Document Type : Research Paper
Authors
Department of Geography, Na.C, Islamic Azad University, Najafabad, Iran
Abstract
A B S T R A C T
Green roofs, as a pivotal strategy in sustainable urban development, play a crucial role in mitigating environmental challenges and strengthening ecological resilience in rapidly growing cities. This study aims to develop an indigenous model for green roof implementation as a pathway toward realizing an ecological city in Najafabad. The research adopts a descriptive-analytical method within a developmental-applied framework, combining library investigations with field-based surveys. In total, 96 items were identified across six indicators related to green roofs and five indicators representing ecological city dimensions. The statistical population included specialists in urban planning and architecture, from which 30 experts were selected through purposive sampling based on their experience and relevance to the subject. Data were analyzed using SPSS through exploratory factor analysis and one-way ANOVA to examine relationships and compare ecological indices across the city. In addition, spatial analysis of the indicators was conducted across the five districts of Najafabad using network analysis tools within the ArcGIS environment to identify spatial variation and prioritize suitable zones. Findings reveal that the environmental dimension, with a path coefficient of 0.980, and the social dimension, with a coefficient of 0.716, exert the greatest influence on the development of green roofs. Districts 3 and 2 demonstrate the highest potential for green roof expansion, with mean values of 3.54 and 3.52, respectively. Moreover, spatial analysis indicates that the structured development network shows strong alignment and consistency with scenarios designed to support Najafabad’s transition toward an ecological city.
Extended Abstract
Introduction
A “green roof” or “living roof” is a roofing system partially or completely covered with vegetation, growing media, and essential waterproofing membranes. In sustainable urban planning, green roofs are increasingly recognized as multifunctional ecological infrastructures that mitigate environmental, social, and physical challenges. Within sustainable architecture and ecological urbanism, transforming underutilized rooftops into productive green spaces is a highly effective strategy. These installations facilitate stormwater management, thermal regulation, air purification, and biodiversity conservation in dense urban environments. They also contribute to improving visual quality, strengthening urban resilience, and enhancing the environmental performance of buildings in both new developments and existing urban fabrics. Moreover, green roofs support urban sustainability by enhancing ecosystem services within densely built environments. They provide microhabitats for plants and insects, contribute to urban biodiversity, and improve the overall environmental balance of cities. By integrating vegetation into building envelopes, green roofs also strengthen climate adaptation strategies and encourage environmentally responsible urban design practices that respond to contemporary ecological challenges faced by rapidly growing cities.
The implementation of green roofs becomes vital in cities facing severe environmental pressures. Najafabad, an urban center in Isfahan Province, suffers from water scarcity, land subsidence, insufficient green spaces, and air pollution. Since horizontal green space expansion is constrained because of land availability and economic limitations, vertical greening offers a localized solution. However, realizing an ecological city through green roofs requires coordinating physical, environmental, socio-cultural, and managerial dimensions. A successful deployment depends on structural feasibility, economic viability, public awareness, and spatial prioritization. Therefore, this study aims to identify, evaluate, and prioritize the key dimensions of green roofs in Najafabad’s urban planning to propose a model supporting ecological city development.
Methodology
This research is developmental-applied in terms of its objective and descriptive-analytical in terms of its nature and method. The study was designed to combine theoretical investigation, field data collection, statistical analysis, and spatial modeling in order to propose a green roof development model for Najafabad. Since the subject of green roofs involves both conceptual and practical dimensions, the research process was organized in two main phases: library-based studies and field-based investigations.
In the library study phase, the theoretical foundations, concepts, criteria, and indicators related to green roofs, ecological cities, sustainable urban planning, and urban environmental management were collected and reviewed. Scientific books, peer-reviewed articles, planning documents, environmental reports, and relevant national and international studies were used to establish the conceptual framework of the research. This phase helped identify the main dimensions of green roof development and clarify their relationship with ecological city principles. Particular attention was paid to environmental, social, physical, economic, and managerial indicators that could affect the feasibility and effectiveness of green roofs in an urban context such as Najafabad.
