1. Introduction
According to the Intergovernmental Panel on Climate Change (IPCC), in 2019, the building sector emitted 19% of global greenhouse gases (GHGs) and 31% of carbon dioxide (CO
2) emissions [
1]. Under the current policy scenario, GHGs associated with the construction sector will increase by 2.2% yearly [
2]. Developing countries are one of the main drivers of global emissions because these economies are growing in population and economy, with increasing floor areas per capita, while employing non-efficient construction methods as a standard practice [
1,
3]. Building-related emissions, particularly CO
2, are closely linked to energy production and use. Energy is responsible for 67% of the emissions from buildings [
4,
5]. Future energy–building consumption growth is a major concern because emerging economies hold a large portion of the world’s housing demand potential [
6], and more than 80% of the nations with the highest projected population growth through 2030 lack any kind of obligatory energy code [
5].
Although carbon emissions per capita in high- and upper-middle-income countries are more elevated than those in low- and lower-middle-income countries, most industrialized economies have implemented programs to reduce energy consumption and mitigate GHG emissions [
7], in particular, in the building sector [
5]. In contrast, many developing nations have chosen to expand their investment in fossil fuel energy and keep their tendencies in the construction and operation of buildings instead of migrating to cleaner options [
8,
9]. The development of programs to reduce energy consumption and mitigate GHG emissions remains one of the main challenges for all sectors and regions, including the building sector in developing countries.
Within the Paris Agreement, 196 participants presented their updated nationally determined contributions (NDCs) in COP26 in 2020 to reiterate their commitment to reducing GHG emissions [
10]. The two most common GHG mitigation measures in international pledges are to increase renewable energy use and enhance building energy efficiency [
5]. However, many nations have struggled to address GHG mitigation in the life cycle of buildings and continue to use inefficient construction and building operation methods [
5,
11]. Scholars, industry practitioners, and government officials have proposed ambitious measures to reduce buildings’ energy consumption and GHG emissions in buildings throughout their life cycle. There are different alternatives to reduce emissions at the product stage, construction phase, usage stage, and end-of-life stage [
12]. Among others, the options include changes in the steel [
13] and cement production [
14] processes; optimization of building designs and alternative construction systems in the construction stage [
15]; passive design and service systems in the operational stage [
16]; and circularity of materials at the end of life stage [
17].
Despite extensive research on GHG emission reduction strategies for the building industry, these strategies are only just beginning to be implemented globally [
5]. A lack of integration among stakeholders is one of the key obstacles to GHG emissions mitigation actions in the building sector [
18]. The reasons for this are multiple. First, the plurality of participants throughout all life cycle phases creates complicated relationships in the building sector [
19]. There are different actors intervening in building design, construction, financing, operation, and maintenance processes [
20]. Second, actors have different interests, affecting decision-making procedures [
20,
21,
22]. Third, different players are impacted in very diverse ways by the adoption of GHG mitigation strategies. Some actors win, and some actors lose, depending on the type of interventions used to minimize GHG emissions [
23]. These factors generate differences and conflicts between actors. One of the main goals established during COP26 to develop mitigation actions to face climate change is mutual work among all stakeholders [
24]. This includes governments, businesses, academia, and civil society. In order to understand the role and importance of different stakeholders inside specific contexts, social network analysis (SNA) has been widely applied [
25,
26]. In the building sector, SNA has been used to understand the relationships between stakeholders of the biomass industry [
25], comprehend the influence of the actors impacting building energy efficiency [
27], and understand stakeholders’ influence on green retrofit projects’ success [
28], among other analyzes.
Therefore, even though SNA has been applied in the building field, and the absence of integration among stakeholders has been recognized as one of the main barriers to achieving GHG emissions mitigation, most studies have focused on specific problems rather than the overall characterization of the sector [
29]. In particular, building sector stakeholders’ characterization via SNA strives to improve engagement and knowledge transfer [
30], align internal collaboration [
29], and identify potential problems [
31]. Thus, due to the necessity of lining up stakeholders toward common goals to achieve GHG emissions mitigation, this study analyzes the network of key actors and stakeholders involved in the design and implementation of the Colombian Net-Zero Carbon Buildings Roadmap.
