Instructors’ Perspectives on Enhancing Sustainability’s Diffusion into Mechanical Engineering Courses

Abstract

This research strives to catalyze a more extensive integration of sustainability topics into mechanical engineering (ME) courses. The process through which higher education instructors choose to integrate sustainability topics into their courses was conceptualized using diffusion of innovation theory. The research explored two questions: (1) What factors were influential to front runners (innovators or early adopters) for sustainability integration in undergraduate courses taken by ME students? (2) What factors could spur non-adopters to integrate sustainability into their courses? The study included a survey (with 53 respondents who taught sustainability and 14 respondents who did not teach sustainability), 10 interviews with innovators and early adopters, and a focus group of 5 participants. The results were explored primarily from the perspective of meeting the needs of instructors (the target users). Peer-to-peer interactions were found to be important across all user groups. Practices that would help motivate later adopters include prepared curriculum- and university- or department-based support in the form of mission statements, training, mandatory sustainability inclusion, and a sustainability office to provide support. Diffusion of innovation theory provides insights into which strategies are likely to be most effective in expanding the number of faculty members who integrate sustainability topics into their courses.

1. Introduction

Engineers have an important role to play in contributing to sustainable development. This requires educating engineers about sustainability in order to prepare them for this challenging endeavor. While the literature contains many examples of how instructors in higher education are teaching sustainability [1], the United Nations Sustainable Development Goals (SDGs) [2], and sustainability in the context of engineering [3,4,5], more widespread integration would be beneficial [6]. For example, a recent study found that 57 of 100 programs showed no evidence of integrating sustainability topics into any of the required ME courses in their curricula [7].

The process through which instructors decide what to teach and how to change their courses over time has been conceptualized via a variety of frameworks and theories. The Academic Plan model of Lattuca and Stark [8] describes the iterative process of curriculum decisions as being affected by internal influences (e.g., personal, unit-level, and institutional), external influences (e.g., market forces and accreditation requirements), the educational environment and outcomes, and the broader sociocultural context. This model has been previously used to explore faculty decisions related to teaching macroethics in engineering [9] and diversity issues in environmental and sustainability programs [10]. Education for sustainability enhancement at a program level has been explored through change management perspectives [11] and the Four Categories of Change Strategies model of Borrego and Henderson [12]. Diffusion of innovations (DoI) theory has been previously applied to study changes in higher education [13,14,15,16]. In higher education settings, the unit of analysis for DoI could be individual instructors, departments, or institutions [17]. No studies applying DoI to sustainability teaching in higher education were found. This research elected to use the DoI model in the hope of providing new insights with respect to individual instructor decisions to incorporate sustainability into their ME courses.

Diffusion of innovations (DoI) theory seeks to explain how innovations are adopted in a population, and an innovation can be an idea, behavior, or object that is perceived as new by its audience [18,19,20]. DoI concepts explain how an innovation gains momentum and diffuses or spreads through a specific population or social system over time. The result of this diffusion is that people, as pieces of a larger social system, adopt the new idea, behavior, or product. Important factors that impact the rate at which innovations are adopted include the attributes of the innovation itself (e.g., relative advantage and compatibility), the types of innovation decisions (e.g., optional vs. mandatory), communication channels, the nature of the social system, and the extent of change agents’ promotion efforts [13,18,21].

DoI theory classifies a population into five different segments based on their propensity to adopt an innovation [18,19]. The first individuals to adopt an innovation are termed innovators, and they make up around 3% of the market. They are followed by early adopters and the early majority, the next ~13% and 34% of individuals who adopt the innovation, respectively. After approximately half of the market has adopted an innovation, those in the late majority (the next 34%) and the laggards (the final 16%) adopt an innovation that achieves full penetration. Research has found that users in these different population segments have unique needs and characteristics [18,19,20]. Thus, strategies to promote an innovation should adapt and change over time, depending on the extent of market penetration that has been achieved.

It is difficult to gauge the extent of sustainability integration by faculty members in mechanical engineering (ME). A previous study found that 45% of 151 ME instructors taught sustainability [22], but it was assumed that survey respondents were over-represented among those who teach ethics and societal impact topics due to leverage salience theory. In a benchmarking study of ME programs at 100 institutions, 17 of the ME programs offered no undergraduate courses that integrated sustainability, while 9 programs had 13 to 38 undergraduate courses with sustainability, based on information submitted to the American Association for the Advancement of Sustainability in Higher Education (AASHE) and university course catalogs [1]. Within these programs, it is unclear what percentage of the ME instructors have integrated sustainability into their courses, but it seems that, depending on their institution, an individual could be a local innovator or part of the late majority. In addition to individual instructor attributes, the courses they were assigned to teach seemed relevant because particular courses, like thermodynamics and design, more commonly integrated sustainability than others (e.g., statics).

