Identification of Boundaries of Measurements for City Environmental Quality

Abstract

Cities have become the largest consumers of resources and contributors to pollution due to urbanization. Therefore, measuring quality and maintaining standards have become crucial, as the boundaries of measurements for a city’s environmental quality are vague. This research study followed a qualitative approach to verify the factors affecting city environmental quality and to identify the boundaries of measurements using Sri Lankan cities as a case study. Data analysis was conducted using a thematic analysis approach, which adhered to the qualitative nature of the research. Findings revealed that seven main factors—energy consumption, water consumption, material and resource consumption, land utilization, disaster resilience, education, and governance—play a significant role in maintaining a city’s environmental quality. It was revealed that measuring boundaries can vary according to individual units (such as household, industrial, or commercial buildings) or city boundaries, in order to maintain quality standards. The findings revealed significant considerations for environmental quality performance, highlighting the influence of urban planning, governance, and public awareness on environmental sustainability outcomes in cities. Notably, this study contributes to a deeper understanding of how environmental quality intersects with social well-being in urban planning, affecting the quality of life and equitable access to urban resources.

1. Introduction

Urbanization is increasing globally, and it is believed that the population living in cities will reach 60% by 2030 [1]. Today, cities largely consume resources and produce more greenhouse gases, making planning and policy initiatives essential [2]. With development, the international community recognized that human activity in urban areas has resulted in a socio-ecological disaster in numerous ways, including a reduction in green spaces, degradation of environmental quality, excessive consumption of natural resources, harm to historical and cultural values, and pollution of air, water, and soil [3,4]. However, the use of sustainability indicators has gained recognition in urban development and planning. These indicators can assess the quality of environmental, social, and economic aspects in the urban development processes and guide decision-makers in evaluating the performance of sustainable urban development [5,6,7]. Therefore, sustainable indicators have become a more effective approach to understanding the impacts of urbanization.

There are ongoing efforts to develop city-level indicators globally, aiming to assess and compare the sustainability of various cities across different countries in terms of their environmental, social, and economic aspects [8,9]. However, it can be argued that a city cannot be precisely defined, and identifying ideal city boundaries for measuring sustainability in world cities is difficult [10]. On the other hand, environmental impacts are more prominent in urban sustainability strategies than social or socioeconomic issues [11]. Therefore, the development of indicators that assess environmental sustainability on both the global and national levels has become significant due to the acceleration of environmental degradation [9]. Furthermore, environmental sustainability boundaries can aid in recognizing sustainable growth trends by evaluating the environmental performance of current actions within these boundaries. However, current interpretations of environmental sustainability boundaries have drawbacks, including regional differences and transparency issues in addressing uncertainties [12]. Accordingly, the absence of a proper assessment criterion that considers these boundaries is a significant problem in understanding a city’s environmental quality.

Therefore, assessing the sustainability of cities in relation to a country’s suitability and identifying their boundaries is essential. However, measuring environmental sustainability and identifying a boundary to measure any of its dimensions have been difficult, as the boundaries of measurements are not yet adequately defined, and the environment cannot be limited to geographical boundaries. For example, Sri Lankan cities exhibit rapid urban growth, accompanied by distinct informal settlement dynamics, which are crucial to understand, as they result in urban sprawl, inadequate infrastructure, environmental degradation, and social issues. Furthermore, Sri Lanka faces specific environmental pressures (such as extreme weather events, water scarcity and pollution, and deforestation and habitat fragmentation) that directly impact urban infrastructure and planning. Furthermore, the country’s urban planning policies and initiatives (such as the National Physical Planning Policy and Plan (NPPP), the Urban Development Authority’s (UDA’s) role, and initiatives for urban regeneration and sustainable development) offer a distinctive regulatory environment that influences urban development outcomes. Thus, this research aims to identify the boundaries of environmental indicators by considering Sri Lankan cities as a case study. Cities are commonly defined as permanent and densely settled areas with administratively defined boundaries [13]. Figure 1 presents a schematic map of Sri Lanka, illustrating this study’s spatial context and scope, which represents major cities in Sri Lanka with their district administrative boundaries. Here, the district boundary is considered as the overall city boundary for research purposes, as there are many sub-cities, towns, and villages in each district.

2. Factors Affecting a City’s Environmental Quality

The environment and environmental system quality together assess how the local environment is preserved and explore the best ways to manage and control waste, protect cultural and natural values, maintain clean streets and public spaces, protect resources, and use minimal energy [16]. However, cities’ environmental footprints are problematic, as they may threaten the natural resources necessary to sustain economic growth [17]. As urban population expansion has reached enormous proportions, a direct relationship exists between environmental sustainability and urbanization [3]. It is argued that environmental quality has important implications for the physical, social, and psychological health of urban residents [18]. Therefore, city planners and policy developers are required to consider sustainability goals, including developing human capital, managing energy and water, utilizing earth-abundant resources, adhering to building regulations, optimizing transportation systems, and promoting social and economic equity [19]. However, it is important to identify the factors that affect a city’s environmental quality.

When considering cities, they occupy approximately 3% of the Earth’s surface and consume around 60–80% of the world’s energy while producing up to 70% of the human-induced greenhouse gas emissions [1]. Therefore, the primary long-term strategy for combating climate change is to reduce energy use, with more than 65% of environmental initiatives focusing on improving building and system energy efficiency, while increasing the use of renewable energy sources [20]. In addition, the urban heat island effect is created by a large area of heat-absorbing surfaces and by the high energy consumption of cities [21]. It is evident that buildings are the primary energy consumers in cities, besides industries and transportation systems [7]. However, transportation can also be identified as a critical component of sustainability, as it significantly contributes to pollution and greenhouse gas emissions [22]. According to estimates, fossil fuels cause significantly more harm to the environment than renewable energy sources, making it crucial to promote concepts such as self-sufficiency, efficiency, the use of renewable energy sources, and emissions minimization [23]. Therefore, at the city level, the greenhouse gas emission indicator is the most widely recognized, primarily comprising electricity used for construction and services, energy used for road transportation, and fossil fuels used for district heating [24]. Therefore, energy consumption in cities can be identified as a main factor that affects a city’s environmental quality.

A city must certainly have access to substantial amounts of clean water to survive, but the proportion of intake and output into surface waters is also significant [25]. Water scarcity now exists in several parts of the world, and it is expected to worsen in the future due to population growth, climate change, and unsustainable living standards [26]. Therefore, an existing system’s supply–demand balance is significantly influenced by the water supply for domestic, commercial, industrial, and other development activities [27]. Although there is an expansion in wastewater volume due to the increased city water supply, a corresponding investment in wastewater collection and treatment is not available, resulting in extensive water pollution [28]. Therefore, alternative water sources, such as rainwater and recycled water, should be encouraged and subsidized to reduce demand and pressure on natural water resources [19]. Additionally, the combination of chemical, biological, and physical methods, or a combination of these methods, can be used to treat contaminated water and achieve any desired level of quality [7]. However, energy consumption and greenhouse gas (GHG) emission percentages increase to meet the effluent quality standards of wastewater treatment [29]. Accordingly, water consumption can be identified as the second factor that affects a city’s environmental quality, as discussed above.