This study aimed to identify the key players within the major enablers of the roadmap (policy, technology, finance, and capacity development) and to identify the critical links and relationships among stakeholders. The results of this analysis are useful for the implementation phase of the Colombian Net-Zero Carbon Buildings Roadmap. Policymakers can take advantage of the findings in multiple ways. First, they can identify fundamental actors per category and their tasks. Second, they also can recognize potential challenges, such as the lack of integration among crucial stakeholders in certain links within the networks. Third, SNA helps identify potential opportunities for collaboration. Due to the complexity of relations among actors in the different enablers to achieving GHG emissions mitigation, SNA is a suitable tool for supporting the subsequent phases of the roadmap.
4. Results
The networks developed for each enabler are shown in
Figure 3. These networks showed the ties established between actors and the way each actor was integrated into the set of SLAs per enabler. This reflected the way the roadmap of the Colombian Net-Zero Carbon Building Roadmap was intended to be implemented. In each network, the size of the node representing each of the actors was proportional to the number of relationships of each stakeholder.
For each link in any network, the thickness and darkness of color were proportional to the number of times the pair of actors needed to participate together per enabler. The darker and thicker the link, the stronger the relationship between stakeholders because they had to participate more times together in second-level actions per enabler. To provide a quantitative interpretation of
Figure 3,
Table 6 and
Table 7 show the results of the network-based metrics and actor-based metrics per network, respectively. These results allowed comparing the networks and actors participating in each enabler.
According to the network-based metrics (
Table 6), all networks showed at least 23 stakeholders and exhibited density values higher than 0.5. The density values obtained meant that more than 50% of the possible relationships between actors took place within the proposed structures. Such density values also indicated that the actors participating in achieving net-zero emissions in the Colombian building sector needed to keep redundant relationships among them. The density values obtained showed a difference from previous studies, in which similar networks exhibited density values lower than 0.5 [
21,
41,
45]. The redundancy in network relationships could also be examined by exploring indicators such as average distance and degree. While many studies in the extant literature exhibited short average path lengths higher than 1.5 [
45,
50], the four structures presented in this study exhibited values lower than those. This denoted that Colombian stakeholders required fewer links to communicate with each other, suggesting that all actors in the enabling networks remained highly interconnected. Furthermore, regarding the average degree, most stakeholders revealed multiple relationships, supporting the idea of a vastly interconnected network.
Even though the above-mentioned network-based metrics (e.g., density and short average path length) suggested the idea of highly interrelated networks with well-connected actors in each enabler, the degree of centralization indicated that the studied networks seemed to be dominated by central actors. In particular, the degree centralization exhibited its highest value in the finance network, in which the degree centralization for the national government showed a value of 0.45 (see
Table 7). Overall, degree centralization values were higher than 0.25 in all networks, indicating the dominance of well-connected players across all arrangements.
Table 7 identifies the main actors whose efforts are necessary to achieve net-zero emissions in the Colombian building sector. This table shows the 15 most prominent actors in each network by considering multiple actor-based metrics (i.e., D—degree centrality, C—closeness centrality, B—betweenness centrality, and E—eigenvector centrality). It is important to highlight that the national government, local governments, guilds and professional associations, financial institutions, the Ministry of Environment, the Ministry of Housing, and the private sector were cross-sectional participants in all enabling networks within the building sector. This means that they all should participate as leading actors in supporting the proposed SLAs.
4.1. Characterization of Enabling Networks: Similarities and Differences
All the enabling networks shared some common structures.
