Narrow Stepped Canyons in Mexico City. Improving Outdoor Comfort and Water Cycles.
Architectural Association School of Architecture
Autorship Declaration Form. AA SED. ARCHITECTURAL ASSOCIATION SCHOOL OF ARCHITECTURE GRADUATE SCHOOL
PROGRAMME: MSc SUSTAINABLE ENVIRONMENTAL DESIGN 2014-15 SUBMISSION: Dissertation TITLE: NARROW STEPPED CANYONS IN MEXICO CITY: Improving Oudoor Comfort and Water Cycles. NUMBER OF WORDS: 14,410 STUDENT NAME: Luis Arturo Reyes Valencia
DECLARATION: “I certify that the contents of this document are entirely my own work and that any quotation or paraphrase from the published or unpublished work of others is duly acknowledged”.
Signature:
Date:
Table of Contents 1.
Abstract
VII
2.
Introduction
10
3.
Literature Review
14
3.1
Urban Canyons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2
Urban Canyons and Outdoor Comfort. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3
PET and mPET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4
Albedo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.5
Vegetation : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6
Shading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.7
Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.8
Urban Heat Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.9
Climate Zones in Mexico City. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.10 Hypothesis
4.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Context and Precedents
26
4.1
Mexico City. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2
Area of Study. Magdalena Contreras. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.3
Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.3.1 Mexico City’s Climate.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.3.2 Magdalena Contreras monthly weather data. . . . . . . . . . . . . . . . . . . . . . 28 4.3.3 Magdalena Contreras Microclimate Classification. . . . . . . . . . . . . . . . . . . 28
4.4
Site Demography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.5
Public and Green Spaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.6
Water Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.7
Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.8
Precedents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.8.1 Vertical Gymnasiums in slums in Venezuela. . . . . . . . . . . . . . . . . . . . . . 32 4.8.2 Water Collection System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.
Fieldwork
38
5.1
Delimitation of the area of study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.2
Case Studies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.2.1 Andador Granada. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5.2.2 2a Cerrada Paraiso. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.3
Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 5.3.1 Responses Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 5.3.2 Responses Comparison with Spot Measurements. . . . . . . . . . . . . . . . . . . 48
5.4
6.
Materiality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Analytic Work
54
7.
6.1
Andador Granada. Wind and
solar radiation analysis. . . . . . . . . . . . . . . . . . 54
6.2
Base Case Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.3
Base Case Shadow Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.4
Base Case Solar Radiation Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.5
Shading with trees.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.6
Shading Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Research Outcomes and Design Applicability
64
7.1
Lessons from Research,
Fieldwork and Analytic Work. . . . . . . . . . . . . . . . . 64
7.2
Shading Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
7.3
Possible Shading Device
7.4
Shading analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
7.5
Water Management System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Arrangement. . . . . . . . . . . . . . . . . . . . . . . . . 66
8.
Conclusion
72
9.
References
76
9.
Appendix
78
List of Figures Figure 1
A Canyon Urban canyon elements.. B Sensible heat exchanges into and out the canyon air volume. Source: Nunez, M. et al (1976) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 2
Diurnal energy balance of each of the canyon surfaces. Source: Nunez, M. et al (1976) . . . . . . . . . . . . . . 16
Figure 3
PET calculations comparison at 14:00 hours and SVF/PET correlation. Sharmin, T. et al (2013) . . . . . . . . . . 17
Figure 4
Changes of wind speed (in %) from originally 10 m height to human-biometeorologicalheight of 1.1 m for different roughness lengths. Source: Matzarakis, A. (2015). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 5
PET, mPET and UTCI comparison.
Figure 6
Maximum and minimum temperatures for Mexico city in 1980. Source: Jauregui (1993) . . . . . . . . . . . . . . 22
Figure 7
Air temperatures. Source: Ballinas (2011). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 8
Main climatic regions found in Mexico City (A). Microclimatic sub-Regions of Mexico city. (B). Source: After Estrada, F. et al. (2009) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 9
Mexico City’s (left) and Cerro del Judio’s (right) location. Source: Google Earth Pro Software. . . . . . . . . . . . 27
Figure 10
Monthly sunlight situation of Mexico City. Source: www.mexico-city.climatemps.com/sunlight.php. visited.: 13/08/2015. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 11
Mexico City’s monthly climate. Source: Meteonorm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 12
Mexico City´s weather graph for year 2100.
