direct and indirect relationships between study constructs. The collected data were analyzed by using SPSS v. 22 and AMOS v. 26 (IBM, Armonk, NY, USA).

Descriptive Statistics
Data presented in Table 1 revealed the mean and standard deviation of the investigated variables related to the study's constructs. Concerning the environmentally sustainable practices (ESPs), the investigated participants perceived a higher level where the average mean ranged from 3.92 to 4.23. The highest perceived practice among the investigated participants was "The hotel installs energy-efficient light bulbs and appliances in public areas and guest rooms" with an average mean of 4.23. On the other hand, using renewable energy systems like wind and solar energy in the investigated hotels was considered the lowest perceived practice (M = 3.92, SD = 1.127). Regarding the green perceived value, the investigated participants ranked "The hotel's environmental functions provide very good value for you" as the highest variable, with an average mean of 4.36. In the customer citizenship behavior context, the investigated participants agreed on all the investigated variables where an average mean ranging from 4.11 to 4.19 was found. They ranked "I have to say positive things about the hotel and/or its staff and recommend it to my friends and relatives" as the highest attribute (M = 4.19, SD = 0.950).

Measurement Model
As mentioned previously, a self-administered questionnaire was used to collect the study data. Therefore, using Harman's single-factor test, the common method of variance/bias (CMV) was calculated [86]. Accordingly, one component accounted for only 46.33% (less than 50%) of the variance, which indicates that CMV is not problematic.
A first-order confirmatory factor analysis using the maximum likelihood technique was conducted before the structural equation model analysis in order to ensure that each latent variable comprises the correct observed variables. As shown in Table 1, the factor loading of all study items ranged from 0.683 to 0.989, which was greater than the criterion of 0.50 [87]. Cronbach's alpha and composite reliability of all latent variables were calculated to verify the internal consistency of measurement items, as well as to determine the constructs' reliability. Results presented in Table 1 revealed that the CR scores and values of Cronbach's alpha ranged from 0.919 to 0.964, and 0.922 to 0.965 respectively, which were higher than the recommended threshold of 0.80 [88], assuring that the constructs' reliability was satisfactory.
Construct validity was also determined using convergent and discriminant validities [89]. As suggested by Duckworth and Kern [87], a factor loading of not less than 0.50 and AVE above 0.50 are necessary for convergent validity. The results in Table 1 demonstrated that all items' factor loading and AVEs were higher than 0.60, which indicates that the convergent validity of the measurement models were satisfactory. In order to be deemed discriminately valid, Fornell-Larcker stated that the square root of the AVE of each construct must be greater than the correlation between that construct and another. The results presented in Table 2 illustrated that the AVE square root of all study constructs is greater than their correlations with the other ones. Additionally, the maximum shared values (MSVs) indicated in Table 1 are less than the average value of each construct, which indicates that the measurement model's discriminant validity is intact.   The goodness-of-fit indices such as, "normed chi-square" (x 2 /df), "Comparative Fit Index (CFI)", "Normed Fit Index (NFI)", "Goodness of Fit Index (GFI)", "Incremental Fit Index (IFI)", "Relative Fit Index (RFI)", "Incremental fit index (IFI)", "Root Mean Square Residual (RMR)", and "Root-Mean Square Error of Approximation (RMSEA)" were analyzed. The results of the goodness-of-fit analysis revealed that the model's fit was good (see Table 1).

