Exploring Sustainability Instruction Methods in Engineering Thermodynamics Courses: Insights from Scholarship of Teaching and Learning

Abstract

It is important that engineers are educated to consider sustainability in their work. Thermodynamics is a fundamental course required in several engineering majors that has a natural connection to sustainability topics (e.g., energy and limits on efficiency). This work examined how sustainability was included in university-level engineering thermodynamics courses, based on 18 peer-reviewed papers that described Scholarship of Teaching and Learning studies. This review found that environmental issues were included in 15 courses, social issues in 9 courses, and economic issues in 5. There were 11 papers that included topics related to one or more of the United Nations’ Sustainable Development Goals (SDGs), with 8 of the 17 SDGs represented by one or more papers. The learning outcomes from the courses provided many examples of cognitive outcomes at all six levels of Bloom’s taxonomy. In contrast, affective domain outcomes were generally not explicit. Methods of integrating sustainability topics included mathematical examples, labs, projects, service-learning, application-based learning, simulation tools, and book reviews. These examples should inspire instructors to foster sociotechnical mindsets toward engineering, which are a key to educating engineers who value sustainability and who will advocate for its importance in engineering.

1. Introduction

Engineers have an important role to play in working toward a more sustainable future. A starting point for making the incorporation of sustainable engineering widespread in real-world engineering practice is education, and engineering courses should start incorporating sustainability-related components [1]. Sustainability-related engineering includes the design, commercialization, and use of processes and products that are feasible and economical while reducing the generation of pollution at the source and minimizing the present and long-term risks to human health and the environment [1].

Traditionally, the education of engineers has focused on technical topics. Efforts to embed social, environmental, and ethical concerns into engineering education have been widely supported by global accreditation standards, including the Washington Accord. For example, graduates should have “knowledge of the role of engineering in society... such as the professional responsibility of an engineer to public safety and sustainable development” [2]. Despite these requirements, engineering education often continues to promote a mindset of sociotechnical dualism [3], whereby technical issues are taught largely without reinforcing the inextricable link to pervasive broader impacts to society and the environment. Calls to address this concern have advocated for embedding social context issues into core, required engineering courses [4].

Thermodynamics is a fundamental engineering science topic that is typically required in several engineering majors, including mechanical, aerospace, environmental, chemical, and architectural engineering. Thermodynamics examines the connections between heat and energy as well as the interrelations among all energy types. A study by Sprouse et al. [5] identified thermodynamics as a core course that was required in mechanical engineering programs at 10 of 12 U.S. institutions. Evidence of its core importance in engineering is the inclusion of thermodynamics in five out of seven engineering specialty examinations that are required on the pathway to becoming a licensed professional engineer in the United States (U.S.)via the National Council of Examiners for Engineering and Surveying (NCEES) Fundamentals of Engineering Exam [6]. Furthermore, program-level criteria for engineering degree accreditation under the ABET (formerly the Accreditation Board for Engineering and Technology) specific to thermodynamics, thermal, and/or energy topics are included in mineral processing, mining, petroleum, ecological, mechanical, and environmental engineering [7]. While the ABET originated in the U.S., there are 1122 accredited programs at 222 institutions across 41 countries outside the U.S.

Traditional thermodynamics courses and textbooks have been grounded in historical developments of steam engines and subsequent fossil fuel technologies [8]. However, some texts are integrating a modern context related to environmental impacts and climate change [9,10,11,12], which acknowledges global energy challenges. The demand for energy is forecasted to double in the coming decades and is expected to keep increasing until the end of the century [13]. Addressing this escalating demand requires a completely new energy infrastructure in the 21st century. This infrastructure should generate more energy at reduced costs, significantly improve energy efficiency, enhance supply security by relying more on stable domestic sources, and drastically reduce greenhouse gas emissions [13]. Comprehending the workings of this evolving market and the principles that guide a sustainable energy system are essential for the success of emerging energy sectors [13]. It is important to use a holistic approach in designing energy devices or processes, ensure ultimate safety, minimize the use of limited energy resources and utilize renewable ones, minimize waste of all kinds, and develop new technologies to improve energy efficiency. These practices usually result in cost reduction as well as the minimization of entropy generation and destruction of usable energy (also known as exergy destruction) [1]. Mitchell [14] states that “...the laws and predictive theories of thermodynamics provide a means of determining the ultimate limits on sustainable activities”, and advocates for a representation of sustainability in which the ecological, social, and economic domains are delineated and redefined in terms of thermodynamics and economics.

