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- Heat stress mitigation by exploring UTCI hotspots and enhancing thermal comfort through street treesPublication . Silva, Tiago; Matias, Márcia; Girotti, Carolina; Vasconcelos, João; Lopes, AntónioHeat stress mitigation actions must be carefully planned in order to achieve efective outcomes. By integrating urban planning guidelines with urban climate knowledge, substantial benefts can be achieved for the community. In Lisbon, the study area, urban planning guidelines are strict in relation to the tree species which should be used for planting. This study examined these species environmental contributions to the community, especially in regard to heat stress mitigation in two urban canyons previously found as UTCI hotspots. For this, microclimatic Envi-met simulations were run which allowed recalculation of the UTCI hotspot analysis and to assess individual species contribution to possible mitigation eforts. Results demonstrated the ability of these trees to lower air temperature and the Universal Thermal Climate Index (UTCI). By reducing UTCI temperatures between 3.19 °C and 6.27 °C on a hot summer’s day, these trees were also able to transform an identifed UTCI hotspot into a coldspot. From the studied species, Pyrus calleryana was found to be the most efective species for mitigating thermal stress, although all three species performed well. Regarding community services, according to the iTree tool, Cercis siliquastrum had the greatest overall impact. These results give to the municipal urban planning which tree species should be prioritized in terms of climate action, as well as a methodological framework to assess at local scale which areas should be intervened.
- A micro-scale look into pedestrian thermophysiological comfort in an urban environmentPublication . Silva, Tiago; Lopes, António; Vasconcelos, JoãoDiferent spatial scales enable the analysis of thermophysiological conditions of pedestrians in an urban environment. A higher resolution hotspot analysis was conceived using GIS technology in some areas of Lisbon with diferent morphological conditions. Eleven hotspots were found across six study areas, located in high to moderate urban density conditions and in diferent types of urban spaces. So, six hotspots were found in avenues (high urban density conditions), three in streets, and two in general open spaces (moderate urban density conditions). These spaces are characterized by being busy areas with high anthropogenic infuence, with high-absorbing and refective materials, and with very poor green infrastructure. Environmental conditions, namely, radiation, mean radiant temperature, and air temperature, were the main cause of hotspot existence, and the main propellers for UTCI intensifcation. The urban density variable was also found to be important, especially in avenues and open spaces. In these areas, the adjusted component for environmental and urban density conditions can increase 0.60 to 1.35 °C in open spaces and 0.30 to 0.60 °C in avenues, each time there is a one-unit increase in the component. Trees, either in the street or in parks, have generally been found to decrease the UTCI.
- Integrated effects of pavement simulation models and scale differences on the thermal environment of tropical cities: physical and numerical modeling experimentsPublication . Kowalski, Luiz; Lopes, António; Masiero, E.Simulation methods attempt to explain what happens in full-scale environments. However, as simplification procedures, they also have their limitations and opportunities. One of the applications is to use the output data of a physical model to calibrate numerical simulation, or even to use outputs of numerical simulations to analyze urban scale studies. But it is uncertain the error in the interaction between these models. This study aims to analyze the impact of scale analysis and pavements simulation model modification on ambient and surface temperature of asphalt pavement in a physical model of a tropical city street canyons. Therefore, a scaled outdoor experiment was conducted, and a numerical simulation model, using ENVI-met software, was used to investigate the spatiotemporal variation of air and pavement surface temperature, in urban (1:1) and reduced (1:15) scales. For studies on the surface temperature of pavements, within the temperature range of 12 ºC to 37 ºC, it is recommended to calibrate physical models using as input, data derived from numerical simulation models, yielding a mean absolute percentage error (MAPE) of 4.9%. For estimating data in real-world urban scale, within the air temperature range of 15 ºC to 37 ºC, it is proposed to use output data from simulated models in ENVI-met, that presented a mean absolute error (MAE) of ± 0.59 or physical models (MAE = ± 0.66). These results would be useful for the development of urban surface temperatures parametrizations.
- A micro-scale look into pedestrian thermophysiological comfort in an urban environmentPublication . Silva, Tiago; Lopes, António; Vasconcelos, JoãoDifferent spatial scales enable the analysis of thermophysiological conditions of pedestrians in an urban environment. A higher resolution hotspot analysis was conceived using GIS technology in some areas of Lisbon with different morphological conditions. Eleven hotspots were found across six study areas, located in high to moderate urban density conditions and in different types of urban spaces. So, six hotspots were found in avenues (high urban density conditions), three in streets, and two in general open spaces (moderate urban density conditions). These spaces are characterized by being busy areas with high anthropogenic influence, with high-absorbing and reflective materials, and with very poor green infrastructure. Environmental conditions, namely, radiation, mean radiant temperature, and air temperature, were the main cause of hotspot existence, and the main propellers for UTCI intensification. The urban density variable was also found to be important, especially in avenues and open spaces. In these areas, the adjusted component for environmental and urban density conditions can increase 0.60 to 1.35 °C in open spaces and 0.30 to 0.60 °C in avenues, each time there is a one-unit increase in the component. Trees, either in the street or in parks, have generally been found to decrease the UTCI.
- Confronting potential future augmentations of the physiologically equivalent temperature through public space design: the case of Rossio, LisbonPublication . Nouri, A. Santos; Lopes, António; Costa, J. Pedro; Matzarakis, A.When considering cities such as Lisbon, which due to their Köppen Geiger classification of ‘Csa’, witness hot and dry summers, the translation of local bottom-up knowhow upon climatic guidelines has been a topic of considerable dissemination over recent years. Depicting upon a concrete case study located in Lisbon’s historical quarter, the results from a previous bioclimatic study undertaken by the authors were taken further in order to consider how worst-case-scenarios of climate change (A1FI/RCP8.5) could potentially impact the existing human thermal environment within the square. In addition to considering its existing layout, public space design interventions were also examined within different thermal/temporal scenarios through the use the Physiologically Equivalent Temperature (PET) and PET(Load) indices. The results of the study revealed that within a climatic worse-case-scenario, and without any adaptive measures to address Physiological Stress (PS) levels, the majority of the square presented potential PS thresholds ranging between ‘Extreme Heat Stress Lv.3/4′, with PET values exceeding that of 51 °C and 56 °C. On the other hand, and particularly in regions prone to high levels of solar radiation, the thermal amelioration effects of the proposed public space design interventions presented reductions of PET values up to 16.6 °C.