Introduction
Literature review
Materials and Methodology
Geometry and Material Parameters
Tools
Ladybug and Honeybee
Colibri and Design Explorer 2
TT Toolbox
Results
Overview of Simulation Setup
General Findings
Ideal Theoretical Material
Optimal Practical Choice
Existing Building Material
Worst Case Material Scenario
Shade Performance Analysis
Optimal Shade Configurations
Discussion
Implications of Findings
Advantages of the Simulation Approach
Future Research Directions
Integration with Urban Development and Policy Making
Declaration of generative AI and AI-assisted technologies in the writing process
Introduction
Buildings account for nearly 40% of global annual energy consumption, highlighting the urgent need for innovative and sustainable design practices to enhance energy efficiency [1]. The building envelope is critical in this regard, serving as the primary barrier against external climatic influences while maintaining indoor comfort levels. In typical office buildings in India, for instance, HVAC systems—vital for maintaining these comfort levels contribute to approximately 55% of total energy usage [2].
This study introduces an innovative optimization framework for facade materials and shading systems in Tehran, emphasizing cost-effective and passive solutions suitable for broad implementation. By integrating advanced simulation tools, specifically Ladybug and Honeybee, this research not only facilitates the integration of daylight and thermal simulations into the design process but also supports enhanced decision-making through interactive monitoring charts that ensure compliance with regulatory standards.
The adoption of parametric modeling enables the efficient exploration of diverse design solutions, allowing for adjustments in parameters such as color, scale, and orientation to optimize energy performance. This approach not only promotes the development of energy-efficient buildings but also aligns with local building codes, thereby supporting sustainable urban development. Moreover, the study underscores the viability of passive, low-cost design solutions that are accessible and practical, fostering wider adoption among urban developers. The findings from this research are poised to offer valuable insights to architects, designers, and urban planners, advocating for the adoption of energy-efficient practices in both new constructions and retrofitting projects, with the potential to significantly impact energy conservation efforts globally.
Literature review
The construction industry plays a significant role in exacerbating energy resource depletion and contributing to global warming, both of which are paramount concerns for humanity. This sector accounts for over one-third of the world’s total energy consumption and is responsible for approximately 40% of carbon dioxide (CO2) emissions [3]. Moreover, the building sector’s energy consumption is projected to increase annually by 1.5% in OECD member countries and by 2.1% in developing nations from 2012 to 2040 [4]. Therefore, within the expansive realm of architectural discourse, the notion of performance holds significant and enduring importance [5].
The profound influence of digitalization is evident in modern architecture, where tools such as those used by Zhang et al. [6] demonstrate that strategic design modifications through parametric tools can significantly reduce energy consumption in residential buildings in Beijing. This shift in design practices, where artificial intelligence and machine capabilities increasingly supplement or even supplant human sensory input, is transforming the conventional manual approach to design into a process characterized by automation, iterative refinement, and innovative form exploration [7]. Sustainable building design aims to achieve a harmonious global equilibrium by minimizing reliance on nonrenewable energy sources and mitigating adverse environmental effects. Extensive research indicates that various building components and systems play pivotal roles in conserving energy and reducing emissions. Notably, design elements—including factors as subtle as color—pertaining to building physics, particularly the building envelope, shape, and shading systems, significantly influence both energy efficiency and indoor comfort levels [8, 9].
Researchers have employed various advanced optimization methods to enhance building energy efficiency. Nguyen et al. [10] and Wright and Farmani [11] explored genetic algorithms for simultaneous optimization of building components, demonstrating how these integrated optimizations can enhance building energy efficiency. Li et al. [12] conducted a systematic review on performance-oriented architectural design, underscoring its role in sustainable architecture through the use of advanced optimization technologies that enhance both energy efficiency and aesthetic value.
Sun et al. [13] and Wright and Farmani [11] highlight active and passive solutions for achieving Nearly Zero Energy Buildings (NZEB) during the operational phase. This includes optimizing energy-intensive systems like lighting, heating, ventilation, and air conditioning (HVAC), as well as implementing shading devices to minimize solar heat gain through the façade. In a closely related effort, Khidmat et al. [14] developed a benchmark model using parametric design exploration to optimize building energy and daylight performance in the early design phases, focusing on variables such as glazing ratio and building orientation to enhance environmental sustainability in Japan’s sub-tropical climate. Yet, the real-time application of these optimized designs in monitoring and adjusting building performance remains a largely untapped area, which this study seeks to explore by introducing cost- effective, passive monitoring solutions.
