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From Energy Performative to Livable Mediterranean Cities: An Annual Outdoor Thermal Comfort and Energy Balance Cross-Climatic Typological Study
Abstract
With the rise of awareness of health and well-being in cities, urban environmental analysis should expand from energy performance to new environmental quality-based considerations. The limited potential to annually evaluate outdoor thermal comfort, predominant among these considerations, has restricted the exploration of the interrelations between urban morphology and annual energy performance. This study aims to bridge this gap by capitalizing on the new capabilities of Eddy3D – a Grasshopper plugin which enables effective calculations of hourly microclimatic wind factors via OpenFOAM which in turn are used to generate annual outdoor thermal comfort plots. Using this method, a parametric study was conducted for different typology and density scenarios in three different hot climatic contexts in Israel. The automated analytical workflow evaluated a total of 60 design iterations for their energy balance, outdoor thermal comfort autonomy (OTCA) and self-shading levels using the shade index. The high correlation found here between the annual shade index and the OTCA, across all climatic contexts, shows the potential of the shade index to serve as an effective indicator, in these contexts, for comparative or optimization outdoor comfort studies. Further results are both the superiority of the courtyard typology in both energy and outdoor comfort studies, and the contrasting impact of higher density on the annual energy balance (lower performance) and outdoor thermal comfort (higher performance) in hot climates. The annual plots of both the energy balance and OTCA reveal various seasonal and monthly trends in the three different climatic zones which can lead to localized and seasonal urban design strategies.
... These forecasts should raise concerns in light of the fact that urbanisation has been identified as a major contributor to the progression of climate change across multiple spatial scales (Pielke, 2005). In response to rising demands, urban density and morphology undergo modifications, which in turn lead to elevated energy consumption, decreased potential for energy generation within the city (Martins et al., 2016), limited availability of daylight (Capeluto, 2003), and impacts on outdoor thermal comfort (Natanian et al., 2020). In addition to modifications in urban density and morphology, there has been an increased implementation of mixed-use developments within the urban fabric in recent times. ...
... The exposure metrics consist of the following: (1) Context Exposure Index (CEI), (2) New block Exposure Index (NEI) aligned with the guidelines of the Israeli green building code -SI 5281 (Standards Institute of Israel, 2015), and (3) Sky Exposure (SE) metric. Alongside these, the shading metrics include: (4) Outdoor Shading Index (OSI) (Natanian et al., 2020), and (5) East-West Facades Shading Index (FSI) . ...
... The East-West Facades Shading Index (FSI) holds significance in both hot climates to mitigate excessive radiation's adverse impact on thermal comfort during cooling seasons. Additionally, the outdoor shading index (OSI) is crucial in ensuring year-round outdoor thermal comfort in the immediate vicinity of the building block, particularly in hot climates where solar radiation predominantly influences outdoor thermal conditions, as also shown in (Natanian et al., 2020). The chosen iteration for Jerusalem displays elevated radiation values on the south facade of both the new block (NEI) and the surrounding context (CEI). ...
Urbanisation trends predict that by 2050, 68% of the global population will reside in cities, requiring substantial urban densification, especially in rapidly developing regions like Israel. This paper integrates mixed-use considerations into the environmental design process through a two-step analytical parametric sequence using Grasshopper and Ladybug in Rhino. In the first step, the solar performance of 11,288 geometrical forms based on six distinct building typologies is analysed and evaluated, considering shading and exposure factors. The second step involves simulating the energy performance of the optimal iteration across different mixed-use scenarios and distributions. The case studies explored in Jerusalem and Eilat, two distinct hot climatic regions in Israel, emphasise the significance of solar-driven considerations in achieving optimal energy efficiency in mixed-use configurations. For example, the study found higher energy efficiency in mixed-use scenarios when office spaces were in the lower half as opposed to the upper half of the building mass in the hot, arid climatic conditions of Eilat. While the computationally inexpensive approach proposed in this study is transferable to other hot climates, the specific built form-related inferences for Eilat and Jerusalem can inform mixed-use design decisions by local designers and policymakers.
... They found that there is a high correlation between the annual shade index and OTC in all climatic contexts, which indicates the potential of the shade index as an effective indicator. In addition, they noted a superiority of one typology in comparison with other different typologies in both EUI and OTCA studies [17]. Mirzabeigi and Razkenari (2022) proposed an optimization framework using Grasshopper plugins, Ladybug tools and Eddy3d to compare six varying urban typologies of low-rise, mid-rise and high-rise categories based on OTC and EUI performance and identify a set of the best design solutions in the conceptual urban typologies in Syracuse, United States [37]. ...
... Eddy3d uses the OpenFOAM blockMesh utility for the background mesh and snap-pyHexMesh to snap the background mesh to the building geometry. A cylindrical simulation domain approach was used for the background mesh, which allows the same computational mesh to be reused for each wind direction, therefore reducing computation time and storage space [17,48]. Within the cylindrical mesh, the mesh within a refinement box that surrounds the buildings of interest was refined. ...
... Eddy3d uses the OpenFOAM blockMesh utility for the background mesh and snappy-HexMesh to snap the background mesh to the building geometry. A cylindrical simulation domain approach was used for the background mesh, which allows the same computational mesh to be reused for each wind direction, therefore reducing computation time and storage space [17,48]. Within the cylindrical mesh, the mesh within a refinement box that surrounds the buildings of interest was refined. ...
With an increasing awareness of urban health and well-being, this study highlights the growing importance of considering environmental quality in urban design beyond mere energy performance. This study integrates outdoor and indoor quality by investigating the effect of design parameters at an urban block scale (building form restricted to width and length as rectangular and square, building orientation, block orientation, building combination, building height, facade length, built-up percentage, setbacks, and canyon aspect ratio) on outdoor thermal comfort and energy use intensity. In addition, it explains the different correlations between outdoor thermal comfort and energy use intensity in different urban block designs in a hot-summer Mediterranean climate in Jordan. The study adopts a performance-driven approach using simulation tools of Ladybug, Honeybee, Dragonfly, and Eddy3d plugins across the grasshopper interface and evaluates 59 different urban block designs with nine different orientations (0°, 1°, 45°, 85°, 87°, 90°, 355°, 358°, and 359°). The results show that there is a positive correlation between the canyon aspect ratio and the environmental performance of the urban block designs. North–south street canyons are more effective at enhancing microclimates. Negatively increasing the street aspect ratio by more than four affected outdoor thermal comfort by increasing longwave radiation. Further results suggest a positive correlation between the compactness of urban blocks and their environmental performance, with north–south street canyons found to be more effective in enhancing microclimates. The study emphasizes the need to understand the distribution of open spaces formed by buildings and to strike a balance between day and night, as well as summer and winter conditions in outdoor spaces.
... Using a holistic approach, current research integrates indoor and outdoor building performance evaluations. Several studies investigated energy use reduction and daylight availability, together with outdoor thermal comforts allowed by different urban patterns in different climates and seasons [13,23,34,61,62]. The analysis of wind velocity and direction as modified by buildings and structures is a critical factor for the form finding of urban patterns. ...
... More comprehensive approaches investigated building types, envelopes and patterns for outdoor thermal comfort; building energy used and generated load match; and daylight availability [34,62]. Several works integrated the analysis of sunlight and solar energy on the building envelope with the wind comfort performance of spaces between and around buildings [30,60,86]. ...
... The second main challenge concerns the integration of simulations and the utilization of different results in the processes of climatic form finding when the design solutions must fulfil several criteria. In this regard, several researchers are involved in developing, testing and validating integrated climatic computational workflows [26,34,37,49,61,62,89] with a twofold objective. On the one hand, one objective is to improve the efficiency and usability of workflows integrating form parameters, different simulation inputs and outputs and the computational methods of automation, iteration, optimization and design exploration. ...
Researchers, architects and planners are increasingly urged to develop and apply sustainable methods and solutions to reduce the impact of the built environment on climate, adapt cities to climate change and reduce or eliminate resource depletion and building-related carbon emissions. In recent years, taking advantage of state-of-the-art computational and environmental design tools, researchers and designers are developing new digital workflows, methods and solutions to investigate climate-optimal and performative buildings and urban forms. This perspective paper analyses state-of-the-art computational methods; form generation processes; and tools, criteria and workflows that present how these are integrated into climatic form finding, allowing the improvement of building and urban environmental performances. Additionally, current challenges and future directions are presented.
... models in many aspects, such as in terms of numerical schemes (Bosselmann et al., 1995;Sousa et al., 2015), turbulence models (Si et al., 2016;Wortmann, 2017;Natanian et al., 2020), grid schemes, mesh generation methods (Marcum and Weatherill, 1995;Löhner, 1997;Nakahashi et al., 2003), making CFD simulations easy to understand and perform. In addition, most CFD plug-ins are user-friendly, providing convenient access to geometry generation, CFD simulation, and visualization within one interface of the design platform, substantially simplifying the simulation workflow. ...
... Moreover, simulations considering the effect of windthermal coupling on the velocity distribution and flow field have been conducted (Hamdan and de Oliveira, 2019;Utkucu and Sözer, 2020a;Loh and Bhiwapurkar, 2021). Several studies have coupled airflow, solar radiation, and thermal simulations to perform thermal comfort assessments (Johansson and Yahia, 2020;Sun and Rao, 2020;Lin et al., 2021) and energy consumption calculations Xu et al., 2019;Graham et al., 2020;Kastner and Dogan, 2020b;Natanian et al., 2020;Ibrahim et al., 2021b). However, pollutant dispersion simulations using CFD plug-ins during the design stages have not been widely studied (Ma et al., 2018;Jia et al., 2021). ...
... All of these studies used a similar workflow: the wind speed results obtained from Butterfly's airflow simulations on urban blocks were input into Ladybug and then combined with weather data, such as air temperature and mean radiant temperature, to quantify thermal comfort (Fig. 4). Natanian et al. (2020) developed another workflow for outdoor thermal comfort assessment based on the Grasshopper. In this workflow, the local microclimate data obtained from the weather stations by the plug-in Dragonfly, the mean radiant temperature on the building surface calculated by the plug-in Honeybee, and the wind factor calculated by Eddy3D were packaged as input into EnergyPlus for detailed outdoor UTCI calculations. ...
The transformation of urban and building design into green development is conducive to alleviating resource and environmental problems. Building design largely determines pollutant emissions and energy consumption throughout the building life cycle. Full consideration of the impact of urban geometries on the microclimate will help construct livable and healthy cities. Computational fluid dynamics (CFD) simulations significantly improve the efficiency of assessing the microclimate and the performance of design schemes. The integration of CFD into design platforms by plug-ins marks a landmark development for the interaction of computer-aided design (CAD) and CFD, allowing architects to perform CFD simulations in their familiar design environments. This review provides a systematic overview of the classification and comprehensive comparison of CFD plug-ins in Autodesk Revit, Rhinoceros/Grasshopper, and SketchUp. The applications of CFD plug-ins in urban and building design are reviewed according to three types: single-objective, multi-objective, and coupling simulations. Two primary roles of CFD plug-ins integrated into the design process, including providing various micro-scale numerical simulations and optimizing the original design via feedback results, are analyzed. The issues of mesh generation, boundary conditions, turbulence models, and simulation accuracy during CFD plug-in applications are discussed. Finally, the limitations and future possibilities of CFD plug-ins are proposed.
