A review on the significance and perspective of the numerical simulations of outdoor thermal environment

Lam, Cho Kwong Charlie; Lee, Hyunjung; Yang, Shing-Ru; Park, Sookuk

doi:10.1016/j.scs.2021.102971

Cited by 64 publications

(31 citation statements)

References 172 publications

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“…Scaled outdoor experiments have been adopted in several studies (2020; Miao et al, 2020), which have examined the effects of urban indicators on a city thermal environment and have reported the substantial cooling potential of tree plantings on wall and air temperature (Chen et al, 2021). The numerical simulation of vegetation is primarily re ected in the change of various indicators to compare the different results and select the optimal scheme, including leaf area index (LAI) (Fahmy et al, 2010), leaf area density (LAD) (Li and Song, 2019), root area density (RAD) (Boukhabl and Alkam, 2012), surface vegetation cover Yang et al, 2019), tree coverage ratio (Chatterjee et al, 2019;Yang et al, 2019), vegetation species (Morakinyo et al, 2017), density, and arrangement (Thom et al, 2016;Lam et al, 2021). Scholars have further proposed a hybrid approach that combines wind tunnel measurement and numerical simulations to examine the effect of vegetation on a pedestrian level (Mijorski et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

A microclimate regulation study of Ficus altissima under winter conditions in lower subtropical China

Deng¹,

Chun-hua²,

Chen³

et al. 2021

Preprint

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As a widespread practice in urban landscape design, tree planting plays a vital role in improving the ecological environment and microclimate. This study obtained the physical, physiological, and meteorological data of Ficus altissima, a typical tree species in lower subtropical China, through field measurement, and analyzed its functional performance in microclimate regulation. Its results indicated that: (1) the leaf area index (LAI), sky visible factor (SVF), ground cover (GC), and other indicators of Ficus altissima had essential relationships with radiation attenuation, temperature, and humidity regulation under winter conditions in lower subtropical China; (2) there were significant differences in leaf surface temperature and transpiration between east, west, north, and south during daytime; and, (3) thermal comfort represented by physiological equivalent temperature(PET)in the shade could be expressed as functions of solar radiation (SR), mean radiation temperature (MRT), air temperature (Ta), air humidity (RH), globe temperature (Tg), and wind speed (V). Based on these results, the following were the suggestions: firstly, Ficus altissima with higher LAI values should be selected for planting; secondly, trees must be planted on the east side of the site should solitary planting be undertaken to obtain maximum thermal comfort; and finally, activities under the canopy of Ficus altissima should be prioritized at 11:00–16:00 during winter.

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Section: Introductionmentioning

confidence: 99%

A microclimate regulation study of Ficus altissima under winter conditions in lower subtropical China

Deng¹,

Chun-hua²,

Chen³

et al. 2021

Preprint

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show abstract

“…This involved ENVI-met simulation and comparison of mean radiant temperature (as a proxy for thermal comfort) of the existing situation ("base case") against a future "green" scenario where the maximum green cover possible in each location is assumed to have taken place ("best case"). MRT is an excellent predictor of thermal comfort and has been widely used in the past as a proxy for thermal comfort [29]. While outdoor human thermal comfort indices such as PET or UTCI exist, these need to be validated for the local context and only a few studies have attempted this (less than 10% of outdoor thermal comfort studies, according to a recent survey [29]).…”

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confidence: 99%

“…MRT is an excellent predictor of thermal comfort and has been widely used in the past as a proxy for thermal comfort [29]. While outdoor human thermal comfort indices such as PET or UTCI exist, these need to be validated for the local context and only a few studies have attempted this (less than 10% of outdoor thermal comfort studies, according to a recent survey [29]). In order to indicate thermal discomfort, we also calculated the predicted percentage of dissatisfied (PPD).…”

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confidence: 99%

How Much Green Is Really “Cool”? Target Setting for Thermal Comfort Enhancement in a Warm, Humid City (Jakarta, Indonesia)

