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Copyright © 2021 The Authors. The urban canyon albedo (UCA) quantifies the ability of street canyons to reflect solar radiation back to the sky. The UCA is controlled by the solar reflectance of road and façades and the street geometry. This study investigates the variability of UCA in a typical residential area of London and its impact on outdoor and indoor microclimates. The results are based on radiation measurements in real urban canyons and on a 1:10 physical model and simulations using ENVImet v 4.4.6 and EnergyPlus. Different scenarios with increased solar reflectance of roads and façades were simulated to investigate the impact on UCA and street level microclimate. The results showed that increasing the road reflectance has high absolute and relative impact on UCA in wide canyons. In deeper canyons, the absolute impact of the road reflectance is reduced while the relative impact of the walls' reflectance is increased. Results also showed that increasing surface reflectance in urban canyons has a detrimental impact on outdoor thermal comfort, due to increased interreflections between surfaces leading to higher mean radiant temperatures. Increasing the road reflectance also increases the incident diffuse radiation on adjacent buildings, producing a small increase in indoor operative temperatures. The findings were used to discuss the best design strategies to improve the urban thermal environment by using reflective materials in urban canyons without compromising outdoor thermal comfort or indoor thermal environments. EPSRC UK under the project ‘Urban albedo computation in high latitude locations: An experimental approach’ (EP/P02517X/1).

This chapter discusses the dominant role played by urban form in determining the local-scale urban heat island intensity across a city. Urban form is intended purely as the geometry of urban surface, determined by the shape and arrangement of buildings at the district scale. The correlation between changes in the urban fabric and urban heat island intensity across a city is described in relation to two features of urban form: urban compactness and vertical density. A set of urban form parameters is provided for applications in urban planning to map the climate performance of different urban textures.

Sun sails are a traditional street-scale shading strategy in Mediterranean cities to improve outdoor comfort. So far, their benefits for indoor comfort remain almost unexplored. To addresses this gap, we carry out thermal simulations using Finite Element Methods (FEM), a still novel approach in urban thermal studies that allows for highly detailed radiative computations at the building and street scales. We assess the potential of street sun sails to limit building cooling demands in a Mediterranean-climate city for twelve urban scenarios differing in orientation, façade reflectance, and sun sail color. Simulations show that the use of street sun sails allows for significant decreases in the air and surface temperature inside buildings, and consequently, in cooling demands (between 12% and 46%). Based on simulation results, we provide design guidelines for the installation of sun sails to maximize their effectiveness. This work illustrates how the rich visual feedback of FEM simulations can aid the decision-making process for urban design.

Many methods to generate future weather files to run building performance simulations have been proposed. However, future weather files do not account for local urban climate modifications, such as urban heat island and may not be representative of urban buildings’ climate conditions. This study describes a methodology to include urban effects in future weather files using multiple tools: the EURO-CORDEX regional climate model data, Urban Weather Generator, the URBVENT canyon wind models and EnergyPlus. Residential buildings located in different areas of London are used to test the methodology. The results confirm the significant impact of urban context on future-urban climate conditions and urban building thermal response.

A central question for urban sustainability is how to build cities that minimize, at the same time, the use of land and energy consumption. Future cities should be as dense as possible to meet the first requirement. However, the energy performance of dense urban areas is still under debate due to the lack of sound arguments. Since the origins of urbanism in the XIXth century, urban planners have incorporated energy considerations into their designs in a qualitative way. Nowadays, the discipline of Urban Physics is a well-established field able to provide them also with quantitative energy information to aid decision-making. This chapter explores how the current energy simulation capabilities, particularly the Finite Elements Methods, can contribute to a systemic study of energy exchanges in dense urban environments. We focus on radiative energy exchanges, which are especially challenging in dense urban morphologies. Finally, we discuss how the feedback between urban thermography and simulations can improve our understanding of the thermal behaviour of real urban environments.