Mechanical engineering was selected as the discipline of interest in this study due to its high impact. Engineering has significant environmental, social, and economic impacts and, thus, plays an important role in global sustainable development efforts. The largest number of engineering bachelor’s degrees in the U.S. are awarded in ME [23], so it is crucial that mechanical engineers entering the workforce have the necessary knowledge, skills, and attitudes to promote sustainable practices. There are many published examples of sustainability’s integration into ME courses (e.g., Enelund et al. [24], Ramanujuan et al. [25], Issa [26], and Jha [27]). However, ME has been found to be lagging behind other engineering disciplines (e.g., environmental, civil, chemical, and material) in teaching sustainability [22,28,29,30,31].

The DoI framework can go hand in hand with the Academic Plan model, and it was selected for its unique perspectives on various user groups. Thus, this study used DoI as a lens to explore factors that contribute to instructors’ integrating sustainability topics into undergraduate courses for mechanical engineering students. The specific research questions were as follows:

• What factors were influential to instructors who were self-described front runners (innovators or early adopters) in sustainability’s integration into undergraduate courses taken by mechanical engineering students?
• What factors could spur non-adopters to integrate sustainability into their higher education courses?

2. Materials and Methods

The research used a mixed-methods approach, starting with a survey followed by interviews and a focus group.

2.1. Survey

A survey was developed to identify basic information about the sustainability teaching motivations and practices of instructors of ME undergraduate courses. The primary goal of the survey was to support the criterion-based selection of individuals to recruit for interviews. The survey was developed based on the research questions and information available in the literature. The survey first asked individuals to identify whether or not they taught undergraduate courses for ME students that included sustainability. Those who answered affirmatively were then asked about the following: what inspired them to incorporate sustainability in their undergraduate courses (6 options provided + 1 other, fill-in); what was helpful when they were first integrating sustainability (3 options + 1 other, fill-in); the courses they taught that included sustainability (7 options + 2 others, fill-in); and the sustainability-related topics they taught (5 options + 1 other, fill-in). For those who indicated that they did not teach sustainability in their undergraduate engineering courses, the follow-up questions concerned the reasons sustainability had not been included (5 options + 2 others, fill-in) and what would encourage them to incorporate sustainability (6 options + 1 other, fill-in). All surveys also asked respondents a final open-response question inviting them to share anything else about teaching sustainability in mechanical engineering and whether they wanted to volunteer to participate in a focus group. More details of the survey were provided by Tisdale [31].

Individuals believed to represent potential front runners of sustainability education in ME were invited to participate in the survey. These individuals were identified using the following criteria: (1) those who had authored papers on sustainability education in ME, thermodynamics courses or engineering design courses; (2) those who had received a grant from the U.S. National Science Foundation for sustainability integration into ME [32]; (3) instructors teaching an ME course that integrated sustainability based on documentation submitted by their institutions to AASHE toward certification under the Sustainability Tracking, Assessment & Rating System (STARS) (see Tisdale and Bielefeldt [1] for more information); (4) all instructors within ME programs at the “top 10” institutions (8 inside the U.S. and 2 outside the U.S.) based on sustainability’s inclusions in the largest number of undergraduate ME courses [1]; (5) respondents to a 2016 survey who checked yes to teaching both sustainability and ME students [22]. University websites were used to retrieve email addresses. Instructors identified in each of the above groups were contacted via email with a survey invitation and a link to the online survey in Qualtrics; 564 invitations to instructors at 125 different institutions were successfully delivered. The email also invited individuals to forward the survey invitation to other faculty members whom they knew taught sustainability to ME undergraduate students to foster snowball sampling. Survey responses were gathered in January to February 2023.

Among the survey responses that included useful information, 53 respondents indicated that they taught sustainability in courses for undergraduate engineering students (representing 38 different institutions, including 4 outside the U.S.). The most common courses where the survey respondents had integrated sustainability were senior capstone (n = 25), renewable/sustainable energy (n = 22), first-year design (n = 13), and thermodynamics (n = 13) courses. The most common sustainability topics taught included environmental issues, followed by economic issues, social issues, renewable energy, and global development/SDGs. There were also 14 survey respondents who did not teach sustainability in undergraduate courses (representing 9 different institutions, including 6 institutions with respondents who taught sustainability).

