Loading...
Publication
O balanço radiativo de um conjunto de edifícios em Telheiras com recurso a termografia infravermelha
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 6.18 MB | Adobe PDF |
Advisor(s)
Abstract(s)
O presente trabalho tem como objetivos calcular o balanço radiativo de um conjunto de fachadas
em Telheiras (Lisboa), obter imagens térmicas das fachadas dos edifícios em estudo, através da
termografia infravermelha, compreender de que forma as temperaturas registadas nas fachadas e
superfícies da área de estudo afetam as temperaturas do ar registadas no canyon urbano, perceber
de que modo os valores do balanço radiativo registados nas fachadas e diferentes superfícies
influenciam as temperaturas do ar e comparar os valores obtidos através do modelo
micrometeorológico ENVI-met com as observações realizadas em campo. Para atingir estes
objetivos foram calculadas as temperaturas de superfície, através de imagens de satélite,
procedeu-se à instalação de uma rede microclimática na área de estudo, para a monitorização da
temperatura e humidade relativa do ar, e com recurso a uma câmara térmica FLIR, foram
recolhidas as temperaturas de superfície das fachadas e respetivos materiais. Foi igualmente
calculado o balanço radiativo destas superfícies e das fachadas dos diferentes edifícios com
recurso a um piranómetro e a um pirgeómetro. Os valores observados foram comparados com os
resultados obtidos na modelação tridimensional, através do cálculo das diferenças entre os valores
observados em campo e os estimados pelo modelo. Os resultados obtidos mostram que os locais
mais expostos à direção predominante do vento (norte e noroeste) apresentam temperaturas do ar
relativamente mais baixas do que os que se encontram em abrigo (ruas perpendiculares a essa
direção). Tanto a temperatura como o balanço radiativo das fachadas e outras superfícies (asfalto,
calçada portuguesa de cor clara e pavimento em azulejo) respondem diretamente à radiação solar
incidente. São as fachadas expostas a sul onde se verificam sempre as temperaturas mais elevadas
das quatro exposições em estudo. As temperaturas e o balanço radiativo mais elevado são quase
sempre registados no asfalto. O modelo ENVI-met, utilizado para a modelação tridimensional de
diferentes variáveis recolhidas em campo conseguiu, de certa forma, modelar corretamente a
variação diurna da temperatura do ar no canyon urbano. Relativamente à temperatura das fachadas
e ao balanço radiativo destas superfícies, o modelo 3D estima valores superiores aos observados
em campo, maioritariamente, quando as fachadas se encontram a receber radiação solar. Este
estudo tem um cariz totalmente inovador em Portugal, sendo necessário prosseguir a investigação
noutras áreas de estudo e períodos do ano, de modo a encontrar soluções de materiais que possam
ajudar a mitigar o efeito de ilha urbana de calor de Lisboa.
This work aims to understand the radiation balance (Q*) of a group of façades in Telheiras (Lisbon) and compare the results with atmospheric temperatures measured in an urban canyon in this neighborhood. A set of thermal images of these façades were obtained using an infrared thermograph camera (FLIR) and Landsat 8 satellite images were obtained to complement the study. This thermography allowed to understand how the temperatures registered in the façades and other urban surfaces affect the air temperature of the urban canyon. The components of the radiation budget were obtained by using a pyranometer and a pyrgeometer. The values were compared with the results of a micrometeorological model (ENVI-met), to validate these results and extent punctual data to the surfaces. To reach the main goals, a microclimatic network to monitor air temperature and relative humidity was installed in Telheiras. The results show that when the streets are more exposed to the prevailing wind direction in Lisbon (North and Northwest), air temperatures is slightly higher than those found in opposite conditions. Both the temperature and the radiative balance of the façades and other surfaces (asphalt, light Portuguese sidewalk and tile floor) respond directly to incident solar radiation. As expected, it was found that south façades have the highest temperatures of the four exposures under study and the highest radiative balance were always recorded on asphalt. The ENVI-met model, used for the threedimensional modeling of different variables collected in the field, was able, in some way, to correctly model the diurnal variation of air temperature in the urban canyon. Regarding the temperature of the façades and the radiative balance of these surfaces, the 3D model estimates higher values than those observed in the field, mostly when the façades are receiving solar radiation. This work is innovative in the way it is the first attempt to integrate all components of this complex system in an urban canyon in the region and to understand which materials are more adequate to mitigate urban heat island effect in Lisbon.
This work aims to understand the radiation balance (Q*) of a group of façades in Telheiras (Lisbon) and compare the results with atmospheric temperatures measured in an urban canyon in this neighborhood. A set of thermal images of these façades were obtained using an infrared thermograph camera (FLIR) and Landsat 8 satellite images were obtained to complement the study. This thermography allowed to understand how the temperatures registered in the façades and other urban surfaces affect the air temperature of the urban canyon. The components of the radiation budget were obtained by using a pyranometer and a pyrgeometer. The values were compared with the results of a micrometeorological model (ENVI-met), to validate these results and extent punctual data to the surfaces. To reach the main goals, a microclimatic network to monitor air temperature and relative humidity was installed in Telheiras. The results show that when the streets are more exposed to the prevailing wind direction in Lisbon (North and Northwest), air temperatures is slightly higher than those found in opposite conditions. Both the temperature and the radiative balance of the façades and other surfaces (asphalt, light Portuguese sidewalk and tile floor) respond directly to incident solar radiation. As expected, it was found that south façades have the highest temperatures of the four exposures under study and the highest radiative balance were always recorded on asphalt. The ENVI-met model, used for the threedimensional modeling of different variables collected in the field, was able, in some way, to correctly model the diurnal variation of air temperature in the urban canyon. Regarding the temperature of the façades and the radiative balance of these surfaces, the 3D model estimates higher values than those observed in the field, mostly when the façades are receiving solar radiation. This work is innovative in the way it is the first attempt to integrate all components of this complex system in an urban canyon in the region and to understand which materials are more adequate to mitigate urban heat island effect in Lisbon.
Description
Keywords
Termografia infravermelha Balanço radiativo ENVI-met IUC Superfícies urbanas