Cities in the Mediterranean basin are characterised by compact and dense urban fabric, leading to a strong night-time urban heat island (UHI) intensity which increases thermal discomfort and building energy use in summer. This chapter reviews several experimental and numerical studies investigating the UHI intensity in representative Mediterranean cities, discussing the limitations and suitability of different approaches based on the purpose of the analysis (i.e. outdoor thermal comfort or building energy efficiency). Some recurrent urban climate characteristics are highlighted, such as the importance of urban morphology and sea breeze, the range of the daytime and night-time UHI intensity and its seasonal variability. Case studies of Rome and Barcelona are used to present modelling approaches to integrate urban climate in building energy performance. The complexity of the urban climate modifications in this context and their net energy impact on buildings are discussed considering UHI intensity, mutual shading between buildings, urban surface temperatures and wind speed in urban canyons. The last section is dedicated to urban and building design strategies for heat management in Mediterranean cities, including effective UHI mitigation measures and flexible passive cooling design strategies for buildings.

While performing building energy simulations, weather data are among the most important pieces of information needed by models and tools. In urban conditions, the typical rural weather files should be modified to take into account the microclimatic effects in urban areas. This chapter presents an overview of the most relevant effects to be considered: shadows, long-wave exchange, urban heat island, urban ventilation patterns, and urban greening, presenting a modelling chain procedure developed by the authors and to be used in TRNSYS tool, as well as the result of simulations done for the cases of Rome (Italy) and Antofagasta (Chile).

This chapter presents the urban microclimate impact on comfort and energy demand by buildings located in high-latitude temperate regions, characterised by higher heating demand compared to cooling. It focusses on London as a case study of such a location and presents results from measurements and computational studies during the last 20 years. The relationship of surface and air UHI in high-latitude cities is first described as well as the relationship between UHI and building energy demand; results from London are used to illustrate the impact. It follows a description of urban albedo outlining contributing parameters. Modelling tools enabling the study of microclimate impact on indoor thermal conditions are then described. Recent results of a study of urban albedo in London and the application of modelling tools are presented.

The increasing urbanisation trend of the last 50 years has drastically changed the landscape worldwide. The majority of world population is now living in cities and urban population growth is still accelerating, especially in developing countries. This chapter introduces the key concepts discussed in this book—i.e. urban heat island, urban climate and urban metabolism—and provides an overview of all the contributions. The fundamental issue discussed in the introduction and throughout the book is the need to overcome current fragmentation between disciplines and knowledge on cities. A new integrated urban science could effectively support the transition of existing cities toward more sustainable environments and also change our way to envision future cities. In this context, even though predicting the future is not possible, urban energy modelling and simulation could be valuable tools to guide the design and planning of future urban environments.

This report presents simulation results on the impact of climate change and urban environment on energy savings for the ReCO2ST demo buildings and installed technologies. It also presents an assessment of nature-based technologies regarding resulting environmental improvements and related costs. It was found that climate change/urban environment has a marked impact on materialised energy savings and resulting environmental conditions in naturally cooled buildings and should be considered in the design of retrofits. Nature based technologies can offer a holistic improvement of internal environment but costs are higher than conventional systems.

El presente artículo estudia la compacidad, la morfología urbana y el acceso solar en Loja para estimar el potencial solar disponible en las fachadas de exteriores de una manzana consolidada ubicada en el centro histórico. Proponiendo tres escenarios de densificación, en donde se analizaron tres morfologías resultantes de la variación de la altura de las edificaciones y que representan un incremento de edificabilidad de aproximadamente 150%, se llegó a determinar que la reducción del potencial solar varía del 16% al 28%.

Report regarding state-of-the-art solutions and future options in the area of sustainable energy for urban spaces This report is part of WP5 Roadmapping Smart Urban Spaces of the R4E project. The R4E partners work together to develop a new type of energy strategy through visions and roadmaps for the 8 partners cities, in co-creation with local stakeholders. The project supports the development of visioning and roadmapping capacities within the municipalities to spur future development and implementation of innovative energy solutions. This report (D5.1) contains the results of the desk study activities regarding state-of-the-art solutions and future options in the area of sustainable energy for urban spaces from January 2016 to April 2017.

The correlation between air and surface temperatures is recurrently used as a descriptor of the urban climate within built environments. The aim of this paper is to explore the possibilities of time-lapse thermography to visualize this relationship in time and space. To this end, thermograms are colorized using a relative-to-air temperature scale, instead of the usual absolute one. This approach was tested for two deep urban canyons belonging to cities with different climates. Relative-to-air thermography has two main advantages: it facilitates comparisons between the thermal responses of urban scenes under different climates and makes convective energy exchanges more comprehensive.

