Assessing urban sustainability: a proposal for indicators, metrics and scoring—a case study in Colombia

Although there are different methodologies for evaluating the sustainability of urban areas in Latin America, they usually apply to a specific city as a whole and cannot be generalized to other cities; besides, they do not address smaller urban units, such as the district, and rarely approach all sustainability dimensions. This study aims to propose a methodology for the evaluation of urban sustainability in the context of a country, whose approach can be adapted to evaluate the urban sustainability of any country or territory, taking into account environmental, social, economic and institutional aspects. The methodology is structured as an ordered protocol in five stages: (I) revision of PROGRAMMES on urban sustainability, (II) revision and cluster of indicators, (III) definition of indicators and metrics, (IV) definition of the scoring method of indicators, and (V) graphical representation of indicators. Accordingly, the methodology was applied in the context of Colombia, particularly to the medium-sized city of Mosquera, as a case study, and both as a whole and by socio-economic strata. As a result, a set of indicators with their corresponding metrics and score in sustainability levels was obtained, as well as a graphical representation that facilitates the interpretation of results and enables the comparison of different urban areas within the city. The results made it possible to identify vulnerable or degraded urban areas, and on a lower level, to detect specific critical aspects that require the implementation of improvements geared towards a more sustainable urban environment. The overall conclusion is that there is room for improvement in the municipality, since its level of sustainability ranges, generally, from 1 to 2 on a scale of 3.