Recently, the circular economy and resource management have been identified as potential solutions to global resource scarcity, and cities have begun applying these principles in practice [24]. Furthermore, adopting and supporting efficient and responsible resource consumption can result in atmospheric protection, deforestation prevention, environmental protection, biodiversity conservation, and pollution control [11,20]. For example, sustainable mining practices have a significant impact on the environment and the social well-being of people, particularly in environmentally vulnerable areas at the regional level [9]. It is evident that the wide levels of resource consumption and the production of substantial amounts of solid and hazardous waste in cities are critical for environmental sustainability, particularly in terms of waste collection, material recycling activities, and demand reduction [30]. Therefore, because the operational boundaries of waste management organizations extend beyond city limits, it is impossible to allocate diverse waste flows reliably [24]. Accordingly, it is evident that material and resource consumption, which also affects waste generation, is another main factor that affects a city’s environmental quality.

Environmental objectives and strategies can be incorporated into development plans, alongside supporting smart mobility structures, creating pedestrian-oriented urban designs, and conserving and establishing public green spaces [7]. Additionally, utilizing open spaces, green belts, and other environmentally sensitive areas for urban farming is crucial for maintaining the sustainability of cities, given the pressure on land demand in urban areas [31]. Therefore, open and green areas, such as forests, gardens, and parks, contribute to the environmental dimension by improving air quality, enhancing urban climate, protecting water quality, absorbing or blocking sound waves, and providing habitats for wildlife [32,33]. When considering land use, maintaining, re-cultivating, or restoring the green and water aspects of urban environments is referred to as site conservation, and reusing lands promotes green urbanism [7]. Residential, economic, cultural, and institutional purposes must be closely integrated to reduce the distances between homes, offices, shops, and other facilities, and to develop suitable neighborhoods that support cycling and walking, with reduced vehicular transportation and lower pollution from traffic [3]. It is argued that the solutions to build sustainable environments should not be limited to developing parks, green areas, and open spaces. Therefore, policymakers can also engage in developing a community that respects and adheres to environmental standards, incorporating educational, cultural, and behavioral considerations [34]. Overall, land utilization in cities can be considered the fourth factor that affects a city’s environmental quality. According to the above discussions, the literature reveals that energy consumption, water consumption, material and resource consumption, and land utilization can be identified as the main factors affecting a city’s environmental quality.

In addition, this study examines the indicators related to the aforementioned factors. Cities require indicators to monitor their effectiveness; however, current indicators are often not standardized, reliable, or comparable over time or across different cities [35]. It should be noted that there is still a problem with standardizing indicators among cities, which raises the issue of what exactly constitutes a city [5]. Any useful framework or tool that begins with the identification of proper indicators should be selected to reflect both the current situation and the extent to which sustainability goals are achieved [7]. Therefore, approaches may be based on specific areas of the city due to cultural and social characteristics, as well as significant differences in terms of development level and industry, including particular indicators for specific issues [7]. Since sustainability is a universal concept, it is possible to say that the same findings can be applied globally to urban renewable projects. However, due to the unique features and requirements of each country, it is helpful to determine how to apply them properly in a global context [3]. Integrating public perceptions of sustainability into indicator systems and maintaining the relevance of indicators to a diverse group of stakeholders is another challenge [36]. Therefore, urban sustainable development can be significantly enhanced through the utilization of more human-centered measurements and indicators [37]. Accordingly, the results of this study aim to identify indicators and their measurement boundaries that can be applied to Sri Lankan cities while also highlighting the prevailing issues in cities through proper evaluation.

3. Methods

This study adopted an interpretivist research philosophy to highlight the significance of context in understanding the social phenomenon of urbanization and its impact on environmental quality. Due to the complex relationships between variables, a qualitative research method was employed to understand and explore the research problem using a semi-structured interview guide. City environmental quality was considered the dependent variable, and broadly identified factors from the literature, including energy consumption, water consumption, material and resource consumption, and land utilization, were used as independent variables to initiate discussion for in-depth interviews. However, due to the vague relationship between the dependent variable (city environmental quality) and the independent variables, a strong conceptual model could not be built. As a solution, a study model was developed. Furthermore, although there were studies to support this internationally, the condition in the Sri Lankan context was unclear. Therefore, after identifying the available factors (independent variables) through the literature survey, the study model was developed with propositions. Then, operationalization was performed to define and measure variables. Accordingly, dimensions for each factor (variable) were identified separately. Figure 2 depicts the study model developed and used in this research. This study model is named the “City Environmental Quality Model (CEQM)”. It is a multidimensional framework designed to evaluate and monitor the environmental quality of urban areas. It integrates physical, ecological, and human-centered indicators to provide a comprehensive assessment of urban environmental quality and its implications for public well-being.

The interview guideline was developed based on this study model, considering four main factors, while also allowing for the addition of any other factors deemed suitable for the Sri Lankan context. Data were collected through in-depth interviews, selecting a purposive sample based on the expert knowledge of respondents from different disciplines in city and urban planning in Sri Lanka. Non-probability sampling is a commonly used sample technique, as qualitative research does not attempt to draw statistical conclusions [38]. Purposive sampling is a strategy frequently used in qualitative research, where individuals are selected based on their subject knowledge relevant to the examination [38].

The number of people who need to be selected and the theoretical saturation point cannot be predicted at the start of a study, whereas qualitative research follows the fundamental guideline of collecting data until new insights are discovered or new information is gained [38]. Saturation is undoubtedly the principle most commonly used to determine sample size and assess its sufficiency [39]. Sample sizes of 20 to 40 interviews are preferred to achieve data saturation of meta-themes in research designs [40]. Therefore, a sample of thirty respondents (R1 to R30) was interviewed in this study to reach data saturation. In this study, a diversified sample was selected based on different disciplines in city/urban planning. The qualitative nature of the research was utilized optimally to identify experts who could contribute to understanding the environmental quality of a city. Therefore, the respondents were selected from fields such as Town and Country Planning, Civil Engineering, Environmental Management, Sustainability, Chemical and Process Engineering, Facilities Management, and Urban Planning and Development.

Table 1. Details of the sample.

Discipline	Respondent	Years of Experience
Town and Country Planning	R1	11
	R9	20
	R17	12
	R27	6
Civil Engineering	R2	27
	R4	5
	R11	18
	R13	6
	R18	10
	R23	6
	R28	7
Environmental Management	R3	30
	R7	6
	R14	8
	R26	10
	R30	14
Sustainability and Urban Planning	R5	6
	R6	11.5
	R16	15
	R22	8
	R24	8
	R29	12
Chemical and Process Engineering	R8	17
	R21	15
Urban Development	R10	28
	R12	16
	R20	9
Facilities Management	R15	7
	R19	6
	R25	7

presents an overview of the interview sample.