2.2. Interviews

Interviews were used to learn from instructors in the innovator and early adopter groups about their experiences with sustainability’s inclusion in ME courses and programs. There were 24 survey respondents who volunteered to participate in interviews. Fifteen individuals who taught sustainability in a wide range of ME courses and institutional settings were invited to participate in interviews, and 10 interviews were completed.

Semi-structured interviews were conducted over Zoom for about 30–60 min and recorded. The interviewees were asked questions such as where they placed themselves in the DoI model adopter categories in terms of integrating sustainability into mechanical engineering courses and why, whether they believed their sustainability teaching practices had influenced others, and whether they had suggestions for encouraging other faculty members to integrate sustainability in their courses and/or curricula. A full list of the interview questions was provided by Tisdale [31].

The interviewees taught and/or previously taught at both public (n = 5) and private institutions (n = 8) (three individuals described two different institutions), institutions from a range of Carnegie classifications (six with very high doctoral research activity, two with high doctoral research activity, one doctoral/professional university, two master’s universities, one special-focus four-year university, and one large public research-intensive institution outside the U.S.) with a variety of locations and institution sizes (small, medium, and large, based on the number of undergraduate students). The interviewees each had 5 to over 21 years of university teaching experience, were tenured/tenure-track (n = 5), and were teaching faculty members/instructors (n = 5). They had degrees from a range of different disciplines (mechanical engineering, n = 8, other engineering disciplines, n = 5, and non-engineering, n = 2), and they were male (n = 4), female (n = 5), and nonbinary (n = 1). Based on their survey responses, the interviewees taught sustainability in courses that were related to renewable/sustainable energy (n = 7), senior capstone courses (n = 5), first-year design (n = 5), thermodynamics (n = 2), heat transfer (n = 2), manufacturing (n = 2), and a variety of other required and elective courses (n = 8); the most commonly integrated topics were environmental, economic, social, renewable/sustainable energy, global development/SDGs, and others (e.g., concerning optimization, circular economy, life cycle assessment, metrics, ethical implications, environmental justice, food systems, nature-inspired, and collapse). To maintain anonymity, the interviewees are referred to with numbers, e.g., Interviewee 1.

2.3. Focus Group

A 1-h focus group over Zoom was conducted with 5 participants (3 individuals who were interviewed and 2 new individuals). The topics included the following: whether they had witnessed any specific resources or sustainability inclusion types that sparked greater interest and inclusion; key factors that led to a sustainability integration that withstood the test of time; the importance (or lack thereof) of a cohort or collaboration among faculty members; effective examples of top-down and bottom-up approaches; and the role of the institutional and educational environment in sustainability adoption.

2.4. Analysis: Coding

Zoom created a transcript of the audio from the recordings of the interviews, and these were then edited manually to correct errors. Deductive and inductive coding were utilized to systematically analyze the interview and focus group transcripts [33]. The two overarching themes of peer-to-peer communication and user-based needs from DoI theory formed the foundation of the coding scheme. Subtypes within these themes were identified, and a constant comparative method was used across the transcripts. The two authors discussed the themes to arrive at an agreement. The codes are shown in

Table 1. Influences on faculty members’ integration of sustainability into their teaching: codes, definitions, and number of responses.

Broad Category	Subcategory	Definitions	Interview n of 10	Survey, n
				Teach Sustainability, of 53	Do Not, of 14
Self-realization of importance		Personal realization of importance due to life experiences, including global travel, becoming a parent or grandparent, and others	5	45 ^	3
Peer-to-peer	Influenced their adoption	Peer-peer conversations, networks, and community; direct interactions, oftentimes with others who share common interests and/or goals, which lead to the adoption of an innovation	4	1 *	NA
	They influenced others		9	0	NA
	Publications	Reading a paper or textbook	3	7 *	0
Faculty (user-based) needs
University-based	Mission and policy	Department, college, or university mission, priorities, policy, and/or support	4	17	7
	Incentives	Reasons and motivations to take the steps and make the sacrifices needed	1	3 *	2 +
	Mentor program	A one-to-one relationship in which a more experienced faculty member can share wisdom, insight, and tools with the goal to assist the less-experienced member	1	13	1
	Sustainability office	An office focused on sustainability support for the university, including assisting professors in their sustainability-related goals	2	1 *	0
Resources	Prepared curriculum	Teaching materials that are ready for instructors/professors to utilize in the course	3	14	7
	Training	Offer instruction for the acquisition of the desired knowledge and expertise	3	7	5
Organization	Bandwidth	The time, openness, and place for the topic to fit in the course or for the course to fit into the major’s four-year plan	1	0	8
	Consistency	A standard set of definitions and a curriculum associated with the term “sustainability”	1	0	1
Meeting student needs	Interest	Engaging, intriguing, desirable, and relatable to students	10	5 *	0
	Whole-person	The ability to be a whole person with emotions Clear opportunities for hope and empowerment	3	0	0