Introduction
The Latin American (LA) region is the second most highly urbanized area in the world and most of its population live in medium-sized and large cities in poor conditions (Jaitman & Brakarz, 2013). This trend is increasing progressively and leads to a rapid and uncontrolled growth, while many inhabitants are still poorly housed, without safe drinking water, sewage systems, adequate building materials, sufficient living space, formal tenure and a secure location (Boullon, 2012). Additionally, considering that urban improvement plans are scarcely applied and, when they are, the initiative is performed in a disjointed and limited manner (Montoya et al., 2020), LA regions are liable to fail to meet the sustainable development goals (SDG) set by the United Nations (2015). Colombia is one of the countries included in the LA region, and its population has concentrated increasingly in cities over the last few decades, this urban population reaching a figure of 81.5% in 2020 (CEPAL, 2020).
In the field of sustainability assessment in the international context, great efforts have been made by the scientific community to measure the level of sustainability of urban areas through indicators grouped in the three classical dimensions: social, economic and environmental. More recently, the institutional dimension has also aroused interest and is being approached in order to increase administrations support, but only tentatively. Sharifi and Murayama (2014) exhaustively reviewed a number of urban sustainability assessment tools and found that many regions have developed their own, such as LEED (US GBC, 2009) in USA, BREEAM (BRE Global, 2011) in UK, CASBEE (IBEC, 2007) in Japan, HQE2R (Blum, 2007) or Ecocity (Gaffron et al., 2008) in Europe, or Green Star (GCBA, 2003) in Australia. As seen, most of these tools apply to Europe, North America and Asia, where robust and proven methodologies for developing sustainability indicators exist and have been widely implemented yet.
However, these kinds of methodologies or tools have been very little developed in LA (Peralta Arias, 2020). Even though several studies that focused in some LA countries were found in the literature. In Peru, Martínez Vitor (2019) analysed the influence of a set of existing urban indicators in the sustainable development of the metropolitan area of Huancayo using three different methodologies (census and cartographic data, urban plans implemented by the city hall along time, and the biogram made by the Inter-American Institute for Cooperation on Agriculture). His work focused on the three dimensions of sustainability, included the monitoring of indicators in different time periods and represented the results through spider graphs in a clear and visual manner. In Chile, Moreno and Inostroza (2019) evaluated the performance and the sustainability level of 4 neighbourhoods of the city of Temuco, through 11 indicators, and established three levels of performance (low, medium and high). Nonetheless, these indicators were only focused on physical (morphological) and environmental aspects, not in socio-economic ones, and did not define the method for granting the score. In Costa Rica, Romero Vargas et al. (2020) explored environmental, social and economic indicators through an expert's panel and identified a total of 327 indicators that finally simplified in 19 and grouped in 9 criteria (water, energy, fauna, green areas, etc.). They also defined a scale from 1 to 5 to score them, but the method used seemed fuzzy. Pinedo and Pimentel (2021) proposed a global index (in a scale of 0-1) to assess the sustainability of the municipality of Sao Joao da Ponta in Brasil, which was decomposed in the social, the economic and the environmental dimensions. They also defined a scale for evaluating four levels of sustainability, according to the value of the index obtained after the evaluation. In the context of Colombia, also some advances in the definition of sustainability indicators can be identified in the recent literature. Carrillo-Rodríguez and Toca (2013) designed a sustainable performance index for the city of Bogota. Gaviria (2013) proposed a set of indicators grouped into five dimensions (institutional, technology and innovation, economic, environmental and social) to assist construction sector companies in their decision-making. Montoya et al. (2020) defined a set of thirteen sustainability indicators for the specific case of Bogota's informal settlements, which were validated by applying them to two case studies. Also in relation to the informal settlements, López Borbón (2016) identified a number of variables, parameters and indicators to evaluate their functioning and prospects. More recently, Mesa García (2021) proposed a methodology for the measurement and assessment of six urban sustainability criteria (scale, accessibility, connectivity, density, diversity and nodal), specifically for the municipality of Bucaramanga; but these approached only morphological aspects (urban form) and the methodology cannot be generalized to other cities or similar regions in the country.
As depicted from the literature, one characteristic of Latin America is that although there is some work done within the development of sustainability indicators, the countries are working at the national level, not offering a global vision of specific regions. Urban sustainability indicators require a holistic approach, the definition of scales, the selection of parameters and levels of characterization and also have to be flexible tools capable of adapting to the urban fabric and features of the city or region where are to be applied, since urban ecosystems are dynamic and changing.
The studies carried out to date in LA focused on the evaluation of a certain city of the country, and then, the method used cannot be applied to other cities. Besides, sometimes the method or procedure used for identifying exiting indicators for their direct application or, otherwise, the development of new ones, seemed a little bit fuzzy. It was also observed that much emphasis was placed on the environmental aspect and less on the socio-economic one. Also, it was seen that the evaluation of the cities included in these studies is mainly addressed to the city as a whole system, but not cover the evaluation of smaller urban units, such as the neighbourhood or the district, in order to identify different sustainability performance within the same city, what is foreseeable to occur due to the marked physical and socio-economic differences that usually occur within the same urban area.
Specifically, in Colombia, the opportunity to measure intermediate Colombian cities through sustainability indicators is strategic, in the search to determine particularized environmental and socio-economic problems, possibly different from other areas at the national or LA level, with a focus on sustainability. The most recent legal framework has been adopted some legislation and tools approaching sustainable building and urban practices, which have been taken into consideration in this study. This is the CONPES 3919 policy (Política Nacional De Edificaciones Sostenibles, 2018), whose objective is to promote the inclusion of sustainability criteria within the life cycle of buildings, through instruments for transition, monitoring and control, and financial incentives that allow the implementation of sustainable construction initiatives. This policy was born from different initiatives for the strengthening the sustainability of cities, such as the previous CONPES 3819 policy ) and National Development Plan 2014, whose main objectives are the consolidation of the city system for economic, social and environmental development, and the mitigation of climate change with the focus on social mobility. As a result of these policies, some Colombian cities have formulated their own policies. This is the case of Bogotá and Valle de Aburrá, as an example of good practices. The policy of ecourbanism and sustainable construction of Bogotá (Alcaldía Mayor de Bogotá, 2014) was designed to address the problem of climate change generated by construction and urban environment, and was based on different sustainability advances in the city and on international standards and regulations, such as the urban sustainability assessment tools above-mentioned (LEED, BREEAM or CASBEE). As for the sustainable construction policy of the Metropolitan Area of Valle de Aburrá (AMVA-UPB, 2015), it works as a tool to implement sustainable construction in the region, at different phases of the life cycle of buildings, and under conditions of economic viability and resilience, eco-efficiency in the consumption of natural resources and low impact in relation to the landscape, biodiversity and ecological connectivity. This policy transcends the scale of the building, also influencing the proper development of public space, offering knowledge for sustainable urban planning.
Nevertheless, despite some efforts have been done in Colombia, no urban sustainability assessment general methodology for establishing of a set of comprehensive, clear and objective indicators capable of assessing the sustainability of urban areas that were adapted to the context and specificities of the region under study and that covered the four dimensions of sustainability, namely environmental, social, economic and institutional, has been developed in LA and Colombia. Nor that it can evaluate smaller urban scales than the whole city, such as the district or neighbourhood or even degraded informal settlements in the periphery of the city.
This paper aims to cover this research gap by presenting a methodology for proposing a set of indicators, their metrics and the method for scoring them in sustainability levels, which allows to assessing and comparing different urban areas, even in the same municipality. The proposed methodology is a contribution for the evaluation of urban sustainability in the context of a country, whose approach can be adapted to evaluate the urban sustainability of any country or territory. For the validation of the methodology, it is applied to Colombia, as a case study, and particularly to the medium-sized city of Mosquera (Cundinamarca, Colombia).