The interview data of the most senior civil engineer (R2), environmentalist (R3), town and country planner (R9), and urban development officer (R10) were used to validate the data gathered from the other professionals internally. The findings from new interviews were compared to those from earlier interviews, and if no new themes were revealed, it was considered that the “saturated terrain” had already been established [41].

The collected data were analyzed using the thematic analysis method, which involved transcribing, coding, and categorizing the data to identify the factors affecting a city’s environmental quality. To analyze the qualitative data, we employed a thematic analysis approach, which involved systematically identifying, organizing, and interpreting patterns of meaning across the dataset. The process began with familiarization through repeated reading of the data, followed by initial coding to capture recurring concepts. These codes were then grouped into broader themes that reflected key dimensions of factors affecting city environmental quality, which are presented in Appendix A 

Table A1. Summary of the main factors.

Factor	Dimensions	Measuring Indicators	Measurement Boundary
Energy consumption	Energy source used	The ratio of renewable sources and non-renewable sources used	Individual Units
	Energy production	Percentage of imported energy Amount of greenhouse gas emissions Particulate matter concentration Amount of energy production	City City City City and Individual Units
	Energy consumption patterns	Amount of energy consumption Energy usage period Number of occupants Number of energy-consuming devices used Percentage of taxes imposed	Individual Units
	Energy efficiency	Number of energy/green certified buildings with energy-efficient designs Number of smart/automated buildings Number of energy-rated equipment used Amount of carbon offsets	City City Individual Units Individual Units
	Transportation	Percentage of green vehicles/electric vehicles used Number of vehicles coming in Fuel consumption Level of carbon emissions Total amount of fuel sales The percentage of people who commute by private vehicles The percentage of people who commute by public transportation	City
Water consumption	Water resource use	Level of groundwater usage Level of surface water usage Percentage of the population with access to clean water Percentage of potable water available Percentage of recycled water usage Percentage of rainwater usage	City City City Individual Units Individual Units Individual Units
	Water consumption patterns	Total water consumption capacity Water usage according to the equipment	Individual Units
	Wastewater generation	Total amount of wastewater generation Percentage of impurities in wastewater	Individual Units
	Wastewater disposal	Total amount of wastewater treated The percentage of treated wastewater complied with standards Number of treatment facilities available Recycling rate	Individual Units Individual Units City Individual Units
	Water pollution	Level of pollutants—E. coli test, heavy metals, biochemical oxygen demand (BOD), chemical oxygen demand (COD), pH level Percentage of effluents discharged to waterbodies	City and Individual Units
Materials and resources consumption	Material extraction	Percentage of extraction of virgin materials The frequency of extracting virgin materials Air quality	City
	Material composition	The percentage of sustainable materials used for production The percentage of renewable materials used for production The percentage of fossil fuel-based materials used for production Embodied carbon in materials	City
	Material type used	Quantity of materials used Percentage of materials with satisfactory quality Percentage of virgin materials used Percentage of reusable materials used Percentage of recyclable materials used Percentage of toxic materials used	Individual Units
	Waste generation	Daily waste generation/per capita generation Toxic/hazardous waste generation	Individual Units City
	Waste disposal	Number of treatment facilities available Number of waste collection points Frequency of waste collection Percentage of waste sent to landfills Landfill site capacity Percentage of waste sent for open dumping Percentage of solid waste going to recycling Percentage of solid waste that will be reused Percentage of solid waste sent for biological treatment	City
Land utilization	Natural land coverage	Percentage of virgin land usage Destruction of natural land cover percentage Percentage of green cover Percentage of wetland and marsh preservation Percentage of forest cover Percentage of shaded areas available	City
	Green and open spaces	Percentage of green area Percentage of open spaces Percentages of green open spaces Percentage of available water bodies Distance to green/open spaces	City
	Regeneration capacity	Number of brownfield developments Percentage of green field usage Percentage of land protected Percentage of land regenerated Number of urban regeneration programs available	City
	Building development	Percentage of green/open spaces Percentage of high-rise/vertical developments Building density Gross floor area Floor area ratio Building footprint The size of the land SRI value of roofing materials/facades	City City Individual Units Individual Units Individual Units Individual Units Individual Units Individual Units
	Transportation networks	Vehicle miles traveled Percentage of land available for walkability SRI value of pavements Percentage of land available for cycling Percentage of land available for public transportation	City
	Regulations	Number of planning regulations available/proposed Percentage of planning regulations executed	City

. The themes were refined iteratively to ensure they accurately represented the data and aligned with this study’s objectives. This method allowed us to uncover nuanced insights into stakeholder perceptions and contextual factors influencing environmental quality in Sri Lankan cities.

4. Results

In this research study, “factors” are the independent variables used to determine their effect on the dependent variable, which is the city’s environmental quality. Underlying “dimensions of factors” can be used to simplify complex and diverse relationships that exist among a set of observed variables by uncovering common dimensions or factors that link together and provide insight into the underlying structure of the data [42]. According to data findings, “measuring indicators” were used to quantify the effect of the identified dimensions. “Measuring boundaries” refers to the points at which measuring indicators should be measured. Figure 3 presents the boundary classification used in this study. Mainly, it is considered from the (1) city perspective or the (2) perspective of individual units, such as household, industrial, or commercial buildings.

Our data analysis revealed seven factors, along with their dimensions, measuring indicators, and boundaries, that could contribute to the environmental quality of a city.

4.1. Energy Consumption

Energy consumption is a critical factor affecting a city’s environmental quality. Its dimensions were identified as the energy source used, energy production, energy consumption patterns, energy efficiency, and transportation. Then, the boundaries of measurements were identified.

A renewable or non-renewable source can be used for the energy consumed in a city, and its impact can be changed accordingly. If a smaller share of non-renewable resources is used in cities, it can have a favorable environmental impact. According to the respondents, the installation of renewable energy sources, such as solar or biogas, at the household, commercial, and industrial levels is more environmentally friendly (R11, R12). Additionally, energy can be generated in a city using renewable or non-renewable raw materials, or it can be transmitted to a specific location within the city. However, both methods can have environmental impacts. The respondents further stated that households, commercial buildings, or industries can consider solar or wind energy sources to produce their own energy, and, as a result, they can minimize energy losses through transmission (R8, R12). Furthermore, R2 stated that energy production within a city is a critical aspect that needs to be considered to reduce energy losses and emissions during transmission. When considering emissions, measuring air quality levels in terms of CO₂ (carbon dioxide), NO₂ (nitrogen dioxide), SO₂ (sulfur dioxide), and particulate matter in parts per million (ppm) is crucial. R10 added, “It is better to measure the ambient air quality in a city directly”. R13 stated, “Measuring systems can be implemented in a central point or somewhere in the city, and air quality can be easily measured”. Therefore, measuring air quality in cities is beneficial for protecting public health, informing urban planning and policymaking (such as transportation planning, zoning laws, and promoting green spaces), and promoting public awareness and engagement.