Preliminary work for this study showed thermodynamics to be the most prevalent required course with sustainability integration in mechanical engineering among 100 universities, including 5 of the 9 institutions outside the U.S. (all of which required a thermodynamics course as part of the curriculum) [15]. This research examines how thermodynamics courses are integrating sustainability topics, such as addressing current and new energy industry challenges. The specific research questions explored are as follows:

• What elements of sustainability are included in terms of focusing on present versus future needs, the integration of the sustainability pillars, and ties to the UN Sustainable Development Goals (SDGs)?
• What are the specified learning objectives?
• What are specific teaching methods utilized?

The results of this exploration will identify current practices, thereby revealing areas for improvement.

The following sections of the paper describe the methods that were used for the study, followed by results answering each of the research questions in turn. Within the section where specific teaching methods are described, an analysis is included to tie these methods back to sustainability pillars, SDGs, and learning objectives. Suggestions are made to enhance the teaching practices described. The discussion section has additional consideration of the broader implications of the findings.

2. Methods

In order to answer the research questions, it was important to select publications that describe sustainability education in thermodynamics. The criteria for inclusion in the literature review are as follows:

• Peer-reviewed journal articles, conference proceedings, or book chapters;
• Scholarship of Teaching and Learning information shared;
• Related to undergraduate-level thermodynamics courses in engineering;
• Learning methods or principles applicable to sustainability in thermodynamics.

Two search engines were utilized, yielding 18 sources. Figure 1 shows a flowchart of the literature selection process. A complete list of papers is included in Appendix A. Searches were conducted in January 2023. The first search was conducted through the University of Colorado Boulder library. This is an omnibus resource that includes a number of databases, such as Web of Science, ProQuest, JSTOR, and EBSCOHost. Through an advanced search, 36 papers containing ‘Thermodynamics’, ‘Engineering Education’, and ‘Sustainability’ were found. Those papers were evaluated further and narrowed to 12. This was based on the focus on the Scholarship of Teaching and Learning and inclusions of ‘how’ sustainability was incorporated into thermodynamics courses.

The second search was conducted in the American Society for Engineering Education (ASEE) Papers on Engineering Education Repository (PEER). The ASEE hosts several conferences each year, most notably the annual conference. All papers undergo double-blind peer review. At the time of the search, the ASEE PEER included papers from 1996 to 2022, with 1755 papers from the 2022 annual conference alone. The advanced search process in PEER is menu-driven. An initial general search in PEER with thermodynamics as the sole search term identified approximately 3600 papers. Therefore, it was decided to restrict the search to only paper titles. Given the large number of sources still identified (236), the search was next confined to the Energy Conversion and Conservation division. This division was chosen due to its inherent relevance to the themes of thermodynamics and their intersection with sustainability principles, which also cuts across engineering disciplines.

The papers selected provide thermodynamics teaching insight from a variety of engineering disciplines, including mechanical engineering (n = 11), civil engineering (n = 2), chemical engineering (n = 2), and general (n = 3). Nine of the papers were siloed around a single course, while three described multiple courses, and six papers were focused around a topic area in the curriculum rather than a single course or group of courses. The publication years of the papers ranged from 2000 to 2021, with 1 in 2000–2005, 3 in 2006–2010, 9 in 2011–2015, and 5 in 2016–2021. Among the 18 papers, the institutional affiliations of the authors were predominated by U.S. institutions (n = 16), with one in Canada and one in Australia.

For each of the selected publications, the following information was recorded: discussed future and/or present needs, sustainability pillars, UN sustainable development goals, learning outcomes, teaching methods, and specific teaching examples. Where interpretation was needed, the two authors worked together to agree on categorization. For example, there was a level of subjectivity in mapping course learning outcomes into the classification levels of Bloom’s cognitive and affective levels of complexity.

This study has limitations. One significant constraint is the limited number of papers reviewed (n = 18). It is likely that other published examples of sustainability integration into engineering thermodynamics courses exist beyond the selection parameters. Only papers written in English were yielded by the searches. And the papers represent a largely U.S. perspective. Note that this manuscript represents work initially conducted as part of the first author’s dissertation [16], which has been subsequently updated and enriched.

3. Results

3.1. Types of Sustainability Inclusion

The types of sustainability inclusion in thermodynamics courses were characterized in three ways. The first is based on the 1987 United Nations Brundtland Commission definition, where sustainability is “meeting the needs of the present without compromising the ability of future generations to meet their own needs” [17]. Among the papers reviewed, seven discussed both present and future needs [8,14,18,19,20,21,22], while five primarily addressed efforts to meet future needs [1,23,24,25,26]. The remaining six papers were unclear about addressing future and/or present needs [27,28,29,30,31,32].