In Tehran, Jalali et al. [15] provide a detailed analysis of facade material choices, identifying travertine as the predominant choice. Their study highlights the relationship between material types and building ages, emphasizing their impact on environmental and architectural sustainability.
This literature review sets the stage for introducing a benchmark-driven optimization model that not only adheres to the principles of sustainable design but also innovates in the realm of real-time performance monitoring. By integrating low-cost, passive monitoring systems into optimized facade designs, this research aims to provide a practical solution that enhances energy efficiency and monitoring in urban buildings, particularly suitable for developing metropolitan areas like Tehran
The construction industry plays a significant role in exacerbating energy resource deple- tion and contributing to global warming, both onergy efficiency and monitoring in urban buildings, particularly suitable for developing metropolitan areas like Tehran.
Materials and Methodology
This study employs simulation and modeling techniques to analyze and optimize facade and shade designs within the urban environment of Tehran, aiming to enhance building energy efficiency and occupant comfort. By using parametric modeling tools integrated with Rhino’s 3D capabilities, this research allows for the manipulation of design variables within an interactive setting, which is critical for developing context-specific optimized design solutions.
The simulations utilize historical weather data sourced from climate.onebuilding.org for Mehrabad station covering the years 2007-2021, ensuring the environmental conditions reflected in the model accurately represent Tehran’s climate. The specific site of investigation, located approximately 7 kilometers from Mehrabad in the Kooye Nasr area of Tehran, provides a setting to explore the influence of local microclimatic conditions on building performance.
The building in focus for this research is a residential structure situated in the Kooye Nasr area of Tehran, located on a plot of 280 square meters. This five-story building is characterized by its use of travertine stone on the façade. The choice of travertine, a common building material in Tehran’s architecture provides a unique opportunity to analyze the interaction between traditional materials and modern building techniques in an urban setting. The architectural and material details of this structure are illustrated in the image below (see Figure 1).
The choice of a residential building in Tehran’s Kooye Nasr area, characterized by its use of travertine—a popular local facade material—serves as an ideal subject for exploring the optimization of building facades for enhanced energy efficiency. This selection is scientifically strategic, as travertine’s thermal properties are representative of traditional materials needing evaluation for energy performance in Tehran’s distinct climate, with its hot summers and cold winters. The building’s typical urban residential design ensures that findings can be generalized across similar structures within the city, providing a blueprint for broader sustainability improvements. Additionally, studying this building within its specific microclimatic conditions near Mehrabad allows for an assessment of localized environmental impacts on energy efficiency, offering insights crucial for developing finely tuned, scalable energy-saving strategies. This approach not only aligns with Tehran’s evolving regulatory framework aimed at reducing energy consumption and environmental impacts but also supports local industries and cultural aesthetics, thereby fostering economic sustainability and cultural preservation alongside environmental goals.
In the modeling process, significant emphasis was placed on accurately representing Tehran’s diverse seasonal climates rather than relying on a single day’s data. While the EPW data for Tehran indicates an average annual temperature of approximately 18.62°C, this does not adequately capture the city’s climatic extremes during summer and winter. Therefore, simulations were specifically conducted for the defined warm (May to September) and cool (November to March) periods, as illustrated in the seasonal temperature variation graph sourced from WeatherSpark [16]. This approach ensures that the simulations more realistically reflect the environmental challenges faced during Tehran’s hottest and coldest months, providing a reliable basis for assessing the thermal performance of facade and shading systems under typical seasonal conditions.
This graph shows the seasonal temperature variations in Tehran, indicating the defined warm (May to September) and cool (November to March) seasons. These periods, sourced from WeatherSpark, were used to set the parameters for our simulation to align the design optimizations with the specific climate conditions of Tehran. The annual temperature profile for Tehran, which substantiates these periods, is depicted in Figure 2[16].
The methodology is centered around a parametric and iterative testing approach, facilitated by the Grasshopper platform, to explore various architectural adjustments under simulated environmental conditions. This detailed approach enables precise control over variables such as lighting, heat transfer, and energy flows, offering granular insights into the impact of diverse design configurations.
Geometry and Material Parameters
External Material Diameter
Adjustable from 1 to 3 cm in 0.5 cm increments, totaling five steps.
Thermal Conductivity of the Material
Set between 0.5 to 3.5 watts per meter-kelvin in increments of 0.5, resulting in seven steps.
Emissivity
Varied from 0.1 to 0.9 with increments of 0.1, resulting in nine distinct steps.
