scholarly journals Microclimate of Urban Canopy Layer and Outdoor Thermal Comfort: A Case Study in Pavlou Mela, Thessaloniki

Urban Science ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 84
Author(s):  
Ioanna Skoufali ◽  
Alessandra Battisti

The present study is based on the assumption that the urban heat island (UHI) mitigation appears compelling and urgent in dense cities. To the above thematic area, recent redevelopmental interventions of open space for the microclimatic improvement and thermal comfort have been made through national and international programs at neighborhood scale (local area). One of these recovery processes is the case study of Pavlou Mela in the Greek context, which in the present discussion, focuses on the microspecific investigation through quantitative analysis of the eleven points distributed in the area of the intervention, extrapolating comparative considerations of different configurative factors post-operam. The results of this analysis tend: (i) To identify the degree of accuracy of the two most applied software packages in the scientific community (ENVImet Pro and Rayman Pro) through microclimatic parameters, namely air temperature (Ta) and surface temperature (Ts) comparing them with in-situ measurements; (ii) to evaluate the thermal sensation of man correlated with the mean radiant temperature (Tmrt) by verifying the actual improvement of thermal comfort outdoor with the index, physiologically equivalent temperature (PET).

Buildings ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 123 ◽  
Author(s):  
Beta Paramita ◽  
Hiroatsu Fukuda ◽  
Rendy Perdana Khidmat ◽  
Andreas Matzarakis

This paper aims to find the microclimate aspect within the building form and configuration of five low-cost apartments (henceforth rusun) in Bandung, Indonesia. There are parallel, square, and interspersed plots investigated with specific discussion on the microclimate aspects that gain human perception of outdoor thermal comfort. The microclimate prognostic model, i.e., ENVI-met, was used to determine the mean radiant temperature (Tmrt), which was then used to describe the living quality of outdoor thermal comfort, i.e., PET (physiologically equivalent temperature) in a hot-humid climate context. A parallel plot with building orientation toward north-south was found as the most beneficial building form and configuration. Somehow, the parallel plot toward the west-east orientation did not provide similar performance. Nevertheless, the square plot provided uncomfortable perception as there was an absence of building shade within the wide open space and ground cover to absorb the insolation. The interspersed plot can be considered for the building configuration because it generates more wind among other plots. The building form and configuration of rusun with passive design seems to not be able to achieve outdoor thermal comfort. The highest PET value of Model D with the square plot had PET = 41 °C (hot) while the lowest PET in Model A with the parallel plot (N-S) had PET = 34.2 °C (slightly warm).


2018 ◽  
Vol 24 (12) ◽  
pp. 9548-9551 ◽  
Author(s):  
Bangun I. R Harsritanto ◽  
Ratih Widiastuti ◽  
Hana Faza Surya Rusyda

Author(s):  
Lei Yu ◽  
Yongyi Ye ◽  
Lu Zhang

It is important to improve residential thermal comfort in the high dense cities, in which wind environment is crucial. Waterside buildings take an advantage of micro-hydrological-climate in summer that should be used to enhance residential thermal comfort especially in the subtropical region. In order to propose design approaches according to the outdoor thermal comfort of the waterside residential, a case study of Shenzhen She Kou residential district has been made. It focused on various factors that could have influence on wind environment for improving thermal comfort. Using wind velocity ratio (ΔRi) criterion, factors of building development volume, building direction and layout pattern, open space arrangement etc. have been broadly explored using FLUENT simulation. To planning parameters, the Floor Area Ratio (FAR) is significantly influence wind environment, the smaller FAR is better. To the vertical layout of the buildings, multi-storey layout and multi-storey & sub high-rise mixed layout would provide better wind environment. To the horizontal layout, the determinant is better than the peripheral. Other factors such as the buildings’ direction towards the road, buildings’ height, and open space setting, have influence on wind environment yet. In general, the more benefit of design layout for wind breezing, the better wind environment it could get


Climate ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 106 ◽  
Author(s):  
Shooshtarian ◽  
Rajagopalan

Dense urbanization influences the livability of cities. Changes in local meteorological conditions can be adverse for human health and well-being. In urban open spaces, it is widely known that changes in building density and configuration in cities influence wind speed (Va). This influence modifies latent heat flux between the human body and surrounding environment and thereby affecting the thermal comfort conditions in open spaces between buildings. Several studies have demonstrated the significant effect of wind speed on outdoor thermal comfort. Melbourne’s Central Business District (CBD) has recently experienced dense urbanization and this pattern of development has instigated noticeable changes in meteorological conditions. Some evidence has suggested that the patterns of wind flow induce thermal discomfort during cool seasons. Conversely, the wind is most welcomed during warm seasons. This study was conducted to assess outdoor users’ responses to Va in three open spaces of an educational precinct in Melbourne’s CBD. The open spaces studied are different in terms of design and function. Users’ responses and meteorological conditions were examined through a series of field measurements and questionnaire surveys from November 2014 to May 2015. This study used three perceptual scales to analyze participants’ experience of Va during field surveys: “Bedford preference”, “thermal sensation” and “personal acceptability”. Analytical results yielded the wind perceptual comfort thresholds for different seasons as well as the entire study period. The results suggested that in addition to the geometry of the urban open space, the function of place could influence people’s perceptions of Va. The research findings contribute to developing thermally comfortable outdoor environments.