The Urban Heat Island (UHI) effect is particularly concerning in Mediterranean zone, as climate change and UHI scenarios foresee a fast growth of energy consumption for next years, due to the widespread of air conditioning systems and the increase of cooling demand. The UHI intensity is thus a key variable for the prediction of energy needs in urban areas. This study investigates the intensity of UHI in Barcelona (Spain), the densest Mediterranean coastal city, and its impact on cooling demand of residential buildings. The experimental analysis is based on temperature data from rural and urban Weather Stations and field measurements at street level. The maximum average UHI intensity is found to be 2.8 °C in winter and 1.7 °C in summer, reaching 4.3 °C at street level. Simulations performed with EnergyPlus indicate that the UHI intensity increases the sensible cooling load of residential buildings by around 18%–28%, depending on UHI intensity, amount of solar gains and cooling set point. In the light of the results, the UHI intensity in Mediterranean context should be properly considered in performing energy evaluations for urban contexts, since standard meteorological data from airport weather stations are not found to be accurate enough.

Energy is considered as a main influence on urban configurations. However, there is a difficulty on translating the city models based on theoretical renewable energy concepts into practical applications. This study considers the possibility of understanding this future model as a transformation of the existing urban centres. With this objective, a methodology to intervene in existing cities based on the study of solar access is developed. Therefore, an analysis of solar potential in relation with urban morphology is carried on through a simulation software in l’Eixample, a neighbourhood of Barcelona. The distribution of the sun factor in the different areas of the building blocks envelope displays possible morphological modifications that would facilitate solar energy collection. Consequently, the analytical method presented could be applied to regulate urban interventions with the aim of obtaining more solar energy based cities.

Climate regional characteristics, urban environmental conditions, and outdoors thermal comfort requirements of residents are important for urban planning. Basic studies of urban microclimate can provide information and useful resources to predict and improve thermal conditions in hot-humid climatic regions. The paper analyzes the thermal bioclimate and its influence as urban design factor in Cuba, using Physiologically Equivalent Temperature (PET). Simulations of wind speed variations and shade conditions were performed to quantify changes in thermal bioclimate due to possible modifications in urban morphology. Climate data from Havana, Camagüey, and Santiago of Cuba for the period 2001 to 2012 were used to calculate PET with the RayMan model. The results show that changes in meteorological parameters influence the urban microclimate, and consequently modify the thermal conditions in outdoors spaces. Shade is the predominant strategy to improve urban microclimate with more significant benefits in terms of PET higher than 30 °C. For climatic regions such as the analyzed ones, human thermal comfort can be improved by a wind speed modification for thresholds of PET above 30 °C, and by a wind speed decreases in conditions below 26 °C. The improvement of human thermal conditions is crucial for urban sustainability. On this regards, our study is a contribution for urban designers, due to the possibility of taking advantage of results for improving microclimatic conditions based on urban forms. The results may enable urban planners to create spaces that people prefer to visit, and also are usable in the reconfiguration of cities. Climate regional characteristics, urban environmental conditions, and outdoors thermal comfort requirements of residents are important for urban planning. Basic studies of urban microclimate can provide information and useful resources to predict and improve thermal conditions in hot-humid climatic regions. The paper analyzes the thermal bioclimate and its influence as urban design factor in Cuba, using Physiologically Equivalent Temperature (PET). Simulations of wind speed variations and shade conditions were performed to quantify changes in thermal bioclimate due to possible modifications in urban morphology. Climate data from Havana, Camagüey, and Santiago of Cuba for the period 2001 to 2012 were used to calculate PET with the RayMan model. The results show that changes in meteorological parameters influence the urban microclimate, and consequently modify the thermal conditions in outdoors spaces. Shade is the predominant strategy to improve urban microclimate with more significant benefits in terms of PET higher than 30 °C. For climatic regions such as the analyzed ones, human thermal comfort can be improved by a wind speed modification for thresholds of PET above 30 °C, and by a wind speed decreases in conditions below 26 °C. The improvement of human thermal conditions is crucial for urban sustainability. On this regards, our study is a contribution for urban designers, due to the possibility of taking advantage of results for improving microclimatic conditions based on urban forms. The results may enable urban planners to create spaces that people prefer to visit, and also are usable in the reconfiguration of cities.