... Nevertheless, a common attribute across the EMME region is that urban pollution renders children more vulnerable, imposing higher health risk relative to carcinogenic and non-carcinogenic effects (Al-Bassam et al., 2009;Jadoon et al., 2020;El-Fadel & Massoud, 2000;Tecer, 2009;Kara et al., 2013;Stergiopoulou et al., 2018;Bourliva et al., 2017;Aminiyan et al., 2018;Farzaneh et al., 2019;Jahandari, 2020;Grmasha et al., 2020;Davoudi et al., 2020;Kalantzi et al., 2011;Ozdemir et al., 2012;Rabee, 2015;Ghanavati et al., 2019;Al-Shidi et al., 2020). Another thematic that EMME countries across the EU divide show high interest in is UHIs, which are highly related to the thermal comfort of urban populations, as well as CC (Potchter and Itzhak Ben-Shalom, 2013;Keramitsoglou et al., 2017;Founda and Santamouris, 2017;Paravantis et al., 2017;Santamouris et al., 2015;Katavoutas and Founda, 2019;Kolokotsa et al., 2009;Pantavou et al., 2011;Natanian et al., 2020;Alizadeh-Choobari et al., 2016;Moghbel and Shamsipour, 2019). These common research interests indicate that regardless of regulatory frameworks, EMME countries are concerned with those factors most affecting public health and welfare, urban pollution and the challenges of extreme urban heat within the context that applies to each country. ...
... Relative to urban heat, a number of studies examined different aspects of health and wellbeing through a MOD lens. For instance, in the context of CC, one study has examined the relationship of mortality and ambient temperature in Beirut, while another offered a wider perspective on outdoor thermal comfort, relating it also to urban development, green spaces and historical reflection, suggesting that local vernacular architecture approaches simulated a higher level of thermal comfort (Natanian et al., 2020;El-Zein et al., 2004). Moreover, the mitigating role of UV and the susceptibility of greenery and drinking water systems in urban settings were assessed employing different techniques (Jaafari et al., 2020;Amini Parsa et al., 2019;Darabi et al., 2018;Hashempour et al., 2020), as well as vulnerability to NH such as flooding, earthquakes and heatwaves (Katavoutas and Founda, 2019;Giannakidou et al., 2020;Ertugay et al., 2016). ...
... HI is the strongest proxy; however, in relation to all the rest, this proxy is intermediate in strength and linkage. Notably, almost all studies invoking historical aspects are dealing with WE and UD as well (Natanian et al., 2020;De Siqueira and Al Balushi, 2020;Rostami et al., 2014;Peterson and Al Kassim, 2020;Farooq, 2020;Skayannis et al., 2017), indicating that past experiences are mostly recalled as a remedy for some type of affliction caused by the improper design of the urban environment. Another frequent interaction of history exists with WM techniques and NH, including past techniques that could be adapted to modern urban environments, the recycling of water resources in arid regions and combatting urban heat against desertification and heatwaves (Shahmohamadi et al., 2011;Alizadeh-Choobari et al., 2016;Shomar and Dare, 2015;Batisha, 2020;Koutsoyiannis et al., 2008;Angelakis et al., 2020). ...
Crises have shocked the global population and forced entire nations to shift their operations and priorities. The adverse effects of these crises primarily impact cities and their inhabitants; nevertheless, inherently, they have the potential to overcome them. Urban centres are home to around half of the global population, and often they are correlated to high standards of life, mostly in the Western world. Nevertheless, cities are highly flawed and, at times, are coming up short when it comes to accommodating human needs. Thus, the motivation of this work is to investigate urban vulnerabilities linked to the broader topic of climate change, focusing on urban centres in the Eastern Mediterranean and the Middle East region. This study has a dual purpose: to introduce a content-based approach of analysis, akin to bibliometrics, using proxies and links to recreate a research landscape and investigate urban vulnerability under specific conditions and how it affects public health; ultimately, offering a tentative definition of it. The novelty of this study is the proxies and links approach, through which we have identified the major trends in urban vulnerability research, as well as possible under-explored themes, by interpreting qualitative findings into more tangible ones.
... The representative article simulated the climate of the Black Forest in southern Germany and made suggestions for tourism, but it lacked an analysis of the impact of the forest on the surrounding built-up urban areas [57]. In the last five years, relevant studies have been conducted in areas mainly in the Mediterranean [58] and tropical coastal cities [29]. In addition, there are studies on the influence of the unique street isthmus morphology of historic urban neighborhoods on thermal comfort [59]. ...
... In recent years, research on building energy consumption combined with the effects of urban morphology is attracting more and more attention from scholars. Existing studies have confirmed that the courtyard form area shows better outdoor thermal comfort and annual energy consumption than the other areas [58,81]. ...
... In terms of research perspectives, environmental studies is a core discipline that has started to focus more on energy consumption [58], air quality [99], and ecology in recent years. An increasing number of interdisciplinary areas have begun to become involved in this research field, including instrument science, physics, chemistry, and computer science, all of which have contributed to further development in terms of equipment for field measurements, air quality analysis, respiratory health, and numerical simulation, together with research objectives. ...
In the context of global climate change, urban morphology is closely related to thermal comfort and contributes to sustainable urban development. Academics started to pay attention to related topics and carried out many studies during the last decades. This paper aims to summarize the research achievements and the development track for future studies. The Web of Science database and CiteSpace were used in this paper to conduct a bibliometric analysis of 556 studies in related fields from 1993 to 2020. Using a three-level co-occurrence analysis of 446 keywords, 1187 cocited literature clusters, and 15 landmark studies, the research topics and mainstream research frameworks were identified. The results show that with the increasing participation of disciplines such as computer science, ecology, and chemistry, the purpose of future research will shift to a focus on anthropogenic heat emissions, energy consumption, air pollution, and other aspects, and new research tools will be needed. In addition to building-scale and block-scale morphology, urban-scale morphology and green infrastructure will become the focus in the future. This study provides a systematic review of research about urban morphology and thermal comfort, which can inspire other researchers and policy makers.
... The second calculated metric was solar irradiation, emerged as the most popular one to assess solar accessibility in high latitudes . Despite rarely used in the outdoor spatial domain, examples of its direct application (Lindberg et al., 2015;Nasrollahi and Rostami, 2023;Sundborg et al., 2019) or as a starting metric for constructing other indices (Aleksandrowicz et al., 2020;Natanian et al., 2020;Vartholomaios, 2021) exist. In this case, the analysis spanned over an entire year and employed a climate-based sky model, using the Solar Energy on Building Envelopes (SEBE) module (Lindberg et al., 2015) within UMEP. ...
... The HOS m and HOS j indices were constructed based on existing literature, standards, and recommendations available in high latitudes countries (Table 3). On the contrary, the SIR a index builds upon the concepts of Shade Index (Aleksandrowicz et al., 2020;Natanian et al., 2020) and SIR (Vartholomaios, 2021), however adopting the spatial constraints applied for HOS m and HOS j (Table 3, column four). Finally, it is important to underline that the final score assigned to the corresponding street segment is the highest among the pedestrian spaces contained in it. ...
... In fact, codes and standards that exist about right-to-light in numerous countries primarily regulate sunlight and the insolation of building interiors [16,17]. Similarly, the right-to-shade (i.e., a right to access shade in public spaces or to shield building portions from direct sunlight) is not legally recognized [18][19][20], and it is rarely mentioned in the literature despite its importance in hot climates and in connection to the raising frequency of extreme events such as heat waves [21]. ...
... In solar neighborhoods, buildings' morphological forms and relations (i.e., building height -H, distance between buildings or width of the street -W) are firstly optimized by guaranteeing either access to or shading from sunlight, accordingly to the specific needs (e.g., direct access to sunlight is preferable for PV modules, not always for pedestrians [19,31]) and climate context (e.g., right-to-shade can be more relevant than right-to-light in extremely hot climate zones). Besides the neighborhood's layout, the application of passive solar design solutions and the optimal localization and installation of active solar systems integrated (e.g., BIPV) or added (i.e., building added photovoltaics) into urban surfaces (e.g., building envelope, shelters, ad-hoc structures, etc.) are prioritized aspects in solar neighborhood planning. ...
Planning of neighborhoods that efficiently implement active solar systems (e.g., solar thermal technologies, photovoltaics) and passive solar strategies (e.g., daylight control, sunlight access through optimized buildings' morphology, cool pavements, greeneries) is increasingly important to achieve positive energy and carbon neutrality targets, as well as to create livable urban spaces. In that regard, solar neighborhoods represent a virtuous series of solutions for communities that prioritize the exploitation of solar energy, with limited energy management systems. The ten questions answered in this article provide a critical overview of the technical, legislative, and environmental aspects to be considered in the planning and design of solar neighborhoods. The article moves from the categorization of “Solar Neighborhood” and the analysis of the state-of-the-art passive and active solar strategies to the identification of challenges and opportunities for solar solutions’ deployment. Insights into legislative aspects and lessons learned from case studies are also provided. Ongoing trends in solar energy digitalization, competing use of urban surfaces, and multi-criteria design workflows for optimal use of solar energy are outlined, emphasizing how they generate new opportunities for urban planners, authorities, and citizens. A framework is introduced to guide the potential evolution of solar neighborhoods in the next decade and to support the design of urban areas and landscapes with architecturally integrated solar energy solutions.
... This study contributes to this growing body of knowledge by investigating the effect of different design parameters on thermal comfort in a cold region of China [14]. The recognition of outdoor thermal comfort as a crucial performance indicator for urban-scale environmental assessment has been the focus of several studies that seek to develop effective methods, tools, and indicators to quantify it in various contexts and scales [15]. As part of a global research initiative to standardize the measurement and quantification of outdoor thermal comfort, the Universal Thermal Comfort Index (UTCI) was introduced as a metric [16]. ...
... The wind and humidity analysis was performed based on the wind speed and relative humidity in the file, as these variables exhibited high reliability in the workflow. While other methods such as wind analysis using Butterfly or Eddy3D [15] are available in Grasshopper and generate wind factors that simulate wind speed in many directions, they are not as accurate as accounting for turbulent heat exchange in the model, which is a feature in the Open FOAM software currently under development and not yet integrated into either of the two plugins. Additionally, the Ladybug Tools model was found to underestimate the UTCI by approximately 3.5 • C compared to the field measurements, which was mainly due to spatial resolution issues in the plant simulation model that may lead to inaccurate sun occlusion angles. ...
In this study, typical open spaces were selected in the urban area of Lanzhou, China, with varying distances from the Yellow River and different plant configuration spaces. Then, the thermal perception of respondents was investigated through meteorological measurements, thermal comfort questionnaires, and parametric modeling. The findings indicate the following: (1) Wind speed decreases significantly as the distance from the Yellow River increases in the three open green spaces. (2) The cold lake effect of the Yellow River dominates the wind environment. (3) The closest site to the Yellow River exhibits the strongest correlation between wind speed and the respondents' thermal sensation. (4) There is a strong positive correlation between the model output and different spatial measurement values. (5) There is a certain discrepancy between the UTCI values and the actual measurements, but the fit is high and consistent with an R-squared value of 0.936. This study quantitatively evaluated the thermal comfort and perception in typical spaces and validated the reliability of parameterized modeling for such spaces, providing a reference basis for thermal environment planning in these spaces.
... Subsequently, the radiant flux calculation is simplified by using a grid to sample points in the 3D model and using the Grasshopper component for ray-tracing calculations to obtain view factors between the human body and each surface (sky, wall and road). The grid points of the human body are spaced 9 m apart, after a sensitivity analysis that reflects the trade-off between computational accuracy and speed (Natanian et al., 2020). Finally, UWG simulations were performed to obtain the temperature of each surface and the radiation intensity received by the human body for use as input parameters for the calculation of the MRT. ...
... This calculation method is different from that used in the UWG model by Nakano (2015), which ignores the effect of solar radiation on the MRT. Unlike the method of Natanian et al. (2020), which considered MRT dir using the SolarCal model (Arens et al., 2015), this study further considers the solar irradiance reflected by building facades and vegetation and then irradiated to the human body. The effect of context with various ground and wall types on the MRT is also better differentiated by defining different materials. ...
