According to UN-Habitat, man-made activities at the city level consume around 78% of the world’s total energy and generate about 60% of greenhouse gases (GHG) globally [1]). In addition to that, even though cities around the world account for less than two percent of the Earth’s surface, the urban population is estimated to rise from 55% to 68% [2]. According to a model developed by urban environment researcher Karen Seto and her colleagues, nearly 6 million square kilometers of land have a slight possibility of becoming urban, and 1.2 million square kilometers have a high potential of becoming citified by 2030 [3]. The material consumption within their urban boundaries might increase up to 89 billion tons by 2050 as well [4]. Most importantly, among all urban sectors, transport and buildings have been identified as the dominant contributors to the carbon footprint and environmental damage [5]. This high carbon footprint is considered to be associated with poor planning and management of environmental resources, overpopulation, unplanned transport systems, inefficient energy systems, and so on [6]. Besides facing complications in their basic operations, cities also suffer from a great loss of biodiversity, resources, and ecological balance due to these anthropic activities. Even though cities carry a huge toll on global carbon emissions, they are, nevertheless, also the driving force of national and global economies.

Compared to rural areas, modern cities generate more than 80 percent of the global GDP today [7]. In search of finding a balance between economic growth, environmental impacts, and climate change, several studies, research works, and projects have been initiated through seminars, summits, and conferences in the last three decades globally. Their main purposes were objectifying climate change, the depletion of natural resources, strengthening the ecological balance, and identifying opportunities to make a more resilient and sustainable world [8]. At the very beginning, the prime agenda was specifically focused on global-scale climate change activities. Most commitments and activities were based on global collaboration and participation, where the government is the prime actor. However, these global-scale planning and measures have not been proven very efficient without involving public involvement and other stakeholder engagements [6]. These processes were incompatible with addressing the climatic and environmental issues at local and regional levels with other nongovernment actors of cities. Currently, the idea of “zero-carbon cities” has become a strong hope for a sustainable future [9]. It is anticipated that massive decarbonization is required to bring ecological balance. Decarbonization usually refers to a holistic process of behavioral–infrastructural–systemic operation change and adaptation of technologies to achieve zero or close-to-zero carbon emissions [10]. To take an active role, very recently, several cities around the world have adopted at least some changes in their functionality and operations through social innovation, technological advancement, policy development, and updated governance [11]. According to the United Nations Environment Programme (UNEP), only a synchronized approach to combining global, national, and local levels of action plans can mitigate environmental exploitation and ensure a sustainable future [4]. Urbanization and industrialization are essential parts of the development process of a region or city [12]. Efficient workforce development with high climate awareness, leadership, and uninterrupted political, technical, and financial support should become the united priority of all the governmental and nongovernmental actors to overcome the traditional barriers and trigger a paradigm [11]. As most cities’ functionalities rely on interacting with large-scale social, environmental, and infrastructural aspects, a path of transitioning to zero-carbon practices has not been identified yet [13]. Lacks of authentic data, efficient governance, and proper monitoring, as well as unfamiliarity with advanced technological features, have been proposed as the major impeding issues [11]. These factors have drawn the attention of scholars and researchers around the world who are relentlessly working towards solving these problems.

Traditionally, towns and cities have always been an attraction for generations of people coming to find work and other services [14]. Fast forwarding to the present times, facilities like housing, education, health care, cultural centers, and other entertainment sources have become great attractions for people to migrate to cities. Historically, higher education institutes (HEIs) have been an intrinsic part of cities around the world. As towns and cities have become the epicenter of the social, economic, and cultural development of a country, the functionality of a city has turned into a complex system. Inspired by so-called urban metabolism ^[15][16][15,16], comparing the city system with the human body, Gardner [17] said cities take in energy in different forms, metabolize material, and generate waste. Similarly, he also pointed out that the efficient operation of a city involves the operation of subsystems like administration, education, housing, transport, industry, health, and other public–private organizations, just like the respiratory, circulatory, and other anatomical systems of the human body. All these subsystems of the city interact with each other simultaneously to function properly and provide a service to their dweller. The city–campus alliance likely has the potential to create a greater impact on city-level sustainability based on the fact that the elements of a university campus resemble the functionality of a city system. An HEI’s purpose is to equip its students, teachers, and staff with knowledge and innovation to become resilient and adapt to changes that are not only beneficial for them but also for the community [18]. Incorporating climate change curricula into higher education or activities integrating HEI campuses to promote sustainability is not a new concept. It is considered to be a well-established path toward achieving sustainable development goals [19]. Even though it started with “Environmental Education” only, society now expects practical-demonstration-based activities from HEIs. Following that, the well-recognized campus–city relationship has also turned into a strategic alliance working towards the cultural, social, and economic growth of society.