Structural Equation Modeling (SEM)
SEM was utilized in order to determine the direction and interrelationships between study constructs. Data in Table 3 revealed that the fit of the research model was good, as recommended by Hair et al. [84]. x 2 /df = 3.452, p < 0.001, CFI = 0.935, NFI = 0.920, GFI = 0.897, RFI = 0.905, IFI = 0.935, RMR = 0.034, and RMSEA = 0.079. In the context of direct and indirect relationships between study constructs, the results in Table 3 and Figure 2 indicate that ESPs significantly and positively affect CCB (β = 0.314, t-value = 5.813, p < 0.001) and GPV (β = 0.364, t-value = 6.888, p < 0.001), respectively. Consequently, hypotheses H 1 and H 2 are accepted. Furthermore, hypothesis H 3 , which predicted that GPV significantly and positively affects CCB, is supported (β = 0.126, t-value = 2.324, p < 0.05). It could be concluded that the higher the green perceived value, the greater the customer citizenship behavior, and vice versa.
In the context of direct and indirect relationships between study constructs, the results in Table 3 and Figure 2 indicate that ESPs significantly and positively affect CCB (β = 0.314, t-value = 5.813, p < 0.001) and GPV (β = 0.364, t-value = 6.888, p < 0.001), respectively. Consequently, hypotheses H1 and H2 are accepted. Furthermore, hypothesis H3, which predicted that GPV significantly and positively affects CCB, is supported (β = 0. 126, t-value = 2.324, p < 0.05). It could be concluded that the higher the green perceived value, the greater the customer citizenship behavior, and vice versa. In order to validate the indirect relationship between environmentally sustainable practices and customer citizenship behaviors through a green perceived value, and to determine its potential role in this relationship, the Bootstrapping method has been utilized. The results in Table 3 illustrate that ESPs had significant, positive, and indirect effects on CCB through GPV (β = 0.046, t-value = 1.6485, p < 0.05). Hence, H4 is accepted. To examine the mediation effect of GPV in the relationship between perceived ESPs and CCB, the path was reviewed using the suggestions of Kelloway [90] and Zhao et al. [91] for partial and full mediation. They illustrated that only full mediation can be established if the indirect effects are significant, while the direct effects are not; partial mediation In order to validate the indirect relationship between environmentally sustainable practices and customer citizenship behaviors through a green perceived value, and to determine its potential role in this relationship, the Bootstrapping method has been utilized. The results in Table 3 illustrate that ESPs had significant, positive, and indirect effects on CCB through GPV (β = 0.046, t-value = 1.6485, p < 0.05). Hence, H 4 is accepted. To examine the mediation effect of GPV in the relationship between perceived ESPs and CCB, the path was reviewed using the suggestions of Kelloway [90] and Zhao et al. [91] for partial and full mediation. They illustrated that only full mediation can be established if the indirect effects are significant, while the direct effects are not; partial mediation occurs when both paths are significant. From the findings of the SEM, it could be concluded that GPV partially mediates the relationship between ESPs and CCB.

Discussion
The current study aimed to examine the effect of environmentally sustainable practices on customer citizenship behavior in a sample of five-star eco-friendly hotels in Egypt. It also aimed to identify the potential mediating role of GPV in the relationship between ESPs and CCB and to examine the extent to which GPV directly affects CCB. The SEM was performed to analyze the causal relationships between ESPs, GPV, and CCB. The findings of the study will be discussed in accordance with the review of the literature as follows.
The study findings revealed that the investigated participants were highly perceived ESPs, adopted by the surveyed eco-friendly hotels. They perceived that the surveyed eco-friendly hotels were more committed to adopting ESPs that related to energy conservation, water conservation, as well as waste management and reduction. These findings follow previous studies, i.e., [6,43,44,47,92,93], that concluded that eco-friendly and green hotels have become more committed to using eco-technologies for saving energy, installing high-efficiency devices, and establishing the reuse of linen and towel programs for water conservation, as well as adopting waste separating practices for waste management and reduction. In contrast, the findings of the study are in line with the results of Abdou et al. [46], who concluded that the least widely perceived practices among the investigated participants was the use of renewable energy systems.
Highly green perceived values in all surveyed items have been mentioned among the investigated participants. They indicated that the eco-friendly hotel's environmental functions provide very good value for them, and they are committed to purchasing the hotel's products/services because they are environmentally friendly. These findings are in line with those found by Ahn and Kwon [94], who examined the impact of guests' perceived value on intentions to revisit green hotel brands in Malaysia. Furthermore, Ban et al. [71] concluded a high perceived value among eco-lodge guests (M = 5.58), who mentioned that eco-lodge was reasonably priced and that they had a good return for their money in terms of the environmental performance of eco-lodge. Regarding CCB, like ESPs and GPV, the investigated participants highly perceived customer citizenship behaviors, specifically advocacy, feedback, tolerance, and helping others, respectively.
In the context of the interrelationships between the study's constructs (ESPs, GPV, and CCB), it could be first concluded that ESPs have a significant and positive impact on CCB. This result is similar to those found by Thai and Nguyen [64], who indicate that green hotel practices have a positive and significant influence on CCB (β = 0.490, p < 0.001) in Vietnamese hotels. Furthermore, this finding is partially aligned with Aljarah and Alrawashdeh [95], who found that corporate social responsibility (CSR) related to the environment made a significant positive contribution to boosting customer help, feedback, and tolerance without any significant effect on customer advocacy. Additionally, these findings also support the results of van Tonder et al. [74] who confirmed that favorable green attitudes positively and significantly affect green feedback and advocacy behaviors (for USA participants) in the non-hospitality industry context. Consequently, it could be concluded that the higher the perceived environmentally sustainable practices, the higher the customer citizenship behavior, and vice versa.
Secondly, the findings of the study revealed that GPV was positively and significantly affected by ESPs (β = 0.478, p < 0.001). This result is in line with the study findings of Han et al. [44], who concluded that water conservation, waste reduction, and management measures significantly increased tourist hedonic and utilitarian values. Moreover, a study by Lee et al. [21] revealed that in the context of the hotel industry, green awards and certificates positively affect customers' perceived value. The study's findings also foster the results of Mohammed and Al-Swidi [96] who emphasized that CSR related to the environment positively and significantly affected customer perceived value (β = 0.437, t = 5.69, p < 0.001). Upon the previous findings, it could be concluded that the higher the perceived ESPs, the better the green perceived value. The lower the perceived ESPs, the lower the green perceived value.
Regarding the impact of GPV on CCB, the findings of the study emphasized that GPV is a key predictor of CCB toward eco-friendly hotels. The finding of SEM supports the results of previous studies that have been conducted in various contexts such as the airline industry [76], the tourism industry [97], online-only retailers [74], and the service context [58]. This finding is in line with the results of Woo [76] and Tsaur et al. [98], who concluded that CPV positively affects CCB. In their empirical study, Cheng et al. [58] demonstrated that CPV plays a vital role in enhancing CCB. Furthermore, the results of the study are partially consistent with van Tonder and Heymans study's findings [74] who indicated that perceived value dimensions (perceived ease of use and perceived usefulness) indirectly affect (through a trust) customer citizenship helping behavior. On the other hand, the findings of the study are inconsistent with the results of Suryani and Listyarti [98], who concluded that CPV insignificantly affects CCB. Upon the previous findings, it could be concluded that the higher the GPV, the greater the perceived CCB and vice versa.
Concerning the mediation role of GPV in the relationship between ESPs and CCB, the findings of the current study showed that GPV plays a partial mediation role in this causal relationship. To the best of our knowledge, no previous studies have examined the mediating role of GPV in the relationship between ESPs and CCB. As a result, this finding is considered new evidence of the importance of GPV in the indirect relationship between ESPs and CCB.

