Conference PaperPDF Available

Thermal IR Images and Energy Balance of Two Urban Canyons in Lisbon (Portugal)

Authors:

Abstract

Considering climate change and the rapid trend towards urbanization, the analysis of urban microclimates is gaining importance. Using a FLIR thermal camera, the temperatures of the facades of the buildings where identified and characterized. The technique that was used - infrared thermography, is emerging and increasingly used in fields such as construction engineering (identification of pathologies in buildings, for example). However, its application in the thermal characterization of building materials in urban space is new. This way, it was identified which materials are more or less reflectors, absorbers and emitters of energy (and their respective colors and exposure to solar radiation). Two locations in Lisbon were selected as case studies: i) Telheiras (in the northern part of Lisbon) and Restauradores in the south. In the neighborhood of Telheiras, the radiative balance of the facades of a group of buildings were studied. This area was chosen because it presents a typical urban canyon that can be found in the northern part of Lisbon. With an infrared thermal camera, radiometers and ENVI-MET software, all the components of this balance were registered and estimated and correlated with the air temperature observed in a micrometeorological network. In Telheiras the surface temperature of the facades is influenced by the exposition: south facade presents the lowest temperature of the four (winter), while north has the highest temperatures between 11am and 7pm. The values registered in the field for summer demonstrate that East facade presents highest temperatures than West facade. The temperature of the facades modulated in the 3D model seem to correlated well with observations. With this study we found that surface materials such as asphalt present a higher radiation net balance than surfaces as brick pavement. The hourly measurements of the two facades shows that the west facade, that receives direct solar radiation in the morning, reaches higher values than the East facade, which only receives solar radiation from 2pm to 6pm. In Restauradores it was concluded that marble and cement have the lowest temperatures (respectively these materials presented the lowest temperature 52% and 13% of the times), in contrast to iron (34%) and plastic (17%). In terms of colors, white (colder, with 63%) and dark green (40%) and black (21%) give the facades the highest temperatures. In the case of Restauradores where the facades are exposed predominantly to east and west, this does not seem to influence the temperatures behavior.
References:
Alcoforado, M. J. (1993). O Clima da Região de Lisboa. Contrastes e Riscos Térmicos. (1st ed.). Lisboa: Centro de Estudos Geográficos.
Alcoforado, M. J., Andrade, H., Lopes, A., Oliveira, S., Fragoso, M., Lombardo, M., Matzarakis, A. (2008). Estudos sobre cidades e alterações
climáticas. Centro de Estudos Geográficos, Universidade de Lisboa
Alcoforado, M. J., Andrade, H., Lopes, A., & Vasconcelos, J. (2009). Application of climatic guidelines to urban planning. The example of
Lisbon (Portugal). Landscape and Urban Planning, 90(12), 5665. https://doi.org/10.1016/j.landurbplan.2008.10.006
Andrade, H. (2003). Bioclima humano e temperatura do ar em Lisboa. Tese de Doutoramento em Geografia Física apresentada à Faculdade
de Letras da Universidade de Lisboa, Lisboa.
Lopes, A., Alves, E., Alcoforado, M. J., & Machete, R. (2013). Lisbon urban heat island updated: New highlights about the relationships
between thermal patterns and wind regimes. Advances in Meteorology, 11.https://doi.org/10.1155/2013/487695
IPMA Portuguese Institute of Sea and Atmosphere - Climate Normals 1981-2010;
3. Materials and Methods
4. Preliminary Results
b)
1.Introduction 2. Main Objectives
5. Concluding remarks:
10th International Conference on Urban Climate
14th Symposium on the Urban Environment
6-10 August 2018, New York, NY
Márcia Matias1,2, Cláudia Reis1,2 e António Lopes1
1Institute of Geography and Spatial Planning (IGOT-ULisboa), Center of Geographical Studies, Universidade de Lisboa, Portugal
2 Master Students in Physical Geography and GIS
e-mail: marcia.a.matias@campus.ul.pt
Thermal IR Images and Energy Balance of Two Urban Canyons in
Lisbon (Portugal)
I. To measure surface temperatures of the façades in two urban canyons in Lisbon;
II. To understand the influence of the façades (geometry) and the materials in the outdoor