Policymakers have to assess and optimize neighborhood-scale planning aspects to profit from climate mitigation and adaptation measures due to various thermal environmental concerns. There are many models to evaluate the local thermal environment, but their outputs or complexity limit their application in performance-oriented neighborhood planning. In this study, the Urban Weather Generator (UWG) was updated to meet the needs of neighborhood planners. The model improves the radiation, vegetation, and convective heat transfer calculation processes to better match the actual physical representation of the neighborhood. Besides, the functions of the model are extended to calculate the mean radiant temperature (MRT) and water temperature for the evaluation of outdoor human thermal comfort and blue infrastructure effects. A new graphical interface also makes it easier for planning decision-makers to start quickly. Then, the prediction results of the updated model are evaluated with the neighborhood observations of the hot and humid regions of Guangzhou and Nanning. The air temperature, relative humidity (RH), and MRT results revealed that this novel model performs quite consistently and demonstrated the reliability and computational efficiency of the UWG model. In the early stages of thermal environment evaluation, the UWG model can be used for performance-oriented neighborhood planning.
... Building typologies take into account the morphology of each design scenario. Although a wide body of literature has investigated simple theoretical urban models such as scatter, courtyard, and high-rise scenarios (Natanian, Kastner, Dogan, & Auer, 2020;Taleghani et al., 2014) as well as more complicated urban models such as galley and asymmetrical scenarios (Sözen & Oral, 2019) in hot climatesonly a limited number of these scenarios are applicable in cold climates. Consequently, design scenarios for this project include six different urban typologies, including low-rises, mid-rises, and high-rise scenarios, that are applicable to new construction and retrofitting solutions (close to existing building stock characteristics) in Syracuse. ...
... A validated Grasshopper's plug-in, Eddy3D, which uses OpenFOAM engine, serves as an annual wind calculation platform for Computational Fluid Dynamics (CFD) . Following the annual wind speed interpolation method of wind factors for multiple wind directions (0,45,90,135,180,225,270,315) (Natanian, Kastner, Dogan, & Auer, 2020), we conducted a cylindrical simulation domain approach to reuse the same mesh for every wind direction. Table 5 shows simulation parameters of annual hourly microclimatic wind factors to generate outdoor thermal comfort results. ...
In the physics-based simulation of urban geometries, the outdoor environment was usually simulated separately from buildings – until recently, when the holistic assessment of the urban environment began to attract more attention. Although analyzing design alternatives with multiple objectives is still a challenge, computational tools enable generating thousands of scenarios to rapidly assess performance corresponding to a specific goal. In this study, we developed a multi-phase optimization framework for conceptual urban design. We tested this framework for urban typologies in Syracuse. The energy performance of each alternative was compared with a baseline. The alternatives that generate wasteful energy performance were filtered out first, then remaining scenarios that performed better than the baseline were analyzed using outdoor thermal comfort autonomy (OTCA). Mid-rise multifamily buildings showed the best performance (55.8% energy improvement compared to the baseline). Although hot week outdoor comfort satisfaction among selected mid-rise typologies was high (92.9–98.5%), the satisfaction in cold week was very low (between 8.4–11.6%) among them. This framework contributes to identifying an acceptable range of design solutions by broadening the perspective of the field toward using a more customized optimization framework in early design that will further guarantee the requirements of energy efficient and sustainable cities.
... The two reconstructed areas are 3 km 2 (TU Delft) and 1.6 km 2 (Stanford), both representing a neighbourhood-scale case [75]. The TU Delft case was reconstructed as a rectangular domain, portraying a typical The Stanford case was reconstructed as a round domain for a cylindrical grid, a validated configuration [60] that allows for easier setup of multiple wind directions, as demonstrated in [20,76,77]. The total number of buildings was 167, along with 5583 additional low vegetation polygons. ...
... The consideration of the building and spatial scales and of the outdoor domain in the planning of PEDs, can take advantage of recently developed digital methods and tools operating at the hybrid scale, integrating different simulation workflows to analyze the combined fulfillment of several KPIs of the design solution. Some studies analyzed energy use and generation load match, indoor daylight availability, and all-year outdoor thermal comfort of building clusters different for typology [36], density, and envelope characteristics [37], while others focused on layout variations of the same office building cluster in different existing urban environments for cooling energy use reduction and outdoor thermal comfort improvement during the hot season [38], and of patterns variations of residential building clusters in an existing urban environment to guarantee facade sunlight exposure as recommended by local regulations and outdoor wind comfort according to established metrics [39]. ...
Positive Energy Districts (PEDs) are emerging as a new symbol for sustainable urbanism and energy transition in the built environment. The pursuit of PED development is increasingly rooted in several EU policies and initiatives , sparking discourse on the interplay between governance, technological and non-technological solutions, multiple stakeholders, and the dynamics of urban and climatic contexts. As their name suggests, PEDs are characterized by surplus renewable energy generation; however, recent developments in urban environmental science emphasize the critical need for an integrated approach to achieve the key performance indicators of the UN 17 Sustainable Development Goals (SDGs). Consequently, PED designs must dynamically integrate several stakeholders. These complexities intersect with urban challenges such as urban heat islands, microclimates, nature-based solutions integration, future climatic conditions, resource availability, social vibrancy, connectiv-ity, walkability, economic activity, and more. Current tools are fragmented, severely limiting their ability to support such a multifaceted design process. This paper describes a holistic framework for tools and methods for PED design through a set of relevant questions. Drawing upon the expertise of nine researchers with complementary practical and scientific experience in various aspects of district-scale environmental performance analysis, we offer a comprehensive overview of the scopes, methods, metrics, and toolchains for PEDs, along with available tools to integrate them into different phases of the design process. This paper highlights both the challenges and opportunities ahead, emphasizing the cutting-edge methods and tools necessary to achieve robust, resilient, and data-driven processes for PED designs in a dynamic, multi-scale, and multidisciplinary urban environment.
... Additionally, previous research in the Mediterranean region emphasizes effective and very specific strategies at different scales to face these challenges. At the microscale level, establishing and promoting habitable spaces, such as courtyards, and implementing shading strategies have demonstrated positive outcomes during HW episodes [18,19]. Increasing green spaces with vegetation at a local level has also been demonstrated as a successful measure [20]. ...
In the context of escalating global temperatures and intensified heat waves, the Mediterranean region emerges as a noteworthy hotspot, experiencing a surge in the frequency and intensity of these extreme heat events. Nature-based solutions, particularly management of urban green infrastructure (UGI) areas, have shown promising outcomes in adapting urban areas to the challenges posed by heat waves. The objective of the current study is twofold: firstly, to identify the compositional patterns of strategically distributed small public green spaces, demonstrating their enhanced capacity to mitigate the impact of heat waves in the Mediterranean region; secondly, to assess the association, direction, and explanatory strength of the relationship between the composition elements of the UGI areas and area typology, specifically focusing on the variation in land surface temperature (LST) values during heat wave episodes spanning from 2017 to 2023. The methodology involved obtaining land surface temperature (LST) values from satellite images and classifying green areas based on composition, orientation, and typology. Ordinal multiple regressions were conducted to analyze the relationship between the considered variables and LST ranges during heat wave episodes that occurred from 2017 to 2023. The findings indicate an increase in LST ranges across many areas, emphasizing heightened thermal stress in a Mediterranean medium-sized compact city, Granada (in the southeast of the Iberian Peninsula). Traditional squares, pocket parks and gardens, and pedestrian areas with trees and impervious surfaces performed better in reducing the probability of exceeding LST values above 41 °C compared to other vegetated patches mainly occupied by herbaceous vegetation and grass. The study concludes by advocating for the strategic incorporation of vegetation, especially trees, along with traditional squares featuring semipermeable pavement with trees and shrubbery, as a potential effective strategy for enhancing resilience against extreme heat events. Overall, this research enhances our understanding of LST dynamics during heat waves and offers guidance for bolstering the resilience of urban green spaces in the Mediterranean region.
... de Sousa Freitas et al. (2020) found that parametric performance analysis plugins (e.g., Ladybug and Honeybee) can aid in the performance evaluation process during the early design phase of building-integrated systems in both new and existing buildings, in addition to enabling the simulation and comparison of multiple design options. Some research (Lobaccaro et al. 2018;Natanian et al. 2020) has demonstrated that energy analysis and environmental impact assessments can be performed using a combination of tools, such as generative modeling tools (Rhinoceros and Grasshopper), evolutionary solvers (Galapagos and Octopus), and dynamic simulation analysis software (Ladybug and DIVA). ...
The energy demand of buildings is currently central to the generation of greenhouse gas emissions, primarily from the combustion of fossil fuels for energy. As energy demand increases, it is critical to reduce energy-related greenhouse gas emissions in the building sector. Several architectural studies have shown that building orientation is one of the primary factors that affect building performance. However, there are still many misaligned buildings where energy costs are higher than when standard methods are used. To address this discrepancy, a research study was conducted using different building profiles. Simulations were conducted as part of the research to link a building’s orientation to performance measures, such as energy use intensity (EUI), cooling load, and heating load. In addition, the impacts of solar heat gain and ventilation air exchange values on building energy performance at various orientations were demonstrated. Although building orientation affects building energy performance, the study shows that not all factors related to building efficiency are equally influenced by orientation, and the effects vary by climate zone and building size. Energy efficiency and optimization are timely topics that require further study and exploration. This study discussed the effect of a building’s orientation on its energy usage and performance using optimization techniques. Research methodology can be employed to determine the optimum orientation of buildings. The simulation was performed for two warm and cold climate zones using IES VE and Rhino/Honeybee tools. It is shown that the orientation of the building does not have a significant effect on the energy use intensity (EUI).
Graphical abstract
Global energy transition scenario
... The ENVI-met model is a prognostic microclimate model that has been specifically developed to simulate the complex interactions among surfaces, plants, and air within an urban setting [7]. The use of this method is prevalent in the estimation and evaluation of outdoor thermal comfort [8], [9] , as well as in the examination of the influence of the urban microclimate on building energy consumption [2], [10]. ...
Despite the fact that the interrelationships between urban microclimates and energy demand have been recognised, there are not many processes that combine microclimatic boundary conditions to estimate energy consumption in parametric morphological investigations. Therefore, this paper will demonstrate a simple step-by-step methodology to incorporate the effect of urban microclimate on building cooling energy demand in semi-arid climatic areas. In this study, the combination of ENVI-met, Urban Weather Generator (UWG) and Rhino grasshopper are used to investigate the connection between microclimate and energy in the climatic environment of Kayseri. This coupling’s potential is investigated across compact high-rise, midrise and low-rise buildings, focusing on the cooling requirement on the hottest days. The comparative study shows how and to what extent urban geometry, building height in this case, contributes to modifying the magnitude of microclimate impact on building cooling performance.
... Scholars have adopted urban form typologies w i t h d i f f e re n t le v e l s o f a b s t r a c t i o n i n microclimate and building energy studies. The simple typologies by Martin and March (1972) were widely used to examine the energy and microclimate performance of urban form (Quan et al., 2014;Natanian et al., 2020), while more complex typologies and their performances were also well discussed (Rode et al., 2013;Saratsis et al., 2017;Joshi et al., 2022), The growing literature and their findings provide useful references for urban environmental planning and design practice. However, those form typologies were mainly derived from urban form solely, rather than environmental performance, which limits their correlations with those performances. ...
... No CFD simulations were performed, as they would require a significant amount of time, which would be a major constraint and unfeasible for performing the 981,120 calculations in the case study. The target areas studied are in a dense urban environment where wind is hindered, and its effect on the UTCI outcome is low (Natanian, Kastner, Dogan, & Auer, 2020;Pacifici & Nieto-Tolosa, 2021). As a result, Eq. (1), based on the wind power law equation, is used for adjusting the wind values from the 10-meter-high weather station values to the 2-meter-high pedestrian level values, while also accounting for the different terrain types (ASHRAE 2005;Aynsley et al., 1977;Tahbaz, 2016). ...