The needs of present and future generations span three core sustainability pillars: social, economic, and environmental.

Table 1. Number of papers with each sustainability pillar.

Pillar	Economic	Environmental	Social	All 3 *
Number of papers with this pillar	1	11	5	4
Percent out of 16	6%	69%	31%	25%
References	[30]	[8,18,19,20,21,23,24,25,29,30]	[8,18,19,24,27]	[1,14,22,26]

* Not included in individual counts.

shows the sustainability pillars that were included in the 18 papers evaluated in this study. There were 16 papers (89%) that described coursework that clearly fit into one or more of the sustainability pillars. Environmental issues were the most commonly integrated, followed by social issues and least frequently economic issues. The two papers where pillar information could not be evaluated [28,32] seemed to rely on an implicit definition of sustainability such that particular pillars were unclear.

To catalyze the global movement toward improving sustainability, in 2015, the United Nations developed 17 Sustainable Development Goals (SDGs) [33]. The purpose of the SDGs was to inspire the achievement of universal prosperity and peace, where all people could meet their basic needs while preserving the planet for future generations. Out of the 18 papers examined, 11 mentioned coursework pertaining to one or more of the SDGs, as shown in Figure 2. The SDG included in the most thermodynamics courses was SDG 7, Affordable and Clean Energy, which was in ten of the papers [1,18,19,20,21,23,24,25,29,30]. This was followed by SDG 12, Responsible Consumption and Production, included in eight papers [1,14,18,19,24,25,26,29]. The remaining SDGs included in the papers reviewed are SDG 11, Sustainable Cities with three [1,19,25]; SDG 6, Clean Water and Sanitation with two [19,21]; SDG 9, Industry, Innovation, and Infrastructure with two [1,19]; SDG 10, Reduced Inequalities with one [18]; SDG 13, Climate Action with one [1]; and SDG 15, Life on Land with one [18].

Two of the papers were particularly strong in integrating SDGs, with topics pertaining to five different SDGs in each paper [1,19]. Cengel [1] describes the concepts of green thermodynamics and delves deep into energy sources and conservation. Cengel then gives five educational examples for the inclusion of these concepts in a thermodynamics course. Zabihian [19] integrated into his thermodynamics course for mechanical engineering service-learning projects for local museums to demonstrate energy and thermodynamic concepts to middle and high school students and the public The variety of projects and community partners listed touched on several of the SDGs.

3.2. Learning Outcomes

The papers were explored to find examples of learning outcomes related to sustainability. Learning outcomes are measurable statements that articulate what students should learn, know, value, or be able to do because of completing a course or program [34]. Both cognitive and affective outcomes are important for sustainability education in engineering [35]. In Bloom’s taxonomy [36], cognitive outcomes have been classified into levels that reflect increasing complexity from 1 (lowest) to 6 (highest); the levels and associated verbs are shown in

Table 2. Levels, definitions, and example verbs of Bloom’s cognitive and affective domains [35,38,39].

Cognitive Levels	Affective Levels
1. Remember—recall information; define, identify, list	1. Receive—be aware of; acknowledge, recognize
2. Comprehend—understand–explain, summarize in own words	2. Respond—exhibit behavior; comply, discuss, examine, participate
3. Apply—solve a problem or use a concept in a new situation; calculate	3. Value—attribute personal worth; accept, apply, defend
4. Analyze—describe relationships among parts; compare, contrast, debate	4. Organize—rank among one’s priorities; display, weigh
5. Synthesize—combine knowledge to create a new whole; create, design	5. Characterize—act consistently with the value; advocate, attest, internalize
6. Evaluate—make judgements; critique, conclude, justify, validate

. Note that most educators currently use the revised Bloom’s cognitive taxonomy, which inverts levels 5 and 6 [37]; we elected to use the original levels, aligned with the Civil Engineering Body of Knowledge [35]. The affective domain emphasizes attitudes, motivations, values, and a degree of acceptance or rejection [38]. The affective domain levels from Bloom’s taxonomy are shown in Table 2. Affective objectives vary from simple attention to values that become personal qualities of character and conscience [38]. It is desirable to encourage students to not just receive information at the bottom of the affective hierarchy, but to respond to what they learn, to value it, and to make it a core personal goal [38]. In this case, we are interested in students’ attitudes toward sustainability and their obligations to promote sustainability in their future work as engineers.