Methodology
To define the set of indicators capable of evaluating the sustainability of urban areas, a general methodology is proposed, which can be adapted to the context-specific characteristics of the region where the sustainability assessment is to be conducted. The methodology ( Fig. 1) is divided into five stages, as described below. Additionally, in order to establish an ordered protocol to apply the stages, a method to approach the analysis of evidence • Stage I. Selection of programmes about urban sustainability The methodology starts with the search and selection of programmes of urban indicators in the context of the region under study and the identification of the indicators included. • Stage II. Revision and cluster of indicators After identifying the indicators, these are classified and grouped according to a common and hierarchical structure, as done in similar work by Arrieta et al. (2016) and Córdoba et al. (2020). The hierarchical structure is composed of thematic categories (level 1) and subcategories (level 2), as proposed by Braulio-Gonzalo et al. (2015) previously, which finally include the indicators (level 3). • Stage III. Definition of indicators and metrics The indicators (level 3) are analysed in detail, and thus, the terminology can be homogenized for proposing a final set of indicators adapted to the context-specific characteristics of the region under study. Afterwards, the indicators are classified in quantitative or qualitative, what would determine the kind of metric to be used. Then, the metric is defined for each indicator. It should be noted that the set of indicators proposed can be applied to large scale urban areas (such as an entire country), or instead to smaller scale urban areas (such as municipalities or even, districts or neighbourhoods). • Stage IV. Definition of the scoring method of indicators In order to classify each of the indicators on a rated scale, so that they are easily comparable, a method for scoring for both quantitative and qualitative indicators was defined.
For those quantitative that can be calculated for different districts/neighbourhoods in the same municipality, a grading of the results of each indicator was established according to the method proposed by Sturges (1926). The optimal class interval (C) can be estimated from the formula: where R is the range and N is the number of items involved in the computation. This formula gives the class interval for the computation of the averages, measures of dispersion and skewness of frequency distributions. It is based on the principle that the proper distribution into classes is given for all numbers which are powers of 2, by a series of binominal coefficients. A numerical value, a sustainability score and a colour, 1 (low, red), 2 (medium, yellow) or 3 (high, green) were assigned to the scale that was finally obtained in order to represent the indicators' results both graphically and in a table with numerical values.
When the indicator is only calculated once (in general for the municipality under study), this value cannot be graded and should be compared to reference values that can be obtained from a country scale, or a smaller scale, if appropriate.
For those qualitative indicators, the procedure for measuring is based on checking if some specific criteria or standard are accomplished or not, then, the score results in level 1 (not accomplished: low, red) or level 3 (accomplished: high, green).