Stepani¹,

Emmanuel

2022

Atmosphere

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Green infrastructure is well recognized as a key urban climate mitigation strategy. In line with this, and following a central government decree, Jakarta Municipal Government has created a green infrastructure target of 30% underpinned by a green space weighting factor. This study questions the efficacy of such a “universal” target setting from the point of view of outdoor thermal comfort and demonstrates the basis for an alternative approach. Based on a “new’ green factor developed from a systematic analysis of the literature, thermal comfort simulations of representative local climate zones (LCZ) show that improvements in current green space policy are possible. We enumerate a rational basis for specifying green space targets per local area based on contextual realities as captured by the LCZ approach. Such a nuanced approach to mitigate the human comfort consequences of inadvertent urban growth is not only more contextually appropriate but also enhances the feasibility of achieving the intended goal of urban greening in Jakarta.

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“…The temperate climate in the Koppen-Geiger climate classification includes subtropical (humid and monsoon), Mediterranean, subtropical highlands, oceanic and subpolar oceanic climates. As Coccolo (2016) and Lam ( 2021) explain, temperate climate is the most studied, with many studies that have applied PET and UTCI in thermal comfort assessment. Temperate category lists a broader range of climates, including locations with high population densities, due to which researchers tend to study these locations frequently.…”

Section: Statement Of the Problem And Understanding The Need For This...mentioning

confidence: 99%

“…"how urban design can influence the microclimate of an urban environment and people's outdoor thermal comfort and, in turn, how people's thermal comfort can influence their use of outdoor urban spaces?" Lam et al, 2021).…”

Section: Thermal Comfort and The Built Environmentmentioning

confidence: 99%

Outdoor thermal comfort - An adaptive model to assess thermal comfort in urban outdoors in New Zealand.

Perera¹

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This research attempts to integrate human thermal adaptation into thermal comfort assessment in order to explore the complex link between microclimate, thermal comfort, thermal adaptation, and user expectations in outdoor urban parks in New Zealand. The study extends the exploratory analysis and the model developed by D.Walton, V. Dravitzky and M. Donn in 2007. It is based on extensive surveys of over 1000 people in urban parks in Wellington – a temperate but windy climate - and Christchurch – a less windy temperate climate with significantly higher and lower outdoor temperatures than Wellington. This study has extended the methodology to define a comprehensive human adaption scale (Combined Adaptive Factor) that combines a number of inputs related to thermal responses. The wind, sun, temperature and humidity were measured simultaneously with the survey implementation. The combined adaptive factor comprises a correlation of thermal sensations, behavioural changes and preferences to probe ‘the degree people have to adapt’ to be comfortable in different outdoor conditions. The exploration process to identify how the climate influences comfort resulted in a Thermal Adaptation Index, a linear model represented by temperature, wind, relative humidity, and solar radiation to predict comfort based on climate. The thermal environment in outdoor urban spaces substantially influences the use of the space as it directly affects peoples’ thermal perception. Improving thermal comfort in the urban outdoor environment can enhance the use of space and ultimately lead to a sustainable social life in cities. The result is improvement in the city inhabitants’ health and wellbeing. Improving the livability and vitality of the urban outdoors also has environmental and economic benefits. It is essential to understand people’s thermal expectations based on their requirements to enhance livability and improve thermal comfort in urban pockets by changing the physical context. Understanding people’s knowledge of the thermal environment and how they accept the thermal effects based on their expectations and functionality can lead to better thermal perception predictions enabling designers to design the physical context for better thermal comfort. Recent outdoor thermal comfort research has moved to investigate the combined effects of sun, wind and temperature integrating human adaptation aspects. Many field experiments have reported discrepancies with physiological models and have inclined to calibrate these models based on human thermal responses.

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A review on the significance and perspective of the numerical simulations of outdoor thermal environment

Cited by 64 publications

References 172 publications

A microclimate regulation study of Ficus altissima under winter conditions in lower subtropical China

A microclimate regulation study of Ficus altissima under winter conditions in lower subtropical China

How Much Green Is Really “Cool”? Target Setting for Thermal Comfort Enhancement in a Warm, Humid City (Jakarta, Indonesia)

Outdoor thermal comfort - An adaptive model to assess thermal comfort in urban outdoors in New Zealand.

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