2021 ◽  
Vol 13 (8) ◽  
pp. 1443
Author(s):  
Maria Angela Dissegna ◽  
Tiangang Yin ◽  
Hao Wu ◽  
Nicolas Lauret ◽  
Shanshan Wei ◽  
...  

The microclimatic conditions of the urban environment influence significantly the thermal comfort of human beings. One of the main human biometeorology parameters of thermal comfort is the Mean Radiant Temperature (Tmrt), which quantifies effective radiative flux reaching a human body. Simulation tools have proven useful to analyze the radiative behavior of an urban space and its impact on the inhabitants. We present a new method to produce detailed modeling of Tmrt spatial distribution using the 3-D Discrete Anisotropic Radiation Transfer model (DART). Our approach is capable to simulate Tmrt at different scales and under a range of parameters including the urban pattern, surface material of ground, walls, roofs, and properties of the vegetation (coverage, shape, spectral signature, Leaf Area Index and Leaf Area Density). The main advantages of our method are found in (1) the fine treatment of radiation in both short-wave and long-wave domains, (2) detailed specification of optical properties of urban surface materials and of vegetation, (3) precise representation of the vegetation component, and (4) capability to assimilate 3-D inputs derived from multisource remote sensing data. We illustrate and provide a first evaluation of the method in Singapore, a tropical city experiencing strong Urban Heat Island effect (UHI) and seeking to enhance the outdoor thermal comfort. The comparison between DART modelled and field estimated Tmrt shows good agreement in our study site under clear-sky condition over a time period from 10:00 to 19:00 (R2 = 0.9697, RMSE = 3.3249). The use of a 3-D radiative transfer model shows promising capability to study urban microclimate and outdoor thermal comfort with increasing landscape details, and to build linkage to remote sensing data. Our methodology has the potential to contribute towards optimizing climate-sensitive urban design when combined with the appropriate tools.


Climate ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 116
Author(s):  
Elisa Gatto ◽  
Fabio Ippolito ◽  
Gennaro Rispoli ◽  
Oliver Savio Carlo ◽  
Jose Luis Santiago ◽  
...  

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.


Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 48
Author(s):  
Kevin Araque ◽  
Paola Palacios ◽  
Dafni Mora ◽  
Miguel Chen Austin

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 Science ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 53
Author(s):  
Haven Hailu ◽  
Eshetu Gelan ◽  
Yared Girma

Indoor thermal comfort is an essential aspect of sustainable architecture and it is critical in maintaining a safe indoor environment. Expectations, acceptability, and preferences of traditional and modern buildings are different in terms of thermal comfort. This study, therefore, attempts to evaluate the indoor thermal comforts of modern and traditional buildings and identify the contributing factors that impede or facilitate indoor thermal comfort in Semera city, Ethiopia. This study employed subjective and objective measurements. The subjective measurement is based on the ASHRAE seven-point thermal sensation scale. An adaptive comfort model was employed according to the ASHRAE standard to evaluate indoor thermal comfort. The results revealed that with regards to thermal sensational votes between −1 and +1, 88% of the respondents are satisfied with the indoor environment in traditional houses, while in modern houses this figure is 22%. Likewise, 83% of occupants in traditional houses expressed a preference for their homes to remain the same or be only slightly cooler or warmer. Traditional houses were, on average, in compliance with the 80% acceptability band of the adaptive comfort standard. The study investigated that traditional building techniques and materials, in combination with consideration of microclimate, were found to play a significant role in regulating the indoor environment.


Author(s):  
Pardeep Kumar ◽  
Amit Sharma

Outdoor thermal comfort (OTC) promotes the usage frequency of public places, recreational activities, and people's wellbeing. Despite the increased interest in OTC research in the past decade, less attention has been paid to OTC research in cold weather, especially in arid regions. The present study investigates the OTC conditions in open spaces at the campus area in the arid region. The study was conducted by using subjective surveys(questionnaire) and onsite monitoring (microclimate parameters). The study was conducted at the Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Haryana-India campus during the cold season of 2019. The timings of surveys were between 9:00 and 17:00 hours. The authors processed the 185 valid questionnaire responses of the respondents to analyze OTC conditions. Only 8.6% of the respondents marked their perceived sensation "Neutral." Regression analysis was applied between respondents' thermal sensations and microclimate parameters to develop the empirical thermal sensation model. The air temperature was the most dominant parameter affecting the sensations of the respondents. The empirical model indicated that by increasing air temperature, relative humidity, and solar radiation, the thermal sensations also increased while wind speed had an opposite effect. Physiological equivalent temperature (PET) was applied for assessing the OTC conditions; the neutral PET range was found to be 18.42-25.37°C with a neutral temperature of 21.89°C. The preferred temperature was 21.99 °C by applying Probit analysis. The study's findings could provide valuable information in designing and planning outdoor spaces for educational institutions in India's arid regions


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