^ Survey option: a personal passion; a number of the “other” responses also elaborated on this; ⁺ survey option: a bonus or financial incentive; * coded write-in responses.

. For their presentation in this paper, clean verbatim quotes are used from which filler language, such as “like” and “um”, were removed.

2.5. Limitations

This work was limited by the number and experience of the interviewees, focus group participants, and survey respondents. Increasing these numbers would have made the study more comprehensive. Among the 14 survey respondents who did not teach sustainability in ME, 11 were ME faculty members in 6 programs with atypically strong integrations of sustainability in ME. The sources for contacts were U.S.- and English-centric and thus, the experiences of other faculty were largely absent. In addition, the clear classification of instructors into user groups was uncertain, based on local norms and facets of sustainability.

3. Results and Discussion

The results include a description of how the interviewees classified themselves in the DoI user groups and the key influences found for the adoption of sustainability education in engineering.

3.1. Adopter Characterization

Based on the process used to select those who were interviewed, the authors classified the interview participants as innovators or early adopters of sustainability’s incorporation into undergraduate ME education. Four interviewees categorized themselves as innovators (Interviewees 6, 7, 8, and 10), five as early adopters (Interviewees 2, 3, 4, 5, and 9), and two as an early majority (Interviewees 1 and 4), with one interviewee citing two adjacent categories and other interviewees noting specific ways in which they were particularly innovative. Interviewee 10 characterized herself as a risk-taker and one of the first in engineering but noted that some colleagues on campus had been working on sustainability since the 1970s and that engineering “is quite late in all of these discussions”. Further, she stated that she had “senior colleagues who have always worked in this space who are quite quiet… perhaps they got a lot of pushback in the beginning… have decided to face outward internationally to colleagues who are like minded…” Another innovator, Interviewee 6, noted that “one makes mistakes because you are the first in”. Looking back, they “approached as an engineer”, which had limitations, and they “made enemies of colleagues and was perceived as a zealot”. Interviewee 4 felt like an early adopter of social sustainability. Most of the interviewees indicated uncertainty concerning what others were doing at their own institutions, nationally, and/or globally. Interviewee 3 stated that “all [mechanical] educators [teaching sustainability] are still early adopters”. Thus, the survey respondents who were teaching sustainability might all be considered innovators or early adopters, while the survey respondents who were not teaching sustainability might become an early majority (e.g., interested enough in sustainability to respond to the survey but not yet teaching sustainability in their undergraduate courses).

The results indicate challenges with characterizing an innovation itself—such as any integration of sustainability into engineering and/or mechanical engineering, teaching sustainability in particular courses (e.g., design or statics), or teaching specific concepts (e.g., environmental life cycle assessment or social impacts). In the survey, two write-in responses indicated the respondents might teach sustainability if they were assigned to particular courses (such as thermodynamics) but that sustainability did not “fit” into their courses (dynamics and automatic controls). In contrast, one survey respondent stated, “Frankly sustainability should be integrated into the whole mechanical engineering curriculum. In my view there is not one traditional mechanical engineering topic that in some way could not address sustainability”. Furthermore, local context mattered. For example, Interviewee 8 noted that nearly everyone in his small program had probably taught sustainability due to courses like first-year projects and senior design in which there was a lot of team or collaborative teaching; in contrast, others worried about whether anyone in their department would continue to teach sustainability after they had retired (e.g., Interviewee 5).

3.2. Personal Life Experience

Among the innovators and early adopters, there were not necessarily models or incentives to teach about sustainability. Rather, many of the interviewees described personal experiences in their lives that led them to realize the critical importance of sustainability and decide to integrate these topics into their teaching. Five interviewees described seeing and experiencing pollution and poverty conditions globally during their travels as influential. Three interviewees described personal motivations concerning the importance for future generations associated with becoming parents or grandparents. Within the survey, the most commonly selected response to the question “what inspired you to incorporate sustainability in your undergraduate courses” was a personal passion (n = 45 of 53); this passion had perhaps originated via personal life experiences. One of the write-in responses noted a “Deep concern about the climate crisis. This is why I went into engineering”. This motivator is likely to grow as global impacts become more readily apparent.

