Performance evaluation of mean radiant temperature calculated from inner surface temperatures of envelope with various emissivities

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.

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How Can We Adapt Thermal Comfort for Disabled Patients? A Case Study of French Healthcare Buildings in Summer

Energies ◽

10.3390/en14154530 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4530

Author(s):

Youcef Bouzidi ◽

Zoubayre El Akili ◽

Antoine Gademer ◽

Nacef Tazi ◽

Adil Chahboun

Keyword(s):

Thermal Comfort ◽

Thermal Environment ◽

Residential Buildings ◽

Linear Regression Analysis ◽

Environmental Parameters ◽

Physical Parameters ◽

Mean Radiant Temperature ◽

Operative Temperature ◽

Neutral Temperature ◽

Radiant Temperature

This paper investigates adaptive thermal comfort during summer in medical residences that are located in the French city of Troyes and managed by the Association of Parents of Disabled Children (APEI). Thermal comfort in these buildings is evaluated using subjective measurements and objective physical parameters. The thermal sensations of respondents were determined by questionnaires, while thermal comfort was estimated using the predicted mean vote (PMV) model. Indoor environmental parameters (relative humidity, mean radiant temperature, air temperature, and air velocity) were measured using a thermal environment sensor during the summer period in July and August 2018. A good correlation was found between operative temperature, mean radiant temperature, and PMV. The neutral temperature was determined by linear regression analysis of the operative temperature and Fanger’s PMV model. The obtained neutral temperature is 23.7 °C. Based on the datasets and questionnaires, the adaptive coefficient α representing patients’ capacity to adapt to heat was found to be 1.261. A strong correlation was also observed between the sequential thermal index n(t) and the adaptive temperature. Finally, a new empirical model of adaptive temperature was developed using the data collected from a longitudinal survey in four residential buildings of APEI in summer, and the obtained adaptive temperature is 25.0 °C with upper and lower limits of 24.7 °C and 25.4 °C.

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Mean radiant temperature in the CIBSE Guide

Building Services Engineering Research and Technology ◽

10.1177/014362449001100205 ◽

1990 ◽

Vol 11 (2) ◽

pp. 69-71

Author(s):

M.G. Davies

Keyword(s):

Mean Radiant Temperature ◽

Radiant Temperature

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Design Range of Indoor Relative Humidity in Radiant Cooling Environment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.4905 ◽

2011 ◽

Vol 243-249 ◽

pp. 4905-4908

Author(s):

Xue Min Sui ◽

Xu Zhang ◽

Guang Hui Han

Keyword(s):

Relative Humidity ◽

Thermal Comfort ◽

Mean Radiant Temperature ◽

Design Standards ◽

Human Thermal Comfort ◽

Radiant Cooling ◽

Climate Parameter ◽

Radiant Temperature ◽

Thermal Comfort Model ◽

The Impact

Relative humidity is an important micro-climate parameter in radiant cooling environment. Based on the human thermal comfort model, this paper studied the effect on PMV index of relative humidity, and studied the relationship of low mean radiant temperature and relative humidity, drew the appropriate design range of indoor relative humidity for radiant cooling systems.The results show that high relative humidity can compensate for the impact on thermal comfort of low mean radiant temperature, on the premise of achieving the same thermal comfort requirements. However, because of the limited compensation range of relative humidity, together with the constraints for it due to anti-condensation of radiant terminal devices, the design range of relative humidity should not be improved, and it can still use the traditional air-conditioning design standards.

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Evaluation of canopy-layer air and mean radiant temperature simulations by a microclimate model over a tropical residential neighbourhood

Building and Environment ◽

10.1016/j.buildenv.2016.11.026 ◽

2017 ◽

Vol 112 ◽

pp. 177-189 ◽

Cited By ~ 42

Author(s):

Matthias Roth ◽

Vanessa Huimin Lim

Keyword(s):

Mean Radiant Temperature ◽

Canopy Layer ◽

Radiant Temperature ◽

Residential Neighbourhood

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Present and projected future mean radiant temperature for three European cities

International Journal of Biometeorology ◽

10.1007/s00484-017-1332-2 ◽

2017 ◽

Vol 61 (9) ◽

pp. 1531-1543 ◽

Cited By ~ 5

Author(s):

Sofia Thorsson ◽

David Rayner ◽

Fredrik Lindberg ◽

Ana Monteiro ◽

Lutz Katzschner ◽

...