Figure 13
Magdalena Contreras micro-climates.
Figure 14
Gender of the population of Magdalena Contreras. Source: INEGI (2010). . . . . . . . . . . . . . . . . . . . . . 30
Figure 15
Population age groups Magdalena contreras. Source: INEGI (2010). . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 16
Number of inhabitants per household. Source INEGI (2010). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 17
Green areas in the site.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 18
Children playgrounds in the site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 19
Children playgrounds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 20
Flooding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 21
River pollution and risk for near houses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 22
Root growth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 23
Vertical Gymnasium. La Cruz. Venezuela. Source: http://www.u-tt.com/projects_ChacaoVG.html. Visited: 03/08/2015. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 24
Grotão – Fábrica de música’, by Urban-think tank, São Paulo, Brazil. . Source: http://www.designboom.com/ architecture/urban-think-tank-grotao-fabrica-de-musica/ Visited: 03/08/2015. . . . . . . . . . . . . . . 33
Figure 25
Grotão – Fábrica de música’, by Urban-think tank, São Paulo, Brazil. . Source: http://www.designboom.com/ architecture/urban-think-tank-grotao-fabrica-de-musica// Visited: 03/08/2015. . . . . . . . . . . . . . . . . . . . 34
Figure 26
Water management model. Fábrica de música’, by Urban-think tank, São Paulo, Brazil. . Source: http://www. designboom.com/architecture/urban-think-tank-grotao-fabrica-de-musica/. Visited: 03/08/2015. . . . . . . . . . . 34
Figure 27
Metro Cable project. Caracas,Venezuela. Source: http://www.u-tt.com/projects_Metrocable.html. Visited: 03/08/2015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 28
Stairways in Venezuela. Source: (http://lindahagberg.com/Barrio-Stairways, Visited: 04/08/2015) . . . . . . . . . 35
Figure 29
Water collection system. Source: (http://lindahagberg.com/Barrio-Stairways, Visited: 04/08/2015) . . . . . . . . . 35
Figure 30
Bioretention system. Source: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 31
Case studies definition. Source: Google Erth Pro software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 32
Spot measurements temperature comparison. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Source: Matzarakis, A. (2015) . . . . . . . . . . . . . . . . . . . . . . . 18
Source: Meteonorm. . . . . . . . . . . . . . . . . . . . . . . . 29 Source: INEGI. . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 33
Spot Measurements PET/mPET comparison. Source: Mayer, H. et al. (1987), Matzarakis, A. et al. (2014). . . . . 41
Figure 34
Andador Granada location and Sky View Factor of spots measured. . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 35
Spot Measurements Andador Granada between 14:00 and 15:00. . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 36
Spot Measurements Andador Granada between 16:00 and 18:00. . . . . . . . . . . . . . . . . . . . . . . . . . 42
Figure 37
Spot Measurements Andador Granada between 10:00 and 12:00.. . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 38
Spot Measurements Andador Granada between 16:00 and 17:30. . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 39
Spot Measurements Andador Granada between 10:00 and 11:00.. . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 40
Spot Measurements Andador Granada between 14:00 and 15:30. . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 41
2a Cerrada Paraiso location and Sky View Factor of spots measured. . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 42
Spot Measurements 2a Cerrada Paraiso between 11:00 and 12:00.. . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 43
Spot Measurements 2a Cerrada Paraiso between 18:00 and 19:00.. . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 44
Spot Measurements 2a Cerrada Paraiso between 12:00 and 13:00.. . . . . . . . . . . . . . . . . . . . . . . . . 46
Figure 45
Spot Measurements 2a Cerrada Paraiso between 12:00 and 13:00.. . . . . . . . . . . . . . . . . . . . . . . . . 46
Figure 46
Use of stairways. Source: survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 47
Age distribution of sample. Source: survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 48
Gender distribution of sample. Source: survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 49
Clothing of sample subjects. Source: survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 50
Thermal Sensation of subjects. Source: survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 51
Sky condition at the moment of the sample. Source: survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 52
Survey spot measurements graph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Figure 53
Infrared photo showing the surface temperature of a section of the site seen from a street in the hill in front. Compared with a photograph taken at the same moment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Figure 54
Materiality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Figure 55
Surface temperature analysis of spot measurements taken on the floor by material. . . . . . . . . . . . . . . . . 51
Figure 56
Surface temperature analysis of spot measurements taken on the walls by material. . . . . . . . . . . . . . . . . 51
Figure 57
Surface temperature analysis of spot measurements taken on the vegetation by material. . . . . . . . . . . . . . 51
Figure 58
Wind study. Andador Granada. Source: Ecotect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Figure 59
Andador Granada Model. Source: Sketchup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Figure 60
Solar radiation study. Andador Granada.