Figure 3 and
Table 6 show that the short average path length in all networks exhibited low values, varying between 1.23 and 1.36, thus, indicating efficiency and few intermediaries in the communication among stakeholders [
50,
53]. In respect of the average stakeholders per network, it is worth appreciating that the average number of actors in charge of each second-level action varied between 8.82 and 10.4, exhibiting high levels of participation per SLA in each enabler. In this sense, the density values varied between 0.57 and 0.77, and the average weighted degree indicated very interrelated networks, strengthening the idea of highly cohesive networks with redundant components and connectivity [
41,
50,
57]. Even though there were common attributes across the enabling networks and relative homogeneity in their network-based metrics, there were also some singular attributes. Specifically, in terms of network sizes, it is important to highlight that despite differences in the number of SLAs assigned to each network, the number of participants in every structure remained very similar across the four studied structures. For instance, while the capacity development network incorporated three times fewer SLAs than the policy network (i.e., 15 vs. 54 SLAs), the number of actors in each one was 23 and 28, respectively. Similarly, the technology and finance networks had associated 43 and 50 SLAs and 30 and 35 participants, respectively. This indicated that the number of actors was not related to the number of second-level actions but to the complexity and synergies of each specific enabling network. Consequently, the set of actors in charge of developing the proposed enablers varied according to the priorities, value chains, and skillsets [
58].
On the other hand, the degree centralization metric displayed in
Table 6 highlighted differences among enablers. Even though all the degree centralization values were low (less than 0.5) compared to some values found in the literature [
59,
60], the enabling networks denoted important variations in this metric. In particular, the values of the finance (0.45) and technology (0.42) networks were close to 0.5, indicating the presence of intertwined structures prone to be controlled by a few main actors (i.e., the national government). This tendency was smaller in the policy and capacity development networks due to these exhibiting less centralized structures. In general, while high centralization values were associated with the degree of power of an actor in the decision-making process, low centralization figures indicated plurality in such a process [
61,
62]. Thus, and according to
Table 6 and
Table 7, the national government seemed to act to coordinate and avoid conflicts among actors, mainly in the policy, technology, and finance enabling networks, as it was the most dominant player in these structures. In contrast, in the capacity development network, in which there was not a clear, prominent player, the guilds and professional associations, national government, and academia seemed to be responsible for playing a crucial function in coordinating their roles to develop innovation [
61].
This proposed set of network-based metrics allowed for understanding the overall structure of the networks’ actors in charge of decarbonizing the Colombian building sector. This analysis exhibited the strengths and weaknesses of each enabler network in terms of connectivity, participation, and centralization by finding similarities and distinctions between the networks of stakeholders. A deeper analysis of the main actors participating in each of the four enabling networks is presented below.
4.2. Characterization of ZCBA Actors across the Enabling Networks
Table 7 displays the 15 most important stakeholders in each enabling network according to their degree centrality (D), closeness centrality (C), betweenness centrality (B), and eigenvector centrality (E). Most of these actors were public entities (Colombian ministries, national government, and local governments). Still, many actors belonged to non-public sectors (private companies, guilds, standards organizations, and civil society), showing the need for joint work and coordination among different actors in achieving net-zero emissions goals in the Colombian building sector.
4.2.1. Public Policy Enabling Network
According to
Figure 3a and
Table 6, the public policy enabling network allowed for visualizing a highly interconnected structure within one single cluster. In this network, the five most prominent actors were the national government, local governments, the private sector, the Ministry of Housing, and guilds and professional associations. These players participated in at least 47 (87%) of the 54 SLAs proposed for this network. They held the highest values in all the actor-based metrics, showing the need to achieve a balance between the public sector and other actors to reach the net-zero emissions targets. Specifically, while the public sector seemed to be in charge of defining technical specifications, determining environmentally friendly procurement methods, and establishing mandatory energy codes, the non-public sector seemed to require working on procurement processes focused on the mitigation of CO
2 emissions [
63].
In addition to the five main actors in this network, four additional stakeholders appeared as second-tier actors, participating in more than 50% of the SLAs. In particular, academia, civil society, the Ministry of Environment, and the Ministry of Energy were seemingly important in implementing 29 of the 54 second-level actions within this network. According to the connection exhibited in
Figure 3a and the metrics shown in
Table 6, these second-tier actors seemed to focus on objectives associated with social inclusion and structural changes within the public policy realm [
64].