When considering energy consumption in a particular household, office, or factory, consumption patterns can vary. Therefore, measuring the whole city will not provide an accurate comparison or identification of the highest energy consumption. R2 internally validated the importance of consumption patterns as a dimension for energy consumption, noting that “According to the people who are living in a particular house or building, it is important to track how much energy is consumed for different purposes, and what equipment is used”. Hence, individual measurements according to different building categories, such as households, commercial buildings, and industries, are more beneficial. Furthermore, R4 stated, “Energy consumption is quite easy to measure if there is a smaller unit of control. So, giving the control to these smaller units might be a better boundary rather than giving the city control”. This was internally validated by R2 as, “If the amount of environmental damage done by individual household energy consumption can be presented, a tax should be imposed for this damage. Then definitely that person might control himself”. Therefore, emphasizing the importance of considering households as a boundary is necessary to demonstrate that individuals are accountable for their consumption, rather than relying on the city’s overall consumption. R7 added that individual energy consumption can be measured by implementing meters in a house, an office, or any other building, and even by categorizing them by equipment use. Therefore, consumption-measuring meters can be implemented in these places to obtain an idea of individual energy consumption, and then comparisons can be performed as required. This can promote public awareness, making individuals more accountable for their energy use, and inform data-driven decision-making (such as insights for upgrading to energy-efficient appliances, adopting responsible consumption habits, and evaluating the impact of solar panels, smart thermostats, or insulation improvements).

Energy efficiency is another important aspect of a city’s environmental quality, where buildings and equipment should be carefully selected with suitable efficiency levels. If energy usage is inefficient, the urban temperature will increase, leading to the heat island effect. Whether residents have adopted any energy efficiency measures, such as smart/automated or energy/green certified buildings, should be considered at the city level. Carbon offsetting is another way to achieve energy efficiency by reducing overall emissions in the city. R12 added, “Carbon capture or offsetting practices such as urban forestry, carbon negative or any other regenerative practices being adopted by the city’s households and industries should be considered”. Therefore, cities have the opportunity to promote energy efficiency at both the individual and city levels.

Transportation makes a significant contribution to a city’s energy consumption, while vehicular emissions impact a city’s environmental quality. As per the opinion of R8, “Vehicular energy consumption can be measured using fuel consumption within the city and fuel sales in fuel stations in the city”. Furthermore, R18 stated, “If the number of vehicles coming into the city and average energy consumption for different categories of vehicles is known, an indirect estimation can be done”. According to the respondents, the most suitable boundary to measure this dimension is the city limit. This boundary was internally validated by R2, who stated that “When considering energy-consuming vehicles, if the amount of fuel consumed by a particular vehicle and the total energy consumption within the city can be quantified, it is easy to make some control within the city”. The use of green transportation is a solution to mitigate harmful vehicular emissions, and this should be measured within cities. Furthermore, minimizing the use of private vehicles can be another solution. R5 added, “The percentage of people who commute by private vehicles, the percentage of people who commute by public transportation, and other sustainable modes like green vehicles is a good indication at the city level”. Therefore, cities need to separately consider the transportation dimension, which is also crucial. This means policy changes, technological innovations (which promote electric and low-emission vehicles), and behavioral shifts can have a favorable impact.

4.2. Water Consumption

Water consumption in a city leads to water pollution, and, therefore, effluent management requires proper attention. Additionally, overconsumption and water wastage have a negative impact on the ecosystem. Through data analysis, boundaries for measurements were identified in the dimensions of water resource use, water consumption patterns, wastewater generation, wastewater disposal, and water pollution.

Cities have various resources for the continuous supply of water to their residents, but the unsustainable use of water has led to issues with water availability. Cities need to consider the usage of groundwater and surface water consumption by considering the amount of water withdrawn and recharged. In addition, potable water, which is supplied to cities from surface and groundwater sources, should be treated to suitable standard levels for consumption. Furthermore, cities need to explore and adopt alternative measures for obtaining water for drinking and other purposes. “Any kind of rainwater harvesting, or any other treatment measures, should be used to capture water for the better utilization of water at different buildings”. As per the opinion of R8, it is better to consider the entire city in terms of water use, who explained that “This can cover the entire city because data can be obtained very easily from one or two sources, including all the total values”. In addition, R18 stated, “Cities can capture the treated amount of water from natural water sources and then directly get those values to determine the consumption”. Therefore, indicators related to water resources used in cities are critical, as they ultimately affect access to clean water in cities for use.

Comparing water consumption can be beneficial in controlling overconsumption issues in a city. However, it would be more beneficial to narrow it down to a small boundary to obtain an idea about the measurement boundaries. R29 added, “Individual consumption can be measured as household consumption or building consumption, and then go to the city level. Also, when considering time, it can be measured as hourly, daily, monthly, and yearly consumption”. Comparing water consumption can be beneficial in controlling overconsumption issues in a city. Water consumption in different areas can be compared using meters or systems specifically installed for the equipment. R2 added, “Meters or systems can be implemented to measure the water usage of equipment or systems within a considerable measurement boundary like household, commercial or industrial buildings where consumption and any overconsumption can be monitored”. Similar to identifying individual energy consumption patterns, identifying water consumption patterns helps individuals take accountability for their consumption and understand the improvements required in their water usage.

When considering a city, the wastewater output generated by water consumption has a direct impact on its environmental quality. Household wastewater generation is a major contributor to water pollution. R9 internally validated this as, “In households, a certain amount of water will be consumed for washing, cooking, and landscaping and would be discharged as wastewater after consumption”. If water is not used sustainably, it will pollute the water and reduce the environmental quality in a city. According to most of the respondents, it is more reliable to consider a narrow boundary when determining the impact of generated wastewater. If any impurities are released from a house, office, or factory, they will pollute the environment. Similarly, R1 highlighted the importance of zoning as “Industrial wastewater generation is remarkably high because what is consumed by industries is higher than that of household and commercial buildings”. If a larger boundary, like a city boundary, is considered, there will be no clear idea regarding this. Therefore, the only controlling point will be a smaller unit, such as a house, an office, or any other outlet. R2 internally validated the above statement as “The boundary should be as narrow as possible, and each person should be given the responsibility”. Therefore, considering wastewater generation is important, as it can promote behavioral changes, such as reducing water waste and avoiding harmful disposal, while enforcing standards to control unusual discharge limits.