... 新 UWG 模型使用的 MRT 算法旨在实现准确度和计算速度之间的良好平衡。 Nakano 在原始 UWG 模型中实现的算法[96] 忽略了人体吸收的太阳辐射对 MRT 的影响，存在重 大缺陷，需要进行改进。与 Natanian 等[245] 使用 SolarCal 模型[255] 计算 MRTdir 的方法不 同，新 UWG 模型进一步考虑了建筑立面和植被反射后照射到人体上的太阳辐射。通过 定义不同的材料性质，还更好地区分了地面和墙体对 MRT 的影响。另一种计算 MRT 的 常用方法是 RayMan 模型 [66] ，它简化了计算短波反射辐射和长波辐射交换的过程 [256] 。 此外，使用 RayMan 模型计算 MRT 需要使用鱼眼照片或三维模型的渲染图来计算天空 可视角，在新 UWG 模型中基于 Rhino 空间建模加速了这一过程，并可以进一步分析复 杂的街区环境对 MRT 的异质性影响。 作为 MRT 计算方法之间的对比，新 UWG 模型和 RayMan 模型模拟的 MRT 与广州 所示，对比结果显示，新 UWG 模型中 MRT 值的模拟效果更好。模拟结果 支持了 Crank 等 [257] 的观点，即 RayMan 很难模拟复杂城市环境中的 MRT。这一比较表 明，通过结合三维建筑物阵列与新 UWG 模型所使用的光线追踪方法，可以提高 MRT 在新 UWG 模型中， UBLM 根据 VDM 提供的空气温度的垂直分布以及 RSM 和 UC-BEM 提供的显热通量，计算城市冠层上方的空气温度，同时考虑了建筑物和环境之间 的相互作用。如图 3-19 所示，广州和南宁的 UBL 高塔的测量空气温度和新 UWG 模型 模拟值的比较显示，从 RSM 到 VDM 的过程没有引入更多的误差，而且这个过程的计 期气象数据进行分析， 发现 LCZ 序列和热负荷大小存在对应关系； 杨小山等 [273] 基于 LCZ 分类对南京城市气温进行观测，发现 LCZ 地块的热岛强度与升温、冷却率变化特征相 对应，城市化强度越高的 LCZ 地块热岛强度越大，各 LCZ 地块的夜间平均热岛强度差 异明显；Alexander 等[274] 在城市气候预测模型中输入 LCZ 情景，进而模拟城市发展路径 对当地气候的影响，以指导规划政策的选择；Liu 等[275] 使用 Fuzzy-AHP 方法整合 LCZ ...
Rapid population growth accelerates urbanization, and human activities exacerbate climate change, leading to a series of urban thermal environment problems, especially in hot and humid regions. In China, regulatory planning is a crucial aspect of urban planning significantly impacting the emergence and development of urban thermal environment problems. However, the current methods for evaluating and optimizing the urban thermal environment at the regulatory planning level are relatively insufficient. In-depth study on the urban thermal environment at the regulatory planning level in hot and humid regions, assessment of the impact and risk of meteorological background on the environment and residents, and then regulation of the thermal environment through parameterization of planning control elements, can consider the urban heat island effect, thermal safety and thermal comfort, building energy consumption and other multi-objectives to effectively mitigate urban thermal environment problems.
Numerical simulation is an important way to study the urban thermal environment, and at the regulatory planning level, new models that combine multi-parameter and multi-objective evaluation are needed. In order to do this, this study shows how the algorithms and functions of the Urban Weather Generator (UWG) model can be made better and how they can be added to. In terms of algorithms, the radiant energy allocation algorithm for uniform three-dimensional rectangular building arrays, the roughness algorithm that takes into account vegetation, the vegetation energy allocation algorithm that takes into account weather, and the convective heat transfer calculation algorithm that improves the wind speed reference height are introduced. In terms of functions, the mean radiant temperature and the water temperature are extended. Following that, simulations are carried out using the improved and extended new UWG model in Guangzhou and Nanning, typical cities in hot and humid regions, and the air temperature, relative humidity, and mean radiant temperature at the regulatory planning level are evaluated using the measured data. The results show that the new UWG model performs well in predicting the trends and numerical results of the evaluated parameters (taking Guangzhou as an example, the coefficients of determination of the predicted air temperature, relative humidity, and mean radiant temperature are 0.966, 0.720, and 0.828, respectively, and the root mean square errors are 0.93 ℃, 6.59 %, and 2.34 ℃, respectively, and the mean bias errors are 0.10 ℃, 1.41 %, and −0.69 ℃, respectively), and the model has sufficient stability to simulate the changes in the thermal environment over long time periods.
To carry out urban thermal environment assessment at the regulatory planning level, it is necessary to parameterize various types of thermal environment information and conduct a comprehensive evaluation from multiple dimensions. In order to do this, this study proposes a multi-dimensional urban thermal environment information extraction and evaluation method and analyzes the central city of Guangzhou as an example. First, the thermal environment information is extracted from multiple data sources such as remote sensing inversion, visual interpretation, field research, and social perception by combining the Local Climate Zone (LCZ) system and building classification, and a thermal environment database is established for the central urban area of Guangzhou. Then, relevant thermal environment parameters were input into the new UWG model to analyze the thermal environment differences in the central area of Guangzhou from three objectives: urban heat island intensity, universal thermal climate index (UTCI), and building cooling energy demand. The research results reveal that there is some variation in the degree of superiority and inferiority of the thermal environment in each LCZ area under different thermal evaluation objectives, and the thermal environment of the area represented by LCZ 3 (compact low-rise building areas) is the most unsatisfactory. The global PAWN sensitivity analysis further shows that building height, building density, and wall-to-ground area ratio are the three factors with the greatest influence on the thermal environment, with their PAWN indices all greater than 0.2. Planning-related factors like urban morphology, blue-green infrastructure, anthropogenic heat from transportation, albedo, and building function type distribution have different effects on the thermal environment over time and space. By quantitatively analyzing each factor, the degree of influence and stability of the spatial and temporal variation of each factor can be developed into a targeted planning strategy to achieve the best thermal mitigation effect.
Uncertainty in the planning and design process could affect the thermal environment, which makes it harder to get the planning results that were wanted. To address this issue, this study constructs a multi-objective parametric thermal environment optimization design platform based on the new UWG model within the parametric plug-in Grasshopper in the planning scheme modeling software Rhinoceros 3D. The platform can evaluate the thermal environment at the regulatory planning level, provide suggestions on the values of planning control elements with full consideration of robustness, generate Pareto-optimal solution sets, and realize multifaceted evaluation and optimization of the thermal environment in the planning and design processes. Further, a climate adaptation planning process with the thermal environment as the core is proposed to incorporate the impact of the thermal environment into the decision-making process at the regulatory planning level. The multi-objective evaluation of thermal environment and parametric optimization applications is carried out with two regulatory planning cases as examples. The former compares the changes in urban heat island intensity, outdoor human thermal safety and comfort, and cooling energy demand for 8,760 hours of a typical meteorological year before and after the program modification and provides a quantitative method for comparing and selecting different control schemes from the thermal environment perspective. The latter provides an effective multi-objective parameterization method for optimizing the thermal environment by filtering out the thermal environment control units that need to be optimized based on the rapid calculation of multiple thermal environment control unit-related parameters, conducting a parametric search to obtain the Pareto-optimal solution set, and then outputting the corresponding proposed values of the planning control elements for the decision of the planner.
In summary, this study suggests a method for evaluating and improving the urban thermal environment at the level of regulatory planning. The method uses the new UWG model to extract multivariate urban thermal environment parameters based on the LCZ system and building classification perspective, constructs a multi-objective parametric thermal environment optimization design platform, evaluates the multidimensional impact of planning control elements on the urban thermal environment, realizes rapid, quantitative, and multi-objective regulation of the thermal environment at the regulatory planning level, and provides a theoretical basis and technical support for evaluating and optimizing the thermal environment at the regulatory planning level.
... To balance the solar exposure of the evaluated building with the reduced solar exposure of its urban context, the context exposure index (EI) [15] was set as the second objective. The EI stands for the ratio between obstructed and unobstructed diurnal cumulative insolation values for the 21 st of December which falls on the rooftops and southern facades of the surrounding buildings, as described by the following equations (Equations 2 and 3): ...
Despite the global trend toward mixed-use developments as a key strategy toward urban sustainability and compactness, quantitative research on the energy performance impacts of heterogeneous urban environments of different building typologies and uses is currently lacking. This study bridges this gap by offering an analytical method to explore and optimize the energy load and generation performance of an urban block in a diverse building-use and layout configuration. The methodology includes a two-phase analytical approach in Grasshopper-first, a multi-objective optimization (MOO) study using the block's energy load cover factor and the context solar exposure as its objectives; and second-a visual selection of the non-dominated results from the optimization based on several environmental performance indicators. The combination of these two analytical modules offers a novel analytical framework for designers and policymakers, through which they can reach an optimized starting point of building-use and mass distribution on the site, based on several quantitative environmental performance indicators.
... Butterfly, Swift, Eddy3D, ixCube CFD, and ProceduralCS on the Grasshopper platform are all plug-ins for CFD simulations that use the CFD solver OpenFOAM and have been validated for high reliability [24]. Given the greater operability and better reproduction of the simultaneous action of multiple wind directions in the airflow simulation [25,26], eddy3D was selected as the CFD solver for this study. Meanwhile, the thermal environment simulation was performed in Rhino and Grasshopper using ladybug [12]. ...
Workers' villages in East China represent a typical form of residential government-built settlements constructed between the 1950s and the 1980s to address the housing shortage. Recent emphasis has been paid to optimizing wind and thermal comfort in older neighborhoods, following the urban renewal trend. This paper collected the geometries of 150 workers' villages. Pedestrian-level wind and Universal Thermal Climate Index (UTCI) were calculated for workers' villages using validated simulation software. Seven machine learning (ML) algorithms were compared for modeling the nonlinear relationship between the building morphology and the outdoor environment of the workers' villages. The ensemble model, especially the Adaboost model, performs best when predicting static wind ratio and UTCI with R² values of 0.89 and 0.99. The trained models were applied to estimate the outdoor environment of 1118 workers' villages in East China. The result shows most workers' villages have static wind ratios over 0.7. Workers' villages in Jiangsu endure more extreme summer heat, whereas workers' villages in Zhejiang have a higher static wind ratio in winter and summer. The use of ML offers a quicker estimation of outdoor wind and thermal comfort in large-scale workers’ villages than numerical simulations, therefore shedding light on the targeting of urban renewal.
... Outdoor space microclimate simulation is an increasingly critical issue in the current situation of climate change and public health, given that simulation can provide information and criteria about the design of our cities [1]. Outdoor comfort control can help to reduce global urban energy consumption and, at the same time, act as an indicator of how well we are mitigating the urban heat island effect [2]. ...
Outdoor comfort is gaining attention in the design of our cities to face the current context of rising temperatures. Although simulation is required to inform the early design stage of projects considering outdoor space and strategies to improve their thermal performance, different tool options must be compared through monitoring to determine the accuracy of their modeling. This study analyses the thermal comfort benefits of the installation of a shading device in a courtyard in the Mediterranean climate. In the study, two simulation workflows were analyzed, one using ENVI-met software and the other using the Ladybug Tools, to evaluate their performance. Air temperature monitoring data were used to validate and calibrate the simulations. Then, both were used to compute the Universal Thermal Climate Index (UTCI) to evaluate comfort. The results show that the simulation reproduced an air temperature reduction when the shading was installed, but this was not as high as the monitoring results (up to 13.7 °C). In the UTCI, in contrast, the two simulation workflows provided contradictory results. These differences were explained by analyzing the different parameters affecting comfort and the mean radiant temperature, and the air temperature was found to be the parameter most affecting the UTCI in this context. Thus, future research should focus on improving the accuracy of the simulations of these two parameters.
... Different turbulence models have little influence on the simulation speed, but they have an essential effect on the simulation accuracy [31,47,74]. When Butterfly is used for urban wind environment prediction, the RNGKE turbulence model can achieve better simulation accuracy. ...
