scholarly journals Sustainable Urban Greening and Cooling Strategies for Thermal Comfort at Pedestrian Level

2021 ◽  
Vol 13 (6) ◽  
pp. 3138
Author(s):  
Maurizio Detommaso ◽  
Antonio Gagliano ◽  
Luigi Marletta ◽  
Francesco Nocera
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Fluid Dynamic ◽  
Green Roofs ◽  
Outdoor Thermal Comfort ◽  
Balance Model ◽  
Urban Greening ◽  
Cfd Model ◽  
Urban Microclimate ◽  
Urban Warming

The increase of the urban warming phenomenon all over the world is gaining increasing attention from scientists as well as planners and policymakers due to its adverse effects on energy consumption, health, wellbeing, and air pollution. The protection of urban areas from the outdoor warming phenomenon is one of the challenges that policy and governments have to tackle as soon as possible and in the best possible way. Among the urban heat island mitigation techniques, cool materials and urban greening are identified as the most effective solutions in reducing the urban warming phenomenon. The effects produced by the adoption of cool materials and urban forestation on the urban microclimate were investigated through a computational fluid-dynamic (CFD) model. The CFD model was calibrated and validated thanks to experimental surveys within the Catania University campus area. The urban microclimate thermal comfort analysis and assessment were carried out with the Klima–Michel Model (KMM) and Munich Energy Balance Model for Individuals (MEMI). In particular, three scenarios were performed: cool, low, and high levels of urban greening. The cool scenario, although it produces air temperature at around 1.00 °C, determines the worst condition of outdoor thermal comfort, especially at the pedestrian level. On the contrary, a high level of urban greening, obtained by the extensive green roofs together with an urban forestation, guarantees the wellbeing of pedestrians, showing more convenient values of PMV and PET.

scholarly journals Analysis of Urban Greening Scenarios for Improving Outdoor Thermal Comfort in Neighbourhoods of Lecce (Southern Italy)

Climate ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 116
Author(s):  
Elisa Gatto ◽  
Fabio Ippolito ◽  
Gennaro Rispoli ◽  
Oliver Savio Carlo ◽  
Jose Luis Santiago ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Urban Environment ◽  
Southern Italy ◽  
Hot Spot ◽  
Outdoor Thermal Comfort ◽  
Urban Greening ◽  
Urban Microclimate ◽  
Field Campaigns ◽  
Typical Summer ◽  
Radiant Temperature

This study analyses the interactions and impacts between multiple factors i.e., urban greening, building layout, and meteorological conditions that characterise the urban microclimate and thermal comfort in the urban environment. The focus was on two neighbourhoods of Lecce city (southern Italy) characterised through field campaigns and modelling simulations on a typical hot summer day. Field campaigns were performed to collect greening, building geometry, and microclimate data, which were employed in numerical simulations of several greening scenarios using the Computational Fluid Dynamics-based and microclimate model ENVI-met. Results show that, on a typical summer day, trees may lead to an average daily decrease of air temperature by up to 1.00 °C and an improvement of thermal comfort in terms of Mean Radiant Temperature (MRT) by up to 5.53 °C and Predicted Mean Vote (PMV) by up to 0.53. This decrease is more evident when the urban greening (in terms of green surfaces and trees) is increased by 1266 m2 in the first neighbourhood and 1988 m2 in the second one, with respect to the current scenario, proving that shading effect mainly contributes to improving the urban microclimate during daytime. On the contrary, the trapping effect of heat, stored by the surfaces during the day and released during the evening, induces an increase of the spatially averaged MRT by up to 2 °C during the evenings and a slight deterioration of thermal comfort, but only locally where the concentration of high LAD trees is higher. This study contributes to a better understanding of the ecosystem services provided by greening with regard to microclimate and thermal comfort within an urban environment for several hours of the day. It adds knowledge about the role of green areas in a Mediterranean city, an important hot spot of climate change, and thus it can be a guide for important urban regeneration plans.

scholarly journals Green living roof implementation and influences of the soil layer on its properties