temperatures;
III. To compare observations from April to July 2018 with micro-meteorological 3D
modelling using ENVI_MET software
Radiation balance components
For the estimation of the radiation balance a KIPP & ZONEN
pyranometer and pyrgeometer were used;
Several materials representative of different vertical surfaces
(including different orientations and colors) and horizontal
surfaces (asphalt, tiles and bricks) were sampled.
Infrared Thermography
In Telheiras the temperature of the urban canyon surfaces, such as asphalt, brick stones and pavement, was also
registered.
Thermal images were collected in tree different days: one in Winter, Spring and Summer
2Micrometeorological network
In the case study of Telheiras a micrometeorological network was installed in the urban canyon.
Tridimensional modelling
The micro-meteorological 3D model ENVI_MET software was
used. The urban canyon in Telheiras was designed in 2D and 3D
structure.
The data obtained in the field, for the air temperature,
radiation balance components and surface temperature of the
façades was compared with the 3D model results.
4
3
1
Material
Time
Asphalt
Portuguese pavement
(white) - Limestone
Brick
Pavement
9:00am
136.2 105.9 69.1
1:00pm
873.9 724.8 888.0
6:00pm
191.9 125.9 136.9
Net all wave radiation balance of different materials in
Telheiras (W/m2), on 7th July 2018
Net all wave radiation balance of East and West façades and
in the urban canyon (Telheiras), on 7th July 2018
Telheiras
West façade at 7pm (Summer, 7th July 2018)
Measures: Sp1= 31ºC; Sp2= 28.6ºC;Sp3= 28.2ºC; Sp4= 27.7ºC
East façade at 1pm (Sumer, 7th July 2018)
Measures: Sp1= 25.1ºC: Sp2= 32.1ºC, Sp3= 25.3ºC, Sp4=29.6ºC
In Restauradores Square, marble and cement present the lowest temperatures and iron and plastic the highest. White
materials presents the lowest temperatures opposing to dark green and black that present the highest. The exposition
of the façades does not seem to influence the temperature registered in the street;
In Telheiras the surface temperature of the façades is influenced by the exposition: north façade presents the lowest
temperature of the four (winter), while south has the highest temperatures between 11am and 7pm. The values
registered in the field for summer demonstrate that west façade presents highest temperatures than east façade. The
temperature of the façades modulated in the 3D model seem to correlated well with observations, although there are
some differences ;
With this study we found that surface materials such as asphalt present a higher radiation net balance than surfaces as
brick pavement;
The hourly measurements of the two façades shows that the east façade, that receives direct solar radiation in the
morning, reaches higher values than the west façade, which only receives solar radiation from 2pm to 6pm.
Restauradores
Maximum
temperature:
21,6ºC
Minimum
temperature:
14,8ºC Minimum
temperature:
12,1ºC
Maximum
temperature:
25,9ºC
Taken on 11th of november 2016,
12:30pm
Taken on 11th of november 2016, 12:30pm
In Summer, the West façade
presents the highest temperatures
at 7pm and the East façade at 1pm
Air temperature (ºC) in winter (21st February 2018) at 10am, 1pm and 4pm
Air temperature (ºC) in summer (7th July 2018 ) at 10am, 1pm and 4pm
Temperature of the façades in winter (21st February 2018) and in summer (7th July 2018)
The city of Lisbon has a temperate climate, with moderate winters, where the hot season
corresponds to the dry season (Alcoforado, 1992; Andrade, 2003; Alcoforado et al., 2008).,
the average temperature is about 16ºC, with minimum values occurring in February (11.6ºC)
and maximum in August (23.5ºC) (Climate Normals 1981-2010; IPMA Portuguese Institute
of Sea and Atmosphere). The urban heat Island intensity is about 3ºC (Lopes et al, 2013).
Two urban canyons were selected for this study: i) Telheiras (in the northern part of Lisbon) and ii) Restauradores in the south.
In the Telheiras neighborhood, the surface temperatures and the radiative balance of the façades of a group of buildings were studied.
0
100
200
300
400
500
600
700
800
900
Q (W m-2)
East Façade West Façade Study Area
40ºC
C
40ºC
C
Location of Telheiras and Restauradores in Lisbon
5
15
25
35
45
55
East West South North
5
15
25
35
45
55
East West South North
ResearchGate has not been able to resolve any citations for this publication.
ResearchGate has not been able to resolve any references for this publication.