Effects of radiative exchange in an urban canyon on building surfaces’ loads and temperatures

Vallati, Andrea; Mauri, Luca; Colucci, Chiara; Ocłoń, Paweł

doi:10.1016/j.enbuild.2017.05.072

Cited by 22 publications

(7 citation statements)

References 19 publications

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“…In this study, we found that focused sensible heat flux directly affects the urban thermal environment relative to the surface type and spatial conditions in an urban canyon [92]. The in-situ data agreed well with the thermal spatial typification results overall.…”

Section: Spatiotemporal Shift In Sensible Heat Fluxsupporting

confidence: 77%

Determining Favourable and Unfavourable Thermal Areas in Seoul Using In-Situ Measurements: A Preliminary Step towards Developing a Smart City

Kwon

Lee

2019

Energies

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Urban heat island effects (UHIE) are becoming increasingly widespread, thus, there is an urgent need to address thermal comfort, which significantly influences the daily lives of people. In this study, a means of improving the thermal environment by spatial analysis of heat was implemented to ensure basic thermal comfort in future smart cities. Using Seoul as the study site, the relationship between sensible heat and land cover type was used to identify heat islands in this city. Thereafter, k-means clustering was employed to extract unfavourable and favourable thermal areas. High sensible heat indicates locations where environmental heat needs to be mitigated. Sensible heat distribution data were used for spatial typification to formulate an effective land cover factor to mitigate the UHIE. In-situ net radiation data measured at six sites were utilised to confirm the spatial typification of the thermal environment. It was found that expanding the green space by 1% reduces the sensible heat by 4.9 W/m2. Further, the building coverage ratio and green coverage influence the sensible heat in compact residential areas. The study results can be used to establish spatial planning standards to improve the thermal environments of sustainable cities.

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Section: Spatiotemporal Shift In Sensible Heat Fluxsupporting

confidence: 77%

Determining Favourable and Unfavourable Thermal Areas in Seoul Using In-Situ Measurements: A Preliminary Step towards Developing a Smart City

Kwon

Lee

2019

Energies

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“…These architectural circumstances restricted the shade from reaching the tree spot and allowed the tree to create shade near the building during the daytime [73]. The two-directional MRT measurement instruments may cause higher MRT under incoming longwave radiation [74]. Each sensor (where each instrument has two longwave radiation sensors) collects the radiation value over a half-hemisphere (180 • ).…”

Section: Study Limitationsmentioning

confidence: 99%

“…In this study, focused longwave radiation directly affects the urban thermal environment relative to the surface temperature in shadowy urban canyons [74]. Considering this point, research on longwave radiation allows the proposal of new methods to secure energy efficiency by manipulating the volume and composition of planting in overpopulated residential areas with concentrated high-rise buildings.…”

Section: Suggestions For Further Researchmentioning

confidence: 99%

Thermal Comfort and Longwave Radiation over Time in Urban Residential Complexes

Kwon

Lee

2019

Sustainability

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Large cities with a high concentration of high-rise buildings are shaded by urban canyon. This brings a cooling effect compared to the space exposed to the sun, but is not always cool due to the longwave radiation emitted from buildings and the built environment. We tested the micro-scale effects of major external spatial factors, trees, and buildings, under shade on longwave radiation shifts to understand the effects of large shaded areas in megacities. Incoming and outgoing longwave radiations (ILR and OLR, respectively) were found to decrease the overall observation by time zone. Longwave radiation on a micro-scale was also inversely proportional to the tree volume. From mean radiant temperature (MRT) analysis, we found that about a 10% decrease in MRT could be achieved by increasing tree volume by around 50%. Larger tree volumes corresponded to greater blocking effects on longwave radiation. Considering the tree volume, a multilayer urban tree canopy composition can more favorably improve the thermal environment and energy sustainability of a city compared to a single-layer canopy. Larger trees planted with harmonious shrubs are the most effective in reducing longwave radiation.

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“…Furthermore, the complex geometry of the urban surface decreases the solar access of building facades (Chatzipoulka, Compagnon, and Nikolopoulou 2016), modifies the wind speed and direction (Di Bernardino et al 2015;Nardecchia et al 2018) and reduces the infrared radiation exchange between buildings and their surroundings (Chatzipoulka, Nikolopoulou, and CONTACT A. Salvati agnese.salvati@brunel.ac.uk Institute of Energy Futures, Brunel University London, CSEF Centre, Elliott Jaques, Brunel University London, Uxbridge, Middlesex, UB83PH, UK Watkins 2015; Allegrini, Dorer, and Carmeliet 2016;Vallati et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Some studies focused on the infrared radiation exchange in urban environments, showing that low sky view factors and higher surface temperatures cause a further increase in the cooling demand of urban buildings (Allegrini, Dorer, and Carmeliet 2012;Vallati et al 2017;.…”

Section: Introductionmentioning

confidence: 99%

Built form, urban climate and building energy modelling: case-studies in Rome and Antofagasta

Salvati

Palme

Chiesa

et al. 2020

Journal of Building Performance Simulation

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The energy performance of urban buildings is affected by multiple climate phenomena such as heat island intensity, wind flow, solar obstructions and infrared radiation exchange in urban canyons, but a modelling procedure to account for all of them in building performance simulation is still missing. This paper contributes to fill this gap by describing a chain strategy to model urban boundary conditions suitable for annual simulations using dynamic thermal simulation tools. The methodology brings together existing physical and empirical climate models and it is applied to 10 case studies in Rome (Italy) and Antofagasta (Chile). The results show that urban climate varies significantly across a city depending on the density of urban texture and its impact on the annual energy demand depends on the region's climate. The urban shadows are crucial in cooling-dominated climates (Antofagasta) while the urban heat island intensity is more important in temperate climates (Rome).

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Effects of radiative exchange in an urban canyon on building surfaces’ loads and temperatures

Cited by 22 publications

References 19 publications

Determining Favourable and Unfavourable Thermal Areas in Seoul Using In-Situ Measurements: A Preliminary Step towards Developing a Smart City

Determining Favourable and Unfavourable Thermal Areas in Seoul Using In-Situ Measurements: A Preliminary Step towards Developing a Smart City

Thermal Comfort and Longwave Radiation over Time in Urban Residential Complexes

Built form, urban climate and building energy modelling: case-studies in Rome and Antofagasta

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