Urban transformations and solar accessibility: a study on FlorianópolisAbstract
This study investigates the evolution of solar radiation accessibility in an urban context by analyzing past, present, and hypothetical future scenarios. Urban planning tools, including the Spacemate diagram, are employed to assess how urban morphology influences the availability of solar radiation. The case study is conducted in Florianópolis, Brazil, and the methodological framework integrates spatial mapping, historical and prospective scenario modeling, annual dynamic solar simulations, and a systematic evaluation of the resulting data. The results indicate that ongoing urban transformations have led to a substantial reduction in solar radiation availability per square meter of built area, particularly in high-rise and high-density developments. Compared to the 2003 scenario, reductions of up to 64% are observed in the projected future scenario. These findings highlight the urgent need to incorporate solar accessibility criteria into urban planning instruments to support climate-adaptive and energy-efficient cities. Integrating solar radiation parameters into urban regulations may help mitigate the negative impacts of excessive densification while promoting more sustainable patterns of urban development.
Keywords
Urban morphology; Solar radiation; Urban planning; Urban densification
Resumo
Este estudo analisa a evolução da acessibilidade à radiação solar em um centro urbano, considerando cenários passados, presentes e um cenário futuro hipotético. Utilizando ferramentas de planejamento urbano, como o Spacemate, avalia-se o impacto da morfologia urbana na disponibilidade de radiação solar. A pesquisa é conduzida em Florianópolis, e a abordagem metodológica inclui o mapeamento da área, a modelagem de cenários passados e futuros, simulações dinâmicas anuais e a avaliação dos resultados obtidos. Os dados encontrados demonstram que as contínuas modificações urbanas ocasionaram uma redução expressiva da radiação solar disponível por metro quadrado edificado, principalmente em edificações de grande altura e com maior densidade, atingindo uma diminuição de 64% em comparação a 2003. Isso evidencia a necessidade urgente de incorporar a acessibilidade à radiação solar no planejamento urbano, a fim de promover cidades mais sustentáveis e adaptadas ao clima, por meio de estratégias que mitiguem os impactos negativos do adensamento excessivo.
Palavras-chave
Morfologia urbana; Radiação solar; Planejamento urbano; Adensamento urbano
1 Introduction
Urban expansion and increasing city densification pose significant challenges to sustainable urban planning, particularly regarding environmental quality and equitable access to renewable energy resources. In this context, solar energy has emerged as a key alternative for mitigating the environmental impacts of accelerated urban growth. Beyond enabling decentralized clean energy generation, solar energy contributes to environmental comfort and improved energy efficiency in urban spaces. Consequently, the incorporation of solar-related parameters into urban planning has become a strategic approach for aligning territorial development with global carbon neutrality targets (Zhao et al., 2023; Lan; Gou; Hou, 2022; Zhang et al., 2024).
Recent studies indicate that urban morphology, defined by building form, density, height, and spatial arrangement, directly influences solar radiation availability in the built environment (Zhao; Gou, 2023; Bastian, 2023). Interactions between building height, spacing, and orientation shape shading patterns and affect the potential use of façades and rooftops for photovoltaic systems. Compact and highly verticalized configurations tend to reduce incident solar radiation, whereas more balanced morphologies, with controlled heights and adequate setbacks, are associated with improved energy performance and more equitable solar access (Godoy-Shimizu; Steadman; Evans, 2021).
In the Brazilian context, research has shown that energy efficiency strategies and distributed photovoltaic generation can operate complementarily during the energy transition. Domingos and Pereira (2021) demonstrated that photovoltaic systems are often more economically viable when implemented independently, while energy efficiency measures contribute to enhanced thermal comfort and long-term reductions in energy consumption. These findings reinforce the importance of integrating both approaches within urban and energy planning frameworks, particularly in cities undergoing densification.
Urban energy planning must also consider the combined effects of morphological and climatic variables. Sun et al. (2025) highlights the relevance of predictive models for assessing solar potential across temporal scenarios, showing that mutual shading can reduce solar energy potential by up to 45% in dense urban areas. This evidence underscores the need to incorporate solar accessibility indicators into zoning regulations and master plans, in line with international net-zero planning practices (Li et al., 2025; Zhao et al., 2023).
Advances in computational tools have supported this shift by enabling detailed analyses of solar incidence across urban typologies. Parametric modeling platforms such as Rhinoceros 3D, combined with Grasshopper and environmental simulation tools like Ladybug, allow the evaluation of multiple scenarios and their environmental performance (Girotti; Maris; Lara, 2019; Zhang et al., 2024). Chen et al. (2025) showed that modest adjustments in height-to-width ratios can increase average façade irradiance by up to 25% in high-density contexts.
In Latin American cities, these issues are particularly critical due to rapid and often insufficiently regulated urban growth. Studies conducted in Salvador, Florianópolis, and São Paulo indicate that the absence of solar accessibility criteria in master plans has resulted in excessive shading and reduced photovoltaic potential in residential areas (Bastian, 2023; Girotti; Maris; Lara, 2019; Domingos; Pereira, 2025).
Within this context, analytical frameworks such as the Spacemate diagram (Berghauser Pont; Haupt, 2009) have gained relevance as decision-support tools, enabling the correlation of morphological indicators with environmental performance. Accordingly, this study analyzes the evolution of solar radiation accessibility in Florianópolis by comparing historical, current, and hypothetical future scenarios. Using parametric modeling and the Spacemate framework, the research evaluates how changes in urban morphology affect solar availability and proposes guidelines to reconcile densification with the maximization of solar radiation, contributing to more sustainable and climate-responsive urban planning.