4.2.2. Technology Enabling Network
According to
Figure 3b and
Table 7, the technology-enabling network showed two prominent actors, the national government and the private sector. These two participants were involved in 42 second-level actions within this structure (i.e., 98% of all SLAs in this network). Both of these actors had the highest values in all actor-based metrics, showing their importance in developing the technology actions required to achieve net-zero emissions in the Colombian building sector. As proposed in previous studies [
65], the government seemed fundamental in supporting research and development for environmental sustainability, while the private sector had a role in supporting innovation by investing in cleaner productive processes [
65].
Apart from the two most prominent actors, eight stakeholders also exhibited essential values in their actor-based metrics (i.e., the Ministry of the Environment, academia, local governments, guilds and professional associations, the Ministry of Housing, the Ministry of Energy, financial institutions, and civil society). All these actors were influential in at least 21 second-level actions (i.e., 49% of all SLAs in this network). These stakeholders are prone to pursue multiple goals: improving sustainability, research, and development by establishing frameworks and supporting innovation, supporting the technological transformation financially, and veiling up for societal welfare.
4.2.3. Finance Enabling Network
Although highly interconnected, the finance enabling network was the least dense network within the four studied structures (
Figure 3c and
Table 7). This can be partially explained by the roles of the leading, prominent actors in this arrangement. In particular, the finance enabling network had the same two prominent actors as the technology enabling network (i.e., the national government and the private sector). However, and in contrast to the policy enabler network and the technology enabler network, the national government and the private sector participated in at least 42 SLAs (i.e., 84% of all SLAs within the network). This percentage was marginally smaller than the share of participation of the main actors in the policy and technology networks, even though the network-based metric values were in line with the values of the previously analyzed structures.
In this sense, the role of the government in this network seemed to be providing financial incentives and resources to make the transition towards net-zero emissions in the building sector economically viable. On the other hand, as suggested by previous studies, the private sector seemed to be involved in continuous collaboration with all stakeholders by mobilizing capital and capabilities [
66].
Along with the leading actors in the finance enabler network, participants such as guilds and professional associations, local governments, financial institutions, the Development Bank, and civil society also stood out as important players in this structure. All these actors participated in at least 24 SLAs (i.e., 48% of all SLAs within the network). Interestingly, this set of actors contained mainly stakeholders belonging to the non-public sector. This group of participants seemed to focus on developing financial mechanisms to achieve net-zero emissions and guarantee coordination among government actors and other players.
4.2.4. Capacity Development Enabling Network
The capacity development enabling network exhibited four main stakeholders, namely, guilds and professional associations, the national government, academia, and the private sector (
Figure 3d and
Table 7). In general, these leading actors had the highest actor-based metrics and dominated the flow of information within the network, as they participated in at least 14 SLAs (i.e., 63% of all SLAs in the structure). However, compared to the other three enabling networks, these actors exhibited slightly less centralized behaviors, which made relationship patterns less dependent on the national government and private sector. Instead, relationships seemed to focus on the roles of guilds and professional associations, and academia, as these players seemed to be centered on disseminating the knowledge and establishing the technical bases required to achieve net-zero emissions.
In addition to the leading actors mentioned before, the local governments, the Ministry of Housing, the Ministry of Environment, and the Ministry of Energy exhibited an important role within this network, as each one of these stakeholders participated in at least eight SLAs (i.e., 53% of all SLAs within the structure). While local governments seemed to be focused on coordinating the dissemination of information and knowledge at local scales, the ministries of housing, environment, and energy showed behaviors associated with developing standards and defining regulations for establishing common ground regarding the knowledge and capacity required to reach net-zero emissions.
5. Discussion
There were common actors leading the four enablers (policy, technology, finance, and capacity development) to achieve GHG emissions reduction in the building sector. Three of these actors, the national government, local governments, and the private sector, appeared as one of the main five leaders in all the categories, suggesting common main actors of all networks. These similitudes were strengthened with the network-based metrics, presenting high values compared to previous literature analyzes [
21,
41,
45]. Despite this, the action category networks also had distinct features. For instance, while in the policy network, the Ministry of Housing was the main actor, in the technology network, this role was occupied by the Ministry of Environment. The guilds and professional associations became the leaders in the finance and capacity development networks.