Description of the case study: city of Mosquera
The municipality of Mosquera is located in Colombia in the western side of the department of Cundinamarca, 23 km from Bogota D.C, as presented in the map in Fig. 2. The city has a territorial extension of 107 km 2 , of which 12.8 km 2 correspond to the urban area and 94.2 km 2 to the rural area, and it is located in a cold climate, with the conditions reported in Table 1. It has a population of 150,665 inhabitants, of which 98.8% live in urban areas and 1.2% in rural areas (Alcaldía de Mosquera, 2020). According to the cadastral census,  The Colombian System for the Selection of Beneficiaries for Social Programmes (SIS-BEN) classifies households into six strata, according to their socio-economic conditions: 1-low-low, 2-low, 3-medium-low, 4-medium, 5-medium-high, and 6-high. In Mosquera, stratum 1 is made up of the neighbourhoods located near the peripheral limits, close to the wastewater discharge points. It is characterized by the presence of traditional self-built dwellings in informal settlements with difficult access. Strata 2 and 3 are made up of VIS located near the centre of the municipality and with leisure areas and paved roads. Strata 4 and 5 consist of dwellings, mostly single-family houses, built with private funds. Stratum 6 comprises semi-detached houses where the population with the highest purchasing power resides.

Stage I. Selection of programmes about urban sustainability in the context of Colombia
The legal framework in Colombia related to building and urban sustainability adopted the international protocols of Kyoto (Corte Constitucional de Colombia, 2000) and Paris COP21 (Congreso de la República de Colombia, 2017) in order to mitigate climate change and to reduce greenhouse gas (GHG) emissions in the country. Taking into account the agreements reached in these protocols, Colombia defined a series of urban planning strategies to fight against climate change (DNP, 2011). To do so, Law 1753 (Congreso de la República de Colombia, 2015) incorporated cross-cutting and regional strategies related to infrastructure, social mobility, transformation of rural areas, security and justice, good governance and ecological growth. This legal framework was accompanied by CONPES 3819 (DNP, 2014), which is focused on the consolidation of cities by creating metropolitan areas with homogeneous aspects by grouping different municipalities and by CONPES 3870 (DNP, 2016), which concentrates on achieving an orderly and sustainable growth by integrating rural and populated areas in agreement with SDG11 (Sustainable cities and communities). In addition, Decree 1077 (Presidencia de la República, 2015) and CONPES 3919 (DNP, 2018) promoted the incorporation of a set of sustainable criteria during the life cycle of buildings and their urban environment. However, what are intended to be criteria are in fact just general guidelines that are difficult to apply and quantify (Córdoba et al., 2020). Also derived from Decree 1077, Resolution 0549 (Ministerio de Vivienda Ciudad y Territorio, 2015) and Colombian Technical Standard 6112 (NTC6112, 2016) defined several sustainable development initiatives for buildings. They were mainly focused on strategies for water and energy savings in specific new buildings (shopping centres, offices, hotels, educational centres, hospitals and non-social interest housing (VIS)). However, these initiatives are only voluntary for VIS and priority interest housing (VIP). These mechanisms therefore do not adopt a global urban approach, but apply only to the specific area of buildings, leaving aside the urban perspective.
From the literature review of the regulatory framework and the programmes applicable to the context of Colombia, the following were selected and analysed in depth: • CONPES 3919 (Política Nacional De Edificaciones Sostenibles, 2018). It includes 38 indicators grouped into 3 criteria (social, environment for the territory and environment for the building) and, in turn, into 9 subcategories (citizen participation, equity and accessibility, location, mobility, adaptation to climate change, efficiency in water, energy efficiency, material and resource management, and indoor environment quality). The indicators are qualitative and are coded in the study as CP01 … CP38 (Table S1). It provides general guidelines but does not use a rating system to calculate the level of sustainability. • BOGOTA (Alcaldía Mayor de Bogotá, 2014). It includes 35 qualitative and quantitative indicators grouped into 6 categories: social, public services, hydrological cycle, pollution, urban context, and buildings, which are coded in this study as BG01 … BG35 (Table S2). The document does not constitute a rating system, but rather a guide to sustainability guidelines to be applied in urban and building environments. • VALLE DE ABURRA (AMVA-UPB, 2015). It is structured into 5 guides, 3 of them applicable to the urban environment (characterization of the place, urban planning and open spaces). These comprise a total of 64 indicators, which address 9 topics: climate and atmosphere, water resources, geology and soil, biotic component, energy resource, materiality, built environment, habitability and viability. The indicators, both qualitative and quantitative, are presented as technical criteria that contribute to the sustainability of the region. However, it does not constitute a rating system either. These are coded in this study according to VA01 … VA62 (Table S3). • CALI (DAGMA, 2019). It includes 31 indicators (qualitative) belonging to 5 topics: knowledge of the territory, water and energy, construction and demolition waste, climate adaptation, and protection of biota. It provides illustrative and non-quantifiable guidelines for each indicator. They are coded in this study as CA01 … CA31 (Table S4). • LEED (US GBC, 2009) was also selected, since it is the international urban sustainability assessment tool promoted by the CCCS. It includes 56 indicators grouped into 5 topics: smart location and linkage, neighbourhood pattern and design, green infrastructure and buildings, innovation and design process and regional priority. The indicators in the study are coded as LEED01 … LEED56 (Table S5). It is a rating system that allows the sustainability of the urban environment to be classified on four levels: certified, silver, gold and platinum.
It should be noticed that the cities of Bogotá, Valle de Aburrá (Medellin) and Santiago de Cali recently joined the international partnership Building Efficiency Accelerator (BEA), which is focused on actions to mitigate climate change and to provide support for cities that are transforming the energy use of their buildings. The programmes developed and described are evidence of the increasing efforts being made in these regions to improve urban sustainability.