2 Methodology
To ensure methodological transparency and reproducibility, the adopted workflow was structured as a sequential process composed of six main stages:
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definition of the study area and spatial boundaries;
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three-dimensional modeling of existing and projected urban scenarios;
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parameterization of urban form based on planning indicators;
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annual solar radiation simulation;
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post-processing and normalization of simulation outputs; and
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comparative analysis across temporal scenarios.
Each stage generates inputs for the subsequent step, allowing the full replication of the methodological procedure by other researchers.
2.1 Site definition
The study focuses on a specific urban segment located in the continental region of Florianópolis. This area is characterized by medium-density development and is classified as a Mixed Services Area (AMS 10.5) according to the macrozoning framework established by the Florianópolis Municipal Master Plan. The site presents a net residential density of 590 inhabitants per hectare (PMF, 2023). The selection of this area is justified by its representativeness of the city’s recent urban growth dynamics and by its capacity to reveal real and measurable impacts of densification processes, which are often underestimated in hypothetical or idealized urban scenarios. The selected area is presented in Figure 1.
2.2 Development of the parametric tool
The parametric modeling framework adopted in this study is based on a performance-oriented design approach derived from the theoretical structures proposed by Oxman (2006a, 2006b) and Oxman and Hammer (2007). This framework follows a cyclical logic that allows iterative modifications between geometric configuration and environmental performance evaluation, making it suitable for studies in which form and performance are treated as interdependent variables.
This approach requires specific technical competencies, including proficiency in parametric modeling, simulation workflows, and performance analysis. It is particularly aligned with contemporary environmental design challenges, as performance-based methodologies have become essential in response to the need to reduce energy consumption and improve environmental efficiency in the built environment (Aksin; Selçuk, 2021).
The simulations were conducted using a parametric modeling environment with adjustable parameters directly linked to environmental simulation engines. The tools employed include Rhinoceros 3D (version 8, educational license) as the geometric modeling platform, Grasshopper as the visual programming interface, and Ladybug Tools for solar radiation analysis. This software combination enables the generation of multiple volumetric configurations and the evaluation of solar radiation through validated simulation engines such as Radiance. The objective of this stage was to assess the annual solar radiation incident on building envelopes under different urban configurations.
Grasshopper was selected due to its capacity to generate parametric models based on logical relationships rather than fixed geometric representations. Through interconnected components, the modeling process allows the automatic updating of the entire system whenever a parameter is modified. This characteristic makes Grasshopper particularly suitable for exploring design variations, automating repetitive processes, and developing complex rule-based urban models. As a result, it is widely used in architectural and urban research contexts that require iterative testing and performance evaluation.
The visual programming structure developed in this study was organized into four sequential action groups, following methodologies previously applied in urban-scale computational simulation research (Mariano, 2018; Mariano; Pereira; Vaz, 2018, 2020). These groups are defined as environment, selection, organization, and simulation. Each stage is activated only after the completion of the preceding one, ensuring a structured and reproducible workflow.
The first action group establishes the spatial context of the study area and its surrounding urban environment. This stage allows the incorporation of two-dimensional cartographic data and the parametrization of building typologies and heights. The second group defines the parameters used to generate the simulation objects, including building typology and number of stories, enabling adjustments to façade orientation and compliance with predefined design criteria. In the third group, both geometric and non-geometric characteristics of the models are systematized. At this stage, simulation parameters such as sensor grid resolution, number of simulations runs, numerical output ranges, and visualization settings are defined using Ladybug components. The final group involves the execution of the simulations and the organization of the resulting data for subsequent analysis.
2.3 Scenario modeling
Four urban scenarios were developed for the analysis, corresponding to the years 2003, 2013, 2023, and a hypothetical future projection. The historical and current scenarios were modeled based on field surveys, aerial imagery, and three-dimensional data obtained from the historical archive of Google Earth. The future scenario was constructed using urban growth projections derived from the Municipal Master Plan, combined with observed trends of verticalization and densification in recent decades.
The simulations considered the actual orientation of buildings in relation to true north and accounted for the global solar radiation incident on building surfaces. A predefined sensor grid was applied to the building envelopes, allowing the visualization of accumulated annual solar radiation values expressed in kWh/m². This approach enables the identification of areas with higher and lower solar exposure across different building typologies and urban configurations.
For the historical and current scenarios, building heights were defined according to documented data for each period. In the future scenario, the maximum building potential permitted by the Master Plan was adopted, reflecting a theoretical limit of urban occupation. This methodological choice allows for an assessment of the cumulative effects of urban densification on solar radiation availability over time.
To define plots suitable for urban expansion in the future scenario, a selection method was developed based on existing land-use patterns within the study area. This method considered plot dimensions, current building typologies, and the potential for land consolidation. The selected plots met three criteria: similarity in construction typology, a maximum of two existing stories, and exclusively residential use. These conditions were adopted to represent realistic scenarios of land consolidation and redevelopment.
This process resulted in hypothetical plot consolidations ranging from two to six individual plots, with an average of three plots per group. The consolidated plots presented an average area of 1,472.12 m², which is comparable to the average size of plots currently occupied by high-rise buildings in the area, measured at 1,403.35 m². These consolidated plots were subsequently adjusted according to the urban planning parameters defined in the Florianópolis Master Plan (PMF, 2023), as illustrated in Figure 2.