3.3. Peer-to-Peer Communication

Peer-to-peer communication has been identified in DoI theory as an important aspect of the adoption of new behaviors, particularly when moving from early adopters to majority audiences [19]. Peer-to-peer interaction was important in their sustainability teaching practices for four interviewees, and nine interviewees also described how their direct interactions had led others to integrate sustainability into their teaching. Mediums for peer-to-peer communication could include the following: general conversations with friends, colleagues, and peers; the inner- and inter-departmental sharing of ideas and materials; guest speaking and conferences; and the general sharing of ideas among groups sharing their goals and motivations.

Three interviewees articulated how sustainability’s incorporation had spread to them and how they had then continued this diffusion. Interviewee 9 explained, “I saw a presentation at ASEE [the American Society for Engineering Education] about 10 years ago, by someone who was incorporating sustainability in their classroom… I went up to him and asked, could I get some of those resources? And he shared his entire drop-box with me”. Interviewee 9 later shared her work with peers at her institution and via conference presentations. This was a powerful example of peer-to-peer impacts on the diffusion of sustainability both to and from the interviewee.

Four interviewees described peer-to-peer examples of their roles in diffusing sustainability education in their own colleges and universities. Interviewee 2 and Interviewee 9 described how they had created sustainability-inclusive course materials in senior design and first-year introduction to engineering courses, respectively, which were then adopted by other faculty members at their institution, thus diffusing the innovation of sustainability inclusion. Interviewee 3 indicated that professors in other departments at his institution reached out to him as his reputation for sustainability work grew. Interviewee 7 described that they were “frequently invited to speak in other departments” about their sustainability teaching practices, and they also discussed how their sustainability work with students that was supported by National Science Foundation grants spread both nationally and internationally.

Publications appear to be important to DoI in academic settings. Publications might be viewed as a form of asynchronous peer interaction, similar to the example in which two women engineering faculty members identified books as sources of mentoring [34]. Interviewee 7 stated, “I wrote a paper in 2008 which now has about 15,000 reads on Research Gate”. Eight of the 10 interviewees had published papers describing their sustainability teaching in engineering courses, but only three discussed these in their interviews. In the survey, write-in comments from five respondents indicated that they found reading to be helpful when they were first integrating sustainability into a curriculum, and another two indicated a textbook; another four cited research, which might entail researching the topic through reading the literature. With publications, faculty members are educating other professors on ways to effectively integrate sustainability into several types of courses.

3.4. User Needs: Instructors

Instructors are the users of this innovation because they decide whether or not to teach sustainability in mechanical engineering courses. The interviewees described their own needs (both past and/or present), as well as their understanding of the needs of those in the later user groups, in the adoption of sustainability education. The survey respondents and focus group participants were in varied user groups, from innovators in sustainability integration to those lacking sustainability integrations. Based on the interviews, areas of professor-based user needs were categorized in the sub-topic areas described in Table 1, including university-based support, resources, organization, and meeting student needs.

3.4.1. University-Based Support

University-based support represents general and/or financial support from the dean, chancellor, or others at a university. University support can come in multiple forms, including supportive policy from the college and/or university, incentives, mentor opportunities, and partnerships with a sustainability office. For example, a focus group participant stated, “I feel like there needs to be something above the individual faculty level, like department level or college level that’s encouraging it, and I’ve noticed that’s been successful on our campus”.

Policies supporting sustainability education from a university can be very impactful. There were 15 of the 53 survey respondents with sustainability in their undergraduate engineering courses who indicated that “a department, college or university mission inspired them to incorporate sustainability into their courses”. Interviewee 1 explained that, at her university, a policy mandates that all undergraduate students are exposed to sustainability principles in one general-education course and one major-specific course. Therefore, all academic departments integrate sustainability in at least one required course. In this case, sustainability was primarily integrated into existing core courses, which did not add any courses to students’ four-year curriculum. Further, Interviewee 8 worked at an engineering college that has a sustainability-dedicated course that is mandatory for all undergraduate engineering students. He described the benefit of this dedicated course as the ability to deeply explore sustainability topics and issues in creative and interactive ways. Interviewees 1 and 8 expressed confidence in their graduates having an awareness of and skills in sustainability. It appears that an administrative structure for sustainability requirements in curricula has been effective both in increasing sustainability integration in undergraduate mechanical engineering courses and in achieving sustainability learning outcomes among students. In considering whether sustainability should be included, Interviewee 5 stated, “This isn’t just a nice course to have. This is the future of the world we’re talking about, and so we need to make it a priority in our programs to incorporate this”.

