1. Introduction
Only in the past few decades have concerns about sustainability and sustainable development become extensively recognized as a societal concern [
1]. According to the World Commission on Environment and Development, sustainability is aimed at “promoting harmony among human beings and between humanity and nature” [
2]; such “harmony” is translated into the “triple bottom line” concept, which propounds a balance between economic, social, and environmental sustainability [
3]. Despite this multidisciplinary perspective of sustainability, there is no consensus about the importance and priorities of each dimension [
4]. The sustainable development concept, introduced in the Brundtland Report [
2], is referred to as “…development that meets the needs of the present without compromising the ability of future generations to meet their own needs”; this has become a reference for scientific research on the environment [
5], underlying the progress of our society from a responsible economic perspective, and is in agreement with environmental and natural practices [
6]. Sustainability frameworks and approaches for scientific research and environmental management keep evolving [
7]. Nevertheless, the terms ‘sustainability’ and ‘sustainable development’ are often used as synonyms [
8], despite there existing a contradiction in that it is not possible to sustain infinite growth on a limited planet [
9]. In this study, we will use the concepts interchangeably, referring to a systems approach that conveys a multidisciplinary sustainability perspective (economic, social, and environmental).
Sustainability has gained significant attention over the years amongst engineers [
10], who play a crucial role in designing, building, and maintaining sustainable systems and infrastructure. It is, therefore, of interest to positively influence the attitudes of engineering students towards sustainability; thus, educators and universities should play an important role in fostering their values and beliefs towards sustainability [
11]. In fact, education aspires to transform the attitudes and behaviors of forthcoming generations towards sustainability through the combined efforts of educators and educational organizations [
11,
12]. A person’s behavior is determined by how highly a goal is valued and by the degree to which the person expects to succeed [
13]. Increasing knowledge could influence one’s beliefs, values, and intentions [
13,
14]. Beliefs convey a person’s acceptance that something is true and deal with the establishment of a person’s values and convictions, that, in turn, can be transformed by knowledge [
15]. Attitudes refer to a person’s lasting evaluations, emotional feelings, and inclinations towards some object or idea, and translate a person’s beliefs that are then confirmed through actions and thoughts, which influence intentions and thus drive a person’s future actions [
14]. Ajzen and Fishbein [
13] suggest that beliefs drive the creation of attitudes that thus affect the intention of an individual to act.
Educating engineers in sustainability is essential to foster fundamental changes in their conviction and values; given sustainability’s transdisciplinary nature [
16], such an endeavor could be achieved by inserting educational content into several engineering disciplines, especially those that have substantial roles in achieving sustainability (although the elements necessary to achieve sustainability stem from all aspects of engineering) [
17]. Consequently, it is of interest to assess the effectiveness of sustainability educational efforts; this is, indeed, if engineering schools are successful in shaping students’ attitudes and beliefs towards sustainability and in developing their sustainability traits. However, there is a lack of sufficient empirical studies that address such a concern [
11,
18]. Given such a context, we hypothesize the following:
H1. Beliefs towards sustainability have a significant direct relationship with the intention to act more sustainably.
H2. Attitudes towards sustainability have a significant direct relationship with the intention to act more sustainably.
Another aspect of sustainable development education is that it should consider students’ emotional development in order to enhance their skills and academic performance, and lay the foundation for a more collaborative and humane society; thus, building sustainable societies implies developing and managing emotional skills in addition to economic, social, and environmental factors [
19]. Emotional intelligence refers to a person’s ability to manage their feelings so that those feelings are expressed appropriately and effectively [
20], or are referred to as “the individual’s ability to use reason to understand and deal with emotions (own and others) and use emotions to understand the context and make more rational decisions” [
21]. Previous research has sought to explain how beliefs and attitudes shape favorable behaviors towards the environment [
22,
23,
24,
25], and has implied that the intelligent usage of emotions is an element of positive environmental behavior [
26], namely the ability to assess and regulate one’s emotions [
26]. On the other hand, emotional intelligence is vital in learning and in individual development [
27], contributes to and enhances the cognitive abilities of students [
28,
29], and is accepted to be essential for the formation of engineers [
30]. Emotional intelligence can be seen as a trait, being that the students’ emotional profile can vary according to gender and age [
31]. In addition, there is evidence of the linkage between sustainable development and emotional intelligence [
22,
32,
33]; this considers the latter to be a dimension of sustainability that plays a principal role in sustainable engineering education. Riemer [
34] suggests that emotional intelligence is not only a tool for engineering students while they are learning, but that it also offers career skills for the engineering graduate. Aguilar et al. [
26] suggest that considering emotional intelligence as moderating the relationship between beliefs, attitudes, and intentions towards sustainable behavior would contribute to a better understanding and better prediction of sustainable behavior. However, despite the progress that has been made in engineering education towards sustainability, emotional intelligence has not received enough attention and there is a lack of empirical studies that address such a gap [
11]. Accordingly, we hypothesize the following:
H3. Students with higher emotional intelligence will be more motivated to learn more about sustainability.