Consolidated plots for the demonstration of new buildings using the maximum parameters defined by the Florianópolis Master Plan (PMF, 2023) – in green – and plots with buildings taller than seven stories—in white
The visual programming routine used to generate buildings on the consolidated plots was adapted to comply with the local zoning category AMS 10. To define the building perimeter, a setback proportional to the estimated building height was applied. The setback distance was calculated as the building height divided by five (H/5). Considering a standard floor height of 3 m and a maximum of ten stories permitted by the zoning regulations, a setback of approximately 6 m was adopted. Figure 3 illustrates the projected future urban configuration resulting from this process, alongside the existing built environment.
Representation of possible urban configurations based on the 2003, 2013, 2023 and future scenario revisions of the Florianópolis Master Plan
2.4 Model simulation
In the final stage, solar radiation exposure on building envelopes was assessed through annual dynamic simulations using the Ladybug plug-in and a SWERA-type climate file. The simulation environment was fully integrated into Grasshopper, enabling the generation of three-dimensional urban models that accurately represent the geometric characteristics of the study area.
Annual cumulative solar radiation simulations were conducted for all modeled scenarios, considering global solar radiation, including direct, diffuse, and reflected components. Climatic input data were obtained from a SWERA-type weather file, developed under the Solar and Wind Energy Resource Assessment (SWERA) project, an international initiative coordinated by the United Nations Environment Programme (UNEP), the National Aeronautics and Space Administration (NASA), and partner institutions. This dataset integrates satellite observations, ground station data, and numerical atmospheric models, providing long-term climatic information suitable for renewable energy assessments, particularly in regions with limited ground-based measurements.
The SWERA-based climatic file was adopted to ensure consistency with previous solar potential studies conducted in Brazil and to provide a representative characterization of local solar conditions in Florianópolis. The same climatic dataset was applied uniformly across all scenarios to ensure that variations in solar radiation availability resulted exclusively from changes in urban morphology.
Solar radiation was calculated for rooftop and vertical envelope surfaces using a regular sensor grid applied to the building geometries. Grid resolution was defined to balance spatial accuracy and computational efficiency, and simulation outputs were generated in kWh/m² per year, allowing direct comparison across building typologies, heights, and urban configurations.
To enable comparison between scenarios with different levels of densification, simulated solar radiation values were normalized by the total built envelope area. For each scenario, cumulative annual incident radiation was divided by the corresponding built envelope area, resulting in an average solar radiation value per square meter (Rad/m²). Relative variations between scenarios were calculated using percentage differences, forming the basis for the comparative analyses presented in the Results section.
For analytical purposes, buildings were grouped into height categories, including low-rise, mid-rise, and high-rise typologies. Thresholds such as eight stories were identified as critical points where solar radiation availability per square meter exhibited stabilization or significant decline, supporting the identification of densification limits relevant for urban planning applications.
3 Results and discussion
The results obtained from the simulations demonstrate a direct relationship between increasing urban densification and the reduction of solar radiation accessibility on the analyzed buildings. This behavior is observed across all scenarios considered in the study, namely 2003, 2013, 2023, and the projected future scenario. The results indicate that unregulated vertical development and increasing Floor Space Index (FSI) values generate cumulative shading effects, which significantly reduce the availability of solar radiation per square meter of built area.
3.1 Temporal evolution and densification patterns
The analyzed area in Florianópolis exhibits a consistent process of urban densification over time, characterized by both an increase in total built area and a gradual shift in building height patterns. This evolution reflects changes in urban morphology driven by planning regulations and real estate dynamics, which directly influence the spatial distribution of solar radiation in the built environment.
Table 1 summarizes the variation in total built area across the analyzed scenarios. Between 2003 and 2013, the built area increased by approximately 20%, followed by a further increase of 30% between 2013 and 2023. When considering the entire historical period, the cumulative growth in built area between 2003 and 2023 reaches 55%. The projected future scenario indicates a much more pronounced expansion, with an increase of approximately 120% relative to 2023, 190% relative to 2013, and 250% when compared to the 2003 baseline. These values highlight the intensity of the densification process anticipated under the full implementation of the current Master Plan.
Beyond quantitative growth, the densification process is also expressed through changes in building height distribution. In 2003, more than 25% of the total built area corresponded to single-story buildings, and the tallest structures in the study area did not exceed five stories. By 2013, the share of single-story buildings had decreased to approximately 20%, and the first building reaching thirteen stories was identified, marking the initial transition toward vertical development. In 2023, the proportion of single-story buildings further declined to approximately one-sixth of the total built area, while five buildings exceeded seven stories, indicating a clear trend toward increased verticalization.
The projected future scenario represents a substantial intensification of this process. Single-story buildings account for only 2% of the total built area, while buildings taller than seven stories represent approximately 80% of the built mass. This configuration reflects a predominantly high-rise urban fabric, with significant implications for solar radiation accessibility, energy performance, and environmental quality. This transformation is summarized in Table 2, which presents the variation in single-story buildings, maximum building heights, and the increasing dominance of high-rise typologies across the analyzed scenarios.
Together, the temporal evolution of built area and building height composition illustrates a transition from a predominantly low-rise urban fabric to a highly verticalized configuration. This transformation provides the morphological basis for the subsequent analysis of solar radiation availability, as increasing density and height are key drivers of shading, surface obstruction, and reduced solar access in dense urban environments.