Figure 61
Base Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Figure 62
SVF of the Base Case (0.175). Source: Skyhelios software.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Figure 63
mPEt values yearly analysis. Present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 64
mPEt values yearly analysis. Future (20100). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 65
Topography and Obstacles used for mPET calculations. Source: Rayman Pro . . . . . . . . . . . . . . . . . . . 57
Figure 66
Shadow analysis for the S-N orientation. Source: Ecotect 2011. . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 67
Shadow analysis for the N-S orientation. Source: Ecotect 2011. . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 68
Shadow analysis for the E-W orientation. Source: Ecotect 2011. . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 69
Shadow analysis for the W-E orientation. Source: Ecotect 2011. . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 70
Solar Radiation Analysis on the W-E axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Source: Ecotect. . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Figure 71
Solar Radiation Analysis on the S-N axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 72
Solar Radiation Analysis on the N-S axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 73
Solar Radiation Analysis on the E-W axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 74
Tree influence on solar Radiation on the S-N axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 75
Tree influence on solar Radiation on the N-S axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 76
Tree influence on solar Radiation on the E-W axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 77
Tree influence on solar Radiation on the W-E axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 78
Solar radiation analysis on umbrellas proposal E-W axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 79
Solar radiation analysis on umbrellas proposal S-N axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 80
Solar radiation analysis on umbrellas proposal N-S axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 81
Solar radiation analysis on umbrellas proposal W-E axis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 82
Umbrella section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Figure 83
Shading device design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Figure 84
Possible views of the umbrellas. Open-Closed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Figure 85
Arrangement possibilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Figure 86
Shadow range 10:00 to 15:00 on a wall covered by a half umbrella. Source: Ecotect 2011. . . . . . . . . . . . . 68
Figure 87
Shadow analysis of an open umbrella.
Figure 88
Representative longitudinal section of the water collection system proposed. . . . . . . . . . . . . . . . . . . . . 69
Figure 89
Representative transversal section of the water collection system proposed. . . . . . . . . . . . . . . . . . . . . 69
Figure 90
Survey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Figure 91
Surveys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Figure 92
Flat canyon South-North axis. For comparison w/ base-case.Source: Ecotect. . . . . . . . . . . . . . . . . . . . 81
Figure 93
Flat canyon North-South axis. For comparison w/ base-case.Source: Ecotect. . . . . . . . . . . . . . . . . . . . 81
Figure 94
Flat canyon North-South axis. For comparison w/ base-case.Source: Ecotect. . . . . . . . . . . . . . . . . . . . 81
Figure 95
PET frequency. 2100.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Figure 96
Shading device design alternative. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Source: Ecotect. . . . . . . . . . . . . . . . . . . . . . . . . . . 68
List of Tables Table 1
Table 1: Albedo and thermal emissivity of natural and manmade materials. . . . . . . . . . . . . . . . . . . . . . 20
Table 2
Table 3: Area of study demographic analysis.
Table 3
Table 2: Demographics Mexico City and Magdalena Contreras. Source:INEGI (2010). . . . . . . . . . . . . . . . 31
Table 4
Table 4: Public Space and potable water. Source: INEGI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 5
Table 5: Green spaces. Source: INEGI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 6
Table 6: Survey answers comparison with PMV, PET and mPET calculations, and Rayman Pro inputs. . . . . . . 49
Table 7
Table 7: Sunlit spaces summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Source: INEGI (2010) . . . . . . . . . . . . . . . . . . 31
Acknowledgments I would like to express my most sincere gratitude to Paula Cadima, Simos Yannas, Jorge Rodr铆guez and all the AA SED staff for their guidance through this year and all the valuable inputs provided for the development of this dissertation. To Becas Magdalena O. Vda. de Brockmann, and Comisi贸n Nacional de Becas para la Educaci贸n Superior for the scholarships given to me for the study of this Master. To my family for their unconditional support and love and to Joe Hicks for his help on proof reading.
