Application of Social-Life Cycle Assessment in Urban Se tt ings: Social Impact Assessment of Green Roofs

: Sustainability brings together three dimensions: environment, economy and society, as according to the Agenda 21, a comprehensive plan of action to be taken globally, nationally, and locally by organizations of the United Nations System, governments, and major groups in every area in which humans impact the environment. To de ﬁ ne whether an intervention or process is ‘sustainable’, these spheres must co-exist and be equally contemplated. Green roofs have been extensively studied from environmental and economic perspectives, but as far as the social dimension is concerned, the literature is limited. Indeed, to de ﬁ ne these interventions as ‘sustainable’, the social dimension must also be investigated. Over time, Social-Life Cycle Assessment (S-LCA), an extension of the be tt er-known Life Cycle Assessment (LCA), has become widespread. S-LCA allows assessing the potential impact that a production process, and consequently a product, can have on people. This paper aims to propose a model for analyzing green roofs by identifying the possible categories of stakeholders involved in the implementation process, and the impact categories to be referred to. By de ﬁ ning these elements, it is possible to estimate the positive or negative social impact that interventions cause. The results of the survey o ﬀ er insights into social issues related to the implementation of green roofs by focusing on the stakeholders involved within the entire life cycle.


Introduction
Green roofs, as Nature Based Solutions (NBS), are an important tool for environmental compensation and mitigation in the urban context.The benefits of green roofs mainly concern: rain water management [1,2], improving air quality [3,4], the reduction and mitigation of the urban heat island phenomenon [5][6][7][8][9][10], reducing sound propagation [11], increasing roof system's durability [12], the integration of new kinds of green infrastructures providing ecosystem services [13], improving photovoltaic panels performance [14,15], and biodiversity enrichment [16][17][18][19][20].In addition, greening systems provide an alternative method of visual access for the occupied space [21].Several studies [22,23] with the same thoroughness, even if the social dimension is deeply concerned with sustainability [Figure 1]; this is probably due to the difficulty in translating social impacts into numerical quantities [33].Even when the focus shifts to the social dimension, the community is the main, or only, stakeholder involved in the process [32].Social aspects are less explored for several reasons; as Klöpffer [34] said, "Industrialized countries tend to emphasize the environmental aspect (…), whereas developing countries give highest priority to economic development".The three pillars have been commonly approved, but their relative weights are not clear [35].Over time, new types of analysis emerged, such as the S-LCA, an extension of the better-known LCA, which allows defining whether a product (or activity) has been produced in a 'socially' sustainable way, based on certain indicators.Specifically, it allows assessing the potential impact that a product process, and a product itself, may have on people and stakeholders, such as the potential impact on workers' health and safety [36].The most complex aspect of the analysis seems to be the combination of concepts and data from different fields, such as sociology and technology [34].
According to Polese and Stren [37], social sustainability is seen as "development (and/or growth) that is compatible with harmonious evolution of civil society, fostering an environment conducive to the compatible cohabitation of culturally and socially diverse groups while at the same time encouraging social integration, with improvements in the quality of life for all segments of the population".
It is possible to argue the thesis that green roofs are sustainable in environmental and economic terms [32,33].However, it is deemed necessary to investigate the social aspects, given the lack of literature on the subject.

Aim of the Study
The contribution of the study concerns both the investigation of social issues in relation to architectural interventions, and a possible modus operandi for assessing the social impacts of green roofs projects.Therefore, the main object of this research was to define a model for the assessment of the social impact of green roofs, investigating the social dimension in the construction of greening systems for the building envelope, the least explored topic in the field of sustainability.
The objectives of the study can be summarized as follows:  identify the main social issues related to the design and construction of green roofs in terms of working conditions, health, and safety etc.;  Determine which groups of people (stakeholders) are involved in the construction and management processes of green roofs;  Develop a checklist for a simplified assessment of the social impact of green roofs.