H4. Differences in beliefs, attitudes, and intentions towards sustainability according to gender will be found.
H5. Emotional intelligence will play a moderating role in the relationship between attitudes and intentions towards sustainability (H5a), and between beliefs and intentions towards sustainability (H5b).
The generic research question of this study asks whether sustainability education could generate positive effects in terms of the beliefs, attitudes, and intentions towards sustainability of a sample of engineering students in Portuguese engineering schools; in addition, it asks whether emotional intelligence plays a role in moderating the relationships between these variables and the engineering students’ motivation to learn more about sustainability (an exploratory approach that is motivated by the current lack of evidence regarding the role of emotional intelligence in contributing to a sustainable mindset).
As such, this study was carried out on a sample of engineering students in two major Portuguese engineering schools, who undertook courses with basic content on sustainability in the first semester of 2022/23; such content and the effort to deliver it were expected to impact the students’ beliefs regarding sustainability, leading to positive changes in their attitudes and intentions, and thus enhancing their sustainability traits. For that purpose, a survey was carried out using measurement instruments drawn from the literature and described in
Section 2, namely concerning beliefs, attitudes, intentions towards sustainability and emotional intelligence.
The remainder of the article Is organized as follows:
Section 2 describes the procedures, measurement instruments, data analysis method used in the study, and the sample characteristics;
Section 3 documents the results, which are discussed in
Section 4; and
Section 5 presents the conclusions and limitations of the study.
3. Results
Table 2 presents the descriptive statistics related to the items of the instruments used in this study: Beliefs, Attitudes, Intentions, and Emotional intelligence. All skewness and kurtosis values are within the normative values, ensuring the normality of the distribution.
Several items were removed from subsequent analysis: items BF4, BF5, and BF6 displayed weak correlations (r < 0.3); items AT5, AT6, AT7, and AT13 had low factor loadings (<0.5). The instruments’ internal consistency was assessed using Cronbach’s alpha (
Table 3). The results found that Cronbach’s α of each construct was greater than 0.7 (0.78–0.89), showing high reliability for our survey instrument [
45]. Furthermore, as shown in
Table 3, the factor loadings of all the constructs exceeded 0.5 and thus conformed to the test of item reliability [
40]. In addition, the composite reliabilities of all constructs exceeded the 0.7 (0.76–0.94) cut-off value, as recommended by Fornell and Larcker [
42]. In addition, the average variance extracted from each construct exceeded 0.5, indicating convergent validity [
42]. In short, the convergent validity test demonstrated that the proposed constructs were adequate.
In addition, discriminant validity was employed to measure how much the constructs differed; if the items in a construct were more strongly associated with each other than with the items measuring other constructs, the measure was seen as having discriminant validity. As portrayed in
Table 4, the shared variance among the variables did not exceed the square root of the AVE. Therefore, discriminant validity is confirmed.
A hierarchical multiple regression was performed to estimate the effects of the control variables and attitudes and beliefs towards sustainability on students’ intentions towards sustainability. An independence of residuals was found, as assessed by a Durbin–Watson statistic of 1.946. The independent variables were entered in three blocks; consequently, two nested models were generated. Model 1 estimated the effect of the control variables (gender, age and country of origin were not statistically significant); Model 2 added beliefs, and Model 3 added attitudes (
Table 5). The results revealed that attitudes and beliefs towards sustainability have a statistically significant positive direct effect on intentions towards sustainability. The full model of gender, beliefs and attitudes that was used to predict intentions towards sustainability (Model 3) was statistically significant,
R2 = 0.626,
F(3,180) = 100.58,
p < 0.001; adjusted
R2 = 0.620. The addition of beliefs to the prediction of intentions towards sustainability (Model 2) led to a statistically significant increase in
R2 of 0.394,
F(1, 181) = 125.741,
p < 0.001. The addition of attitudes to the prediction of intentions towards sustainability (Model 3) also led to a statistically significant increase in
R2 of 0.193,
F(1, 180) = 93.091,
p < 0.05. Therefore, H1 and H2 are accepted.