3.2 Relationship between urban morphology and solar availability
The total solar radiation available per square meter of built envelope (Rad/m²) in 2013 was 7% lower than the value recorded in 2003. Comparing 2023 to 2013, a reduction of approximately 15% is observed, and when comparing 2023 to 2003, the decrease reaches 20% in solar availability per square meter, as illustrated in the graph in Figure 4a. In the current scenario, a stabilization trend in Rad/m² values is evident starting with buildings with four stories. In the projected future scenario, the overall solar radiation availability per square meter shows a significantly greater reduction, being approximately 64% lower than in 2003, 60% lower than in 2013, and 55% lower than in 2023. The observed reduction in solar radiation availability across scenarios is primarily associated with morphological changes rather than climatic variability. As urban density increases, mutual shading between buildings intensifies, reducing the visible sky fraction and limiting the penetration of solar radiation, particularly on vertical surfaces. The progressive increase in building height and built-up mass amplifies obstruction effects, leading to systematic losses in incident radiation per square meter of built envelope. This pattern highlights the strong dependence of solar availability on urban form, reinforcing the role of density, height, and spatial configuration as key drivers of energy performance in dense urban environments.
(a) Solar radiation per square meter of built envelope; (b) Spacemate diagram with solar radiation per square meter of built envelope
Between 2003 and 2023, the built area increased by 55%, while the average incident solar radiation per square meter of envelope decreased by approximately 20%. Projections for the future scenario indicate that, if the full building potential allowed by the Municipal Master Plan (Lei Complementar No. 739/2023) is utilized, the cumulative loss may reach 64% compared to the initial 2003 scenario. This reduction is particularly pronounced in buildings with ten or more stories, where shaded surfaces account for up to 73% of the potentially active façade area.
The acceleration of solar radiation losses observed in the projected future scenario reflects the cumulative effects of unrestricted build-out within the limits established by current urban regulations. While the historical scenarios (2003, 2013, and 2023) show a gradual decline in solar availability, the future scenario represents a threshold condition in which additional densification produces disproportionately large reductions in incident radiation. This nonlinear behavior indicates that, beyond a certain level of built intensity, incremental increases in height and floor area result in amplified shading effects, particularly in compact urban blocks. Consequently, the projected losses are not merely a continuation of past trends but a structural shift driven by the full exploitation of allowable urban density. The physical parameters of the scenarios are consolidated in Table 3 (2003, 2013, 2023).
These results are consistent with the findings of Sun et al. (2025), who analyzed twelve Asian cities and identified an average annual irradiance loss of 58% in dense urban fabrics lacking height control regulations. Similarly, Chen et al. (2025) demonstrated that in high-density areas with Floor Space Index (FSI) values above 4.0, mutual shading between towers is the primary factor contributing to reduced solar capture, surpassing the effects of latitude or solar orientation. In the case of Florianópolis, spatial analysis reveals that the greatest radiation deficits are concentrated in blocks with minimal lateral setbacks and narrow streets, where the solid angle between opposing façades is reduced. This phenomenon has been widely discussed in the literature as an indicator of urban energy inefficiency (Li et al., 2025; Zhao et al., 2023), since excessive shading diminishes photovoltaic potential and increases the demand for artificial lighting and climate control.
The most significant reduction in solar availability per square meter (Rad/m²) occurs between buildings with one and two stories, with an average decrease of 50%. Between two and three stories, the reduction is more moderate, at around 15%, while the comparison between three and four stories shows another sharp decline of approximately 40%. From five stories onward, including buildings with seven, eight, and ten stories, average reductions stabilize around 50%, with minor variations between these heights (approximately 5% to 10%).
The pronounced reductions in solar radiation availability observed between one- and two-story buildings, as well as between three- and four-story configurations, indicate the strong sensitivity of solar performance to early stages of verticalization. In these ranges, relatively small increases in height substantially intensify mutual shading and reduce the sky view factor, leading to sharp losses in incident radiation. The subsequent stabilization observed in taller buildings suggests the emergence of a morphological threshold, beyond which additional height contributes less significantly to further reductions in average solar availability per square meter. This behavior reflects a shift in the dominant radiation-receiving surfaces from horizontal to vertical envelopes and highlights the existence of critical height ranges that are particularly relevant for urban design and regulatory control.
The consolidated data from Figure 4a is in Table 4. The magnitude of the solar radiation losses identified in this study is consistent with results reported in international literature addressing dense urban environments. Sun et al. (2025) observed average irradiance reductions exceeding 50% in compact urban fabrics lacking performance-based height controls, while Chen et al. (2025) demonstrated that, in areas with Floor Space Index (FSI) values above 4.0, mutual shading becomes the dominant factor limiting solar capture, regardless of latitude or orientation. Similarly, Li et al. (2025) reported substantial declines in solar availability associated with intensified verticalization in high-density contexts. In comparison, the reductions observed in Florianópolis, ranging from approximately 20% in historical scenarios to over 60% in the projected future scenario, fall within the same order of magnitude, reinforcing the robustness of the results and situating the local findings within a broader international pattern of solar performance degradation under increasing urban density.
This stabilization can be explained by the increasing influence of incident radiation on vertical surfaces, which will be discussed in detail later. In the case of the tallest building analyzed, with thirteen stories, its solar radiation availability corresponds to only 27% of the radiation received by a single-story building, highlighting the cumulative impact of shading and reduced solar exposure in taller structures.
In the projected future scenario, a significant reduction in solar radiation availability per square meter of built area is observed, particularly in high-rise and high-density typologies such as ten-story residential buildings and mixed-use configurations combining three-story commercial with ten-story residential components. In these cases, values fall below 400 kWh/m², in stark contrast to the 2003, 2013, and 2023 scenarios, in which lower-rise buildings exhibit values exceeding 1,400 kWh/m². This reduction is attributed to increased shading and obstruction caused by projected urban densification, which negatively affects the energy efficiency of vertical building typologies. In contrast, rooftop surfaces maintain high radiation levels, approaching 2,000 kWh/m², underscoring their potential for solar energy utilization. These findings reinforce the need for urban planning strategies that mitigate the impacts of densification on solar access, such as increased spacing between buildings and height regulation, emphasizing the importance of design interventions to counteract the adverse effects of excessive density.