Over the last 50 years, an exponential growth of enrollment in tertiary-level education has been observed over the world. In 2020, the undergraduate student enrollment number was 15.9 million, combining all states in the USA [20]. Back in 2011, the South East Asian countries enrolled around 182.2 million tertiary level students, which is a significant portion of the global enrollment student number. The first idea of natural resource consumption and the depletion of those resources came to light in the 1950s [21]. The discussions were highly focused on utilizing natural resources for greater environmental and socioeconomic development. Following that, the first “Earth Summit” conference was held in Stockholm in 1972, which adopted a declaration to set up action plans to preserve and enhance the human environment globally [22]. Several global and regional conferences and agreements have been signed in the last three decades addressing global-, local-, and urban-level environment, urban sustainability, city infrastructure, transportation, public health, etc. In the early 1970s, international institutions responsible for global education, environment, and development started reviewing the role of higher education institutions in terms of promoting sustainable economic and social development nationally and globally [23]. Even though the global initiative started with “Environmental education,” in 1997, the United Nations highlighted the application of “environmental education,” which established the need for low-carbon-emission campus design and construction for the very first time [24].

The 1993 Kyoto Declaration stated that HEIs should promote sustainability by evaluating their operations and practices [25]. A gradual development of environmental concern about city-scale sustainability has initiated the idea of sustainable communities or entities inside cities. It has been highlighted in many studies how the city–campus relationship has the potential to influence changes in city environments. Over time, the importance of HEIs’ role in climate action and sustainability has been mentioned. Ideally, HEIs are expected to be more responsible actors in society, promoting education, equality, and innovation, reducing adverse environmental impacts, and amplifying the economic, societal, and public health benefits to society [18]. In the book Campus Ecology, Smith [26] illustrated HEIs as “microcosms” of environmental problems. He explained how different campus activities in classrooms, offices consuming high energy, and labs using hazardous chemicals and experiments can pollute water, air, and soil and how these activities have the potential to hamper the campus and its surrounding environment. It also became clear that the responsibility of ensuring sustainable development cannot only be on any specific governmental body but also on all public–private organizations, including those of higher education. Every entity should actively participate in the task to achieve this final goal for everyone [27].

In the UK, the building sector is marked as the main energy consumer, with 40% of the total country’s share ^[28][29]. In Canada, local HEIs generally consume around 60% of the electricity allocated for the combined educational institutes of different levels ^[29][30]. In the USA, the water consumption of educational buildings accounts for around 6% of total public water ^[30][31]. In China, the water and energy usage of HEI campuses is around four times higher than residential or other usages ^[31][32]. Globally, HEIs have been identified as one of the biggest shareholders and carbon emitters through consumed electricity and natural gas usage ^[28][29]. An HEI campus can be categorized based on several factors. Based on the university’s resources, infrastructure, geographic location, and operation, these tangible typologies can be justified. Along with other authors, Tan et al. ^[31][32] categorized campus assessment activity into three levels. For sustainability assessment and monitoring, the three levels of buildings, community or campuses, and city are crucial to identify the best practices. Their research conclusion was that “green buildings” could be the potential drivers among the three levels as they can influence the whole process from the micro-level. In addition to that, campuses consisting of several green buildings can be more energy-efficient, and having more energy-efficient campuses in a city can play a vital role in promoting zero-carbon practices on a city scale ^[32][33]. Beyond regional, contextual, and climatic differences, all university campuses around the world can be illustrated through these lenses of typologies. Additionally, it can be said that the physical type and size of university campuses have a great influence on users’ behavior.

According to UNEP, only a synchronized approach to combining global, regional, national, and local levels of action plans can mitigate environmental exploitation and ensure a sustainable future [5]. Among all the other public and private subsystems, HEIs resemble the multidimensional activity of a city interacting with different subsystems: education, administration, transport, housing, health, and food ^[33][34]. They have often been marked as a “small-scale city model” by numerous researchers ^[34][35]. Taking all that into account, HEI campuses have become a beacon of hope for change. Along with its scalable infrastructure, a zero-carbon campus can take the lead and pave the way for practicing, promoting, and demonstrating the transition to a zero-carbon city.