A Mann–Whitney test was conducted to compare beliefs, attitudes, and intentions towards sustainability for gender, for the groups who have/have not had prior training in sustainability, school of origin, and nationality; differences were found only for gender (
Table 6) concerning beliefs and intentions towards sustainability, being that, in both cases, females scored significantly higher. Consequently, H4 is accepted. An independent-samples
t-test was run to determine whether there were differences in emotional intelligence between men and women; women scored higher in EI (
M = 5.43,
SD = 0.49) than men (
M = 5.37,
SD = 0.67), but this difference was not statistically significant,
M = −0.23, 95% CI [−0.50, 0.04],
t(182) = −1.688,
p = 0.093. Another independent-samples
t-test was run to determine whether there were differences between the emotional intelligence levels of the respondents who felt more motivated to learn about sustainability and those who did not; students that felt more motivated scored higher in EI (
M = 5.30,
SD = 0.89) than men (
M = 5.12,
SD = 0.78), making this difference statistically significant,
M = −0.18, 95% CI [−0.42, 0.06],
t(182) = −1.456,
p = 0.147, and thus supporting H3.
A moderation analysis was conducted to test the hypothesis that emotional intelligence plays a moderating role in the relationship between attitudes (H5a) and beliefs (H5b), and intentions towards sustainability. Firstly, intentions towards sustainability was set as the dependent variable, attitudes was set as the independent variable, and emotional intelligence was set as the moderating variable. The results indicate the negative and significant moderating effect of EI on the relationship between ATT and INT (B = −0.224, 95% CI (−0.39; −0.06), t = −2.717, p = 0.007), being that the interaction term increases the explained variance of INT (∆R2 = 1,7%, (F(1,180) = 7.38, p = 0.007), supporting H5a. A simple slope analysis carried out to better understand the nature of this moderating effect, at the mean of EI and ±1 standard deviation from the mean, reveals that the impact of ATT on INT is stronger for lower levels of EI (B = −0.926, 95% CI (0.77; 1.00), t = 11.859, p < 0.001) than for higher EI (B = −0.644, 95% CI (0.47; 0.82), t = 7.422, p < 0.001); in other words, as the level of EI increases, the strength of the relationship between ATT and INT decreases. Similarly, students’ intentions towards sustainability was again set as the dependent variable, beliefs was set as the independent variable, and emotional intelligence was set as the moderating variable. The results indicate the negative yet non-significant moderating impact of EI on the relationship between BLF and INT (B = −0.096, 95% CI (−0.23; −0.04), t = −1.405, p = 0.162), increasing the explained variance of INT (∆R2 = 0.6% (F(1,180) = 1.97, p = 0.162); thus, H5b is rejected. In sum, all hypotheses were accepted except H5b.
4. Discussion
The results document that, after being delivered, the educational sustainability content in the courses undertaken by respondents revealed a widespread moderate to strong agreement between beliefs, attitudes, and intentions towards sustainability, which is in line with [
11,
12,
46]. Among the items that scored the highest within beliefs, one can highlight the conviction that students should act with regard to environmental issues and should take responsibility for sustainable development. Regarding attitudes towards sustainability, they indicate a willingness to set aside garbage for reuse, recycling, or safe disposal, and show a stronger awareness of current environmental, social, economic, and cultural issues. These results align with the literature, which confirms that sustainability education can positively affect students’ ecological footprint [
18]. The item that scored the lowest was refusing the use of packaging (
M = 2.96,
SD = 1.073), possibly reflecting an impediment to the acceptance of a more sustainable lifestyle. In terms of the intention to act towards sustainability, the results enhance the students’ willingness to work with environmentally and socially responsible employers and their inclination to adapt their lifestyle for higher levels of sustainability. In general, the courses have created motivation among the students to follow a sustainable lifestyle and practices, as can be inferred by the mean ratings obtained in most items (all above 3.0, except for item AT6).
A model was found in which attitudes, beliefs, and gender significantly correlate with students’ intentions towards sustainability; as predictors of such an intention, they explain, as a whole, 62.6% of the variance in these dependent variables. This is in line with previous research [
11,
18] that has suggested that sustainability education could change beliefs and attitudes, and, in turn, impact students’ intentions to act towards sustainability; this is also in line with the suggestion that there may be differences concerning gender [
31]. Furthermore, women scored significantly higher in attitudes and intentions towards sustainability, which is possibly linked to the fact that they also revealed higher levels of global emotional intelligence; this is an outcome that aligned with Zhoc et al. [
29], who state that EI contributes to key learning outcomes in higher education (including social, cognitive and self-growth outcomes) and that women develop higher levels of emotional intelligence [
30]. However, this is in contrast with the results obtained by Ryu et al. [
18], who found that gender had no statistical significance in post-sustainability training regarding attitudes and intentions towards sustainability.