As illustrated in the Spacemate diagram (Figure 4b), the impact of densification on solar availability follows a downward trend in average radiation values as Floor Space Index (FSI) and Ground Space Index (GSI) increase. Low-rise and wide buildings exhibit average radiation values between 1,800 and 2,000 Wh/m², intermediate typologies range from 1,000 to 1,600 Wh/m², while tall and slender buildings register average values between 500 and 600 Wh/m². This relationship demonstrates that building typology directly influences average solar radiation availability, with significant losses observed in taller and more compact structures. The current design approach results in a gradual decline in solar radiation for taller buildings, reinforcing the challenge of maintaining adequate solar access under increasing urban density.
When analyzing rooftop radiation availability, the comparative values across scenarios mirror the general analysis. In terms of average values, the year 2013 showed an 8% reduction in rooftop radiation availability compared to 2003. Comparing 2023 to 2013, the reduction reached 15%, while the comparison between 2023 and 2003 revealed a decrease of approximately 22%, as illustrated in Figure 5a. In the future scenario, a significant reduction in solar radiation availability is observed, reflecting the impacts of urban densification and increased building heights. Single-story buildings show a decrease of approximately 22% compared to 2023 and 35% compared to 2003. Two-story buildings experience a smaller reduction, around 11% compared to 2023 and 15% compared to 2013. For three-story buildings, the reduction is more pronounced, reaching approximately 41% compared to 2023 and 42% compared to 2013. This trend continues in four- and five-story buildings, with reductions of up to 32% compared to 2023. In taller buildings, such as those with seven and ten stories, solar availability is drastically reduced, with losses of 21% and 22% compared to 2023, respectively. Rooftop surfaces also experience significant reductions, reaching 22% compared to 2023 and 32% compared to 2003. In mixed-use buildings, single-story commercial structures exhibit the highest percentage drop, with a 47% reduction compared to 2023, while three-story commercial buildings show a 38% decrease. In configurations combining commercial and residential uses, losses are similarly substantial, reinforcing the impact of building density and height on solar radiation availability.
(a) Solar radiation per square meter of rooftop surface; (b) Spacemate diagram with solar radiation per square meter of rooftop surface
The consolidated data from Figure 5a is in Table 5. When analyzing buildings with varying heights, a significant reduction in available solar radiation is observed. For instance, there is an approximate 50% decrease in solar radiation per square meter of built area when comparing two-story buildings with single-story buildings. When comparing three-story buildings with two-story ones, the reduction reaches approximately 30%. This downward trend continues in taller buildings, with a thirteen-story building receiving only 5% of the solar radiation per square meter compared to a single-story building. The difference in rooftop solar availability across building typologies is even more pronounced, as shown in Figure 5b.
It is important to note that the total rooftop area remains constant despite the increase in built area resulting from additional stories. Therefore, analyses of solar radiation on vertical envelopes become essential in the context of urban verticalization and densification.
The average solar radiation per square meter on vertical walls in 2013 was 8% lower than in 2003. The reduction observed in 2023 compared to 2013 was approximately 11% and 9% when compared to 2003, as illustrated in Figure 6a. In buildings with one, two, and three stories, the variations were relatively small, ranging from 2% to 7%. However, in taller buildings, the losses were more substantial, reaching up to 22% due to shading in the 2023 scenario. When comparing taller buildings with lower ones, the difference in available solar radiation per square meter reaches approximately 37%. In the projected future scenario, an even more pronounced reduction is observed, with significant declines in solar radiation across all building heights. Notably, three-story buildings show a 62% reduction compared to 2023, and seven-story buildings show a 43% reduction, reinforcing the impact of densification and verticalization on solar availability.
(a) Solar radiation per square meter on vertical walls; (b) Spacemate diagram with solar radiation per square meter on vertical walls
The stronger reductions observed on vertical façades are mainly associated with increased lateral obstruction and the canyon effect in dense urban configurations. As building height and proximity increase, façades experience greater shading from adjacent structures, limiting direct solar exposure and reducing diffuse radiation contributions. This effect is particularly critical in compact blocks with narrow street widths, where vertical surfaces become highly sensitive to changes in height and spacing. As a result, façade solar availability emerges as a limiting factor for photovoltaic integration and daylight performance in dense urban environments. The consolidated values for solar radiation on vertical walls are presented in Table 6, showing the progressive reduction in façade solar availability across the temporal scenarios and the projected future configuration.
The difference in solar radiation availability per square meter on vertical walls across building typologies is less pronounced, primarily because taller buildings possess larger wall surface areas for solar capture, as illustrated in Figure 6b.
The ongoing urbanization and vertical development in Florianópolis over the years have resulted in a significant decline in solar radiation accessibility, both on rooftops and vertical façades. These findings underscore the urgent need to incorporate solar accessibility into urban planning strategies to foster more sustainable and climate-responsive cities. Buildings with more stories are disproportionately affected by reduced solar exposure, emphasizing the importance of design strategies that account for building height to optimize solar capture.