Methodology
The Guidelines for Social Life Cycle Assessment [36] were the inspiration for the research, and provided the background for the developed methodology [Figure 2].The definition of S-LCA, according to the Life Cycle Initiative [38], is "a method that can be used to assess the social and sociological aspects of products, their actual and potential positive as well as negative impacts along the life cycle".S-LCA is, therefore, understood as an analysis of a product that allows determining its social sustainability to promote people's and society's well-being [36].
According to the S-LCA Guidelines, it is necessary to consider three groups of basic indicators: satisfaction of basic needs and quality of life, social justice, and social coherence.The analysis provides information on social and socio-economic aspects, and assesses the potential impacts of a product or activity on society and/or on different categories of people.
This paper focuses on the impacts of green roofs on the different stakeholders involved, according to the S-LCA Guidelines [36].
Therefore, the methodology adopted includes a preliminary study of the topic through interviews with people working in the sector.Such preliminary study supported the draft of two anonymous questionnaires related to the social issues which emerged.The questionnaires were administered to relevant stakeholders, i.e., workers and users (as described in Section 3.2).

Definition of the Boundary Conditions
As anticipated [Figure 2], the implementation of the S-LCA involves the definition of the objective of the study [36]; in this case, the assessment of the potential social impact of green roofs.Once the scope has been delineated, it is possible to identify the stakeholder categories involved in the process.
The boundary conditions outline which stages of the production process are going to be considered in the research.The current study will not look at all phases of the life cycle, but it will focus on construction, use, and disposal, i.e., from gate to grave.The decision to exclude the stages related to the extraction of raw materials and their transport stems from the difficulties of finding reliable data.Consequently, it was decided to restrict the scope to those stages that could be examined directly [Figure 3].The boundary conditions also include the definitions of the spatio-temporal boundaries, relating to the place and period in which the survey was carried out.In this case, the data collection took place in Italy in the period between September 2022 and February 2023.

Definition of Stakeholder Categories
According to the Guidelines for S-LCA [36], the stakeholders involved in the production processes include: workers, the local community, society, consumers, and the players in the value chain.The categories of people that have been chosen for this investigation are the workers, who actively participate in the design and implementation of green roofs, and the users of these interventions who oversee management and maintenance.The category workers is already included in the Guidelines; the category users was defined ex novo (the word suggested by the Guidelines [36] is 'consumer', which does not seem appropriate for public spaces).

Definition of Impact Categories and Sub-Categories
The impact categories described in the Guidelines for S-LCA [36] are divided into: Human rights, Working conditions, Health and safety, Cultural heritage, Governance, Socio-economic repercussions [Figure 4].Impacts are assessed based on certain indicators, which may differ according to the objective of the study.In the Guidelines [36], general indicators are provided, but they may be modified, or new indicators may be created; however, the exclusion or inclusion of impact categories must be justified.
The impact categories and sub-categories [Figure 5] are related to the 17 Sustainable Development Goals (SDG) included in the 2030 Agenda for Sustainable Development [39].The analysis involves the exclusion or inclusion of categories depending on the scope and the object of study.Once the cut-off criteria have been justified, it is possible to proceed with their analysis.Preliminary interviews helped to identify the most crucial macrosocial issues, and from there, the questions in the questionnaires developed.
For the first stakeholder-workers-the impact categories considered were Working conditions and Health and safety.The reasons for excluding the other categories are the difficulty in finding data or the lack of relevance for the analysis.
The category Working conditions includes the sub-categories [36]: The 5-6-7 categories were added following preliminary interviews.In the Health and safety category, the following sub-categories are considered [36]: These sub-categories were integrated to achieve the aim of this study.For the stakeholder 'users', the categories of interest are the Conditions of use and the Socio-economic and environmental repercussions.The inspiration is taken from the impact categories listed in the Guidelines [36].The impact categories are redefined according to the aim of the study and the definition of the new stakeholder category "users".The Conditions of use category is created from scratch, and the category of Socio-economic repercussions is implemented by adding environmental consequences.
The sub-categories included in the Conditions of use category include: 1. Governance; 2. Transparency; 3. Sustainability involvement.
They have been defined ex novo in order to deepen the impact deriving from the use of the green roof systems.
The category of Socio-economic and environmental consequences, redefined and implemented, includes the following sub-categories: 1. Community involvement; 2. Creation of new jobs; 3. Environmental benefits.