Total Shade Angle
Ranged from -0.5 to +0.5 radians, adjusted in 0.2 radians increments.
Blade Angle
Adjustable from -0.9 to +1.1 radians in 0.2 radians increments, covering eleven steps.
Number of Blades
Varied from 3 to 6, with four distinct settings.
Shade Width
Set between 0.2 to 0.8 meters in 0.2 meter increments.
Blade Depth
Determined by dividing the total width by the number of blades.
These parameters enabled two distinct sets of simulations: 315 iterations focused on exploring various material properties and 1056 iterations dedicated to optimizing shade configurations. This approach allowed for an extensive examination of both material properties and shade designs to enhance building thermal efficiency, tailored to the specific seasonal solar conditions of Tehran. For shading configurations, the analysis focused on calculating the differential impact of radiation between the cold and warm seasons to assess efficacy in enhancing winter gain while reducing summer exposure. The specifics of each variable used in the shading optimization process are illustrated in Figure 3 and Table 1. Additionally, an aggregate radiation value for both seasons was computed to gauge overall exposure levels. Material optimizations were assessed based on seasonal performance metrics including heat transfer and radiation for summer and winter, followed by a comprehensive evaluation of the combined seasonal impacts to provide a holistic view of thermal performance across the year.
Table 1.
Design parameters for facade materials and shading in energy optimization
Tools
This research utilized a suite of parametric and simulation tools integrated into the 3D modeling software Rhinoceros, via the Grasshopper platform. This integration allowed for flexible manipulation of design variables, essential for the parametric exploration of facade and shade designs.
The research was conducted in a range of consecutive stages, commencing with ideation and ending with design exploration, which will be elaborated in the subsequent section.
Ladybug and Honeybee
These plugins from Ladybug Tools were crucial for conducting environmental and energy analyses, allowing for the analysis of microclimates and the importation of EnergyPlus Weather data (EPW). Honeybee connected Grasshopper to several simulation engines such as EnergyPlus, Radiance, Daysim, and OpenStudio, enhancing the environmental analysis capabilities. The comprehensive work scheme of the Ladybug and Honeybee plugins is depicted in Figure 4[17].
Colibri and Design Explorer 2
Instrumental in refining design options, these tools supported the iterative exploration of parametric design variations and developed interactive benchmarks.
TT Toolbox
Supported by Thornton Tomasetti, this toolbox helped manage data and workflows within Grasshopper, streamlining the design exploration and optimization process.
The combination of these tools facilitated the creation of an interactive benchmark model that supports decision-making processes, incorporating multifaceted design impacts including aesthetic, environmental, social, and economic factors prior to construction. Figure 5 illustrates the research workflow.
Results
The overarching aim of this study was to significantly enhance the thermal efficiency of the building by adapting to Tehran’s unique seasonal solar conditions. The effectiveness of each design configuration was quantified by assessing the difference in radiation between the seasons, with the optimal designs achieving the largest differential in radiation, thus demonstrating a sustainable approach to architectural design in varying climatic conditions.
This section presents the findings from the simulation and optimization processes conducted to enhance the energy efficiency and comfort of building facade and shade designs within urban settings. Utilizing advanced parametric modeling tools and environmental analysis plugins, we systematically evaluated and refined various design configurations. The results, depicted in Figure 6, highlight the performance differences among the best, worst, existing, and optimal practical material choices, providing valuable insights into their impact on energy consumption and thermal performance. The correlation between material properties and thermal performance metrics, such as heat loss and radiation, is shown in Figure 7. Detailed comparative analyses of shading devices and facade materials are included, supported by quantitative data and visual representations to illustrate the effectiveness of the proposed design optimizations.
Overview of Simulation Setup
This study utilized Design Explorer to evaluate facade and shading design parameters. The setup facilitated a methodical variation of design elements such as material thickness, conductivity, emissivity, and shading configurations.
These visualizations underscore the iterative optimization process employed, pinpointing designs that optimize energy efficiency and comfort in urban building environments.
General Findings
The analysis underscores significant variations in radiation and heat loss across different materials and shading configurations, essential for optimizing building energy performance in Tehran. The Ideal Theoretical Material demonstrated the most effective reduction in heat loss and radiation, while the Worst Case Material Scenario exhibited the highest levels, as illustrated in Figure 7. Additionally, the shade design analysis showed a notable difference in radiation between seasons, with the optimal configuration effectively balancing radiation during the cold and warm seasons as depicted in Figure 6. These findings highlight the importance of selecting appropriate materials and designs to enhance energy conservation and meet Tehran’s specific climatic and regulatory needs. Figures illustrating these variations are presented below in Figure 8 and Figure 9.