Stage II. Revision and cluster of indicators
Prior to comparing the programmes selected in Stage I, it is necessary to define a common structure as each of them uses different classification topics and a distinct nomenclature. To address this, the structure proposed by Braulio-Gonzalo et al. (2015) was applied, based on a hierarchical structure composed of three levels. Level 1 was made up of 14 categories (site and soil (SS), urban morphology (UM), mobility and transport (MT), nature and biodiversity (NB), building and housing (BH), energy (E), water (Wr), materials (M), waste (Ws), pollution (P), social aspects (SA), economic aspects (EA), management and institution (MI), innovation (I)) and Level 2 of 69 subcategories, as reported in Table 2. The indicators found in the selected programmes were reviewed, and those related to the urban context were extracted. Table 2 shows the indicators belonging to each programme with a direct relationship with each category and subcategory. The full description of each indicator (CPXX, LEEDXX, BGXX, VAXX and CAXX) is detailed in the Supplementary Information. As observed in Table 2, some of the subcategories are not covered by any of the indicators included in the programmes analysed. These are: transport management in the MOB category; diversity of housing and maintenance of buildings in BUD; civil association and energy poverty in SOC; tourism and new business and investment in ECO; administrative transparency, knowledge and information management, information and communications technology (ICT), investment in activities for society, environmental education, and regulations to improve sustainability in MI.
These results were represented graphically in order to identify which aspects are the most and least discussed, and to be able to compare them. Figure 3 presents, as percentages, the number of indicators that each programme contributes to the 14 categories.