While rooftop surfaces consistently maintain higher levels of solar radiation across all scenarios, vertical façades become increasingly constrained under higher density conditions. Rooftops benefit from reduced obstruction and greater sky exposure, whereas façades are more directly affected by mutual shading and street geometry. Consequently, in highly verticalized scenarios, façades represent the critical surface for assessing solar accessibility, as they exhibit the most pronounced relative losses despite the persistence of favorable rooftop conditions.
Overall, the results indicate that increasing urban density and building height systematically reduce solar radiation availability per square meter of built envelope, with particularly severe impacts on vertical surfaces. The identification of height-related thresholds and nonlinear loss patterns highlights the limitations of density-based indicators alone in capturing energy performance outcomes. These findings support the need for complementary metrics capable of integrating urban form and solar performance, providing the basis for the Solar Accessibility Index (SAI) introduced in the following section.
3.3 Comparison with International and National Studies: An Integrated Perspective
To complement the analysis based on absolute solar radiation values (Rad/m²), this study introduces the Solar Accessibility Index (SAI) as a normalized indicator designed to capture the relationship between urban density and available solar radiation. The SAI enables a more explicit comparison of solar performance across scenarios with different levels of verticalization and built intensity, addressing limitations associated with the use of absolute radiation values alone in dense urban contexts.
The Solar Accessibility Index was calculated by normalizing the average annual solar radiation incident on the built envelope by the corresponding level of urban densification. In this study, the SAI expresses the ratio between the available solar radiation per square meter of built envelope and the built intensity represented by urban morphology indicators. By integrating radiation availability and density-related parameters, the index provides a synthetic measure of how efficiently urban form allows access to solar resources under different spatial configurations. The resulting classification is presented in Table 7, which compares the average solar radiation, relative built intensity, and Solar Accessibility Index across the analyzed scenarios.
As shown in Table 7, the Solar Accessibility Index (SAI) highlights a clear decoupling between urban densification and solar performance across the analyzed scenarios. While historical configurations exhibit relatively balanced relationships between built intensity and solar availability, the progressive increase in density observed in recent and projected scenarios results in a disproportionate reduction in solar accessibility. In the future scenario, the low SAI value indicates that additional built intensity is no longer compensated by proportional access to solar radiation, confirming the presence of critical densification thresholds. This behavior reinforces the limitations of density-based indicators alone and demonstrates the relevance of normalized metrics such as the SAI for evaluating the solar performance of dense urban forms.
The results indicate a progressive decline in SAI values across the analyzed scenarios. Historical scenarios exhibit higher index values, reflecting urban configurations in which solar availability remains relatively proportional to built density. In contrast, the projected future scenario presents substantially lower SAI values, indicating that increases in built area and height are no longer compensated by proportional access to solar radiation. This behavior confirms that densification beyond certain thresholds leads to disproportionate losses in solar accessibility, even when total radiation levels remain high on specific surfaces such as rooftops.
When analyzed by building height, the SAI reveals marked differences between low-rise and high-rise typologies. Low-rise buildings consistently present higher index values, indicating more favorable conditions for solar access per unit of built area. Conversely, high-rise buildings show significantly lower SAI values, reflecting the cumulative effects of mutual shading, reduced sky exposure, and increased obstruction of vertical envelopes. These results reinforce the interpretation that building height plays a decisive role in mediating the relationship between density and solar performance.
From a comparative perspective, the trends observed in the SAI are consistent with findings reported in international studies addressing solar accessibility and urban form. Zhao et al. (2023) emphasize the importance of considering solar access as a distributive urban resource, particularly in dense environments where unequal exposure may exacerbate energy and environmental inequities. Similarly, Li et al. (2025) propose the use of normalized solar indicators to support zoning strategies that reconcile densification with energy performance. In this context, the SAI contributes to the operationalization of these concepts by providing a quantitative metric that links urban morphology to solar accessibility outcomes.
Overall, the Solar Accessibility Index enhances the analytical framework of this study by translating complex interactions between density, height, and radiation into a comparable metric. Its application allows the identification of critical densification thresholds and supports the evaluation of urban configurations from an energy-performance perspective. As such, the SAI represents a valuable tool for informing performance-based urban planning strategies, particularly in cities undergoing rapid verticalization, such as Florianópolis.
4 Discussion
The results of this study reinforce the central role of urban morphology in shaping solar radiation accessibility and, consequently, the energy performance of buildings in dense urban environments. Rather than reflecting isolated design conditions, the observed reductions in solar availability emerge as a systemic outcome of cumulative densification processes governed by conventional planning parameters. These findings highlight that the interaction between building height, spacing, and built intensity produces nonlinear impacts on solar performance that are not adequately captured by density-based indicators alone.
The progressive decline in solar accessibility associated with increasing Floor Space Index (FSI) and Ground Space Index (GSI) illustrates the limitations of regulatory frameworks that prioritize buildable potential without explicitly addressing energy-related performance. While these indices effectively control urban form in quantitative terms, they remain largely insensitive to the spatial configuration of buildings and the resulting patterns of shading and obstruction. As demonstrated in this study, the stabilization of solar losses only at higher building heights indicates the existence of morphological thresholds beyond which additional verticalization yields diminishing returns in terms of usable solar access.
The introduction of the Solar Accessibility Index (SAI) contributes to addressing this regulatory gap by providing a normalized metric capable of linking urban density to solar performance outcomes. Unlike absolute radiation values, the SAI captures the efficiency with which urban form enables access to solar resources under different densification regimes. In this sense, the index aligns with recent international efforts to operationalize solar accessibility as a planning variable rather than treating solar radiation solely as a building-scale design constraint (Zhao et al., 2023; Li et al., 2025). Its application allows the identification of critical conditions under which densification compromises solar access, supporting more informed evaluations of urban development scenarios.