In eight of the papers, sustainability-related learning objectives in the thermodynamics courses were reported. Some of those learning outcomes are shown in

Table 3. Learning objectives mapped to cognitive levels, affective levels, and general categorizations. Content updated from Table 29 [16].

Learning Objective—After the Course, Students Will Be Able to	Cognitive Level	Affective Level	General Categorization
Explain knowledge of contemporary energy-related issues.	2 Comprehend	1 Receive	Thermodynamic centered
Include technology policy, ethics and social responsibility, the historical development of thermodynamics, and the contributions of women and people of color to the field both historically and in the present [8].	2 Comprehend	2 Respond
Apply exergy costing to various cycles [24].	3 Apply	2 Respond
Examine the interrelationship between energy-intensive systems and public policy instruments and strategies [24].	4 Analyze	1 Receive
Model exergetic efficiencies for various cycles and exergy generation at points throughout the cycle [24].	5 Create	2 Respond
Ensure that all material and energy inputs and outputs are as inherently safe and benign as possible [1].	6 Evaluate	2 Respond
Develop and apply engineering solutions while being cognizant of local geography, aspirations, and cultures [1].	3 Apply	2 Respond	Engineering focused
Engineer processes and products holistically, use systems analysis, and integrate environmental impact assessment tools [1].	4 Analyze	2 Respond
Enhance awareness and inform engineering decision making related to societal issues, such as energy sources and environmental quality [18].	4 Analyze	2 Respond
Use life-cycle thinking in all engineering activities [1].	4 Analyze	2 Respond
Incorporate four social aspects of design and construction: corporate social responsibility, community involvement, safety, and social design (designs considering the needs of the workers and end users) [22].	5 Synthesize	2 Respond
Improve, innovate, and invent (technologies) to achieve sustainability [1].	5 Create	3 Value
Actively engage communities and stakeholders in the development of engineering solutions [1].	5 Synthesize	4 Organize
Contain knowledge of sustainability principles [23].	1 Remember	1 Receive	Sustainability based
Hold a comprehensive picture of conventional and alternative energy sources and conversion technologies, while keeping in mind broad environmental, political, economic, and social issues [30].	2 Understand	2 Respond
Strive to prevent waste [1].	4 Analyze	3 Value
Minimize depletion of natural resources [1].	4 Analyze	3 Value
Improve natural ecosystems while protecting human health and well-being [1].	4 Analyze	3 Value
Value the importance of sustainability considerations in the mechanical engineering profession [23].	N/A	3 Value

. The course learning outcomes related to sustainability were first grouped into three categories: thermodynamics-centered, engineering-focused, and sustainability-based. The thermodynamics-centered outcomes are the ones that are most obviously aligned with typical learning objectives for thermodynamics courses. The engineering-focused outcomes extend beyond thermodynamics to important skills and attitudes for engineers and could be appropriate for many engineering courses beyond thermodynamics. The sustainability-based outcomes are specifically focused on sustainability. It is worth noting that the engineering and sustainability learning outcomes could easily become more focused on thermodynamics topics. For example, the prevention of waste could be focused on the thermal pollution of water in thermoelectric power generation.

The classifications of the learning outcomes into Bloom’s cognitive levels were somewhat subjective. While many of the verbs are readily found on classification lists [35,40], other outcomes did not appear to have been written with Bloom’s cognitive levels in mind. The relevant verbs that helped establish the level of classification are highlighted in bold text in Table 3. All but 1 of the 19 learning outcomes were primarily cognitive in nature, with the outcomes representing all six cognitive levels.

Among the 19 learning outcomes, only 1 was primarily in the affective domain. For the other outcomes, the authors inferred the appropriate affective level. Most outcomes were mapped to the ‘respond’ level since students must be willing to respond in order to complete an assignment to demonstrate achievement of the stated learning objective. None of the thermodynamics-centered outcomes were rated at above the respond level, while the majority of the sustainability-based outcomes were mapped at the value level. In general, outcomes that mapped to higher cognitive levels also appeared to foster higher affective outcomes.

3.3. Coursework Examples

The courses described in the papers used a variety of pedagogies to teach sustainability topics. Some papers shared examples of traditional course work, such as mathematical examples and labs. Other forms of coursework included projects, application-based learning, simulation-based tools, service-learning, and book reviews. The various teaching techniques can require students to consider the interrelationships between various aspects of sustainability-related systems and topics. Each of these can work toward helping students learn socio-contextual knowledge, core content knowledge, and professional skills [27]. The sustainability integration methods in the papers reviewed are briefly described in the following sections.