After water is discharged as wastewater, the primary environmental quality issue is the improper disposal procedures followed in a city, which compromise water quality. Most areas outside the municipal council area lack proper sewage networks, resulting in wastewater being disposed of individually in most properties. Therefore, some dispose of wastewater in nearby water bodies, such as rivers and canals, while others have waste soakage pits. However, both are environmentally harmful, and disposal into natural water bodies especially degrades environmental quality. Hence, the availability of treatment facilities in cities can be considered a strategic approach to managing water and developing water-sensitive designs or water-wise cities. According to the respondents, wastewater disposal can be quantified using the recycling rate and the total amount or percentage of wastewater treated or recycled by industries or residences (R5, R11, R16). Additionally, when considering wastewater disposal, it is more reliable to measure it building by building. This was internally validated by R10 as, “Although the wastewater is disposed within the city limits, the disposal patterns are different among the different contributors”. However, it is essential to identify wastewater disposal, as it further supports infrastructure planning with regard to the design and capacity of sewage treatment plants, pipelines, and drainage systems, thereby preventing the overloading of wastewater systems and reducing the risk of spills and contamination.

Improper wastewater disposal pollutes a city’s water sources. Effluent discharged into waterways can be treated or untreated sewage. All these effluents, which lead to inland waterways being highly polluted, affect the degradation of the overall ecosystem due to water pollution. It is essential to analyze the quality of wastewater that is discharged. R12 explained how water pollution can influence the city’s environmental quality, “Water pollution affects public health as well as the urban wildlife directly. Therefore, pollution should be measured considering each individual water resource or stream. Then, it can be interfered with and measured on how the city is polluted”. Therefore, Water quality can be measured to determine whether water is polluted and to identify the negative impacts on urban wildlife and humans. This is very crucial as it ultimately affects the health of the urban area.

4.3. Material and Resource Consumption

Material consumption can impact the environmental quality of a city, affecting both the type of material used and the waste generated during disposal. Therefore, it is critical to adopt proper waste management practices. Through data analysis, six dimensions were identified, namely, material and resource consumption, material extraction, material composition, material type used, waste generation, and waste disposal, to establish the boundaries of measurement.

Most natural materials should be extracted for use. Overextraction of these materials leads to environmental damage, negatively impacting the quality of the environment. All types of material extraction result in environmental issues. Consideration of the amount of virgin material extracted from the natural environment of cities is crucial. According to the respondents, it is comparatively more environmentally friendly to reuse and recycle materials than to use regular extraction processes, as extracting more virgin material for human consumption is harmful to the environment (R3, R12, R17). Furthermore, the respondents highlighted that dust, particulate matter, and emissions from machinery contribute to air quality degradation in cities (R2, R9). Therefore, air quality is crucial, as it can lead to respiratory issues and contribute to climate change through the release of greenhouse gases.

Material selection, in terms of composition and lifecycle impacts, is essential for achieving a higher quality level in urban environments. According to the respondents, when a particular material is consumed throughout the lifecycle of a product, there will be impacts from production to disposal, as embodied carbon has an adverse effect on the environment (R6, R16). Furthermore, R7 stated, “Except for sustainable material usage, any other toxic material usage will directly affect the environmental quality”. This was internally validated by R2 as, “If sustainable materials are used, they are not going to harm or pollute the environment”. Producers need to consider the material composition used at the city level, as explained by R16, “Producers need to evaluate the production in terms of using more natural renewable materials and reducing the use of fossil fuel-based materials like plastic, polythene materials”. This is an important aspect that requires further awareness among producers and the general public.

It is essential to consider the material types used in terms of both quality and quantity to minimize the environmental impact on a city. According to the respondents, material consumption in a city matters in terms of the percentage of virgin material used, as well as the reduction, reuse, and recycling of material components (R1, R6, R7, R11). Furthermore, the respondents stated that the general boundary for the material type used can be the city, and then it can be determined for households and buildings at the city level (R7, R10). When considering material procurement, the lifecycle impact plays a significant role in various establishments within a city. Therefore, considering narrow boundaries within the city is required. This was explained by R26 as, “Industries, households or even the commercial establishments in a city should consider sustainable procurement standards and lifecycle impact of the materials that they consume”. R7 explained this by considering a household as an example, “Even in a house, the boundary can be implemented to get ideas on how much of new materials can be used, how much can be reused, what is the quality of material standards and also after the material usage, how they can be reused or recycled”. This was internally validated by R2 as, “As the boundary, an individual unit like household can be taken. For example, each person can decide what is going to be used as their material, whether toxic materials are brought into their own house and disposed of, or it can be controlled”. Therefore, the general public can engage in deciding the types of materials they consume by considering how environmentally favorable they are.

Material consumption and waste are directly related, with waste being the primary output of material consumption. Thus, waste management practices help to maintain a city’s environmental quality. If material consumption is high, waste generation tends to be high. Therefore, completing more work with less material is ideal. Especially when new construction is underway, material waste management is crucial for maintaining environmental quality. In this regard, the total lifecycle of those materials should be considered. In an entire city, they must cover the daily waste generation (per capita generation). According to the respondents, when determining the boundary of waste generation, it is better to select a boundary based on different areas within the city. R6 stated, “Definitely the solid waste generation from the industries, households, and other establishments which are in that city is important to track”. R8 added, “If an entire city cannot be covered, then basically some statistical method should be used to get a proper sample”. Additionally, the generation of toxic waste poses a considerable risk to a city. R2 stated, “If it is toxic material or any material that can produce toxic waste, it will definitely affect the environment”. According to the respondents, proper steps should be taken to assess the toxic waste generated within a city as a whole (R5, R22, R23). Furthermore, understanding waste generation in a city would ultimately facilitate the development of proper systems for efficient waste disposal, as explained in the next section.

Waste generation and improper waste disposal by citizens and municipalities (such as a lack of proper treatment facilities and open burning) will negatively impact the environment through mosquito breeding, unpleasant smells, and blocked drainage. Most cities use landfills for waste disposal. R15 stated, “Landfills have environmental issues by poor waste management where rivers and other water sources can be polluted (plastic and polythene in particular) while affecting the natural ecosystems adversely”. Further, R6 stated, “Open dumping in landfills can lead to an increase in dengue, cholera, and other diseases while animals are seriously affected by feeding on those solid waste (especially polythene)”. Therefore, it is important to track the waste sent into landfills by percentage. R5 stated, “The solid waste can be quantified by obtaining separate measurements as waste sent for landfills and waste diverted for recycling, reusing, and other purposes”. Waste collection can be performed within the city boundary based on collection points. R1 added, “Waste can be collected within the city boundaries and there can be collection frequency allocated to these collection points”. In addition, R17 stated, “After the municipality does the collection, they should plan the landfilling site capacity required for the disposal within the city boundary as well”. Therefore, cities need to plan waste disposal properly to be more environmentally friendly, with informed urban policies and infrastructure planning to create a livable city.

4.4. Land Utilization

It is essential to plan a city effectively when utilizing land for various purposes. Mostly, adverse impacts caused by the destruction of natural land cover should be considered, and it is best to have alternatives such as greenfield and brownfield development. Through data analysis, six dimensions for land utilization were identified, namely, natural land coverage, regeneration capacity, building development, transportation networks, green and open spaces, and regulations. Then, boundaries for measurements were identified.