The results suggest multiple ways to take advantage of each enabler’s network structures and show options to anticipate the best strategies. Regarding the policy networks, the two main actors were the national government and local governments. The experts recognized the role of the national government in leading the decision-making process to implement the roadmap to net-zero buildings. However, according to the results, this is only possible with the intervention of local governments implementing the policies in a differentiated way according to each region’s context. Therefore, it is essential to consider decentralization mechanisms [
67] for a successful low-carbon roadmap application. Additional to this, other actors such as the private sector, the guilds and professional associations, academia, and civil society exhibit the importance of coordinating public policies articulated by the interest of all the actors in the Colombian building sector.
Concerning the technology network, in addition to the national government and the local governments, the private sector, the Ministry of Environment, and academia were the following three main actors. It is possible to visualize the role of the private sector in supporting the adoption of new technology via the Ministry of Environment’s regulations and the academia’s innovation [
65].
The two main actors in the finance network corresponded to the national government and the private sector. The private sector plays a role in funding sustainable infrastructure jointly with the national government [
68] and simultaneously opened the debate on the feasibility of exploring alternative financial methods such as public–private partnerships [
69].
In contrast to the other networks, the guilds and professional associations played the primary role in the capacity development network. They are vital in adopting new technologies and in promoting new capacities. The national and local governments, academia, and the private sector are essential in supporting the new capacity formation in the entire Colombian building sector.
Lastly, it is necessary to depict potential problems associated with the enablers’ network structure. Even though it has been widely assumed that high cohesion values, associated with density, lead to improving team performance, some studies have shown that excessive density values can exhibit underperformance issues [
70]. The four major categories of the roadmap presented network-based metrics higher than previous studies [
21,
41], potentially leading to stagnation, poor team performance, and lack of coordination [
70]. For this reason, the Colombian government should constantly evaluate the role of the main actors and define their tasks specifically. Additionally, future studies based on improving team performance can be carried out to the extent of the execution of the Colombian roadmap.
7. Conclusions
We analyzed the networks of actors involved in designing and implementing the Colombian Net-Zero Carbon Buildings Roadmap. Through SNA, we identified the key players within the major categories of the roadmap (policy, technology, finance, and capacity development) and the critical links and relationships among actors. Compact and dense structures characterized the four enabling networks (e.g., public policy, finance, technology, and capacity development) required to achieve net-zero emissions in the Colombian building sector. Small short average path lengths and a high degree of collaboration defined these network structures. Three types of players composed the networks:
₋ Leading stakeholders participated in more than two-thirds of the SLAs. They exhibited high centrality values and dominated most network connections and information flows.
₋ Second-tier actors participated in approximately one-half of the SLAs and coordinated specific objectives and information flows.
₋ Perimeter actors had low centrality values and participated in less than one-half of the SLAs. They were in charge of developing punctual actions of the roadmap and worked together with the leading and second-tier actors.
The studied networks had singularities, most of them regarding their leading actors and roles. While the national government and the private sector participated as leading actors in all enabling fields, other main actors changed according to the attributes of each network. For example, while academia was one of the five most prominent actors in the technology and capacity development networks, its role was less pronounced in the policy network and very limited in the finance network.
Overall, this research supports the field of sustainability and management in several ways. Even though the academic literature provides examples of social networks for sustainability in specific contexts, there is little evidence of using this methodology to analyze a whole economic sector. Social network analyzes allow identifying the actors, their interactions, and their roles in implementing net-zero roadmaps in the building sector. The diversity of actors intervening in the building sector and the complexity of the relations are vital factors in implementing effective GHG mitigation strategies.
This study provides a novel approach to studying decarbonization roadmaps by using SNA. Developing a social network through the actions required to achieve net-zero emissions allows a better definition of responsible actors at different levels and is an alternative for changing the focus from traditional actor maps to relational structures incorporating communication flows between multiple stakeholders. Governments and policymakers can take advantage of the shape of the enabling networks to achieve strategic goals within their roadmaps toward net-zero emissions.