Several studies report that emotional intelligence has positive effects on engineering learning [
32,
37] and that it enhances behaviors towards sustainability [
22,
26]; this study’s results are similar, finding that students with higher emotional intelligence are more motivated to learn about sustainable development and how they can help build a more sustainable future for all. On the other hand, EI was found to negatively and significantly moderate the relationship between attitudes and students’ intentions towards sustainability, being that the lower the emotional intelligence, the stronger the relationship. A possible explanation for such an outcome is that the higher the emotional intelligence, the less conditioned students are by beliefs or attitudes, likely because they are more complex and may reflect more on sustainability issues. However, the moderating effect of EI on the relationship between beliefs and intentions towards sustainability in our sample was not statistically significant, though it was not distant from the effect on the relationship between attitudes and intentions towards sustainability.
The findings of this study underline the impact of inserting educational content on sustainability into engineering courses, which may, among engineering students, generate stronger beliefs, attitudes, and intentions to act more sustainably and also enhance the effect of emotional intelligence in the learning process. Among the reasons to include emotional intelligence in an education on sustainability in engineering, one can mention that it could improve the ability of engineers to understand the emotional context of sustainability issues and to communicate effectively with stakeholders (for example, engineers who are trained in emotional intelligence are better equipped to understand the emotional barriers that may prevent stakeholders from engaging in sustainability initiatives). In addition, emotional intelligence helps engineers recognize the impact of their emotions and biases on the sustainability decision-making process and take steps to mitigate these effects. In addition, emotional intelligence enables engineers to collaborate effectively with others in promoting sustainability by fostering trust, empathy, and mutual respect. However, most of all, emotional intelligence impacts the learning process itself [
20,
34,
47], suggesting that it should be adequately used to ensure that education on sustainability is more effective among engineering students; as suggested by some authors, EI could even be seen as a competence for engineering education [
30,
48]. In that regard, a recommendation that may contribute to the education of engineers towards sustainability is integrating EI-related skills into engineering curricula to foster its relevance in education, across disciplines, and in society. Furthermore, improvements in EI may support students to build up knowledge in their discipline more thoroughly, alongside other core skills needed for becoming an engineer [
30]. That could be achieved, for instance, by using EI-oriented contents, context-specific role-plays, PBL, or exercises that enhance context and self-awareness, communication skills, team working, the conveyance of ideas, the acceptance of criticism, learning to adapt, leadership [
30,
34,
37,
49], and reflection skills and abilities [
34]; this is compared to embodying sustainability topics (e.g., sustainable engineering, sustainable technologies and processes, risk and sustainable analysis, sustainable engineering design, and leadership, as recommended by Boyle [
17]).
Our results and the implications described above should take into account that this study has some limitations. Firstly, the sample could benefit from being larger and including a more diverse range of students, namely, to allow for investigating significant differences in engineering disciplines and courses. Another limitation is that we relied on the assumption that all the students provided honest answers to the questionnaire; because the respondents were asked to answer it at the end of a lesson, we should expect that some may not have taken it seriously. Furthermore, being a cross-sectional study, we tried to capture whether the educational content on sustainability that was included in the semester’s courses indeed impacted the students; nevertheless, we had to rely on the respondents’ judgment regarding whether that content had changed their beliefs, attitudes, and intentions to act more sustainably from the beginning to the end of the semester. Another shortfall is that we only approached engineering students on their way to completing undergraduate courses or attending master’s degree lectures. The reason for this decision was the consideration that sustainable engineering demands the capability to realize the multifaceted systems that exist within the environment and in society, as well as the restraints on those systems, and thus a greater maturity than that of most traditional engineering disciplines [
17]. However, EI competencies also vary with age, suggesting that their use as an effective sustainability learning tool should also involve students at earlier stages of their undergraduate education, as there is also evidence that we can influence students’ sustainable behavior then as well [
50]. A longitudinal study may be of interest to ensure that the same cohort of students is followed over time and that more reliable conclusions are drawn concerning the impact of efforts to provide education on sustainability and the use of EI within such a context. Finally, our study has addressed emotional intelligence as a whole; that is, we have not decomposed EI into a series of sub-dimensions that deserve analysis on their own (namely, attention to one’s emotions, sensitivity to others’ emotions, emotional maturity, empathy and emotional contagion, understanding of the causes of one’s emotions, self-encouragement, understanding of one’s emotions, and emotional self-control). Students could score differently in such sub-dimensions, possibly affecting the effectiveness of the educational approach in student groups, namely concerning gender and age [
31].