Sustainable city planning must consider the use of natural land cover to mitigate environmental issues. However, if the zones are appropriately managed, these issues can be mitigated by preserving the natural lands in cities. The destruction of natural land has a direct impact on a city’s ecosystem. Specifically, virgin land use will affect environmental quality when used for city development, as ecosystem resources are important. Therefore, allocating virgin lands for the urban population should be performed by preserving land for the natural environment. R12 explained that “Many infrastructures, such as roads and utilities, being built for a few homes where the plan could be left for natural habitat, is a critical issue in cities”. As per the opinion of R13, “When the zones are managed properly, there can be a higher population density in those areas which are inhabited, and the other remaining areas can be left for the natural environment”. R8 added, “Shaded areas should be allocated in the cities for the urban movement and to reduce the heat island effect”. Furthermore, important land areas should be identified and highlighted in city plans to preserve and protect the natural landscape. Water-sensitive urban design manages environmental quality by designing cities to collect and drain stormwater through special arrangements, such as bioswales and bioretention ponds, which are beneficial. The geographical boundary can determine the boundary of natural land coverage. When there is forest cover closer to a city, it will improve the environmental quality of the city. R2 added, “If there is any natural land coverage that will affect environmental quality, the geographical boundary can be considered to see what percentage of land is utilized”. Accordingly, it is essential to preserve natural lands within cities for biodiversity conservation, urban cooling and resilience, air purification, protection of water bodies, and soil protection.

Cities should have green and open spaces for both aesthetic appeal and to promote urban environmental quality and health. As per the opinion of R3, “When green spaces and open spaces are not properly developed within the cities, it reduces environmental quality and also people tend to move out of the city because greenery is essential for them psychologically”. In terms of green cover, the share of green areas within a city, such as public parks, is essential for residents to enjoy closer proximity to nature and appreciate the natural environment. According to the respondents, this can be measured as a percentage of green areas, open areas, open green areas, and water bodies available in a city, as well as the accessibility of these areas (R3, R5, R6). R10 internally validated this statement by expressing how the distribution of green coverage should be considered for proper planning, “When considering a city, the percentage of green areas may not be exactly accurate. Because if only one part is covered by that green area, it is probably not the best. That means having green areas carefully planned in between is appropriate. So, the available greenery factor (not the available complete greenery itself) should be considered to decide whether that is properly distributed”. Therefore, access to green spaces improves mental well-being, reduces stress, and promotes physical activity.

In cities, land can be newly developed for its intended purpose, or existing land can be used sustainably. Destruction of greenery is a severe problem that affects the environmental quality of a city. As a solution, brownfield development is a method of sustainable land usage in a city. According to the opinions of the respondents, regeneration can be measured through greenfield or brownfield developments, which can be considered and quantified. Then, an idea about how much the environment will be protected or developed sustainably can be obtained. This statement was internally validated by R10 as, “The percentage of land protected and regenerated can be measured after obtaining an overall idea of land usage in a city and by categorizing them into greenfield or brownfields”. R10 added, “If green fields are used for developments, how much of the environment will be affected and how much of the forests will be reduced can also be tracked”. Furthermore, R22 stated, “Hazardous developments can be resolved through urban regeneration programs in cities to address related environmental issues”. Ultimately, this informs better urban planning and encourages sustainable urban growth.

Proper city planning, along with effective land utilization, ensures a habitable environment with high environmental quality for living. If the land use is incompatible, it can lead to adverse environmental effects. According to the respondents, improper planning, with high-rise buildings built in an ad hoc manner, has made urban living difficult due to the heat island effect and dust accumulation, which are unpleasant. R8 suggested that the city boundary should be selected for the building development because, “If one area is considered, it may not accurately reflect the true situation in the entire city. Therefore, the city boundary is more reliable as it is not difficult to measure how it is developed as a whole”. R2 internally validated the selection of the city boundary, noting that it can be considered a physical or geographical boundary.

Transportation networks occupy a considerable amount of land in cities, and, primarily, they have a significant impact on environmental quality. According to the respondents, road networks directly determine transportation options, and when sufficient infrastructure is not available, vehicle-related emissions increase, which can affect the urban environment (R5, R12). Furthermore, the respondents explained that when people can commute using public transport, walking, or cycling, they can get to their offices, schools, or any particular area of a city in a more environmentally friendly way (R6, R14). R1 added, “If cities could improve the Solar Reflective Index (SRI) of pavement materials, surface temperatures can be reduced, and it can reduce the amount of heat absorbed into the pavement, making cities more comfortable”. Therefore, well-planned transportation networks support compact urban development and minimize urban sprawl. Also, they can reduce traffic congestion, fuel consumption, and travel time.

Urban development officials have implemented regulations as a solution to mitigate land-use-related issues. Land utilization-related regulations must be considered within the city boundary. R29 added, “Exploring whether cities have planning regulations and the effectiveness of enforcing them should be considered to get a proper idea of city planning”. R6 explained this as follows: “It can be looked at from a city perspective in terms of land utilization more than at the individual level, because it must always be driven by the master plan set for the city. Certain things can have individual discretion, but the city must issue the overall control regulations”. Therefore, land use must be carefully planned to develop an environmentally sustainable city, and urban authorities are accountable for considering environmental impacts when imposing rules and regulations within cities. Table A1 provides a summary of the main factors, dimensions, measuring indicators, and their measurement boundaries identified from the above discussion.

In addition to the main factors discussed above, three additional factors were identified and verified through the interviews: disaster resilience, education, and governance. The importance of these factors is discussed below.

4.5. Disaster Resilience

Disasters can impact the environmental quality of a city, resulting in immediate damage or long-term consequences, depending on their severity. This can be mitigated by proper disaster management with resilience.

According to the respondents, cities can enhance their emergency preparedness for natural disasters by developing effective plans and implementing disaster preparedness measures. R18 explained that cities can enhance emergency preparedness by preventing the construction of buildings in areas vulnerable to disasters. When considering the boundary, R8, R12, and R30 stated that the boundary should be the entire city because natural disasters have different coverage. Emergency preparedness for disasters can enhance both environmental quality and quality of life. The respondents explained that in addition to natural disasters, human-caused disasters also have an impact on a city’s environmental quality. Thus, emergency preparedness should be implemented by industries to mitigate human-caused disasters. When considering the boundary, emergency preparedness should be considered in terms of different establishments in a city. R12 explained this as, “Institutions having health and safety precautions as well as emergency management frameworks in place at a city level, and then to what level they have been integrated into those organizations in a management approach at commercial and industrial levels are important” (R12). R8 stated that this can be considered at an individual level. However, a city’s perspective would be more relevant because, in terms of preparedness, an individual’s actions can ultimately affect a city. Furthermore, R3 internally validated that the level of emergency preparedness and its impact at the city level are critical aspects.