The deterioration of the urban environment is a problem which has captured the attention of governmental departments and researchers, who are committed to improving the urban environment from the perspective of optimizing urban morphology. Although many researchers have applied computational fluid dynamics (CFD) plug-ins to study the problems of urban ventilation and pollutant accumulation, studies on the reliability and simulation accuracy verification of CFD plug-ins are currently scarce. Therefore, we used three CFD plug-ins based on different architectural design platforms to evaluate and compare their operation difficulty, simulation accuracy, and efficiency through the analysis of the simulation results of urban ventilation. This study complements the reliability validation of CFD plug-in simulations and guides urban planners and architects in the selection and application of CFD plug-ins. The results show that the CFD plug-in generally underestimates the wind speed at the pedestrian level and the prediction accuracy is poor in the wake area of obstacles, especially with the GH_Wind plug-in. Under the 0° inflow direction, the simulation results of the Butterfly plug-in were the most consistent with the experimental values. When the inflow direction increased to 22.5° and 45°, the Autodesk CFD showed the best simulation accuracy. Overall, Autodesk CFD achieves a balance between simulation accuracy and speed in urban airflow simulation.
... Ladybug tools makes enable developing an integral analysis on the same interface. Several studies employed this resource to assess the external comfort, such as Ottone et al. (2019), Natanian et al. (2020) and De Luca, Naboni and Lobaccaro (2021), who coupled the urban climate changes created by the UWG in the Grasshopper process. ...
Climate change is a global reality, leading to consequences for both the natural and urban environment. These changes and their implications can be perceived in features such as ecological cycles, in the economic status of a country, or on the well-being and physical integrity of a population. Hence, this study aimed to analyse the effects of climate change on urban thermal comfort and the physiological limits of a population in a tropical city, applying the Physiological Equivalent Temperature (PET) index and correlating it to the local wet-bulb temperature. The method adopted consists of four stages: (1) assembling weather files for future scenarios; (2) setting up scenarios for computational simulations; (3) choosing the most adequate urban thermal comfort index; and (4) selecting a risk parameter to evaluate human health risk. The results show that the presumed urban temperatures, considering 2050 and 2080 scenarios as parameters, can cause serious damage to inhabitants' health, given the frequency of high temperatures recorded in some months of the year. Accordingly, it is clear that there is a need for balance between the temperature variables and relative air humidity is required, striving for better comfort conditions, as well as improving users' permanence in external environments.
... It is worth noticing that this classification has been proposed for sorting the large number of documents that has been reviewed and identifying the documents in line with the scope of the present manuscript. The identified topics should not be interpreted as separated but intertwined, e.g., energy and microclimate [125][126][127][128][129][130][131], energy and indoor [132], energy and design [133], energy and assessment [134], and microclimate and design [135]. Specifically, the term energy has been used to characterize studies aiming at evaluating the energy performances of buildings in terms of energy consumption for cooling, energy consumption for heating, and energy production potential. ...
In the last decades, a tendency towards urban tissue densification has been observed to counteract the urban sprawl. Densification may be achieved through more compact built areas, preferring the vertical to the horizontal development of buildings but avoiding bulky high-rise building blocks. This strategy significantly affects several aspects of the microclimate and produces direct and indirect effects on human health and well-being. In this regard, air pollution and heat stress constitute two increasing threats to human health and well-being that need to be faced immediately. The involved phenomena are various, intertwined, and may lead to conflicting results. Hence, regenerating existing, well-structured, and stratified urban areas by densification is not an easy challenge. Urban ventilation may favor the mitigation of detrimental effects of air pollution and heat stress on human life. Therefore, a multidisciplinary methodology is presented for embedding urban ventilation performance evaluation into urban management and planning processes. The scope is to propose a framework for urban renewal plans that is citizens-centered and aims at improving their health and well-being in existing urban areas. The methodology builds upon the performance-based approach and is supported by the conceptual framework and the literature reviews provided through the paper.
... An energy balance evaluates the relationship between input and output energies. Energy balance analysis is a common approach to improve building's efficiency, from architecture (Schlueter and Geyer, 2018), engineering (Tornay et al., 2017), climatic (Natanian et al., 2020) or biomimetic (Imani and Vale, 2020) points of view. The design strategies to improve energy efficiency in terms of energy balance are well-established: efficient envelope to minimize heat flows, efficient appliances, sun irradiance control, efficient climate systems and optimal operational use of the building are the most important. ...
The energy performance of a building located in La Roca del Vallès, close to Barcelona in Spain designed under the near Zero Energy Building (nZEB) and Net Zero Energy Building (NZEB) criteria was investigated. The aim was to introduce entropy generation rate as a magnitude to describe energy efficiency in buildings. This was achieved by studying the energy and entropy balances using a commercial energy performance simulation software for different scenarios proposing different efficiency conditions. The annual energy and entropy flow balances cancel. Entropy generation was due to heat losses through the envelope, sun irradiance, appliances, lighting and occupation of the building. The building designed following nZEB criteria was compared with the same building with poorer energy performance. The first one generated 45,834 kJ K⁻¹ while the second one generated 79,985 kJ K⁻¹. This is an important result because with a single magnitude, entropy generation, we combine the impact of all energy transformations taking place in the building. Sun irradiance is found to be the most important entropy generation source: a building with sun irradiance can generate nearly 3.4 times more entropy than a shadowed building. Finally, we evaluated the generated entropy ratio between the transferred entropy to the environment in terms of Gouy-Stodola theorem and the cumulated entropy that contributes to building degradation. Although cumulated degradation entropy is well below the threshold of building collapse, practical degradation effects in the building were shown.
... Exposure metrics include-(1) the Context Exposure Index (CEI), the New building Exposure Index (NEI) based on the Israeli green building code's thresholds (SI 5281 [9]), and (3) the Sky Exposure (SE) metric [6]. Shading metrics include -(4) the Outdoor Shading Index (OSI) [10], and (5) the East-West Facades Shading Index (FSI) [11]. The examination of these metrics allows the user to expand the performative perspective to various environmental performance considerations as well as to explore the balance between the different impacts of solar exposure, e.g., the tradeoff in higher density between visual comfort (SE), outdoor thermal comfort (OSI) and energy efficiency (FSI). ...
This paper addresses the limitations of existing Solar Envelope (SE) methods to explore the trade-offs of solar radiation and urban shading, and to simultaneously account for several different Key Performance Indicators (KPIs). It offers an alternative parametric workflow-the Solar Block Generator (SBG)-which is based on an additive voxelization method by which multiple solar-driven massing alternatives are generated and evaluated for a given site, corresponding to a set of user-defined environmental KPIs. This method is tested here on an urban redevelopment case study in the Mediterranean (Tel Aviv). The results help achieve a more holistic approach for solar driven urban design.
... The tools used in this research are Ladybug, Honeybee, and Colibri that were using the Mediterranean district's weather data. The research's main finding was the mitigation of the different performance of each typology and the potential of the workflow to assist the designer during the decision-making phase [14]- [16]. ...
Along with the enormous impact on computational development in architecture and urban design, the way in approaching the built environment is shifting and intended to look closer to performance and evidence-based design. This development holds promise in handling complex computation to approach desired targeted design goals. However, the implementation of form-finding and design performance optimization still lacks, particularly in Japan’s sub-tropical climate. This paper describes the parametric design and design exploration process’s implementation through the generative algorithm platform to develop a benchmark model to predict building energy and daylight performance and find possible design solutions from the iteration process during the early phase of the design process. The variables incorporated related to the glazing ratio, the length of the overhang, and building orientation. Grasshopper, a parametric-based plugin that works in Rhinoceros, is used to arrange a parametric definition for the overall experiment. The tools used to investigate the environmental analysis and energy consumption are Ladybug and Honeybee, and the exploration process will be conducted using Design Explorer. The context will be situated in Orio district and uses the EPW file of Kitakyushu city, Fukuoka, Japan. The results of this research furthermore can potentially be a comparison for more dynamic factors.
This paper uniquely and systematically explores the relationship between energy performance of buildings and urban morphology by studying an existing urban fabric in a Mediterranean climate. The study took place in the city of Hebron which is geographically confined in area with continuous urbanization. Using (GIS), the K-means clustering technique was chosen to perform the statistical analysis. The coefficient variables of Floor Space Index (FSI), Ground Space Index (GSI), Open Space Ratio(OSR), and buildings’ height (L), were identified at the urban level to classify the urban tissue of the city. Accordingly, six urban patterns with equal area of 33,000 m2 were selected as representative samples of the different urban patterns of the city’s urban fabric. Then, a prototype building was placed in each of the selected patterns by the mean centre in the GIS based on the horizontal-vertical built density. Building energy simulation was performed using Design Builder software to assess the prototype’s performance. The results showed that the urban form plays a significant role in determining performance quality and energy demand. The results indicate that the cooling demand decreases when the ratio of (FSI) and (GSI) increases and when the (OSR) decreases, and vice versa in relation to the heating demand. Notably, Pattern 4, with (FSI) of 1.2, (GSI) of 0.6, (OSR) of 0.6, and (L) of 1.7, exhibited the highest heating demand at 40.3 kWh/m2/year, whereas Pattern 3, with (FSI) of 0.7, (GSI) of 0.3, (OSR) of 2.5, and (L) of 2.0, recorded the lowest at 18.6 kWh/m2/year. Conversely, Pattern 3 had the highest cooling demand, while Pattern 2, with (FSI) of 1.0, (GSI) of 0.3, (OSR) of 1.6, and (L) of 3.0, had the lowest cooling demand. To enhance energy efficiency, urban planners should consider increasing the (FSI) and (GSI) while managing the (OSR) to balance heating and cooling demands. Patterns with moderate (FSI) and (GSI) and higher (OSR) generally result in lower cooling demands and more efficient energy use. Enhancing the energy efficiency of cities should be tackled not only on the single building level but also on the urban scale. This should be addressed in urban regeneration, master plans and building regulations. Incorporating tools that consider the impact of all urban parameters can contribute to energy savings.
The thermal environment and thermal comfort of an outdoor space have large spatial and temporal variations. To provide an overall picture, outdoor thermal comfort (OTC) should be analyzed on a yearly basic with high temporal-spatial resolution. The difficulty of annual OTC evaluation lies in the huge computational cost of wind simulations. Therefore, our study proposed a method to accelerate wind simulations through the use of Fast Fluid Dynamics (FFD), Proper Orthogonal Decomposition (POD) and Reynolds Number Independence (Re-independence). A case study of an actual urban building complex was employed to validate our study by comparing the integrated index Universal Thermal Climate Index (UTCI) results by our method with those by fully-resolved simulations. The average difference of UTCI was just 0.06 ∘C, indicating that the accuracy of our method is guaranteed. Besides, it only took 8 hours to complete the OTC assessment of this site with an area of 125,600 m2. The framework proposed in this study can be used to reveal the complete picture of OTC with affordable computational cost and reasonable accuracy.
To address the increased energy demands and carbon emissions caused by global urbanization, it is imperative to seek high-performance urban design solutions. Urban form generation and optimization (UFGO) is a powerful way of supporting performance-driven urban design by strategically searching for a possible design space to approach optimal solutions. Relevant areas of urban form generative design, urban energy and environment simulation, and urban form optimization have been widely studied. However, UFGO, which integrates these parts into an effective workflow, is still an emerging and meaningful research field lacking a systematic review. We examined studies that utilized UFGO techniques for urban design at different scales and outlined the general workflow. An overview of the available methods and tools, as well as their basic principles for each step, namely, urban form generation, performance simulation, and optimization, is provided. The reader will be well versed in the key problems and technical paths of UFGO. According to the review, UFGO is technically feasible; nevertheless, existing limitations necessitate further exploration. Future studies should focus on developing userfriendly UFGO software packages for urban designers, systematic and flexible generative design methods, and efficient data-driven models for urban performance evaluation. In addition, an evaluation system for UFGO techniques is also required to facilitate comparative studies and the widespread application of UFGO techniques.