Incentives can play an important role in sustainability adoption. A focus group participant described this need: “You need some incentive to want to put the time in, to alter your questions and add a sustainability piece into whatever you’re already doing”. This was also expressed by Interviewee 1, who said, “So if you’ve got mentors to help figure out how to integrate it into a course or monetary support to change a course, that’s going to motivate different people to do it. I think because we’re all so busy in what we do, having some kind of incentive to incorporate it more into your curriculum is needed, but also having the support of your department chair, your dean, or the Chancellor...all those pieces are necessary to really propagate it”. In responding to the survey question regarding what would encourage them to incorporate sustainability into one course or more of their courses, the responses among the 14 respondents who were not currently teaching sustainability were as follows: seven cited department incentives, three cited a bonus or financial incentives, and two cited sustainability’s inclusion as part of their performance reviews.

A partnership with a sustainability office on campus is another support for integrating sustainability into courses. One survey respondent stated that the sustainability office at their university was very helpful to them when they were first integrating sustainability into the curriculum. AASHE STARS 2.2 also awards a point if a campus offers sustainability coordination via a committee, office, or officer [35]. A successful example of this is the Green Academy at Nottingham Trent University, which reaches out to all schools and departments at the university to help with the incorporation of sustainable development in their curricula [36].

Among the 53 survey respondents who taught sustainability in their undergraduate courses, 13 indicated that mentorship was helpful to them when they were first incorporating sustainability. In addition, one of the individuals who was not teaching sustainability indicated on the survey that a mentor would encourage them to incorporate sustainability into one or more of their courses. Mentoring has been found to foster collegiality and collaboration while increasing teaching and research productivity [37]. Mentoring contributes to building positive relationships, and it can encourage professors to challenge assumptions underlying current unsustainable practices [38].

3.4.2. Resources

A number of faculty members indicated that they did not feel prepared to integrate sustainability topics into their courses, and outside resources might help these faculty overcome this obstacle. Five of the 14 survey respondents who did not teach sustainability in their mechanical engineering courses cited their lack of expertise in sustainability as a reason. Interviewee 4 echoed this sentiment: “I think there are still some people who are afraid to approach some of these topics”. A prepared curriculum and/or training could help meet these needs.

A prepared curriculum was noted as helpful in both the interviews and the survey. Six of the 14 survey respondents who did not teach sustainability in their mechanical engineering undergraduate courses stated that a sustainability curriculum for their specific subject area would encourage them to incorporate sustainability into one or more courses. And 13 of the 53 survey respondents who did teach sustainability in their undergraduate mechanical engineering courses said that a prepared curriculum was helpful to them when they were first integrating sustainability. Two of the interviewees reiterated this sentiment that a prepared curriculum was helpful to them as they were first incorporating sustainability into their curricula. Interviewee 3 articulated a need for a prepared curriculum: “There weren’t many textbooks available. So, it took pulling stuff from all over the place. I definitely did not have a whole lot of material to pull from. I had to develop a lot of stuff on my own”. Curriculum examples include the Engineering for One Planet initiative [39] and the Center for Sustainable Engineering Curriculum Modules [40].

A desire for training was evident in both the survey and interview results. Five of the 14 survey respondents who did not include sustainability in their undergraduate engineering courses said that a workshop or training would encourage them to incorporate sustainability into one or more of their courses. And six of the 53 survey respondents with sustainability in their curricula said that a workshop and/or training was helpful to them when they were first integrating sustainability. Interviewee 9 said “I have the training” when describing her ability to include sustainability in her courses, demonstrating confidence and empowerment. Interviewees 3 and 5 expressed an initial lack of training or expertise in sustainability. Interviewee 3 said, “I’ll even tell the students: ‘I am not an expert in this conversation, but let’s have the conversation.’”

3.4.3. Organization

The organizational aspects that emerged as needs were space in a curriculum and consistency in defining sustainability. A crowded curriculum was identified as a hindrance. Eight of the 14 survey respondents who did not include sustainability in their undergraduate engineering courses said that there were too many other topics to cover in the course and that this was a reason why they had not included sustainability in their courses, and one stated that “no time” was a reason. Interviewee 2 asked, “How do you incorporate all these things into your classes with the core curriculum that you need to teach, right? And how do you have time?” And thus, the presence of space within a four-year plan and/or within a specific course’s content is a need that professors face when exploring the option of adding sustainability into an existing course or adding a dedicated sustainability course.