1. Abstract Solar radiation is identified as the main factor driving comfort levels in narrow stepped canyons in neglected neighbourhoods of Magdalena Contreras municipality in the South-West of Mexico City. Globe temperatures inside them can surpass 30ยบC just after a short clear sky period. Also, water cycles generate problems of flooding and potable water shortages in the area. A system of shading devices and rainwater collectors is proposed to provide outdoor comfort and reduce the mentioned problems with water management.
Introduction
Improving Outdoor Comfort and Water Cycles
2. Introduction The research project here presented examines the outdoor comfort and water cycle improvement possibilities for narrow stepped urban canyons in Mexico City. The canyons are located in consolidated residential areas in Magdalena Contreras municipality in the south western part of the city. Formerly established as illegal settlements, located in hilly terrains, the settlements occupied protected reservoirs affecting the microclimate. The area presents a rough and tight urban fabric. Its unplanned growth makes extremely difficult the insertion of basic services and public spaces for the community. The site is located on the outskirts of the city with an altitude of more than 2400m above sea level. This, added to the slopes of the terrain, exposes the site to high levels of solar radiation. Also, the site has a strong thermal interaction with the centre of the city. The Urban Heat Island present in it and its roughness reduce the speed of the winds which reach the site. Although the city´s weather is classified as mild, the fieldwork done in the area of study during the first week of July 2015, in the wet season, will demonstrate the influence of solar radiation in outdoor comfort. First, short periods of sunny and cloudless sky can elevate surface temperatures up to 40ºC for certain materials. Second, wind speed measurements taken, were always below 2m/s. Therefore, increasing globe temperature to 30ºC and above during sunny periods. The stepped canyons serve as the only access to many households in the area. Inhabitants have to go up and down the stairs several times a day. mPET calculations show the influence of the high metabolic rates pedestrians are subject to, causing discomfort especially under direct solar radiation exposure. The high solar angles of the city and the sloped terrains reduce the self shading capabilities of the canyons. Even North-South oriented cases proved to receive high levels of solar exposure. After the research, the need for shading became evident. The provision of shade using trees proved to have limitations as it can generate security hazards. Root growth of some species of trees located in the site can break the walls that contain them and the concrete slabs on the floor. The falling of big trees can cause severe damage. Allowing more control over the shading devices to the users proved to be more effective. Vegetation can be introduced with plants and vines instead of trees. Water management is also a problem in the area. As well as reduced wind speeds, the UHI effect interaction with the site increases precipitation. The fast growth of the area surpassed the capabilities of the governments to built effective infrastructure. Sewage systems combine black and gray waters which causes overflows. Therefore flooding is a constant problem in the lower parts of the terrain. A combination of shading devices and rain water collectors are proposed as a possible solution for outdoor comfort and water cycle problems. The shading devices will be connected to a rain water storage system of tanks using gravity to get rid of excessive flows. A simple filtration system is also proposed to be built on top of the existing rain water management infrastructure which at the moment only channels the water to the sewage.
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Literature Review
Improving Outdoor Comfort and Water Cycles
3. Literature Review The main objective of this dissertation project is to provide inhabitants, government institutions, private organizations and any other interested party, with guidelines for the effective design of public spaces in neglected neighbourhoods of Mexico City. For this, identifying the great regenerative potential those comfortable and pleasant public environments have on communities and how they can improve the quality of life of its inhabitants is the first step for the proposition of viable projects. This cannot be achieved without appropriate understanding of the effects and consequences that every design decision has on the overall performance of these spaces. Environmental considerations are rarely part of projects for public space in Mexico. Pedestrian comfort is not even part of the discussion, perhaps because of the lack of knowledge on the possibilities that it offers in terms of reduction of energy consumption and the preservation of natural resources when provided with the required infrastructure. This lack of knowledge is directly related with the fact that the relatively mild weather conditions of the city do not require heating or cooling in any season inside buildings, therefore it is more difficult to assess the impact that public spaces have on energy consumption for its own functioning and for the buildings in its surroundings. Microclimate assessment then, becomes of vital importance to overcome this problem. This research is developed based on narrow steeped urban canyons with a wide variety of configurations and orientations, with Height/Width ratios that can range between 0.85 to 2.83 or even more.