In the last decades, parametric design has developed greatly, and its goals have expanded to include environmental, social and other goals. Due to the urban expansion that Egypt is currently witnessing; besides climate change, this research aims to use parametric urbanism in optimizing outdoor thermal comfort for urban spaces located in hot arid climates. To achieve this aim, simulation methodology was used to assess outdoor thermal comfort and deduce the most important factors affecting it in the hot arid climate. The simulation was conducted on 120 different cases of a hypothetical urban space using ladybug tools. It was found that outdoor thermal comfort can be greatly optimized by decreasing sky view factor, and increasing the floor area ratio. It was also found that the surrounding urban context has an important role in influencing the outdoor thermal comfort. Lastly, the simulation concluded that the eastern and western sides have a significant impact on the outdoor thermal comfort in the summer, in contrast to the northern and southern sides, which have little effect.
Air pollution is globally rising, especially in low- and middle-income countries, due to rapid urbanization. In hot arid environments like Egypt, adequate outdoor ventilation is required to aid in the removal of heat and pollutants and provide healthy living environments. In this context, the current research analyses the urban ventilation of typical Egyptian housing layouts using a simulated multi-directional approach. It is significant because few studies on evaluating urban ventilation of housing prototypes were undertaken in Egypt, and the approaches used were employed in nearly no relevant research in the region. Linear parallel, clustered, dot, and clustered-shifted patterns were investigated. Eight wind directions were analyzed to assess five parameters: 1) wind velocity, 2) age of air (aoa), 3) airflow, 4) pressure coefficient (cp) and 5) comfort index. An automated toolkit that enables the simultaneous simulation of several wind directions was employed. It consists of Eddy3D, a validated Grasshopper tool that uses OpenFOAM’s RANS models. The results showed that best velocities were found in the linear-parallel-unaligned and clustered layouts, directions NNE and N. The latter exhibited favorable airflow within its courtyards. In addition, wind directions had little influence on aoa, as did the layout pattern. Uncomfortable wind was greater in the clustered layout and lowest in the clustered-shifted layout. Except for ENE direction, cp was in opposition with ventilation, since W and WNW directions witnessed the greatest cross-ventilation potential. While linear-parallel-unaligned and clustered layouts created optimum ventilation and allowed outdoor activities, they require more research to increase cp and reduce uncomfortable winds.
Though building-scale energy demand and indoor thermal comfort have been extensively covered by recent studies, the automation of middle- and larger-scale outdoor microclimate evaluation in parametric design is less covered. The relatively slow computation and the need for sophisticated expertise are some of the current issues. This paper proposes a Rhino–Grasshopper custom script to automatically compute spatial indicators for a quick thermal comfort estimation. The Galapagos evolutionary algorithm is used to optimize thermal comfort and select the best combinations of spatial indicators. In a summer case study located in Shantou, China, the proposed workflow was three times faster than a non-automated indicator calculation in ArcGIS, while the optimization method achieved 25% to 33% reduction in land areas under extreme heat stress. This automated process applies to existing states and new urban designs. It is adaptable to customized prediction models under different climatic zones.
Global warming is a growing trend that challenges cities to adapt to future thermal conditions. Heat stress is one of the consequences that must be tackled through urban planning and architectural design by linking urban geometry and human biometeorology. The present research quantifies the effects of urban street configuration on human thermal comfort to formulate urban guidelines for city growth and protection of human life in the era of climate change. Meteorological data from a weather station (2010-2019) was used to assess thermal indices such as Physiologically Equivalent Temperature (PET) in open spaces and in various urban canyon configurations. A parametric study was conducted using the RayMan model in two urban development schemes: in-filling and sprawl. Simulations applied to the urban canyon addressed aspect ratio and orientation using temporal analyses. Findings reveal a similar pattern of thermal conditions in both schemes, except for sprawl with H/W = 2.5. In the summer months, the east-west axis displays the highest PET discomfort value, while the north-south axis offers the highest PET comfort value. The pattern showed that the lower the aspect ratio, the greater the heat stress in January, but performance was stable in July with aspect ratio ≥1.5.
Global warming is a growing trend that challenges cities to adapt to future thermal conditions. Heat stress is one of the consequences that must be tackled through urban planning and architectural design by linking urban geometry and human biometeorology. The present research quantifies the effects of urban street configuration on human thermal comfort to formulate urban guidelines for city growth and protection of human life in the era of climate change. Meteorological data from a weather station (2010-2019) was used to assess thermal indices such as Physiologically Equivalent Temperature (PET) in open spaces and in various urban canyon configurations. A parametric study was conducted using the RayMan model in two urban development schemes: in-filling and sprawl. Simulations applied to the urban canyon addressed aspect ratio and orientation using temporal analyses. Findings reveal a similar pattern of thermal conditions in both schemes, except for sprawl with H/W = 2.5. In the summer months, the east-west axis displays the highest PET discomfort value, while the north-south axis offers the highest PET comfort value. The pattern showed that the lower the aspect ratio, the greater the heat stress in January, but performance was stable in July with aspect ratio ≥1.5.
Numerous studies have demonstrated that the climate of cities and human settlements can affect building performance and human comfort. Historically, ambient data were collected through on-site measurements or simulations using physical models. Nowadays, with the advancement of data-based techniques and computing resources, especially Building Information Modeling (BIM) used to address the requirement for building data and numerical simulation with Computational Fluid Dynamics (CFD) used to assess building outdoor environments have increased in popularity. This paper presents a review of publications on this topic till 2022. The reviewed publications are categorized into different sections according to the following characteristics: general BIM-CFD integration process, building design optimization, and integration process optimization. In addition, the reviewed publications are categorized by the BIM design parameters, CFD simulation equations, building locations, BIM software, and BIM-CFD integration approach under consideration. This review discusses current research trends and major research issues in detail and presents future perspectives. The results show that from the early to late stages of the BIM-CFD integrated environmental studies, the BIM parameters considered were shifted from 3D to nD (e.g., energy). Meanwhile, CFD models and new technologies were chosen more carefully to meet the needs of different building scenario simulations. Although the current dynamic data transfer and synchronization capabilities between BIM and CFD need to be improved and rely heavily on the development of efficient Application Programming Interfaces (API), both BIM and CFD still play an indispensable role in building design practice.
Thermal inertia and natural ventilation are strategies widely used and studied in indoor building performance. However, little analysis has been done on its effect on the outdoor microclimate. Furthermore, this analysis is needed for the specific case of inner courtyards, given that these outdoor spaces are highly affected by their surrounding building surfaces. This study takes a real-scale prototype constructed for the 2019 Solar Decathlon competition in Hungary as a case study to analyze the thermal inertia and ventilation effects on the thermal performance of courtyards. Monitoring data are used to calibrate a simulation model that combines BES and CFD to predict the thermal performance for three wall configurations with different inertia and two situations: the closed courtyard and the ventilated courtyard. Results show that the thermal inertia and ventilation effects inside the courtyard are similar to what is generally observed inside the buildings. Thermal inertia for the close courtyard was able to increase the courtyard tempering effect up to 1.6 °C and comfort up to 1.4 °C UTCI. The ventilation reduced the tempering potential of the courtyard during the day, but it also reduced overheating during the night. Depending on the wind speed it can also increase thermal comfort.
The energy demand of buildings is currently central to the generation of greenhouse gas emissions, primarily from the combustion of fossil fuels for energy. As energy demand increases, it is critical to reduce energy-related greenhouse gas emissions in the building sector. Several architectural studies have shown that building orientation is one of the first decisions that affect building performance. However, there are still many misaligned buildings where energy costs are higher than when standard methods are used. To address this discrepancy, a research study was conducted using different building profiles. Simulations were run as part of the research to link a building's orientation to performance measures such energy use intensity (EUI), cooling load, and heating load. In addition, the impacts of solar heat gain and ventilation air exchange values on building energy performance at various orientations were demonstrated. Although building orientation affects building energy performance, the study shows that not all building efficiency factors are equally affected by orientation, and the effects vary by climate zone and building size.
This chapter offers new innovative approaches for architectural design using digital tools.
Thermal environment influences human thermal comfort significantly when people have outdoor activities. Four environmental parameters determine outdoor thermal comfort, which are air temperature, relative humidity, wind speed, and solar radiation. It is noteworthy that, different from the indoor environment, solar radiation significantly affects outdoor thermal comfort, which needs to be comprehensively understood and analyzed. In this paper, we focused on thermophysiological models and thermal comfort models with consideration of solar radiation, applications of these models, and discussed existing problems and future potential works. Here, those key points are summarized: (1) Many comprehensive thermophysiological models for simple and complex body models have been put forward. For solar load on the human body, Fanger's model showed a good fitting degree in predicting absorbed solar radiation. (2) Existing thermal indexes may not be suited to dynamic conditions of solar radiation while the DTS model may be a good example for thermal comfort evaluation under dynamic solar radiation. (3) For temporary conditions, non-Fourier models, such as the dual phase-lag model, may be applied in thermophysiological models due to the non-uniform internal structure of biological tissues. (4) A scheme of establishing dynamic thermal comfort models is put forward, considering dynamic features of environment parameters, thermophysiological parameters, and thermal adaptation.
Courtyards are a passive strategy to improve the energy performance of buildings. However, the accurate simulation of courtyards’ thermodynamic performance in the early design stage is still challenging, even though there has been an emergence of new methods to assess outdoor simulation. This paper tests a novel workflow using the Ladybug Tools that uses CFD for outdoor temperature and comfort simulation of courtyards and is suitable for the early stage of building design, comparing the results with monitored data and simulated data from ENVI-met. Results show high accuracy in the prediction of temperature from Ladybug Tools with error ranges from 3.8–7.5%, which is lower than with ENVI-met. In terms of comfort, the simulated Universal Thermal Climate Index values differ by up to 10°C between ENVI-met and the Ladybug Tools. The results show a significant improvement towards the design of the courtyard in the search for net-zero energy buildings.
Conventional CFD models can resolve complex physical fields around single or multiple buildings with high spatial resolution, but they are unable to meet the demand for fast simulations with meter-level spatial resolution and minute-level temporal resolution due to the huge computational domain with numerous grids for urban residential areas. In this paper, three fast fluid dynamics (FFD) models with different pressure-correction schemes (i.e., SIPC, NIPC and RIPC) for solving Navier-Stokes (N-S) equations are implemented in OpenFOAM. The computational accuracy and speed of these FFD models is validated and analyzed through three cases. For the prediction of airflow distribution in urban residential areas, the average relative error between the simulation results of the FFD models and the wind tunnel experimental data is less than 15 %. The speeds of these FFD models show SIPC>NIPC>RIPC from fast to slow under the same number of grids, turbulence model and time step size, and these speeds are about 15 times faster than the commercial CFD code Ansys Fluent. The computing time of the three FFD models approximately shows a linear increase with the number of grids, and the difference in computing time between the other two FFD schemes and the SIPC scheme becomes larger and larger as the number of grids increases from 0.3 million to 3.0 million. There is almost no difference in the number of grids required to achieve grid independence for the three FFD models. On the premise of ensuring accuracy, the SIPC scheme has the fastest computational speed, and it could be preferred to quickly evaluate the airflow distribution of different residential areas in urban planning stage.
Global warming and increasingly dense cities lead to poor outdoor thermal comfort that may not only be detrimental to our health and well-being but also decreases social and commercial activities. Although workflows for the analysis of thermal comfort exist, they have yet transitioned into the quotidian architectural design process. Our work-flow allows for annual outdoor comfort analyses that are seamlessly integrated into a commonly-used CAD environment. We simulated the annual outdoor thermal comfort on a university campus and discuss which simplifications seem appropriate by means of preliminary on-site measurements. The results exemplify the possibility to conduct such analyses within reasonable time and accuracy if some simplifications to the UTCI estimation are acceptable.
For urban CFD simulations, it is considered a best practice to use a box-shaped simulation domain. Box-shaped domains, however, show drawbacks for airflow from several wind directions as remeshing and additional preprocessing steps become necessary. We introduce a routine to create a cylindrical mesh that expedites the simulation of arbitrary wind directions using OpenFOAM. Results computed with the cylindrical domain are validated against wind tunnel data. We report that the cylindrical method yields comparable results in terms of accuracy and convergence behaviour. Further, run time comparisons in a real-world scenario are conducted to discuss its advantages and limitations. Based on the findings, we recommend using the cylindrical approach if at least eight wind directions are analyzed for which we report 18% run time savings. The cylindrical domain along with automated best practice boundary conditions has been implemented in Eddy3D – a plugin for Rhinoceros.