Theoretical Implications
Several theoretical implications can be drawn from the findings of this study. Firstly, as a result of this study, significant contributions are made to the literature on environmental sustainability by providing insights into the direct and indirect relationships (via the GPV) between ESPs and CCB within the context of the eco-friendly hotel industry. In eco-friendly hotels, to the best of the authors' knowledge, this is the first study directly examining the relationship between ESPs and CCB with the existence of GPV, particularly in a developing country (i.e., Egypt). Secondly, this is the first study to examine GPV as a potential mediator between ESPs and CCB in the hotel industry. Thirdly, the study extends the scope of social exchange theory's application by highlighting how it is involved in connecting the constructs of this study. Based on the social exchange theory, this study showed that when hotels care for their environment, their customers gain a great deal of green perceived value and make them more likely to participate in voluntary activities (i.e., CCBs) that demonstrate their positive behavior for the hotel, such as tolerance for delays or failures in service delivery, offering feedback if they have positive ideas for improving service, speaking positively, referring friends and family to the hotel, and helping other customers when needed. Lastly, a novel ESP model indicating GPV and CCB can be identified in the current study, which contributes to the literature on green marketing and CCS in the hotel industry. The results of the study are significant, since the developed model may not only contribute to closing the gap between ESPs, GPV, and CCBs, but could also serve as a guide for further research in the hospitality industry context.

Practical Implications
Some practical implications can be identified based on the study's findings. According to the results of the study, customers voluntarily help, provide feedback, speak positively, and become more tolerant towards hotels that care about environmental sustainability. Such a finding can benefit hospitality marketers and executives seeking to boost positive customer attitudes through adopting and implementing customer-centric environmentally sustainable initiatives. Moreover, the study findings revealed the positive impact of ESPs on GPV, which positively affects CCB. Consequently, hotel operators need to integrate ESPs into their operational plans proactively. These practices pave the way for the customer to recommend eco-hotels to others through positive word-of-mouth. Moreover, periodic measurement of customer perceived value is crucial. Customers' feedback and recommendations are essential for improving environmental hotel services. Hotel management should encourage guests to participate in ES initiatives by offering incentives (i.e., special discounts, free meals, . . . etc.) Finally, the results of the study indicated that the least perceived practice among the investigated participants was using renewable energy sources (i.e., solar and wind sources). Consequently, it is highly recommended that hotel energy sources be replaced, where possible, with renewable energy ones (i.e., solar and wind) in order to mitigate greenhouse gas emissions.

Limitations and Future Research
The present study has some limitations. First, the study was conducted in order to examine the customer perceptions toward ESPs, GPV, and CCB of only five-star eco-friendly hotels in Egypt. The findings may not be generalizable to other geographical areas beyond this population. Further research with a broader and larger sample may yield valuable insights. Second, the study was conducted on eco-friendly hotels and further research may be applied to other sectors of the hospitality industry (i.e., green restaurants, green cruises, . . . etc.) Third, the study addressed the potential mediating role of GPV in the relationship between ESPs and CCB, but other variables may be investigated, such as green customer satisfaction, green image, and green trust. Fourth, the study investigated the impact of ESPs on CCB as unidimensional. Future research could explore CCB as a multi-dimensional construct.