2016 ◽  
Vol 20 (suppl. 5) ◽  
pp. 1511-1520 ◽  
Author(s):  
Dragana Dimitrijevic ◽  
Predrag Zivkovic ◽  
Mladen Stojiljkovic ◽  
Maja Todorovic ◽  
Sanja Spasic-Djordjevic
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Green Roof ◽  
Soil Layer ◽  
Green Roofs ◽  
Building Energy ◽  
Building Envelope ◽  
Outdoor Thermal Comfort ◽  
Comfort Levels ◽  
Transient Thermal

Affected by undeniable climatic change, the temperature of the urban areas rises continually, increasing rapidly the energy problem of cities and amplifying the pollution problems. The thermal stress is increased, thus both the indoor and the outdoor thermal comfort levels are decreased, enhancing the health problems. Green roof implementation in the building envelope is strategy that provides heat island amelioration, thermal comfort for occupants and reduces energy consumption of buildings. Green living roofs are a passive cooling technique, which can stop the incoming solar radiation from reaching the building structure below. In this paper, we assessed the importance of the green roofs in providing environmental and building energy benefits, and brief investigation on the different configuration of the soil layer in the green roof assembly influences to the temperature of the roof surface was presented. Investigation was conducted for first phase of the living roof growth. Four cells were designed in SolidWorks software where the transient thermal study was performed in order to determine differences between the behavior of the conventional roof and three green roof types.

scholarly journals Biomimicry-Based Strategies for Urban Heat Island Mitigation: A Numerical Case Study under Tropical Climate

Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 48
Author(s):  
Kevin Araque ◽  
Paola Palacios ◽  
Dafni Mora ◽  
Miguel Chen Austin
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Outdoor Thermal Comfort ◽  
Base Case ◽  
Heat Island ◽  
Urban Heat ◽  
Historical Heritage ◽  
Pet Index ◽  
Radiant Temperature

In recent years, demographic growth has caused cities to expand their urban areas, increasing the risk of overheating, creating insurmountable microclimatic conditions within the urban area, which is why studies have been carried out on the urban heat island effect (UHI) and its mitigation. Therefore, this research aims to evaluate the cooling potential in the application of strategies based on biomimicry for the microclimate in a historical heritage city of Panama. For this, three case studies (base case, case 1, and case 2) of outdoor thermal comfort were evaluated, in which the Envi-met software was used to emulate and evaluate the thermal performance of these strategies during March (highest temperature month) and October (rainier month). The strategies used were extracted from the contrast of zebra skin, human skin, evaporative cooling, and ant skin. The results showed a reduction of 2.8 °C in the air temperature at 11:00, the radiant temperature decreased by 2.2 °C, and the PET index managed to reduce the thermal comfort indicator among its categories. The importance of thinking based on biomimicry in sustainable strategies is concluded; although significant changes were obtained, high risks of discomfort persist due to the layout and proximity of the building.

Urban Greening Strategies for Enhancing Outdoor Thermal Comfort

2021 ◽  
pp. 85-100
Author(s):  
Kevin Ka-Lun Lau ◽  
Zheng Tan ◽  
Tobi Eniolu Morakinyo ◽  
Chao Ren
Keyword(s):  
Thermal Comfort ◽  
Outdoor Thermal Comfort ◽  
Urban Greening

scholarly journals Green Roofs and Walls Design Intended to Mitigate Climate Change in Urban Areas across All Continents

2021 ◽  
Vol 13 (4) ◽  
pp. 2245
Author(s):  
Fernando Barriuso ◽  
Beatriz Urbano
Keyword(s):  
Climate Change ◽  
Urban Areas ◽  
Urban Climate ◽  
Environmental Pollutants ◽  
Climate Extremes ◽  
Green Roofs ◽  
Urban Greening ◽  
Runoff Water ◽  
Growing Seasons ◽  
Urban Stormwater Runoff