Keyword(s):

Mean Radiant Temperature ◽

European Cities ◽

Radiant Temperature

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Estimation of Mean Radiant Temperature in Urban Canyons Using Google Street View: A Case Study on Seoul

Remote Sensing ◽

10.3390/rs14020260 ◽

2022 ◽

Vol 14 (2) ◽

pp. 260

Author(s):

Eun-Sub Kim ◽

Seok-Hwan Yun ◽

Chae-Yeon Park ◽

Han-Kyul Heo ◽

Dong-Kun Lee

Keyword(s):

Heat Stress ◽

Spatial Patterns ◽

High Density ◽

View Factor ◽

Mean Radiant Temperature ◽

Street Canyons ◽

Google Street View ◽

Street Level ◽

Street View ◽

Radiant Temperature

Extreme heat exposure has severe negative impacts on humans, and the issue is exacerbated by climate change. Estimating spatial heat stress such as mean radiant temperature (MRT) is currently difficult to apply at city scale. This study constructed a method for estimating the MRT of street canyons using Google Street View (GSV) images and investigated its large-scale spatial patterns at street level. We used image segmentation using deep learning to calculate the view factor (VF) and project panorama into fisheye images. We calculated sun paths to estimate MRT using panorama images from Google Street View. This paper shows that regression analysis can be used to validate between estimated short-wave, long-wave radiation and the measurement data at seven field measurements in the clear-sky (0.97 and 0.77, respectively). Additionally, we compared the calculated MRT and land surface temperature (LST) from Landsat 8 on a city scale. As a result of investigating spatial patterns of MRT in Seoul, South Korea, we found that a high MRT of street canyons (>59.4 °C) is mainly distributed in open space areas and compact low-rise density buildings where the sky view factor is 0.6–1.0 and the building view factor (BVF) is 0.35–0.5, or west-east oriented street canyons with an SVF of 0.3–0.55. However, high-density buildings (BVF: 0.4–0.6) or high-density tree areas (Tree View Factor, TVF: 0.6–0.99) showed low MRT (<47.6). The mapped MRT results had a similar spatial distribution to the LST; however, the MRT was lower than the LST in low tree density or low-rise high-density building areas. The method proposed in this study is suitable for a complex urban environment consisting of buildings, trees, and streets. This will help decision makers understand spatial patterns of heat stress at the street level.

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A climatic study of an urban green space: the Gulbenkian Park in Lisbon (Portugal)

Finisterra ◽

10.18055/finis1420 ◽

2012 ◽

Vol 42 (84) ◽

Cited By ~ 2

Author(s):

Henrique Andrade ◽

Rute Vieira

Keyword(s):

Solar Radiation ◽

Thermal Comfort ◽

Green Space ◽

Urban Green Space ◽

Mean Radiant Temperature ◽

Climatic Parameters ◽

Incident Solar Radiation ◽

Urban Green ◽

Isolated Trees ◽

Radiant Temperature

Measurements of various climatic parameters were carried out in an average-sized green space in the centre of Lisbon (the Fundação Calouste Gulbenkian Park). The aims consisted of assessing the thermal differentiation between the park and the surrounding built-up area and analysing the microclimatic patterns within the park itself. The main results demonstrate that the park is cooler than the built-up area in all the seasons and both during the daytime and at night, but especially so in the daytime during the summer. The most signiﬁcant microclimatic contrasts were found to occur with respect to solar radiation and mean radiant temperature, with consequences upon the level of thermal comfort. The structure of the vegetation was also found to have a signiﬁcant microclimatic inﬂuence, since the reduction in the level of incident solar radiation brought on by the presence of groups of trees was much larger than that associated with isolated trees.

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