3.3.1. Mathematical Examples

Mathematical examples including complete problems and solutions were provided in three of the papers. These mathematical examples map primarily to SDG 12, Responsible Consumption and Production, and secondarily to SDG 7, Affordable and Clean Energy, and are primarily focused on the environmental and economic pillars. With each mathematical calculation comes an opportunity to raise awareness on the importance of efficiency and sources of energy. These calculation approaches favor cognitive outcomes, typically at Level 3, Apply. A number of topics were presented, including lighting needs of classrooms and buildings [1,26]; energy savings that provide cost and environmental benefits from lower tire-rolling resistance and efficiencies from motor [1,26]; and power production associated with wind energy [1,29]..

3.3.2. Labs

Labs were described in three of the papers [20,21,31], which map to SDGs 6, 7, and 12. Two of the papers had students find the efficiency of a light bulb. In one paper by Shuman and Mason [31], the students had to determine what type of energy is consumed and how that energy can be measured. The light bulb was immersed in water, and the students were provided with a variety of necessary and unnecessary tools that they could opt to use [31]. A variation of this lab was discussed in a study by Lee et al. [21]. Voltage and current were applied to a light bulb immersed in a water plus India ink mixture. The voltage, current, and temperature of the water were measured to determine the heat produced. The students learned about power, energy, and specific heat and verified the first law of thermodynamics [21]. The students could test and compare the efficiencies of different types of light bulbs. This can lead to a discussion of the larger-scale impacts of the efficiency differences in terms of material/energy usage and environmental impact, including greenhouse gas emission differences.

Other labs included energy for pumping water, a solar cooker, and a thermoelectric heat engine. The first of these is described in Lee et al.’s paper [21], and it encourages the responsible use of water and energy. Student teams were given a reservoir (floor level), a tank (above the floor with adjustable height), an orifice, a small pump, a small turbine, and a multi-meter. Building on concepts of energy conversion from kinetic to potential energy, the students considered the pumping power and height differences. The lab was geared to simulate an actual Engineers Without Borders project so that students could learn about the nexus of water and energy with associated social impacts.

In a paper by Shepard and George [20], solar cookers were used in a lab involving a transient analysis of the first law of thermodynamics. The students compared the heating process of water in an open pot and a pressure cooker and also compared the heating process of water in a pot exposed to wind versus a pot with a convective loss reduction device. Students gathered data on temperature and pressure and monitored incoming solar radiation with a pyranometer [20]. This lab brings the opportunity to discuss energy sources and their pros and cons and evaluate the energy used for cooking and ways to increase efficiency, thus minimizing impact.

Lee et al. [21] described a lab using a commercially purchased thermoelectric heat engine. A copper block was heated with an electric resistance heater, and students varied the block’s temperature by changing the power input. A second copper block was cooled using ice water. The thermoelectric device was placed between the two blocks and generated power based on the temperature difference. Students graphed efficiency and Carnot efficiency (as functions of T_low/T_high). Efficiency calculations can lead to conversations on the greater impact of the varying efficiencies. This could be examined based on material inputs and the societal and environmental consequences of such material uses and disposals.

3.3.3. Projects

Projects were described in four of the papers [20,23,24,29] and map to SDGs 7 and 12. The projects create a space to integrate technical aspects with broader considerations, encompassing social and environmental impacts. The projects offer opportunities to explore real-world examples, whether existing or hypothetical. Each project enables students to apply their engineering expertise in innovative ways to practical challenges. And in each there is the opportunity for the professor to expand upon the topic with sustainability-based discussions or readings according to their choosing and comfort level. Projects can often achieve higher levels of cognitive and affective outcomes. Below are concise summaries of the identified projects.

In Shepard and George’s paper [20], a solar cooker design project was used to teach energy conversion and the first law of thermodynamics. Student teams were tasked with utilizing a provided solar concentrating device in the design of a safe and easily adjustable solar cooker with minimal convective heat loss. Students were encouraged to be creative in tackling this open-ended project. The completed solar cookers were used in the lab described above [20].