Green roofs and walls can mitigate the environmental and climate change of a city. They can decrease the urban heat island (UHI), reduce greenhouse gas emissions, fix environmental pollutants, manage urban stormwater runoff, attenuate noise, and enhance biodiversity. This paper aims to analyse green roofs and walls in the possible mitigation of urban climate change and compare it by continent. Green roofs and walls might decrease the air temperature in a city up to 11.3 °C and lower the thermal transmittance into buildings up to 0.27 W/m2 K. Urban greening might sequester up to 375 g C·m−2 per two growing seasons and increase stormwater retention up to 100%. Urban greening might attenuate city noise up to 9.5 dB. The results found green roofs and walls of varied effectiveness in ameliorating climate extremes present in host continents. Results show urban planners might focus on green roofs and walls exposure to attenuate temperatures in hotter Asian cities and advise greening in cities in Africa and Asia. European and American designers might optimise runoff water capacity of green roofs and walls systems and use greening in old buildings to improve insulation. Recommendations are made based on the study to concentrate certain designs to have greater impact on priority climate challenges, whether UHI or stormwater related. This study provides information for decision and policymakers regarding design and exposure of green roofs and walls to mitigate urban environmental and climate change.

scholarly journals Spatially Resolved Analysis of Urban Thermal Environments Based on a Three-Dimensional Sampling Algorithm and UAV-Based Radiometric Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4847
Author(s):  
Daniel Rüdisser ◽  
Tobias Weiss ◽  
Lukas Unger
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Global Radiation ◽  
Three Dimensional ◽  
Evaluation Process ◽  
Outdoor Thermal Comfort ◽  
Wave Radiation ◽  
Imaging Data ◽  
Three Dimensional Model ◽  
Spatially Resolved

A new method and workflow to assess outdoor thermal comfort and thermal stress in urban areas is developed. The new methodology is applied to a case of an urban quarter in the city of Graz. The method recognises the significance of detailed and accurate spatially resolved determination of mean radiant temperatures taking into account all relevant radiative components, comprising thermal radiation, as well as global radiation. The method relies on radiometric imaging data that are mapped onto a three-dimensional model. The image data are acquired by means of drones (UAVs) equipped with multispectral and thermographic cameras to capture short- and long-wave radiation. Pre-existing city models and a Monte Carlo raytracing algorithm to perform anisotropic sampling based on a 3D model with human topology are used to determine local radiation temperatures with high spatial resolution. Along with spot measurements carried out on the ground simultaneously, the spatially resolved and three-dimensionally determined mean radiation temperatures are used to calculate thermal comfort indicator maps using UTCI and PMV calculation. Additional ground measurements are further used to validate the detection, as well as the entire evaluation process.

scholarly journals Sky View Factors from Synthetic Fisheye Photos for Thermal Comfort Routing—A Case Study in Phoenix, Arizona

2017 ◽  
Vol 2 (1) ◽  
pp. 19-30 ◽  
Author(s):  
Ariane Middel ◽  
Jonas Lukasczyk ◽  
Ross Maciejewski
Keyword(s):  
Thermal Comfort ◽  
Urban Form ◽  
Urban Areas ◽  
Meteorological Data ◽  
Routing Algorithm ◽  
Google Earth ◽  
Urban Environments ◽  
Tree Planting ◽  
Outdoor Thermal Comfort ◽  
View Factor

The Sky View Factor (SVF) is a dimension-reduced representation of urban form and one of the major variables in radiation models that estimate outdoor thermal comfort. Common ways of retrieving SVFs in urban environments include capturing fisheye photographs or creating a digital 3D city or elevation model of the environment. Such techniques have previously been limited due to a lack of imagery or lack of full scale detailed models of urban areas. We developed a web based tool that automatically generates synthetic hemispherical fisheye views from Google Earth at arbitrary spatial resolution and calculates the corresponding SVFs through equiangular projection. SVF results were validated using Google Maps Street View and compared to results from other SVF calculation tools. We generated 5-meter resolution SVF maps for two neighborhoods in Phoenix, Arizona to illustrate fine-scale variations of intra-urban horizon limitations due to urban form and vegetation. To demonstrate the utility of our synthetic fisheye approach for heat stress applications, we automated a radiation model to generate outdoor thermal comfort maps for Arizona State University’s Tempe campus for a hot summer day using synthetic fisheye photos and on-site meteorological data. Model output was tested against mobile transect measurements of the six-directional radiant flux density. Based on the thermal comfort maps, we implemented a pedestrian routing algorithm that is optimized for distance and thermal comfort preferences. Our synthetic fisheye approach can help planners assess urban design and tree planting strategies to maximize thermal comfort outcomes and can support heat hazard mitigation in urban areas.

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