Stage III. Definition of indicators and metrics
After analysing the programmes currently available in Colombia and classifying their 222 indicators into 14 categories and 69 subcategories, Stage III proposes a set of 105 indicators capable of assessing the sustainability of the current urban context in Colombia.
The selection of indicators was done throughout the following criteria. The distribution of the 222 total indicators found in the policies in Table 2 showed that for some indicators there is more than one way to measure them, for which the indicator that fitted better to the problems of any municipality in Colombia was selected, leaving a total of 115 indicators. Therefore, for each subcategory at least one indicator has been suggested, which is intended to be intelligible and easy to apply. It was also considered that the indicators presented in the study would cover all aspects of sustainability on an urban scale, either in the entire municipality or at the district level. Besides, for the formulation of the set of indicators, the building and housing (BUI) category has been excluded, as it is related to the building scale, which falls outside the scope of this study. Excluding these 10 indicators that make up this category, the proposed system of indicators was finally made up of 105 indicators.
The proposed indicators are based on some of the those belonging to the programmes reviewed, while others are indicators belonging to other international verified programmes (Agencia de Ecología Urbana de Barcelona, 2007; Ministerio de Medio Ambiente y Medio Rural y Marino, 2010) or our own proposal developed ad hoc in this study. The indicators are reported in Tables 3, 4, 5, 6, 7 and 8 and are grouped into 7 topics: site & biodiversity, infrastructure, urban metabolism (inputs), urban metabolism (outputs), social, economic, and institutional and innovation. These tables are structured in six columns, described as follows: the code of the indicators is indicated in the first column; secondly, the type indicates if whether the indicator is qualitative (QL) or quantitative (QT); in the third column, the description provides the title of the indicator and a comprehensive explanation; fourthly, unit defines the units for measuring each indicator; in the fifth column, the metric provides the formula for evaluating each indicator, when quantitative, and the criteria, when qualitative; finally, the reference provide the bibliographic detail from which  the indicator was retrieved or, otherwise, indicates "proposed" when the indicator was proposed in the framework of this study. The indicators are qualitative or quantitative and can be applied both at the global level of the municipality and at the neighbourhood or district level, depending on the information available to quantify them. In the case of quantitative indicators, their metric is provided through a mathematical expression used to calculate them. Qualitative indicators are advisory in nature and offer sustainability guidelines to carry out good practices.

Stage IV. Definition of the scoring method of indicators
The information needed to apply the metrics proposed for each of the indicators was collected from the sources of data available in Mosquera. Depending on the data source, some indicators can be calculated by strata and others for Mosquera as a whole. Despite the efforts made to collect all the data, some of it is missing for the calculation of indicators ENG4, MAT1, POL1 and POL7, so that these metrics cannot be obtained. Results are reported in Table 9, according to the colour scale described in Stage IV, which represents the sustainability score in three levels: 1 (low, red), 2 (medium, yellow) and 3 (high, green). The reference values to rate each indicator, which resulted from the Sturges (1926) formula or Colombian standards, are presented in "Appendix 1" in Tables 10, 11 and 12.

Stage V. Graphical representation of indicators
Results are reported graphically in Figs. 4 and 5, using spider graphs. Figure 4 shows the results for the overall municipality of Mosquera, in such a way that it provides a general vision and diagnosis, while Fig. 5 shows the comparison by socio-economic strata (for those indicators calculated by strata). Finally, Fig. 6 presents the results on a map of

Discussion
The results showed that none of the socio-economic strata reached the highest level of sustainability (3, green), as depicted in Fig. 6. Strata 2 and 3 achieved the medium level (2, yellow), while strata 1, 4, 5 and 6 presented the lowest levels (1, red). As shown in the spider graphs in Fig. 5, strata 2 and 3 successfully covered a large number of the indicators, especially those related to URB and MOB. The fact that they are located near the city centre leads to better sustainability performance, due to higher building compactness, and the presence of mixed-use buildings (both housing and equipment) brings people closer to services and helps to reduce distances and the use of private vehicles. Stratum 1, located in informal peripheral settlements and characterized by self-constructed dwellings, houses the families with the lowest incomes and embraces the lowest sustainability level regarding infrastructure, due to the low quality of water and energy services, the proximity to wastewater discharge points, the lack of green areas and the difficulties in having direct access to everyday services. Strata 4, 5 and 6, despite accommodating people with higher levels of income and being made up of residential buildings with good quality construction features, are usually also located in peripheral districts outside the city centre. This implies lower compactness and dispersed residential areas with poor direct access both to services (high distances) and also to public transport. This, together with their inhabitants' high levels of income, gives rise to the intensive use of private vehicles, thereby compromising the sustainability of transport. In general, mobility is one of the most critical aspects in the city, also because of the low frequencies and long times spent travelling.       Social and economic issues are, however, more developed in strata 1, 2 and 3, where the cost of services and housing are more affordable and citizen association and participation is more active thanks to the Community Action Boards (Juntas de Acción Comunal, JAC), which support neighbourhood development and interaction with the local government. At the institutional level of the city as a whole, it was identified that many sustainability initiatives are being launched, such as the promotion of local employment, the improvement of educational programmes for inhabitants to reduce illiteracy rates and also carrying out environmental awareness campaigns. Overall, it can be concluded that there is room for improvement in Mosquera, since its level of sustainability ranges from levels 1-2 on a scale of 3. Greater efforts should therefore be made to improve the weaknesses found herein. To do so, the involvement and support of the local government is essential to ensure collaboration between stakeholders and to make a serious commitment towards urban sustainability. However, as concluded from the evaluation of programmes that have previously been implemented and tested, for instance BEA, some limitations during the real implementation of the indicators proposed may be expected, such as the lack of third-party inspection and validation, insufficient support through monetary resources, and the non-mandatory and regular character of the measurement of the indicators (Evans et al., 2018). In order to ensure a successful implementation of indicators, these aspects should be revised, focused and strengthened.
The results of the application of the indicators to the case study of Mosquera are aligned with the results obtained in the studies analysed in the literature review. Mesa García (2021), in the context of Colombia, obtained similar conclusions. She rated the indicators in a scale of three levels (not accomplished, little accomplished, accomplished), and most of indicators were scored as not accomplished or little accomplished. Martínez Vitor (2019) in Peru, who also represented the indicators through spider graphs, obtained low values in a qualitative scale comprised between the levels of collapse, critical and unstable, not being any of them in stable or optimum levels. Moreno García and Inostroza Seguel (2019) evaluated four different neighbourhoods in Chile and the results denoted that although some aspects such as public transport, proximity to green areas and to recycling points presented high performances, most of the other aspects evaluated showed low or medium performances. In Brazil, Pinedo and Pimentel (2021) developed a numerical global index for evaluating the environmental, social and economic aspects; however, all these indices adopted values lower than 0.50 in a scale from 0 to 1.