Ideal Theoretical Material
The Ideal Theoretical Material, with a thickness of 3 cm, thermal conductivity of 0.5 W/m·K, and emissivity of 0.1, demonstrated outstanding thermal performance across different seasonal conditions. In summer, it achieved a heat transfer of 0.012615 kWh/m² and radiation of 0.259336 kWh/m², leading to a total of 0.271951 kWh/m². During winter, the heat transfer increased to 0.018976 kWh/m² and radiation to 0.49472 kWh/m², culminating in a total of 0.513696 kWh/m². The combined seasonal total was 0.785647 kWh/m², reflecting the material’s capability to significantly reduce heat loss and radiation throughout the year. Figure 10 showcases these thermal performance metrics, emphasizing the material’s suitability for the specific climatic and architectural conditions of the studied building.
Optimal Practical Choice
For the Optimal Practical Choice, polished white limestone was selected, featuring a thickness of 3 cm, thermal conductivity of 1.5 W/m·K, and emissivity of 0.8. During the summer, this configuration led to a heat transfer of 0.026469 kWh/m² and radiation of 2.074688 kWh/m², amounting to a total of 2.101157 kWh/m². In the winter, the heat transfer increased to 0.039453 kWh/m² and radiation to 3.957758 kWh/m², resulting in a total of 3.99721 kWh/m². The combined total for summer and winter was 6.098367 kWh/m², demonstrating the material’s effectiveness in managing thermal properties across seasons. Figure 11 illustrates these metrics, highlighting the limestone’s adherence to Iran’s building regulations and its efficiency in enhancing thermal retention while minimizing radiation.
This practical choice balances performance with compliance and aesthetic qualities, making it a viable option for widespread architectural application, particularly in climates similar to Iran’s.
This version clearly connects the specific properties of the chosen material to the practical requirements of building regulations and environmental considerations in Iran, emphasizing its applicability and benefits.
Existing Building Material
The existing facade material, cream travertine, has a thickness of 1.5 cm, thermal conductivity of 2.5 W/m·K, and emissivity of 0.9. During the summer, this material results in a heat transfer of 0.035653 kWh/m² and radiation of 2.334024 kWh/m², giving a total of 2.369677 kWh/m². In winter, the heat transfer increases to 0.052727 kWh/m² and radiation to 4.452477 kWh/m², leading to a total of 4.505204 kWh/m². The combined heat transfer and radiation for both seasons total 6.874881 kWh/m². Figure 12 illustrates these metrics, highlighting the material’s performance within the existing building structure. While cream travertine offers aesthetic appeal, its thermal properties contribute to slightly higher energy consumption compared to more optimal practical choices. Moreover, even though cream travertine is favored for some applications, it should be noted that the stone has inherent porosity, leading to holes, and its high emissivity can be a disadvantage in energy-efficient building design. These factors emphasize the need for careful material selection in energy-efficient building design.
Worst Case Material Scenario
The worst case material scenario features a facade with a thickness of only 1 cm, a high thermal conductivity of 3.5 W/m·K, and emissivity of 0.9. For this configuration, the summer heat transfer is recorded at 0.041007 kWh/m² and radiation at 2.334024 kWh/m², resulting in a total of 2.375031 kWh/m². In the winter, heat transfer increases to 0.060317 kWh/m² with radiation reaching 4.452477 kWh/m², bringing the total to 4.512794 kWh/m². The combined heat transfer and radiation for both seasons amount to 6.887825 kWh/m². These figures are graphically represented in Figure 13, demonstrating the inefficacy of this material in thermal management.
This scenario underscores the critical impact of selecting appropriate facade materials. Its high conductivity and thin profile lead to excessive energy losses, marking it as an unsuitable option for energy-efficient building design.
This example clearly illustrates the negative consequences of using materials with poor thermal properties, emphasizing the importance of careful material selection to achieve optimal energy efficiency.
Shade Performance Analysis
The shade performance analysis employed parametric modeling to evaluate and optimize the shading system’s effectiveness across different seasonal conditions in Tehran. The analysis, as illustrated in Figure 14, considered multiple outcomes based on radiation metrics.