From a comparative perspective, the patterns observed in Florianópolis are consistent with findings reported in other high-density contexts. Studies conducted in Asian and European cities have demonstrated that compact urban fabrics lacking performance-based height and setback controls experience substantial losses in photovoltaic potential and façade irradiance (Sun et al., 2025; Chen et al., 2025). The alignment between these international cases and the results obtained in Florianópolis suggests that the observed mechanisms are not context-specific but reflect broader morphological dynamics inherent to dense urban development.
Beyond energy performance, reduced solar accessibility has broader implications for urban environmental quality and social equity. Concentrated shading in high-density areas may exacerbate disparities in access to renewable energy, daylight, and thermal comfort, particularly in neighborhoods characterized by intense verticalization and high real estate pressure. As discussed in the solar equity framework, access to sunlight can be understood as a shared urban resource whose distribution is influenced by planning decisions (Zhao et al., 2023). In this regard, the results indicate that treating solar accessibility as an explicit planning parameter may contribute not only to energy efficiency but also to more equitable urban environments.
The methodological approach adopted in this study further supports these interpretations. The combined use of Spacemate with parametric modeling and solar simulation tools enables a three-dimensional understanding of how urban form mediates energy performance across multiple scales. This integrated framework facilitates the identification of relationships between density, typology, and solar availability that remain obscured in two-dimensional or purely regulatory analyses. Similar methodological strategies have been advocated in recent studies on low-carbon and performance-based urban planning, underscoring their relevance for policy-oriented research (Li et al., 2025).
Nevertheless, the translation of solar accessibility metrics into planning practice remains challenging. Regulatory instruments must balance competing objectives, including housing demand, land value, and infrastructure capacity. As such, the incorporation of solar performance indicators is unlikely to occur through blanket restrictions but may be more effectively implemented through targeted mechanisms, such as pilot zones, adaptive setbacks, or differentiated height-to-width ratios. In this context, the designation of Urban Solar Zones (USZs) emerges as a flexible strategy for testing performance-based controls while accommodating local development pressures.
Overall, the findings suggest that advancing solar-responsive urban development requires moving beyond density-focused regulation toward a more integrated understanding of urban form and energy performance. By demonstrating how solar accessibility responds to specific morphological conditions, this study contributes to ongoing discussions on how planning frameworks can better align densification processes with energy transition objectives, particularly in rapidly verticalizing cities.
5 Conclusions
This study investigated the evolution of solar radiation accessibility in Florianópolis by comparing historical, current, and projected urban scenarios through three-dimensional parametric modeling and solar radiation simulations. The results confirm that urban morphology plays a decisive role in shaping solar availability in dense environments, demonstrating that increases in built density and building height systematically constrain access to solar radiation at the building scale.
The comparative analysis across scenarios shows that urban densification, when driven primarily by conventional planning indicators such as Floor Space Index (FSI) and Ground Space Index (GSI), leads to substantial reductions in solar radiation availability per square meter of built envelope. These reductions become particularly pronounced in highly verticalized configurations, indicating the existence of critical densification thresholds beyond which additional built intensity results in disproportionate losses in solar accessibility.
By introducing the Solar Accessibility Index (SAI), this study provides a complementary metric capable of linking urban form and solar performance within a single analytical framework. The SAI enables a normalized assessment of solar accessibility across different urban configurations, supporting the identification of morphological conditions under which densification compromises energy-related performance. As such, the index offers a practical contribution to performance-oriented urban analysis, especially in cities undergoing rapid vertical development.
From a planning perspective, the findings highlight the limitations of density-based regulatory approaches that do not explicitly account for solar performance. Incorporating solar accessibility parameters into urban regulations may support the development of more balanced urban forms, capable of reconciling densification with energy efficiency and environmental quality. In this context, the integration of indicators such as the SAI into zoning instruments and planning guidelines represents a relevant step toward more solar-responsive urban development.
Overall, the methodological approach and results presented in this study contribute to ongoing efforts to align urban planning with energy transition goals. By demonstrating how urban form directly influences solar accessibility, the study reinforces the importance of integrating energy-related performance criteria into local planning practices, particularly in subtropical cities where building height, spacing, and orientation play a critical role in shaping access to solar resources.
Although the adopted methodology provides consistent results with high spatial resolution, the study presents some limitations that should be acknowledged. First, the simulations were based on average annual meteorological conditions and did not account for microclimatic variations or extreme weather events, which may influence thermal behavior and radiation fluxes in urban areas. Additionally, the future scenario represents a theoretical limit based on the maximum building potential allowed by the Master Plan and may diverge from actual real estate market trends.
Another limitation concerns the absence of socioeconomic variables in the model. While the study focuses on physical and energy aspects, solar accessibility also has a social dimension associated with equitable access to energy and urban environmental quality. Future research could integrate socio-spatial and energy vulnerability indicators, aligning with the solar equity framework proposed by Zhao et al. (2023).
As a continuation, it is recommended to expand the methodology to other Brazilian urban contexts, testing the applicability of the Solar Accessibility Index across different morphologies and developing decision-support tools for public managers capable of cross-referencing morphological and climatic data in real time. It is also suggested to incorporate multi-objective analyses that simultaneously consider solar capture, natural ventilation, and thermal comfort, as recommended by Chen et al. (2025), to support integrated guidelines for sustainable urban planning.