As a result of the current economic and energy crisis, it has become necessary to rethink urban planning, starting from a global concept of efficiency and considering buildings not as isolated entities, but as part of an urban system, which consumes energy on a much larger scale. The connection between urban morphology and microclimate is a widely discussed question, including issues like the urban heat island phenomenon or outdoor comfort in open spaces. However, there is still a lot of work to be done regarding the influence of these microclimatic variations on building energy consumption. In that sense, would it be possible to apply efficient measures of microclimate modification on an urban scale to increase comfort levels in public spaces while at the same time, reducing building consumption? This paper focuses on urban canopy shading. Its effectiveness as a shading device and its capability to improve outdoor climate in areas with an excess of solar radiation is widely demonstrated. In this case, its effect on indoor climate of is evaluated. The case study is located in Cordoba (Spain), as an example of a climate with a hot and dry summer (according to CTE, level 4). A complete street canyon model has been created. Two buildings, one on each side of the street canyon, have been tested using an energy simulation software (Design Builder). Model features and simulation settings correspond to real values. Urban canopy shading effectiveness has been analyzed according to cooling demand decrease, taking into account both buildings. Spatial factors (street orientation, width-height ratio, windows-opaque ratio) and material factors (U-values and skin mass, % obstruction) have been considered. Results show 18% to 45% cooling demand decrease due to the canopy shading. Spatial factors are much more relevant than material factors: windows-opaque ratio is a determining factor, in contrast to mass and U-values. This study shows the importance of evaluating both urban facades, which means working from an urban perspective beyond the local scale of a single building.

The combined effects of urban heat island (UHI), urban population growth and energy overexploitation are undermining the safety of urban areas. Urban morphology plays a prominent role in this context, because it affects building's energy demand and local climate at urban scale. However, this contribution is recurrently neglected. The present contribution seeks to investigate the direct and indirect effect of urban morphology on buildings energy performance in the Mediterranean climate. Urban morphology affects energy demand by modifying two relevant variables: outdoor air temperatures and incident radiation. The relevance of these effects were studied on a sample of urban textures of Rome and Barcelona. The study is parametric in approach. The textures were modelled and parameterized and their performances were compared. The UHI in different urban textures was calculated, by Urban Weather Generator tool. Then a sensitivity analysis of the building energy demand to the outdoor air emperatures and the incoming solar radiation was carried out, by EnergyPlus engine. Results confirm the relevance of urban morphology to the UHI intensity. Warmer temperatures lead to an average increase of energy demand from 10% to 35%, according to different urban densities. At the same time, the incident radiation reduction due to urban obstruction is desirable in Mediterranean climate; it allows a reduction of annual energy demand up to the 19% compared to an unobstructed environment. Therefore, relevant errors may occur if urban morphology’s contribution to energy demand is neglected, approximately 89% for space heating and 131% for space cooling calculations, depending on the texture density and the building orientation.

Architecture has been an essential resouce in retail to keep products in suitable technical conditions, provide confort to costumers during the purchase process, and set up a communication bond across the attraction process moves to trigger the purchase. The addition of more architecture in commercialization of products (stores, supply chains, etc.) has been an inherent fact to historical retail development in intensity and extent. However, a glance of the whole retail system in any city provide the verification of coexistence and development of many architectural typologies used for retailing, formed with dissimilar ammounts of resources (energy, material, information, technology), that entail different environmental impacts.

Report regarding state-of-the-art solutions and future options in the area of sustainable energy for buildings. This report is part of WP3 Roadmapping Smart Buildings of the R4E project. In the Roadmaps for Energy (R4E) project, the partners will work together to develop a new energy strategy: their Energy Roadmap. The difference between the regular energy strategies and action plans and these new Energy Roadmaps is the much earlier and more developed involvement of local stakeholders. This report (D3.1) contains the results of the desk study activities regarding state-of-the-art solutions and future options in the area of sustainable energy for buildings from January 2016 to April 2017.