In the field study phase, data were collected through a structured questionnaire. The questionnaire was designed based on a five-point Likert scale in order to measure the importance and effectiveness of the selected variables and indicators. The statistical population consisted of senior managers, experts, and specialists associated with urban planning, environmental studies, municipal management, architecture, and related administrative sectors in Najafabad. The total population included 100 individuals, from whom 30 experts were selected purposively as the research sample. These experts were drawn from academic institutions, the Roads and Urban Development Department, Najafabad Municipality, and other relevant organizations. The criteria for selecting the experts included theoretical knowledge, professional experience, familiarity with local urban and environmental conditions, willingness to participate in the research, and accessibility to the researcher.
The collected data were analyzed using statistical and spatial techniques. Structural equation modeling based on the partial least squares method was used to examine the relationships among the main indicators and to determine the relative importance of different dimensions. In addition, a one-way analysis of variance was applied to compare the potential of different urban zones for green roof development. To support spatial decision-making and develop a practical model, GIS-based analyses were performed in the ArcGIS environment. Tracking Analysis Tools and Network Analysis Tools were used to analyze spatial patterns and urban accessibility conditions related to the studied indicators. Furthermore, optimization procedures were incorporated into the modeling process. The study applied the Imperialist Competitive Algorithm and the Minimum Spanning Tree algorithm in MATLAB to design optimized scenarios for green roof development. This combination of statistical analysis, GIS-based spatial evaluation, and algorithmic optimization provided an integrated methodological framework for identifying priority areas and reducing the potential costs of implementation.
Results and Discussion
The findings of the study indicate that Najafabad has considerable potential for the development of green roofs as a strategic approach toward the realization of an ecological city. Nevertheless, the city also faces serious environmental and infrastructural challenges that must be carefully considered in any planning model. Among the most important challenges are water scarcity, land subsidence estimated at approximately 12 centimeters annually, insufficient per capita green space, and air pollution. The per capita green space in different parts of the city varies between approximately 7 and 15 square meters per person, indicating an uneven distribution of green resources and a need for more balanced spatial planning. In this regard, green roofs can play a complementary role by adding new layers of urban greenery without requiring extensive horizontal land allocation.
The results of structural equation modeling revealed that environmental and social indicators have a decisive role in the acceptance and implementation of green roofs in Najafabad. The path coefficient for the environmental indicator was 0.980, showing that environmental conditions and ecological needs are the most influential factors in the development of green roofs. This means that issues such as air pollution, thermal comfort, green space shortage, water management, and climate adaptation are central to the justification and prioritization of green roof projects. The path coefficient for the social indicator was 0.716, indicating that citizens’ socio-cultural motivations, environmental awareness, and willingness to accept green infrastructure are also highly significant. These results confirm that green roof planning should not be limited to technical and physical considerations; rather, it must also take into account public education, cultural acceptance, participation, and social motivation.
The findings are consistent with international studies, such as those by Jim and Hui(2022), which emphasize the importance of public education and social awareness in the success of urban greening projects. They also correspond with national studies, including those by Taheri Mirghaed and Saberi(2021), which highlight the role of citizen participation and environmental knowledge in promoting sustainable urban interventions. Therefore, any successful green roof strategy in Najafabad should comprise educational programs, incentive policies, awareness campaigns, and participatory planning mechanisms. Without social acceptance and institutional support, even technically suitable projects may face difficulties in implementation and long-term maintenance.
The results of the one-way ANOVA test also exhibited significant differences among the five urban zones of Najafabad in terms of their potential for green roof development. The statistical result was significant at the 0.05 level, with F = 4.90 and P < 0.05. Among the study zones, Zone 3, corresponding to Vilashahr, and Zone 2, located in the western part of the central city area, obtained the highest mean scores of 3.54 and 3.52, respectively. These zones therefore hold the greatest potential for the development of green roofs. Their higher scores may be related to more suitable physical conditions, better urban structure, greater environmental capacity, or stronger social and institutional readiness. In contrast, Zone 1, including the center and eastern parts of the central city area, and Zone 5, corresponding to the Amirabad area, obtained lower mean scores of 3.02 and 3.36, respectively. Such areas demand additional interventions, encompassing infrastructure upgrades, policy reinforcement, public awareness initiatives, and comprehensive feasibility assessments.