Although the interrelations between urban microclimates and energy demand have been acknowledged, few workflows integrate microclimatic boundary conditions to predict energy demand in parametric morphological studies. This paper helps bridge this gap by introducing a novel workflow which brings together energy and microclimatic modelling for a synergetic assessment at the block scale. The interrelation between form, energy and urban microclimatic conditions is explored here in the climatic context of Tel Aviv by coupling Envimet and EnergyPlus. The potential of this coupling is explored in three different block typologies, each tested for four different density scenarios focusing on the cooling demand on a typical hot day. Results show the substantial increase of as high as 50% in cooling demand when the microclimatic weather data is taken into account and indicate the potential to capitalize on new computational tools which allow to quantify the interrelations between urban form, microclimate and energy performance more accurately.
This article presents a methodology for evaluating microclimatic summer conditions across an entire city, focusing on the provision of outdoor shade as a primary comfort indicator. Based on high-resolution 2.5D and 3D mapping of buildings, ground, and tree canopies in Tel Aviv-Yafo, a city of hot-summer Mediterranean climate, we employed a detailed calculation of solar exposure of streets and open spaces (public and private) using commonly available GIS algorithms. The raw results of these calculations were used for calculating summer Shade Index values for every street segment and neighbourhood of the city, which were then plotted to a comprehensive 'shade maps' reflecting the city's spatial hierarchy of shade. The shade maps, combined with analysis of tree canopy cover on similar scales, enabled to relate building and tree morphologies to outdoor shade conditions. For prioritizing intervention of local planning authorities in improving poor shade conditions or conserving highly-shaded locations, we related the climatic analysis to space-syntax classification of streets according to their potential to attract pedestrian movement, and produced a city-wide map that highlighted streets that have high pedestrian movement potential while requiring high level of shade intensification or conservation.
Despite the global call for a paradigm shift towards new environmentally conscious urban planning, little has changed in practice, especially in hot climatic regions. This paper helps bridge this gap by introducing an automated parametric workflow for performance driven urban design. The methodology was tested here in the climatic and urban Mediterranean context consists of a parametric typological analysis, automated through Grasshopper with a total of 1920 iterations. For each iteration the performative effects of both building (i.e. typology, window to wall ratio and glazing properties) and urban design parameters (i.e. distance between buildings, floor area ratio and the orientation) were evaluated for residential and office building uses. The performance metrics - monthly/hourly energy load match and spatial daylight autonomy - were calculated using Energyplus and Radiance, respectively, and recorded for each iteration. The main results indicate substantial performative differences between typologies under different design and density scenarios; the correlation between the shape factor and the energy load match index as well as the benefits of the courtyard typology in terms of energy balance, with its challenging daylight performance, were established. These results demonstrate the potential of this workflow to highlight the design trade-offs between form and environmental performance considerations by designers and thus provide a new way to bridge the performative gap between buildings and their urban surroundings. Its application should help designers and policy makers contextualize nearly zero energy block concepts as well as define new criteria and goals.
Reviewed assessment methods for the urban environment • Critically analysed papers working on urban climate and energy demand, outdoor thermal comfort and the urban energy systems. • Demonstrated the links between the processes • An integrated workflow is proposed for assessment of the urban environment. Abstract The current climate change is calling for a drastic reduction of energy demand as well as of greenhouse gases. Besides this, cities also need to adapt to face the challenges related to climate change. Cities, with their complex urban texture and fabric, can be represented as a diverse ecosystem that does not have a clear and defined boundary. Multiple software tools that have been developed, in recent years, for assessment of urban climate, building energy demand, the outdoor thermal comfort and the energy systems. In this review, we, however, noted that these tools often address only one or two of these urban planning aspects. There is nonetheless an intricate link between them. For instance, the outdoor comfort assessment has shown that there is a strong link between biometeorology and architecture and urban climate. Additionally, to address the challenges of the energy transition, there will be a convergence of the energy needs in the future with an energy nexus regrouping the energy demand of urban areas. It is also highlighted that the uncertainty related to future climatic data makes urban adaptation and mitigation strategies complex to implement and to design given the lack of a comprehensive framework. We thus conclude by suggesting the need for a holistic interface to take into account this multi-dimensional problem. With the help of such a platform, a positive loop in urban design can be initiated leading to the development of low carbon cities and/or with the use of blue and green infrastructure to have a positive impact on the mitigation and adaptation strategies.
Urban heat island effect is almost always neglected in building energy simulations, due to difficulties in obtaining site-specific climate data with a district-scale resolution. This study aims at filling this gap for the Mediterranean urban context, presenting a set of tools to estimate the climatic performance of urban fabric at the local scale.
The results are based on climatic analysis conducted in Rome (Italy) and Barcelona (Spain) with the Urban Weather Generator (UWG) model, validated using temperature measurements taken in urban meteorological stations. Parametric analysis of the UHI intensity was performed considering five key variables: urban morphology, vegetation cover, anthropogenic heat from buildings, anthropogenic heat from traffic and albedo. The results show that the variability of urban morphology has the major impact on urban temperature. Two robust relationships between three morphology descriptors of urban fabric and UHI intensity were established applying multiple regression analysis. Such relationships indicate that both the horizontal and the vertical density of buildings play a major role on the temperature increase in urban areas.
Easy-to-use graphical tools have been provided to compare the climate performance of different urban textures and to estimate the average UHI intensity variability in Mediterranean cities.
As research on the correlation between urban design and environmental performance is still lacking, the following long-standing
question still stands – How far can we densify urban districts without sacrificing their energy balance and indoor environmental
quality? This question served as the starting point for a parametric typological study conducted at the block scale in the context of
Tel Aviv, with the overall aim of promoting performance driven design of Mediterranean urban environments. Dynamic input
parameters included fenestration ratio, aspect ratios and floor area ratios of 5 different building typologies in both office and
residential land uses. Environmental outputs included energy cooling loads, spatial daylight autonomy and the monthly average
load match between energy demand and photovoltaic energy supply. The courtyard typology was found to achieve the best
performance in terms of monthly Load Match, however mostly in residential uses of lower density. Although the high-rise typology
offered the best daylight conditions, it recorded the worse performance in terms of energy balance and energy cooling demand.
Results demonstrate the potential of a parametric typological workflow to effectively indicate the tradeoffs between single building
and urban scale design considerations. This potential could be harnessed to assess the environmental feasibility of net zero energy
typologies in Mediterranean climates and will be used for district energy studies as part of future work.
Urban sprawl and energy consumption issues suggest to consider how to design energy efficient dense cities. Solar radiation is a significant heat input in well insulated buildings in temperate climates. However, the solar masks generated by the surrounding buildings in dense urban areas can reduce significantly this energy gain. This paper proposes a definition of a district as a periodic urban fabric, where a given configuration of buildings, called urban cell, is repeated to represent the urban outline. It allows us to evaluate the relationship between cumulative solar potential on façades and urban shape, with solar masks that are consistent with the considered area. In this study, an evolutionary algorithm is used to explore the set of urban cells composed of a square grid of blocks of varying height. Four conditions for solar radiation are taken into account: clear sky direct radiation at the latitude of 50° North for three particular days (winter solstice, summer solstice and equinox), and annual direct and diffuse radiation based on the meteorological data of Paris, France. For each condition of solar radiation, the influence on the optimization results of the size of the area of interest and its built density is assessed. The results provide information on what are the urban shapes maximizing solar potential and give some quantitative indications on the amount of solar radiation that can be captured.
Residential architecture constitutes one of the largest market segments in the construction sector. However, the attention that it is given in the field of daylight performance simulation is surprisingly low. This poses the question of whether existing daylighting metrics are well suited for residential design. Findings from 79 references are summarized, and a critical review of current climate-based daylighting metrics in the context of residential architecture is provided. It is found that existing workflows often overlook relevant aspects of daylight in residential spaces, such as diurnal and seasonal availability of daylight and access to direct sunlight. Hence, a concept for a new climate-based, annual evaluation framework that overcomes these shortcomings, called the residential daylight score, is introduced.
The study presents the results of a parametric analysis of the impact of urban form on domestic energy consumption for heating and cooling. Three urban typologies, the pavilion, the slab and the perimeter urban block are examined using the dynamic building energy simulation software EnergyPlus. The simulation results are processed through a sensitivity analysis using the ‘standardised rank regression coefficients’ technique to determine the relative influence of the examined parameters on energy consumption. The study focuses on the Mediterranean city of Thessaloniki which has both heating and cooling requirements. The results support the argument that there is a synergy between the strategies of high urban compactness and passive solar design and that this synergy can be achieved at different urban densities.
Increasing urban density leads to a conflict between space-use efficiency and daylight access. Cities have traditionally relied on zoning guidelines that consist of section-based geometric evaluation techniques and/or hours of access to direct sunlight. However, it is now possible to quantify the performance of detailed design proposals before construction. Annual climate-based daylighting performance metrics for urban environments can be computed accurately, in high spatial resolution and in a timely manner. Given that massing design decisions at the urban planning level may make or break the long-term daylighting potential of a whole neighbourhood, the adoption of these tools by zoning boards, developers and urban planners seems particularly relevant. A simulation-based daylighting analysis procedure reveals the capabilities for both formulating more nuanced prescriptive zoning rules as well as for use by design teams. The procedure is used to evaluate the daylighting performance of 50 block typologies in New York City (NYC). The analysis demonstrates that certain urban massing approaches (e.g. pencil towers on a contextual base) outperform conventional massing strategies. A second case study application of an actual city block shows that innovative urban massings can improve access to daylight for the massing itself as well as for neighbouring buildings.
This paper discusses the impact of the geometry of an urban street canyon on outdoor thermal comfort. The study focuses on the Mediterranean subtropical climate of Tunis, Tunisia. The investigation was carried out by using the ENVI-met model, and run for a typical summer day in Tunis. We compared three fabrics whose streets have various H/W ratios and different orientations. The assessment of the outdoor thermal comfort was based on the UTCI. The results showed that the deepest streets are the most comfortable. This research demonstrated the importance of the prospect of the street and its orientation in the creation of a comfortable environment.
As high performance design is becoming more desirable in the field of architecture, the need for supporting architects with environmental analysis tools is also growing. Rhino/Grasshopper is one of the most widely used platforms that are used by designers today. There are already a number of environmental plugins developed for Rhino/Grasshopper. However, Ladybug offers several advantages that are currently not offered by existing Rhino/Grasshopper related environmental design plugins. Ladybug imports standard EnergyPlus Weather files (.EPW) in Grasshopper and provides a variety of 2D and 3D designer-friendly interactive graphics to support the decision-making process during the initial stages of design. It also simplifies the process of analysis, automates and expedites the calculations, and provides easy to understand graphical visualizations in the 3D modeling interface of Rhino/Grasshopper. It also allows users to work with validated energy and daylighting engines such as EnergyPlus, Radiance and Daysim. Integration with the parametric tools of grasshopper allows for almost instantaneous feedback on design modifications, and as it runs within the design environment, the information and analysis is interactive. The development is a free and open source; users can customize the tool based on their needs and contribute to the source code.Copyright
This paper describes the development of a new tool that allows designers to simulate and evaluate the daylight potential of urban master plan proposals. The tool is a plug-in for the Rhinoceros3D CAD modeler and follows a two-step workflow. During the initial step, hourly solar radiation levels on all facades within an urban scene are simulated based on Radiance/Daysim. During the second step, exterior radiation levels are converted into hourly interior illuminance distributions using a generalized impulse response. Climate based daylighting metrics, such as daylight autonomy, are also computed. The results yielded by the new method are carefully compared to regular and substantially more time-consuming Daysim simulations. This comparison shows that the overall daylit area in the investigated master plan matches Daysim predictions within 10%. Given its implementation into the Rhinoceros3D environment, as well as the almost instant simulation feedback, the tool may serve as a generative method for designers.