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Declaration of Generative AI and AI-Assisted Technologies in the Writing Process
During the preparation of this work, the author used ChatGPT to assist with the grammatical review of the text translation. Following the use of this tool, the author critically reviewed and edited the content, taking full responsibility for the accuracy, integrity, and final phrasing of the published work.
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Financial Support
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. However, some authors were scholarship holders from national research funding agencies that indirectly made it possible. We would like also to thank National Council for Scientific and Technological (CNPq) Brazil – Finance Code PQ 302014/2025-0.
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DOMINGOS, R. M. A.; MARIANO, P. O. P.; PEREIRA, F. O. R. Urban transformations and solar accessibility: a study on Florianópolis. Ambiente Construído, Porto Alegre, v. 26, e151617, jan./dez. 2026. ISSN 1678-8621 Associação Nacional de Tecnologia do Ambiente Construído. http://dx.doi.org/10.1590/s1678-86212026000100993
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
- AKSIN, F. N.; SELÇUK, S. A. Theories and models of parametric design thinking. In: CONFERENCE ON EDUCATION AND RESEARCH IN COMPUTER AIDED ARCHITECTURAL DESIGN IN EUROPE, 39., Novi Sad, 2021. Proceedings [...] Novi Sad, 2021.
- BASTIAN, A. V. Morfologia urbana e a geração de energia solar fotovoltaica em Salvador Salvador, 2023. Tese (Doutorado em Arquitetura e Urbanismo) – Universidade Federal da Bahia, Salvador, 2023.
- BERGHAUSER PONT, M. Y.; HAUPT, P. A. Space, density and urban form Dissertation (TU Delft) – Delft University of Technology, Delft, 2009.
- CHEN, L. et al. Multi-objective optimization of photovoltaic integration in high-density urban fabrics. Renewable Energy, v. 236, p. 123176, 2025.
- DOMINGOS, R. M. A.; PEREIRA, F. O. R. Comparative cost-benefit analysis of the energy efficiency measures and photovoltaic generation in houses of social interest in Brazil. Energy and Buildings, v. 243, 111013, 2021.
- GIROTTI, C.; MARINS, K. R. C.; LARA, A. H. Análise da morfologia urbana para maximização de geração de energia fotovoltaica no Belenzinho, em São Paulo. Ambiente Construído, Porto Alegre, v. 19, n. 4, p. 7–22, out./dez. 2019.
- GODOY-SHIMIZU, D.; STEADMAN, P.; EVANS, S. Density and morphology: from the building scale to the city scale. Buildings and Cities, v. 2, n. 1, p. 92–113, 2021.
- LAN, H.; GOU, Z.; HOU, C. Understanding the relationship between urban morphology and solar potential in mixed-use neighborhoods using machine learning algorithms. Sustainable Cities and Society, v. 87, 104225, 2022.
- LI, X. et al Integrating solar energy and urban morphology for net-zero planning. Landscape and Urban Planning, v. 256, 105890, 2025.
- MARIANO, P. O. P. Processo de projeto paramétrico de elementos de fachada com características da geometria fractal Florianópolis, 2018. 189 f. Dissertação (Mestrado em Arquitetura e Urbanismo) – Universidade Federal de Santa Catarina, Florianópolis, 2018.
- MARIANO, P. O. P.; PEREIRA, A. T. C.; VAZ, C. V. Autonomous parametric process for daylight simulation applied to the proposal of a daylighting of buildings performance tool. In: CONGRESSO DA SOCIEDADE IBERO-AMERICANA DE GRÁFICA DIGITAL, 24., Medellín, 2020. Proceedings [...] Medellín: SIGRADI, 2020.
- MARIANO, P. O. P.; PEREIRA, A. T. C.; VAZ, C. V. Avaliação luminosa de elementos de fachada com características fractais. PARC Pesquisa em Arquitetura e Construção, v. 9, n. 1, p. 3–18, mar. 2018.
- OXMAN, R. Digital design thinking: in the new design is the new pedagogy. In: COMPUTER-AIDED ARCHITECTURAL DESIGN RESEARCH IN ASIA ANNUAL CONFERENCE, 11., Kumamoto, 2006. Proceedings […] Kumamoto, 2006a.
- OXMAN, R. Theory and design in the first digital age. Design Studies, v. 27, n. 3, p. 229–265, may 2006b.
- OXMAN, R.; HAMMER, R.; ARI, S. B. Performative design in architecture: employment of virtual prototyping as a simulation environment in design generation. In: ECAADE, 25., Frankfurt, 2007. Proceedings [...] Frankfurt, 2007.
- Prefeitura Municipal de Florianópolis. Lei Complementar nº 739, de 2023. Altera a Lei Complementar nº 482, de 2014 (Plano Diretor de Florianópolis) e consolida seu processo de revisão. Florianópolis, 2023.
- SUN, R. et al Assessing the spatiotemporal evolution of urban solar potential under densification scenarios. Energy Reports, v. 18, p. 149–164, 2025.
- ZHANG, X. et al A systematic review of urban form generation and optimization for performance-driven urban design. Building and Environment, v. 253, 111269, 2024.
- ZHAO, H. et al. Solar building envelope potential in urban environments: a state-of-the-art review of assessment methods and framework. Building and Environment, v. 244, 110831, 2023.
- ZHAO, K.; GOU, Z. Influence of urban morphology on facade solar potential in mixed-use neighborhoods: block prototypes and design benchmark. Energy and Buildings, v. 297, 113446, 2023.
Edited by
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Editor-in-chief:
Enedir Ghisi
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Guest editor:
Fernando Sá Cavalcanti