Methodological Sheets
The methodological sheets were drafted to provide an overview of the sub-category under study [Table 1].The sheets include an initial basic definition of the sub-category, which enables its most relevant aspects to be understood and its declinations to be described.Then the definition of its purpose in relation to the analysis and its relevance to sustainable development is included, i.e., why it is considered in the analysis and which aspects it entails in terms of sustainability.Once these initial aspects have been defined, we move on to the evaluation of the data, which are divided into quantitative, semi-quantitative, and qualitative data, depending on the type of sub-category being examined: e.g., for the sub-category working hours, the quantitative data requested is the number of working hours per week; semi-quantitative data report affirmative or negative (yes/no) evaluations or rating scales, in the case, for example, of the degree of appreciation of one's work; qualitative data refer to short texts, e.g., in the case of the sub-category related to social benefits.Data sources are divided into generic data and site-specific data.The former can be traced back to the country of reference and are used as screening tools to highlight possible weaknesses in each topic.Depending on the scope, it is then possible to carry out specific investigations in areas where social risks have been highlighted.
In the generic data section, institutional, governmental, and inter-governmental sites are used to provide a benchmark.In the site-specific research section, reference data are obtained from the stakeholders' interviews.
Finally, the limitations of the sub-category are listed to highlight any critical issues.

Data Collection
A preliminary overview on the context was obtained by means of telephone interviews with architects, agronomists, associations, and companies specialized in the production and design of green roof systems.Such interviews allowed to preliminarily define the questions to include in the two anonymous questionnaires, the first to be administered to the stakeholder workers, and the second to the users [Table 2].Both questionnaires are based on the most relevant indicators discussed in the Guidelines for S-LCA [36].The first questionnaire (workers) was administered to two associations and two main companies, with relevant and international experience on the topic, to architectural firms, to agronomists and gardeners, and to different associations involved in redeveloping urban areas.The questionnaires were circulated by e-mail and via social networks such as LinkedIn and Facebook.
The user questionnaire was shared with the previously selected operators who were in contact with their clients, and with various associations promoting green roofs.
The questionnaires' samples are relevant and suitable for the specific field, as they include associations, such as the Italian Federation of Green Roofs, and companies operating in the green roof sector.The number of responses is reduced, but it provides useful information; this approach was adopted by other investigations [32,40].
The first questionnaire [Table 3] is made up of 22 questions divided into two sections; the first section is drafted to obtain generic data on the respondents and their jobs, and the second investigates the relationship between green roofs practice and the potential impact categories involved.The second questionnaire [Table 4] is divided into 23 questions; the first section aims at collecting users' personal information in relation with green interventions, and the second one explores the topic of green roofs through the different impact categories considered for the specific stakeholder.