Planning for future energy-efficient and energy-producing buildings requires specific knowledge during the design process. Many design decisions taken by urban planners –form, density, roof type and orientation – have a significant effect on the conditions of such buildings, although urban planners might not always be aware of the effect of their design. This study examines the effects of important design decisions on the solar energy potential of net zero energy solar buildings. Typical Swedish building blocks with varying form, density, roof type and orientation were used to simulate the annual solar irradiation and energy production, and to calculate the load match for heating and electricity under Swedish conditions. Results of this study show that the urban density is the most influential parameter on the solar potential of building blocks. Furthermore, flat roofs often returned the highest load match value, while the effect of orientation on the solar potential turned out not to be that straightforward. With the results of this study, urban planners can make better informed decisions, while it also provides a ground for the net zero energy solar buildings discussion by exposing the boundaries of such buildings in the urban environment.
The aim was to identify microclimate characteristics in relation to ground cover in green areas and the reflectivity of building coating materials. Furthermore, microclimate modeling of temperatures was conducted using ENVI-met, to analyze the effects of improved thermal environments based on increased green areas and increased reflectivity of exterior coatings. The accuracy of ENVI-met was validated through comparisons with field temperature measurements. The RMSE deviation of the predicted and actual field temperature values was 3-6°C; however, the explanatory power was as high as 60%. ENVI-met was performed for commercial and single residential areas that have high densities of artificial cover materials, before and after changes related to development of green areas and to increase in the reflectivity of coating materials. The results indicated that both areas exhibited distinct temperature reductions due to the creation of green spaces. When the reflectivity of the coating material was increased, a temperature increase was observed in all land-use types. Therefore, in order to improve the thermal environment of complex urban areas, it is necessary to improve green-area development and to use high-reflectivity ground and building cover materials, while taking into account the spatial characteristics of land-use types and their surrounding areas.
One widely recognized opportunity to reduce global carbon emissions is to make urban neighborhoods more resource efficient. Significant effort has hence gone into developing computer-based design tools to ensure that individual buildings use less energy. While these tools are increasingly used in practice, they currently do not allow design teams to model groups of dozens or hundreds of buildings effectively, which is why a growing number of research teams are working on dedicated urban modeling tools. Many of these teams concentrate on isolated sustainable performance aspects such as operational building energy use or transportation; however, limited progress has been made on integrating multiple performance aspects into one tool and/or on penetrating urban design education and practice. In this paper a new Rhinoceros-based urban modeling design tool called umi is presented which allows users to carry out operational energy, daylighting and walkability evaluations of complete neighborhoods. The underlying simulation engines are EnergyPlus, Radiance/Daysim as well as a series of Grasshopper and Python scripts. Technical details of umi along with a case study of a mixed use development in Boston are documented.
The quality of life of millions of people living in cities can be improved if the factors that affect the urban microclimate are understood and the form of the city responds to them in a manner that is appropriate to its location. Underlying this approach is the idea that climatically responsive urban design is vital to any notion of sustainability: it enables individual buildings to make better use of 'natural' energy, it enhances the potential for pedestrian comfort and activity in outdoor spaces, and it encourages city dwellers to moderate their dependence on air-conditioned buildings and private vehicles (Erell et al, 2010). This paper suggests principles for successful integration of climatic strategies in urban planning processes, and provides case studies illustrating their implementation in practice.
The growing need for valid assessment procedures of the outdoor thermal environment in the fields of public weather services, public health systems, urban planning, tourism & recreation and climate impact research raised the idea to develop the Universal Thermal Climate Index UTCI based on the most recent scientific progress both in thermo-physiology and in heat exchange theory. Following extensive validation of accessible models of human thermoregulation, the advanced multi-node 'Fiala' model was selected to form the basis of UTCI. This model was coupled with an adaptive clothing model which considers clothing habits by the general urban population and behavioral changes in clothing insulation related to actual environmental temperature. UTCI was developed conceptually as an equivalent temperature. Thus, for any combination of air temperature , wind, radiation, and humidity, UTCI is defined as the air temperature in the reference condition which would elicit the same dynamic response of the physiological model. This review analyses the sensitivity of UTCI to humidity and radiation in the heat and to wind in the cold and compares the results with observational studies and internationally standardized assessment procedures. The capabilities, restrictions and potential future extensions of UTCI are discussed.
A model is proposed that adapts data from a standard meteorological station to provide realistic site-specific air temperature in a city street exposed to the same meso-scale environment. In addition to a rudimentary description of the two sites, the canyon air temperature (CAT) model requires only inputs measured at standard weather stations; yet it is capable of accurately predicting the evolution of air temperature in all weather conditions for extended periods. It simulates the effect of urban geometry on radiant exchange; the effect of moisture availability on latent heat flux; energy stored in the ground and in building surfaces; air flow in the street based on wind above roof height; and the sensible heat flux from individual surfaces and from the street canyon as a whole. The CAT model has been tested on field data measured in a monitoring program carried out in Adelaide, Australia, in 2000–2001. After calibrating the model, predicted air temperature correlated well with measured data in all weather conditions over extended periods. The experimental validation provides additional evidence in support of a number of parameterisation schemes incorporated in the model to account for sensible heat and storage flux. Copyright © 2006 Royal Meteorological Society
In the energy simulation of buildings there has been little focus on their impact on the microclimate; simulation tools have usually dealt either with building or with outdoor simulation, and only recently these aspects are being interconnected. Within this framework, the paper describes a novel simulation workflow developed in the Grasshopper environment, where the Ladybug Tools are used to model the mutual relations amongst urban microclimate, building energy performance and outdoor thermal comfort. With reference to an urban canyon located in Catania, Southern Italy, the workflow – by coupling the indoor and the outdoor thermal field – provides both the dynamic thermal load of the buildings overlooking the canyon and the parameters needed to measure the outdoor comfort perceived by pedestrians. In comparison to other existing approaches, this workflow offers significant flexibility and makes it possible to perform a parametric investigation of the effects of different design solutions on both the indoor and the outdoor environment.
The outdoor Mean Radiant Temperature calculated through the model is compared to on-site measurements performed with a black globe thermometer during two different days in the summer. The comparison suggests good agreement in the shaded areas of the canyon, but a non-negligible overestimation in sunlit areas. These results have driven the authors to a critical insight into the algorithms implanted in the Ladybug Tools, and have helped to highlight some critical issues that will be further investigated in upcoming research.
Despite the urgent global call for an energy transition and the promotion of health and well-being in cities, a holistic approach to evaluating the trade-offs between an urban energy balance and environmental quality considerations is lacking. This paper bridges this gap by introducing a Grasshopper digital workflow through which the impacts of a wide range of building and urban design parameters on both energy performance and environmental quality can be effectively evaluated. This workflow is tested here for both theoretical and site-specific urban test cases in the context of Tel Aviv. For these test cases, the performance metrics - energy load match, spatial daylight autonomy and universal thermal climate index - were calculated using EnergyPlus, Radiance and ENVI-met simulation engines for different block typologies and were then analyzed. The results showed that among the block typologies, the courtyard achieved the optimal combination across the tested environmental criteria, despite the daylight and energy generation penalty associated with self-shading in compact block typologies. This workflow highlights the performative tradeoffs between energy and environmental quality considerations and can thus help urban designers achieve not only a lower environmental impact but also regenerative and healthier design outcomes.
The regenerative approach to design goes beyond limiting the environmental impact of the built environment and towards the enrichment of the ecosystem, adaptation to climate change, and the improvement of human health. This concept is being applied to buildings through new standards such as the Living Building Challenge, yet examples of implementation of regenerative design at the urban scale are rare. While this is a promising direction for sustainable design, in theory new metrics, design tools and workflows need to be developed to translate regenerative design concepts into practice effectively. Among other factors, barriers to implementation remain rooted in the shortcomings of existing urban simulation tools to evaluate a wide range of performance metrics simultaneously. This paper thus proposes a prototype workflow to evaluate regenerative performance using existing evaluation tools in a single digital workflow. A series of existing and customised plugins, most of which are already in use and open source, were integrated into a multi-parametric workflow based on the Grasshopper visual programming tool. The workflow was tested on Malaga as a case study and incorporated key performance indicators related to outdoor human thermal comfort, biophilia, daylight performance, and energy use and production, based on data exchange and synergies across the different tools. These indicators were evaluated for present and future climate scenarios obtained from a weather generator. This paper demonstrates the potential of this workflow to receive visual feedback on various aspects of regenerative urban design, thus enabling designers to more effectively pursue an evidence-based urban design process.
Thermal comfort in the built environment is a crucial factor impacting health, well-being, and productivity of urban dwellers. Accordingly, comprehensive analyses are needed to ensure that acceptable criteria of thermal comfort are defined and met in urban environments. The main objective of this study is to define such performance metrics and quality measures of outdoor thermal comfort (OTC), aiming to inform climate-conscious urban design. This article first discusses the motivations for introducing comprehensive thermal comfort metrics, addressing the shortcomings of conventional OTC evaluations that neglect the temporal or spatial variability of OTC. It then introduces four performance metrics, which collectively inform urban planners and designers on the performance of outdoor space with regards to thermal comfort. These metrics build upon the concept of “autonomy” previously introduced for indoor spaces and are extended to include the unique characteristics of outdoor thermal comfort. Second, we discuss the capability of these metrics given the limitations of modeling tools available for urban microclimate analysis, and evaluate the critical factors for an accurate evaluation of Outdoor Thermal Comfort Autonomy (OTCA). We observe that the spatial distribution of airflow at the pedestrian height is critical for OTCA calculation, while the consideration of realistic surface heating depends on the urban density. Lastly, we present an example of employing weather clustering methods such that OTC performance metrics are achieved on an annual basis in a comprehensive yet efficient way. By discussing the capability and the limitations of these metrics we aim to promote climate-conscious design using metrics that are tangible and accessible to non-simulationexperts.
This paper presents the results of an investigation on the relationship between urban block typology, solar energy harvesting potential and building energy use efficiency in the context of the tropical high-density city Singapore. Thirty generic urban block cases in six typologies that represent a diverse range of urban forms were examined through simulation-based studies under the same planning conditions and simulation assumptions so as to rule out the impact of non-design related factors. Several key planning and geometric parameters which capture the formal characteristics of the urban blocks were examined as independent variables, and the dependent variables include the performance indicators on solar energy harvesting potential and building net energy use intensity that capture the dual benefits of photovoltaic (PV) systems in reducing building cooling loads and offsetting local plug loads with electricity generated on site. The results indicate that, under the same planning conditions and design premises, differences in urban block typology could lead to up to 200% increase in solar energy harvesting potential and electricity generated from rooftop PV, twelve times higher rate of reduction in building cooling loads, tow times higher rate of reduction in net purchased electricity, and 25% lower building net energy use intensity. The courtyard and hybrid urban block typologies consistently outperform the other typologies, especially the commonly implemented tower and slab blocks, and they benefit the most from PV deployment in the tropics. The comparison between an existing residential precinct and a hypothetical alternative hybrid urban block further demonstrated the significant impact of urban design on efficiency of PV electricity generation and building energy use efficiency. In addition to the significant economic benefit in reduction in utility cost and environmental implication in terms of equivalent reduction in CO2 emissions on urban scale, this study highlights the crucial role that urban design plays in terms of maximising on-site renewable energy production such as solar energy. The significant planning and geometric parameters in relation to the performance indicators provide insight as reference for establishing solar energy friendly urban planning and architectural design guidelines. The methodology and technical workflow as developed can support reliable and efficient feasibility studies, especially in the early stage of urban planning and architectural design. Integrated with other performance evaluations, they can facilitate decision-making on implementation of renewable energy integrated green building technologies and passive design strategies.