Knowing what to teach concerning sustainability can constitute a challenge, as there is a lack of consistency in opinions on the key knowledge and competencies engineering students should learn about sustainability. A focus group participant observed, “When I started out trying to figure out for myself what sustainability meant, I realized that people use that word in a million different ways…and there’s really no broad consensus about it”. And Interviewee 5 stated, “It is really hard to know what should be in a sustainability course…. I think people may think of sustainability as not so much like a discipline or a topic, as it is something kind of equivalent to critical thinking”. Interviewee 5 went on to describe the standards for what would be included in a thermodynamics course and explained that there would be consistency across programs and universities and that this is not the case with sustainability. Professors may find it helpful if there were a standard or consistent curriculum for sustainability courses or sustainability inclusion principles.

3.4.4. Meeting Student Needs

Meeting the needs of their students was cited as a motivator by some of the faculty members. These can be short-term student needs (e.g., providing motivation and support for learning and developing them as whole people) and long-term needs as engineering professionals who, we hope, design for sustainability. Most of the interviews focused on the short-term needs of students as learners and as whole people, rather than specific needs in their future careers as engineers. Based on their actions, it could be presumed that all the interviewees believed sustainability awareness would be beneficial to students in their futures.

Student interest in the topic of sustainability was identified as a motivator by four interviewees and five survey respondents. Interviewee 3 said, “I think they (i.e., the students) definitely find the sustainability stuff interesting”. Interviewee 4 described the intrigue experienced by most students in a manufacturing case study concerning the popular toy Lego. In the survey, two respondents indicated student interest or motivation as something that inspired them to incorporate sustainability into their undergraduate courses (e.g., “I believe it is a motivator for students”), and three additional responses to the final open-ended question noted student interest (e.g., “Student interest has led the way”). Students may be among the biggest proponents of sustainability’s integration; in a study with over 1700 university students, almost all the students agreed that higher education institutions should actively incorporate and promote sustainable development [41].

Relating to real-world content can pique student interest. All ten interviewees described bringing sustainability issues into their classes through real-world examples, case studies, and scenarios. This included reading assignments concerning current events as part of homework assignments alongside solving technical problems, playing games that embedded sustainability principles, and in-class discussions. For example, Interviewee 6 said, “I take a minute to even recognize what’s going on in the world...that we’re a part of the world, not separate from it…I don’t separate the learning about sustainability from the participation in a planet of 8 billion people”. Interviewee 4 asked her class “why” questions concerning current events that had links to engineering. Interviewee 2 said, “I do an activity where I show them quotes and then they get to disagree or agree with it. And that leads to a nice conversation about different aspects of sustainability. …. I love how they transform by understanding the culture, while suddenly studying the mathematics at the same time”. Interviewee 8 described playing a game centered around manufacturing a product with limited time and money, factoring in mining for the rare earth metals needed. The activity included reflecting on their personal environmental impact, as well as designing for recyclability or repairability. Interviewee 1 said, “over the years I’ve actually added a lot more realism to my class… We always have a climate week…. we integrate politics into things, and discuss public perception and marketing … I added all that in there because I felt that my students were so focused on the math and the design that they weren’t understanding that, hey, you gotta look at the big picture”. Previous research has found that real-world contexts positively impact learning due to learner motivation [42,43].

Some classes are more challenging to integrate sustainability into. Interviewee 4 discussed the difficulty of integrating sustainability topics into statics, contrasted with the relative ease in her manufacturing course. However, Interviewee 3 included sustainability in statics by connecting the base of a problem to something real in sustainability and then using that as an opportunity for discussion: for example, completing statics calculations on a nuclear energy gantry crane and then talking about energy options.

Acknowledging that each student is a whole person with emotions came up as important in meeting student needs concerning sustainability education. Interviewee 6 said, “To really process any and all of the meaning of all the sustainability stuff, you need your whole body…You need to be able to go, that feels scary. How do I deal with my fear? …. We’re talking about people’s futures and the life they imagine for themselves.… You can precipitate an existential crisis…” Being cognizant of that is important to student well-being. Interviewee 10 focused on framing sustainability from a place of hope and empowerment: “I’ve tried to always bring it to students in a way, you know, we can do something about this, you can do something about this”. Interviewee 3 also shared this perspective of trying to keep students motivated despite the gloom.