Questionnaires Outcomes
In this paragraph, the interviews' results are summarized to highlight the social issues deriving from the construction, use, and disposal of green roofs projects.
The data collected through the questionnaires addressed to the worker stakeholders show that: the construction sector has a strong male dominance; out of 35 persons interviewed only three were women.In recent decades, the economic status of women has changed considerably, and women now occupy virtually equal positions in sectors that were once predominantly male-dominated [41].Although there is no extensive literature on gender inequalities in the construction sector [42], the predominance of males in the construction sector can be related to: cultural and social influences, personal or physiological reasons, stereotypes of various kinds, family, and economic motivations [43].
Another relevant datum that emerged is that 74% of the respondents were freelancers.By isolating the freelancers' data, some considerations can be made.Of the freelancers surveyed, 85% generally work more than 40 h per week.Less than 20% of the professionals answered that they have other social benefits besides retirement (such as training, disability benefits, or others).The results show that for both categories, the guaranteed social benefits are limited [Figure 6]; for example, only 11% claimed to have paid maternity and paternity leave.The lack of subsidies in this respect is confirmed by the drafting of new laws and regulations focused on maternity or paternity leave [44].The data on the wage difference is not striking, since most respondents (29 out of 35) stated that there was no wage discrimination between men and women [Figure 7].However, it should be emphasized that among the 35 respondents, only three women participated in the interview, and, therefore, the data is not reliable and complete.It can also be noted, however, that the six persons claiming differences in salary were all male freelancers (mostly gardeners).Regarding the user questionnaire, the main results are the following.The data show a significant majority of private (75%) rather than public (20%) green roof interventions.Only 20% of the projects referred to in the questionnaires are public.This figure is relevant in terms of accessibility.The possibility for the 'public' to access these roofs, in the case of public buildings or community spaces, would provide additional community benefits.
In terms of sustainability, it appears that users are aware of the sustainability issues and the social, environmental, and economic benefits derived from the projects [Figure 8].Good community involvement is one of the most important aspects of social responsibility [45].Users' understanding of issues related to the use of materials, their management and maintenance, and their eventual disposal, promotes a conscious and sustainable attitude.Although social and economic benefits are emerging, environmental benefits prevail as more investigations and experiments have been conducted in this field [32].Another interesting finding concerns the socio-economic dimension [Figure 9].As mentioned previously, issues relating to economic and social impacts are not as developed as environmental ones.However, it was possible to focus on the new job creation.Of respondents, 23% answered that the construction of a green roof created job opportunities, mainly in the maintenance and management sectors.In some cases, reintegration activities for former prisoners or support for people in need were mentioned.

Check-List
One of the goals of the study was to create a simplified checklist to support the designers during the construction of green roofs.The list [Table 5] describes step by step how to deal with these projects in a socially sustainable way.It consists of a series of questions to undertake in the implementation of a green roof system in order to consider the social dimension.These steps are related to different thresholds units and references to evaluate useful benchmarks, such as the Guidelines for S-LCA [36] and the SDG [39].The latter are important to introduce different social themes related to the questions.The first step, concerning the groups of people involved in the production process, is important to understanding how and how many people are involved in a project.This step is relevant to understanding the part of society affected by the implementation process and its repercussions.
The fair salary issue is important to ensure decent living conditions for all.This topic is also relevant for the SDG Goal number 1-End poverty in all its forms everywhere, and number 8-Decent work and economic growth.The possible threshold of this step can be identified when a person's salary does not fall within the minimum standards defined by law, or when the same salary does not allow people to support their basic needs.Specific European directives address this issue, as the Directive (EU) 2022/2041 on adequate minimum wages in the European Union [46].In addition, working hours must comply with the regulations and the national and international standards (SDG8).Also in this case, sustainability standards can be deduced from the compliance with national decrees, such as the Italian Legislative Decree No. 66/2003 [47] [52].
The International Labour Organization (ILO) and the World Health Organization (WHO) focus on the safety at work.In this field, relevant criteria for assessment include statistical surveys on accidents at work (for example, from the National Institute for Industrial Accidents Insurance INAIL statistical database), or the compliance of the national legislative decrees on the specific topic (Italian Legislative Decree No. 81/2008) [53].
The quality of work is directly linked to the well-being of the workers, and thus constitutes one of the fundamental elements in determining better living conditions for people.The sample surveys on the quality of work developed by the Institute for the Development of Professional Training for Workers (ISFOL), or the one on Working conditions in a global perspective by ILO and Eurofound, can be cited to identify validity thresholds.It must be pointed out that the question may lead to courtesy bias and that consequently the data may be forced and unreliable.Recent research [54] has reported that the formulation of a question (positive/negative) can influence the way participants answer, and therefore, a neutral tone should be preferred.
Information on social interactions is useful to understand what kind of relationships arise in the workplace (with direct influence on job quality).
From the data observed, it emerged that paying attention to the duration of a project is relevant, in terms of both construction and maintenance (SGD [11][12]. Transparency is relevant in terms of, e.g., responsible use of soil (Goal 12 and Goal 15-Life on land) and the relationship between workers and users to enable greater user involvement (as according to the European Directive 2022/2464 on Corporate Sustainability Reporting Directive [55] and UNI EN ISO 26000/2020 on social responsibility) [45].Each project should also be properly managed (Goal 11).Finally, for social responsibility, citizen involvement is also relevant, to support users in making informed choices in an ethically correct and transparent manner.
The last steps focus on the socio-economic and environmental impacts of a project.Economic impacts are related to job creation [36], while environmental impacts are related to the benefits provided by green roofs, described in the introduction.