Disasters can affect specific areas of cities, significantly damaging environmental quality. According to the respondents, landslides, droughts, and floods are the main natural disasters affecting Sri Lankan cities. According to the respondents, considering city boundaries is crucial for gaining a proper understanding of the issue. R7 stated, “The whole city should be considered to get an idea because disasters cannot be categorized into individual level, hence it should be at the public or city level”. City development authorities need to pay more attention to natural ways of disaster resilience. R6 stated, “Restoration of certain nature-based solutions like forest cover on steep slopes, Mangrove cover closer to coastal cities and wetlands and marshes in cities, and the prevailing levels are important”. Natural defense mechanisms help individuals cope with disasters by primarily contributing to reducing disaster risk, damage, or exposure. Therefore, restoration and preservation of these areas are required. Damage caused by disasters is another critical aspect to be considered. This needs to be examined in terms of common disastrous events that have occurred within the cities of Sri Lanka. R9 internally validated the importance of considering impact evaluation at the city level as “Damages, which is based on the affected population, depends on the local areas. So, it will give a clear picture of regional level intervention through the districts”.

4.6. Education

Education about the environment is crucial for effective city management. It is necessary to understand awareness, attitudes, and knowledge regarding environmental quality.

In terms of education, people’s attitudes play a crucial role in creating a better environment in cities. Not only knowledge but also the attitude of people will critically affect the environment. It is essential to maintain a positive mindset and attitude towards the behaviors of those living in the city. R4 stated the need to have a community with a good mindset and behaviors, which is preferable for the environment, as “Having only a government with rules and regulations is not enough to maintain the environmental quality and sustainable living. So, there must be a good community”. Therefore, ensuring that people are mindful of their environmental impact at the city level is important.

Environmental awareness is crucial in education, and when people are aware of the consequences of their actions, they are more likely to act responsibly. It is essential to incorporate environmental awareness into the education system; however, even educated individuals sometimes fail to follow it. City boundaries are more reliable for these assessments. As per the opinion of R27, “The city boundary can be considered and surveys can be done to measure the level of awareness of the people, their attitudes and knowledge on the environmental quality improvements”. However, R2 stated, “The overall city should be the boundary that should be educated on the environmental quality”. Therefore, it is essential to monitor the environmental awareness programs proposed and implemented at the city level. Both culture and education have an impact on maintaining a city’s environmental quality. As a part of the culture, people must be responsible when living in their cities. R13 added, “If a person in a city with unique cultures says that opening a window and throwing out something to the road or the environment is like a disaster, which will not be done as a habit. So that is coming from culture and cultural education is there”. Therefore, cultural education can be considered at the city level.

4.7. Governance

Governance can be considered a critical aspect that significantly impacts a city’s environmental quality, as it influences proper city planning through the actions of governing bodies. Governance is based on policies that comprise various rules and regulations. Therefore, proper governance is required to manage all the above factors sustainably.

Primarily, how management is conducted in a city is crucial because the governing body is responsible for establishing and enforcing rules and regulations. R22 added, “What level of environmental and social aspects should be considered in terms of governance policies for proper management within the cities?”. Effective people management is crucial to achieving the desired outcomes in terms of a city’s environmental quality. This should come from the local authority’s top-level officials. When considering governance, proper planning within government bodies is necessary to achieve the desired environmental quality of a city. Therefore, governance is a significant factor affecting the long-standing problem of ad hoc buildings and transportation systems, and it requires adjustments to plans accordingly. R27 added, “The extent of policies or rules related to the environment quality, and the strength of policies and how they are implemented in these policies for planning at the city level is critical”. Furthermore, R15 stated, “Policies can be imposed, considering the city level, and then it can be implemented to an individual level. But it gives an overall idea about the city”. R6 added, “In terms of quality of the people who are part of those governing institutions, their expertise, experience, and background with other areas like environment and society, economic considerations in governance are essential”. R9 internally validated the above statement as “Institutions are required for implementing policies or rules”. Therefore, the institutions and the responsible persons who should implement policies and rules at the city level should be considered.

The availability of experts in specific areas of governance can help address and mitigate environmental quality-related issues in a city. Specialized individuals should be appointed to certain government institutions who possess the technical understanding and experience to implement effective approaches related to the city environment. The local community and governance bodies must work together to engage people in a city to identify and mitigate issues related to the city’s environmental quality. People’s concerns are appropriate for the city environment. R6 explained how the engagement of people should be considered in decision-making as follows. “The requirement of integrating environmental and social considerations into city plans, what level authorities have appointed responsible persons for proper integration and having stakeholder engagement, like review meetings, are important aspects to be considered” (R6). Furthermore, R12 added, “City government must adopt any resident involvement programs. For example, residents can observe environmental issues in the city (for example, solid waste being dumped), and they can share a picture with the local authority to take action to resolve them”. Therefore, engaging people at the city level is an important aspect to consider in maintaining a city’s environmental quality.

Table 2. Summary of the other factors identified.

Factor	Dimensions	Measuring Indicators	Measurement Boundary
Disaster resilience	Emergency preparedness	Number of industries with health and safety measures Number of high-risk industries available Number of emergency management frameworks available Number of emergency management frameworks integrated into organizations Number of actions available for disaster preparedness Percentage of buildings in vulnerable areas	City
	Affected area	Percentage of usage or built-up area in hilly areas The level of wetlands is filled Area of landfilling Percentage destruction of forest areas Number of landslide events Number of flooding events Number of drought events	City
	Nature-based solutions	Percentage of mangrove available area Percentage of wetlands and marshes available area	City
	Impact valuation	Number of landslide events Number of flooding events Number of drought events Number of industrial accidents	City
Education	Attitudes	Percentage of people who are mindful of their impact on the environment	City
	Environmental awareness	Number of environmental awareness programs available/proposed	City
	Cultural education	The percentage of people who have received cultural education	City
Governance	Management	Number of sustainable plans available/proposed Number of goals achieved Percentage of environmental and social aspects considered	City
	Planning	Number of policies or rules available Percentage of implemented policies Level of satisfaction with policies	City
	Expertise	Number of experts available	City
	People engagement	Number of responsible parties Number of citizen involvement programs available/proposed	City

provides a summary of the additional factors, dimensions, measuring indicators, and their measurement boundaries.

5. Discussion

Overall, seven factors were identified in this study. When considering each factor, it was evident that they have different dimensions, which clearly shows the impact of maintaining a city’s environmental quality. However, the boundary of these dimensions and their measuring indicators differ from city to city, and their reliability depends on the level of control within a city.

As discussed in the literature on energy consumption [1,22,23,24], greenhouse gas (GHG) emissions are the primary adverse impact of energy use in cities. Furthermore, transportation plays a significant role because most air pollutants in a city originate from emissions from the internal combustion engines of vehicles [22]. Therefore, as stated in the literature [20,23,34], the use of renewable energy sources, energy efficiency, and green transport-related indicators is crucial for improving city environmental quality. The data findings revealed that consumption patterns are important in terms of the amount of energy consumed, the period of energy usage, occupancy, energy-consuming devices, and the imposition of taxes. Furthermore, the data analysis revealed that consumption patterns and energy sources used should be evaluated based on individual consumption in households, industries, and commercial buildings. Therefore, identifying energy consumption patterns in city buildings is crucial for mitigating human-induced greenhouse gas emissions [1,7]. Energy production and energy efficiency should also be considered at both the city-wide and individual unit levels. However, it was revealed that transportation-related indicators should be measured at the city boundary.