Thinking about students’ emotions is quite different from the perspective of one of the survey respondents who did not teach sustainability: “It would be much easier to incorporate sustainability topics if there were well-established, objective curriculum materials that treated sustainability concepts with the rigor we want for an engineering course (by that, I’m thinking of ways to assess student learning of sustainability concepts via exams that include quantitative problems)”. Thus, the best way to teach sustainability as viewed by innovators and early adopters perhaps differs from the perspective of later adopters.

3.5. Adopter Group Synthesis

The influences on the faculty integration of sustainability into ME courses that presented themselves in this research were cross-referenced with the suggestions for different adopter categories described in diffusion of innovation theory [18,19], as shown in Figure 1. Aligned with DoI recommendations, the results of this study indicated that early adopters could be motivated by providing incentives like performance evaluations and/or financial bonuses for new and innovative ideas in sustainability integrations or for spreading their innovative sustainability practices to other professors, courses, or programs. Second, a mentorship program and other peer-to-peer communities could provide strong support and feedback. Early adopters may also appreciate public praise as front runners and innovators. Grant opportunities for funding to keep pushing the frontiers and taking sustainability to the next level could be of interest.

For faculty members with dispositions in the early majority, both training and a prepared curriculum could maximize the ease and simplicity of incorporating sustainability into their courses. A university sustainability office could provide “customer service and support”. Support could also be provided via peer-to-peer channels. If a university and/or college requires a certain number of courses per major or adopts strategic goals related to sustainability (such as committing to earn the AASHE STARS platinum rating), this promotes the social norm of sustainability education, which may spur late-majority faculty. Student interest and peer-to-peer communities could also promote a new social norm of sustainability’s importance in ME courses and curricula. Aligned with this idea of social norms, in the focus group, it was asked, “do you think mechanical engineers think that sustainability is a part of their job?” Unanimous head shaking occurred, signifying “no”. Another encouragement for late-majority faculty would be to make sustainability integration highly convenient by having a standard set of curricula or definitions on what sustainability inclusions look like and/or pre-existing integration into the textbooks that they are already using.

It is worth noting that particular ME departments may have a range of adoption levels among their faculties, such that different user groups are locally relevant. For example, a faculty member in an ME department without sustainability integration in any courses would be a local innovator, but by looking beyond their own department, they might be part of a late majority at their institution. For example, a focus group participant stated, “I would say that the majority of the sustainability thinking, I think happens outside of engineering”. In addition, particular types of sustainability topics or teaching approaches may be locally innovative and still involve global peers who are willing to mentor, share information, or publish about their teaching practices.

4. Summary and Conclusions

In this study, the factors found to bolster front runners’ sustainability teaching practices in ME courses included publications, training, a prepared curriculum, and a variety of other supports. Of those who were interviewed, all ten were motivated by perceived student interest in sustainability. Three interviewees described how they empowered their students by helping them see that they could make a difference and be one piece of the complex puzzle of working toward a more sustainable future. Half of those who were interviewed shared personal experiences that were significant motivators in their commitment to sustainability education. Additionally, peer-to-peer interactions and institution’s missions or policies were both factors that influenced four of the interviewed front runners. For example, two of the interviewees worked for higher education institutions that mandated sustainability courses for all students, thereby setting a social norm of sustainability inclusion. Significantly, these two professors had the highest confidence in student awareness of sustainability upon graduation versus those teaching at institutions without mandatory sustainability inclusion.

Among the 53 survey respondents who taught sustainability, 85% indicated that a personal passion was among their reasons for teaching sustainability, followed by 32% citing an institution mission or policy, 26% acknowledging the importance of a prepared curriculum (thus increasing convenience), and 25% the importance of having a mentor (providing face-to-face support and regular feedback). Reading publications, training, and student interest were additional motivators and supports.

The factors that could spur non-adopters to integrate sustainability into their courses, as reported by 14 survey respondents, included a prepared curriculum (n = 6), incentives (n = 6), and training (n = 5). The inhibitors of sustainability’s integration included too many other topics to cover in their courses (n = 8).

This research identified numerous suggestions to help propagate sustainability education among more instructors in mechanical engineering. The results listed here should not be considered exhaustive due to the limited number and characteristics of the interview and survey participants, but they still provide useful suggestions. All instructors can have a role to play in educating engineers to contribute to a sustainable future. And diffusion of innovation theory may provide helpful lessons to reach instructors who are not teaching sustainability in mechanical engineering and other disciplines.