Conclusions
This paper proposed a methodology for the evaluation of urban sustainability in the context of a country, considering environmental, social, economic and institutional aspects. It was applied to the context of Colombia, and a set of 105 indicators were developed, implemented and tested in Mosquera, a medium-sized city in Cundinamarca which forms part of the metropolitan area of Bogota together with other municipalities. The scale of implementation was the stratum, which allowed to compare different urban areas even in the same municipality. For those quantitative indicators, a metric for calculating them is proposed, along with a three-level scale for both quantitative and qualitative indicators. This would allow all the proposed indicators to be measured objectively and then different urban areas can be compared.
Many of the indicators included in the study could only be measured at the whole city level, limiting the quality of the results. To improve the quality of measurement and to be able go deeper into the comparison of smaller urban areas, there is a need for more publicly available data and information that is disaggregated at a lower level, i.e. the stratum or even neighbourhood level. For instance, the cadastral office can systematically collect socio-economic georeferenced information in order to be mapped easily by means of a geographical information system (GIS).
The methodology proposed in this paper can be applied in any city in Colombia or any other territory and allows the set of indicators to be adapted to the environmental and socio-economic specificities of the region, by modifying some of the indicators included (i.e. adapted to the climatic zone) or including new ones, but maintaining the original hierarchical structure of the topics, categories and subcategories as a reference. The scheme proposed is thus intended to be dynamic and adaptable to the context of the region where the indicators are applied. Additionally, the implementation of the indicators would enable the progress of the city to be analysed and would serve local governments as a tool for measuring and demonstrating to citizens the implementation of urban improvements towards enhanced sustainability, with administrative transparency.

Appendix 1
Tables 10, 11 and 12 Table 10 Results of the scoring method for quantitative indicators implemented by strata in Mosquera, according to Sturges (1926) formula Author contributions AJ-O contributed to investigation and writing. MB-G contributed to project administration, conceptualization, methodology, resources, supervision, writing-review and editing. MDB contributed to methodology, writing-review and editing.
Funding Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Not applicable.

Data availability (data transparency) Data retrieved from official documents and databases.
Code availability (software application or custom code) Not applicable.

Conflict of interest
The author's declared that they have no conflict of interest.
Ethical approval Not applicable.

Consent to participate Not applicable.
Consent for publication Not applicable.

Humans and animal rights Not applicable.
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