In Miller et al.’s paper [23], students chose a type of energy system related to electric power, transportation, or heating/cooling to study via a semester-long project. Milestones included the evaluation of a current or conventional system, the evaluation of one alternative energy source, and an estimation of how to meet the predicted increase in energy demands using conventional systems, alternative systems, or a combination of both. In a paper by Muckel and Bailey [24], student teams conducted a stakeholder analysis and exergy-based thermodynamic analysis on a self-selected contemporary issue in mechanical engineering.

In Zhang’s paper [29], the class project involved creating a custom computational tool using Microsoft Excel.. Throughout the course, students developed their own computational tool based on their understanding of fundamental thermodynamic principles and the governing equations of energy cycles. By utilizing this tool, students gained a deeper comprehension of energy system performance under various design and operational conditions. They also conducted parametric analyses to effectively visualize key parameters. This tool facilitated effective student learning and afforded the potential to assign more comprehensive and challenging problems.

3.3.4. Application Based—Local Power Facilities

Application-based learning was described in two of the papers [26,30]. Many universities across the U.S. have Central Utility Plants (CUP) that provide chilled water and hot water (or steam) for heating, ventilation, and air conditioning (HVAC) and process use [26]. Common equipment in a university CUP includes chillers, cooling towers, boilers, hot water pumps, chilled water pumps, and variable frequency drives (VFDs) [26]. A field trip to a university CUP provides a unique opportunity for students to visualize what they learn in their thermodynamics course [26].

A university CUP can also provide the focus of an analysis-based design project. In Norberg et al.’s paper [30], students designed an improved combined heat-and-power plant that included an economic analysis based on material and energy costs. The students were presented with various scenarios, such as utilizing the power plant for steam and heat but purchasing electrical power from the grid, or the hypothetical scenario of the equipment in the power plant being destroyed in a fire and rebuilding vs. abandoning the university plant and using the grid. Students gained an appreciation of the current energy picture and also assessed the feasibility of future energy scenarios.

Visiting and studying a campus CUP can open the door to conversations and studies around campus energy and utility needs. The impacts can be assessed, leading to discussion and/or analysis around the impacts of efficiency measures, sources, and waste. This can bring sustainability home to the student and to their campus in a very real way.

3.3.5. Simulation-Based Tools

Simulation-based tools can be powerful aids to help students analyze complex systems. The Buildings Industry Transportation Electricity Generation Scenarios (BITES) tool produced by the U.S. National Renewable Energy Laboratory allows users to create ‘what if’ scenarios by adjusting energy inputs to buildings, industry, transportation, and electricity generation sectors in the United States and compare their carbon footprint outcomes to baseline reference cases. Nagchaudhuri [25] described a team assignment incorporating the BITES tool that maps to SDGs 7, 11, and 12. Student teams investigated efficiency, carbon emissions, and the coefficient of performance (COP) of electricity generation plants and internal combustion engines. The students also remarked on considerations in the Montreal protocol and Kigali agreement and the use of alternative refrigerants in heating, refrigeration, and air-conditioning systems. Along with environmental implications, there are also human safety considerations that can be discussed using case studies.

3.3.6. Service-Learning

Service-learning is an experiential learning approach to foster students’ deeper understanding of academic content in courses through activities involving community partners to address community needs and social problems. Zabihian [19] incorporated service-learning into their thermodynamics course. Students collaborated with non-profits and/or governmental entities to address their needs. Students produced experiments, demonstrations, presentations, and/or posters to explain thermodynamic- or energy-related concepts to the public, particularly elementary and middle school students. Their work was presented as an exhibition in a museum, in a college open house, and in a school science class. Examples of project topics requested by the community organizations are as follows [19]:

• How electric vehicles operate compared to combustion engines and their energy use and environmental impacts.
• The challenge of voltage vampires in homes, such as microwave clocks, TVs, and DVRs.
• How utilities use biosolids to reduce impacts on landfills and generate energy.
• How insulated windows, reflective film in windows, insulation, wall construction, etc., work to save energy.

More information and a comprehensive list of projects are included in Zabihian’s paper [19]. The various projects map to SDGs 6, 7, 9, 11, and 12. Note that service-learning requires time to develop reciprocal relationships with community partners. It will be difficult within the scope of a single semester project embedded within a thermodynamics course to yield a finished product that is truly beneficial to community partners. Thus, a thermodynamics course is perhaps appropriate as one component within a larger community partnership that spans longer time periods and multiple learning settings [41].