Optimal Shade Configurations
Maximized Differential Configuration
This design, depicted in Figure 15, strategically maximizes the differential in radiation between the cold and warm seasons, optimizing thermal comfort throughout the year. The configuration features three blades, each set at an angle of -0.1 radians, with a total shade angle of -0.5 radians, a width of 0.8 meters, and a blade depth of approximately 0.267 meters. The radiation during the cold season is measured at 4.657425 kWh/m², while in the warm season, it is 1.839769 kWh/m², resulting in a beneficial net differential of 2.817656 kWh/m². Additionally, the combined radiation for both seasons totals 6.497194 kWh/m². This shade design proves most effective in maximizing solar heat gain during the cold season while significantly reducing unwanted solar radiation in the warm season.
Minimized Total Radiation Configuration
This setup, depicted in Figure 16, is designed to minimize the total seasonal radiation, effectively reducing overall energy absorption by the facade. The optimized configuration achieves the lowest collective radiation exposure in both seasons, thereby balancing the need to limit both heating and cooling demands. The configuration includes three blades, each set at an angle of -0.1 radians, with a total shade angle of 0.5 radians, a width of 0.8 meters, and a blade depth of approximately 0.267 meters. The radiation during the cold season is measured at 3.654784 kWh/m², while in the warm season, it is 1.363829 kWh/m², resulting in a net difference of 2.290955 kWh/m². The combined radiation for both seasons totals 5.018612 kWh/m².
This analysis highlights the critical role of precise blade angles and shade orientation in optimizing building energy performance. The suboptimal results of this configuration emphasize the necessity for careful design consideration to achieve desired energy efficiency and comfort levels in buildings situated in climates with significant seasonal variation like Tehran.
Discussion
Implications of Findings
The outcomes of this research elucidate the substantial benefits of using optimized facade materials and shading devices, tailored to the specific climatic conditions of Tehran. The variations in seasonal radiation due to the building’s orientation, where summer radiation is unexpectedly lower than in winter, provide a unique opportunity to enhance energy efficiency. This anomaly can be attributed to the building’s specific orientation and the urban layout, which shield the building from excessive summer sun while allowing winter sunlight to penetrate, thereby reducing cooling demands and optimizing passive heating. Figure 17 illustrates Sun Path Diagram Showing Monthly Sun Orientation and Incident Angles on the Building.

Figure 17.
Sun Path Diagram Showing Monthly Sun Orientation and Incident Angles on the Building. This visualization captures the trajectory of the sun across different months, illustrated by nodes marked with respective month numbers, highlighting the dynamic solar exposure of the building throughout the year.
These results underscore the importance of considering local environmental and architectural contexts in building design, which can deviate significantly from typical expectations and norms. The optimal material and shading solutions not only meet regulatory requirements but also push the boundaries of traditional design practices by integrating innovative, cost-effective, and passive strategies that are broadly accessible and implementable.
Advantages of the Simulation Approach
The use of advanced simulation tools like Ladybug and Honeybee has enabled a comprehensive analysis that combines daylight and thermal simulations with real-time performance monitoring. This integration facilitates a more dynamic and responsive approach to building design, where decisions are informed by immediate feedback loops that simulate various environmental and material conditions. This method allows for a more nuanced understanding of how different variables interact and impact overall building performance, leading to more informed and effective design choices.
Moreover, the simulation-driven approach promotes sustainability by allowing for the exploration of various scenarios before actual implementation, reducing resource waste and enabling the optimization of materials and designs to achieve the best possible energy efficiency outcomes.
Future Research Directions
While this study provides significant insights into optimizing facade materials and shading systems, future research could explore the scalability of these solutions in different urban settings and climates. Extending this research to include a broader variety of building types and environmental conditions could help to develop more generalized solutions that can be adapted for global use.
Additionally, the integration of new technologies such as artificial intelligence and machine learning into the simulation process could further enhance the predictive capabilities and efficiency of building performance simulations. Exploring these technologies could lead to even more sophisticated tools that automate and refine the design process, leading to smarter, more reactive building systems that continually adapt to their environment.
Integration with Urban Development and Policy Making
Given the clear benefits demonstrated by this study, there is a strong case for integrating these optimization tools and methodologies into urban planning and policy frameworks. By mandating the use of simulation and optimization tools in the planning stage of building developments, policymakers can ensure that new constructions are designed with the utmost energy efficiency. This approach not only aligns with global sustainability goals but also with economic strategies aiming to reduce energy expenditures in the long term.
Declaration of generative AI and AI-assisted technologies in the writing process
During the preparation of this work the authors used ChatGPT in order to correct the formatting inconsistencies. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.