Conclusions
In conclusion, this study shows that the social impact of green roofs projects can be assessed.Despite the limits of the present study and possible future developments, it was shown that surveys can be effective tolls in such studies, producing relevant results, which could also broaden the debate on the social dimension.The following main conclusions can be drafted:  The research developed a tool (checklist) to aid the design of green roofs to investigate the social impact of these interventions.Studying the projects from a more inclusive point of view allows focusing on social issues linked to construction and management processes;  The involvement of stakeholders provides a holistic view of the intervention and its repercussions.To investigate precise social issues, diverse categories and sub-categories were analyzed.Understanding the most relevant social themes is crucial to considering the positive or negative effects of these projects on people.
This paper shows that, in addition to analyzing the potential environmental and economic impacts of green roofs, social aspects can also be assessed to evaluate their sustainability.
The presented analysis offers a simplified way of assessing social impacts in projects where the social dimension is not always considered.Future research will be focused on consolidating the method and expanding the data samples offered, to provide a broader view of the subject.

Figure 1 .
Figure 1.Diagram of the "Triple Bottom Line" adapted from John Elkington.

Figure 2 .
Figure 2. Diagram S-LCA methodology based on the Guidelines for Social Life Cycle Assessment (Benoît Norris et al., 2020).

Figure 3 .
Figure 3. Diagram of a product life cycle-methodology-specific boundary condition highlighted (Life Cycle Initiative).

Figure 4 .
Figure 4. Assessment system from categories to inventory data.Adapted from Benoît et al., 2020.Connections are exemplary and not exhaustive.

Figure 5 .
Figure 5. List of stakeholder categories and impact sub-categories.Adapted from Benoît et al., 2020.

7 .
Sustainability of the intervention.

Figure 6 .
Figure 6.Social benefits results from the workers' questionnaire.

Figure 7 .
Figure 7. Wage gap results from the workers' questionnaire.

Figure 8 .
Figure 8. Project sustainability results from the users' questionnaire.

Figure 9 .
Figure 9. Project benefits results from the users' questionnaire.

Table 1 .
Summary of methodological sheets.Adapted from Methodological Sheets for Sub-categories in Social Life Cycle Assessment (S-LCA).

Table 2 .
Summary tables with questionnaire data.

Table 3 .
Table of questions from the workers' questionnaire and their categories and sub-categories.

Table 4 .
Table of questions from the users' questionnaire and their categories and sub-categories.
on the organization of working time, or international conventions, such as the No. 1 of 1919 on working hours drawn up by the International Labour Organization [48].Gender equality is a human right.The lack of equal opportunities for all is an important obstacle to sustainable development.Possible limits are enshrined in the 1951 Convention No. 100 on Equal Remuneration for Men and Women for Work of Equal Value of the International Labour Organization [49] and the Universal Declaration of Human Rights [50].Social benefits help individuals and communities by ensuring better working conditions and increased productivity.In this case, the most relevant conventions include: 1952 Convention No. 102 on Social security [51] and 1967 Convention No. 128 on Invalidity, Old-Age and Survivors' Benefits