3.3.7. Book Review

Bailey [32] described an assignment that requires students to critically read a technical book related to thermodynamics, write a technical review of the book, and orally present results to the class in an informal setting. The books selected by the students include a wide variety of topics that may include sustainability issues, such as hybrid vehicle design and infrastructure. Students must relate the topics explored within the book with thermodynamics topics. In writing a review, the students combine the skills of describing what is on the page and analyzing how the book tried to achieve its purpose as well as how it relates to thermodynamics and expressing personal reactions [32].

This approach has the advantage of allowing students to select a book that matches their interests, which can increase motivation and engagement. The assignment could be restructured to require a book that relates to sustainability, with a menu of options provided and still allowing students to find a book on their own. The discussion portion of the assignment could also be restructured to require a reflection on sustainability topics, such as a present versus future focus, each of the three pillars, and/or the UN SDGs.

Given recent reports on the decline in reading habits and preferences among students, it may be wise to select shorter articles (perhaps from gray literature) rather than books. Some collections of related articles include On Energy Transformation by The Atlantic [42] and Renewable Energy by Scientific American [43].

4. Discussion

This section discusses the findings in a broader context, including suggestions for integrating sustainability topics into thermodynamics and other engineering science courses. To promote sustainable development, it is important that students develop a mindset that all engineering work is inherently sociotechnical. Integrating sustainability topics into core, required courses that have traditionally been taught with an exclusive focus on technical issues will help achieve this goal. Thermodynamics and sustainability go together, and it is recommended that sustainability topics are taught in all thermodynamics courses. This begins by attending to the complete definition of sustainability and considering appropriate learning objectives.

Among the 18 papers examined, few thermodynamics courses took a holistic approach to sustainability: 7 papers discussed meeting both present and future needs and 4 integrated all three pillars (environmental, social, and economic); the Mitchell [14] and Haselbach [22] papers met both of these criteria. There is also an opportunity to link thermodynamics topics with social issues among the UN SDGs. The use of fossil fuels can be directly linked to undermining some of the SDGs [44,45], including SGD 3, Good Health and Well-Being; 4, Quality Education; 5, Gender Equality; and 16, Peace and Justice. None of the 18 papers in this small study mapped to those goals. A good model linking thermodynamics to social factors is presented by Lucia et al. [46], who proposes a Thermodynamic Human Development Index and Thermodynamic Income Index. Additional examples in Zevenhoven’s paper [47] of carbon dioxide mineral sequestration, the recovery of diluted nanoparticles, and heat pumps illustrate compelling links between thermodynamics and sustainability. However, published examples of integrating these ideas into engineering courses were not found.

Learning objectives and goals are important to establish to ensure that both instructors and students understand the purpose of the course [48]. If instructors truly value the integration of sustainability, they need to articulate associated learning objectives to communicate to students that these are expected learning outcomes rather than a nice add-on. Depending on the curriculum at a particular institution, a thermodynamics instructor may need to start at the most basic levels of sustainability cognitive learning outcomes (e.g., define sustainable engineering) and build from there. Alternatively, in some institutions, basic sustainability information may be taught in earlier required courses, and a thermodynamics instructor can target higher-level cognitive outcomes [48]. Affective objectives relating to interests, attitudes, and values [49] are of particular importance in students’ learning and subsequent actions regarding sustainability. In this study, the majority of the learning objectives directly mapped to cognitive outcomes based on the verbs used (e.g., explain, examine, and model), while only one objective was explicitly affective (e.g., value).

True sustainability transformation will require reaching higher affective outcomes, thereby producing changes in behavior, goals, and values. These higher-level affective sustainability objectives were not explicitly found in the papers reviewed in this study. Expecting students to reach the characterization level for sustainability due to a thermodynamics course alone seems unlikely, particularly if engineering students have not been introduced to sustainability ideas in earlier courses. It is more practical to consider how graduates might reach this level across their curriculum, and thermodynamics can be viewed as one course within this larger plan. In addition, affective outcomes are more likely to be achieved using particular teaching approaches, such as service-learning [50,51,52].

Table 4. Bloom’s affective domain with verbs and examples.

Bloom’s Affective Level	Verbs [35,53]	Sustainability Related Learning Outcome Examples for Thermodynamics
3 Valuing	appreciates, cherish, treasure, demonstrates, initiates, invites, joins, justifies, proposes, respect, shares	Propose energy solutions that have considered environmental and societal impacts.
4 Organization	compares, codify, defends, order, relates, synthesizes, weighs	Synthesize sustainability and thermodynamics principles in problem solving.
5 Characterization	acts, displays, influences, internalizes, modifies, performs, qualifies, questions, revises, serves, solves, verifies	Influence refrigerant selection for environmental and human safety.

provides examples of higher-level sustainability-related affective learning outcomes, which encompass valuing, organization and characterization, or internalizing values. Examples of verbs that can be worked into sustainability-related learning objectives that target higher affective levels are also shown in Table 4. Reaching these higher affective levels can be of benefit for increasing sustainability in students’ lives and engineering practices while also applying thermodynamics principles.