These spatial differences demonstrate that green roof development should not be implemented uniformly across the city. Instead, it should be based on spatial prioritization and local characteristics. Areas with higher potential can be selected as pilot zones for early implementation, while areas with lower potential may require preparatory measures before large-scale development. This finding is consistent with national studies by Saberi and Barati(2022), which emphasized the importance of balanced green space distribution in semi-arid cities. In cities such as Najafabad, where environmental resources are limited and climatic conditions are sensitive, spatial justice in the distribution of green infrastructure is especially important.
The novelty of the research lies in its integrated approach. Unlike many previous studies that focus on the physical, environmental, or architectural aspects of green roofs, this study combines structural equation modeling, GIS-based spatial analysis, and algorithmic optimization. The integration of the Imperialist Competitive Algorithm with localized spatial data distinguishes this study from earlier research, including studies such as that of Ömer Ekmekcioğlu(2023), which concentrated mainly on the management and identification of green roof types in high-precipitation regions such as Turkey. By contrast, this study addresses the conditions of a semi-arid city and attempts to propose a localized model suitable for Najafabad’s environmental, social, and spatial characteristics.
Another chief contribution of the study is the design of four optimized scenarios using the Minimum Spanning Tree algorithm in MATLAB. These scenarios emphasize local search and jump phases and aim to reduce infrastructure costs while improving the efficiency of green roof development. Cost reduction is a crucial issue in the practical implementation of green roofs, especially in cities where municipal budgets are inadequate and private owners may hesitate to invest in unfamiliar technologies. By incorporating optimization methods, the study provides a more practical and decision-oriented framework for urban managers.
Despite these contributions, this study is subject to certain limitations—notably the unavailability of fully updated spatial boundary data for Najafabad's five urban zones. This may affect the precision of spatial analysis and the interpretation of zonal differences. Another limitation is the need for stronger collaboration with local stakeholders, particularly Najafabad Municipality and related executive organizations. The practical implementation of green roofs requires institutional coordination, financial mechanisms, technical guidelines, and public participation. Therefore, future studies should use more comprehensive and updated spatial data, include a larger group of stakeholders, and apply dynamic simulation tools such as SWMM models to evaluate water management performance. Such studies can further refine the proposed model and provide a more accurate assessment of the role of green roofs in mitigating climate change impacts, reducing runoff, and improving urban environmental quality.
Conclusion
The concept of an ecological city represents a comprehensive structural approach that integrates environmental, economic, physical, social, and managerial dimensions. It seeks to create urban environments that function in harmony with natural systems while improving human well-being and reducing ecological pressures. In Najafabad, the development of green roofs can be considered an effective strategy for moving toward such an ecological urban model. Given the city’s challenges, including water scarcity, limited land availability, insufficient green space, air pollution, and environmental vulnerability, green roofs provide an opportunity to expand urban greenery vertically and make better use of existing built surfaces.
The results indicate that green roofs can contribute to increasing per capita green space, improving urban environmental quality, reducing pollution, enhancing urban aesthetics, moderating microclimatic conditions, and strengthening the ecological performance of buildings. They can also help reduce heating and cooling loads, purify air, decrease carbon dioxide levels, mitigate noise pollution, extend the lifespan of roof membranes, reduce the effects of urban heat islands, and create additional usable and pleasant spaces for residents. In this sense, green roofs are not only an architectural solution but also an urban planning strategy with environmental, social, and economic benefits.
For Najafabad, the successful development of green roofs requires a prioritized, localized, and participatory approach. Environmental indicators should be considered the most important basis for decision-making, while social acceptance and public awareness should be strengthened through education and incentive policies. Zones with higher potential, particularly Zones 2 and 3, should be used as pilot areas, while Zones 1 and 5 require supportive interventions before broader implementation. Overall, the implementation of green roof principles and dimensions can provide a foundation for environmental enhancement, reduction of pollution-related health impacts, improvement of living standards, and progress toward transforming Najafabad into an ecological city.
Funding
There is no funding support.
Authors’ Contribution
First author: Drafting the introduction, problem statement, parts of the methodology, statistical analyses and initial writing of the article, making refereeing corrections
Second author: Participation in the initial research design and general review of the article structure
Third author: Drafting the discussion section, conclusions, interpretation of findings and completing the writing of the article
Fourth author: Participation in data collection, final review of the text and minor corrections of the article.
Conflict of Interest
Authors declared no conflict of interest.
Acknowledgments
We are grateful to all the scientific consultants of this paper.
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