Excessive consumption of water generates wastewater, and inadequate treatment facilities result in polluted water [28]. The findings revealed that cities need to focus on key dimensions, including water resources utilized, water consumption patterns, wastewater generation, wastewater disposal, and water pollution. Similarly, the data analysis highlighted the importance of water treatment facilities, wastewater treatment, recycling rates, and the use of rainwater for city usage. The literature also emphasized the absence of proper investments and the need for effective strategies to develop these areas [19,28]. The findings revealed it is better to consider a narrow boundary, such as household, commercial, or industrial units, to evaluate water consumption patterns, wastewater generation, and disposal in cities. It was clear that water pollution caused by the addition of impurities to water sources should be considered at both the individual unit and city levels. It is better to consider natural water source-related measurements and the use of recycled water and rainwater at the household, commercial, or industrial levels, as well as within city boundaries. Furthermore, the findings highlighted the significance of access to clean water resources [25], which ultimately affects the health of urban life.

Similarly, as discussed in the literature, the findings revealed that material consumption is a primary cause of waste generation [30], where the number of different wastes generated and waste disposal-related indicators [5,34] are crucial for cities. It was evident that implementing the circular economy concept and utilizing reusable and recyclable materials [24,43] are environmentally friendly approaches for cities. As specified in the literature, material extraction in vulnerable areas is crucial [9], and it has been revealed that it is preferable to use recyclable/reusable materials rather than extracting more virgin materials. Furthermore, the material composition was analyzed based on the use of sustainable materials, the use of renewable materials in production, the use of fossil fuel-based materials in production, and the embodied carbon in materials. It was identified that material extraction, material composition, and waste disposal-related indicators should be measured at the city level. In addition, narrow boundaries, such as households, commercial, or industrial buildings, were identified as being more reliable for measuring the type of material used. However, for waste generation measurements, it is recommended to use individual units for toxic waste and city-wise measurements for daily waste generation.

In terms of land usage, the literature [7,32,33] has focused more on the natural land coverage of green and water aspects in urban environments. However, development plans are also important in land utilization [7]. The findings revealed the significance of building development, transportation networks, and regulations. In addition, the regeneration capacities of lands using brownfields were discussed, as highlighted in the literature [3]. To promote cycling and walking and reduce vehicular transportation, residential, economic, cultural, and institutional purposes need to be closely integrated, thereby reducing pollutants from traffic. Therefore, percentage-wise availability of public transportation, walking spaces, and cycling lanes was revealed as an indicator of sustainable infrastructure development. All land utilization-related indicators were measurable within the city boundary, considering it as a geographical boundary.

When considering disaster resilience, it was revealed that the main dimensions are emergency preparedness for disasters, affected areas in cities, availability of natural solutions for disasters, and impact valuation in terms of disastrous events. Here, it is essential to consider both human-caused disasters and natural disasters, as both have a significant impact on environmental quality in terms of destruction. When considering the related indicators, it was revealed that measuring them at the city boundary is more reliable. As revealed by the findings, personal attitudes, environmental awareness, and cultural education play a significant role in preserving a city’s environment through education. This can lead to behavioral changes in people for the sake of environmental protection. As highlighted in the data analysis, not only knowledge but also attitudes are important for this change. Here, a city was considered the boundary for these dimensions as the final factor. Governance has an overall impact on a city’s environmental quality in terms of management, planning, expertise, and people engagement. Furthermore, governance should have proper policies in place with designated responsible parties and required integration for the effective management of all six factors identified above. Therefore, the overall city was considered a reliable boundary for governance-related measurements.

Therefore, this study advances the discourse on urban environmental planning in Sri Lankan cities, providing a comprehensive picture of the aspects to be considered in urban planning. Furthermore, the findings emphasize the need for proper indicators and measurement boundaries that can accommodate the complexity of urban ecosystems and support more equitable and effective environmental governance, as well as the integration of urban planning and policy. For example, these findings can inform urban planning applications, such as land use and zoning decisions, infrastructure development, transportation planning, and climate adaptation. In addition, governance and policy applications, performance monitoring, evidence-based policy making, and public engagement with improved transparency can ultimately enable cities to use indicators and measurement boundaries to attract green investments or justify funding for environmental projects.

6. Conclusions

Energy consumption, water consumption, material and resource consumption, and land utilization factors, as identified in the literature, were further explored in this research study. It was evident that these four factors have a significant effect on the environmental quality of a city, based on professional judgments. Furthermore, more than 50% of the respondents highlighted the contribution of all the dimensions identified under these four factors. Therefore, it can be concluded that these dimensions are more reliable. Furthermore, three other factors were identified, namely, disaster resilience, education, and governance, based on the professionals’ judgments. Although these are not significant factors, their contributions affect the environmental quality of a city in terms of its different dimensions. Finally, a total of 123 measuring indicators were developed, which can be used to consider reliable boundaries for measuring the 32 dimensions identified above. A boundary can be based on a city’s perspective or individual units, such as households, industrial, and commercial buildings.

When considering the identified factors in this research study, it can be recommended that they are suitable for an environmentally friendly city. This can serve as a foundation for urban development programs in Sri Lanka, offering a unique solution for evaluating cities in terms of environmental quality. Many cities have not considered all the factors that can affect a city’s environmental quality. Therefore, this research output can be utilized as a comprehensive solution that encompasses nearly all factors and dimensions, with a clear boundary for measurement and evaluation. As a result, this can highlight the prevailing issues in cities through proper evaluation. Ultimately, this research helps identify weaknesses in cities and develop solutions accordingly. Further research is recommended to utilize the developed boundary identification model for evaluating and comparing cities in Sri Lanka, as well as to focus more on the identified dimensions and explore solutions for the existing issues within the identified boundaries. Additionally, in-depth research can be conducted by examining the environmental impact of the identified factors individually.

While this study provides a detailed assessment of environmental quality across Sri Lankan cities, its geographic scope may limit its global applicability. The urban characteristics, environmental challenges, and socioeconomic conditions specific to Sri Lanka informed the design and implementation of the methodology. As such, direct application to cities in other regions may require contextual adaptation. While the findings are grounded in Sri Lanka’s urban realities, their relevance extends beyond national boundaries. To better understand this study’s broader applicability, it is useful to consider how similar environmental issues manifest in other global urban contexts. These global comparisons will offer valuable benchmarks and highlight potential pathways for enhancing environmental quality in Sri Lanka. By incorporating such comparative insights, future studies can be further refined and tested across diverse urban settings. This would not only enhance robustness but also contribute to a more globally relevant tool for assessing and improving urban environmental quality. This would enable validation across diverse urban typologies and enhance this study’s relevance to broader environmental planning and policy-making efforts.