We encourage faculty to strive toward high levels of Bloom’s cognitive and affective domains for transformation in student ethics around sustainability and as a motivator for student behavior. Examples of how this can be integrated into the learning outcomes for thermodynamics courses are provided in Table 3 and Table 4. Explicitly articulating these goals at the inception of the course can guide faculty as they design course modules, lectures, activities, assignments, and discussions.

Educators should likely look for models of sustainability education in engineering outside the U.S. Other countries are ahead in promoting sustainability, given stronger accreditation requirements with respect to sustainable engineering and development (e.g., [54,55]). For example, Polmear et al. [56] found that a higher percentage of faculty taught sustainability topics in engineering in non-U.S. Anglo and Western European countries as compared to faculty at U.S. institutions. However, instructors must carefully consider where their course fits into a broader curriculum around sustainable engineering. Some institutions may scaffold sustainable engineering in a first-year course required for all students, for example, and thus their thermodynamics course is able to build on that earlier knowledge.

Faculty who plan to integrate sustainability topics into thermodynamics or other engineering courses should consider the holistic nature of sustainability. Instructors should try to include both current and future needs and all three pillars of sustainability (social, environmental, and economic) and discuss ties to SDGs. Sustainability-related learning outcomes related to both cognitive and affective domains should be clearly articulated. From these foundations, appropriate teaching and assessment methods can be selected.

5. Conclusions

Any standard of living considered acceptable in current conceptions requires significant amounts of energy [57]. Thermodynamics is the study of this energy that is needed to provide for human-life-based energy needs and wants. Thus, the study of thermodynamics is pertinent to meeting the needs of human life. The principles and predictive models of thermodynamics offer a way to establish the ultimate limits on sustainable activities [14] and advocate a representation of sustainability in which the ecological, social, and economic domains are delineated and redefined in terms of thermodynamics and economics [14,18]. The goal is for students to both grow strong in their thermodynamics technical skills while also gaining awareness of the people and planet that are impacted by their thermodynamic (and engineering) decisions and designs. Thermodynamics courses can serve as vehicles to advance a mindset that acknowledges the intrinsic sociotechnical nature of all engineering work. Developing this mindset in engineering students will take more than reaching cognitive outcomes and must also speak to broader values and attitudes.

A number of conclusions about sustainability integration into engineering thermodynamics courses were drawn from the 18 papers that were reviewed. The sustainability topics focused on future needs (e.g., carbon footprint) in more papers than meeting present needs (e.g., addressing social issues such as poverty). Only 4 papers clearly integrated all three sustainability pillars; environmental issues were included in 11 additional papers, social in 5, and economic in 1. In terms of the UN Sustainable Development Goals (SDGs), goal 7, Affordable and Clean Energy, and goal 12, Responsible Consumption and Production, were the most common topics. Eight of the papers explicitly stated sustainability-related cognitive learning outcomes, but affective domain outcomes (e.g., valuing) were clearly evident in only one paper. A number of different teaching approaches were used to integrate sustainability in thermodynamics courses, including mathematical examples, labs, projects, book reviews, simulation-based tools, service-learning, and the utilization of local/university utility plants as application-based learning. The sustainability teaching method shared in many of the papers could be adopted as-is or slightly modified.

To improve the sustainability of real-world engineering practices, engineering courses need to educate students on technical elements related to sustainability (e.g., the ability to design for energy efficiency) while also valuing the importance of sustainability [1]. The thermodynamics examples from this paper could inspire sustainability integration into other engineering science courses. These courses can extend beyond a focus solely on technical aspects to communicate the sociotechnical nature of engineering by asking students to ponder important questions. Why does efficiency matter? What are the environmental consequences of wasteful processes? Who is being impacted by our energy systems? Who receives the benefits? Who experiences most of the risks and negative consequences? How can we design energy systems that minimize environmental and human or societal impacts? It can be helpful to relate these conversations with current events and real-world examples. These real-world issues may increase students’ motivation for learning technical subjects like sustainability. Instructors can draw on many published resources to inform their efforts, including those reviewed in this paper.