3.1 Urban Canyons Micro climatic conditions of canyons in general are studied by Nunez, M. et al (1976) on a canyon (Figure 1) located in an industrial/residential area of Vancouver Canada. Oriented north-south, on the long axis, 79 m long and 7.54 m wide. The canyon was observed from 9 -11 of September of 1973. With cloudless skies and weak airflows of less than 2m/s by day and less than 1m/s by night. The calculation of its energy balances showed the importance of canyon orientation. The north-south axis receives a peak of solar radiation towards mid-day, but on the west and east walls 1.5h before and after solar noon respectively. The most important changes in surface temperatures where detected during early morning in the west wall, at midday in the floor and in the afternoon in the east wall. On the other hand, the angle of incidence, the surface albedo, emissivity and temperature proved to be significant along with the incidence of solar radiation. Also wind direction and speed proved to be of importance in the energy exchanges of the canyon as long as they were parallel to the canyon axis.
A Â
B Figure 1: A Canyon Urban canyon elements.. B Sensible heat exchanges into and out the canyon air volume. Source: Nunez, M. et al (1976)
The results of the study showed the strong influence of canyon geometry and orientation in the energy exchanges produced inside it. (Figure 2) The floor was detected as the main source of exchange while all the surfaces showed an excess of heat during the day transmitted to the air from the outer layers of the surfaces, although it was also observed that significant heat was stored in the inner layers of those same surfaces. The calculation of the total energy balance of the canyon showed that approximately 60% of the midday heat excess was lost as sensible heat to the air and approximately 30% was stored in canyon materials while the remaining 10% is consumed by evapotranspiration from the canyon floor. 15
Narrow stepped caNyoNs iN mexico city
Urban Canyons and Outdoor Comfort.
Figure 2: Diurnal energy balance of each of the canyon surfaces. Source: Nunez, M. et al (1976)
Nunez, M. et al (1976) showefd that during the night, low wind speeds reduce significantly the heat exchange between the surfaces of the canyon and the air. So the canyon is balanced by the release of the heat stored in the materials during the day. At the same time, simulations carried out by Marciotto, E. et al. (2010) demonstrated the significant effect of the W/H ratio inside street canyons on the energy fluxes and temperatures in urban areas were relatively homogeneous. Two numerical models were compared (UCM and TEB) isolating the building height as the only changing variable which when increased resulted on a increase of the stored energy flux while the sensible heat flux decreases at the top part of the canopy layer, meaning that the higher the building gets the direct solar radiation and its immediate effect on the heating and reflection on the surfaces gets decreased while the retention of heat in the deeper layers of the materials gets increased, showing important effects during the night when that energy gets released to the canyon again. The analysis of solar trajectories through days and seasons will be of vital importance for this research along with orientation to understand the energy exchanges inside the urban canyons.
3.2 Urban Canyons and Outdoor Comfort. The processes involved in the effective provision of outdoor comfort present significant variations depending on geographical and weather conditions. In the case of Mexico City, even though the climate is considered to be mild, solar radiation has a critical impact on outdoor comfort conditions throughout the year. This factor makes relevant the comparison with case studies in warm, warm-humid cities, as the research conducted in Dhaka city to assess the effects of canyon geometry on outdoor thermal comfort, Sharmin, T. et al (2013) shows, having analysed as is well known, that the primary challenge on the effective design of streets and therefore urban canyons in tropical and equatorial climates is to protect the users from unwanted solar radiation, because of the high solar position in warm climates. As Givoni, B. (1994) emphasised, reducing solar and long-wave radiation is a main importance strategy to provide comfort in outdoor spaces inside urban canyons. Surface temperatures of near constructions, the sensible heat flux exchanged from surfaces to the air and as result also the air temperature (Ta) is affected by high levels of solar radiation. Temperature variations of urban canyons vary in time depending on the weather, although in the different spaces of the canyon the variations have almost no impact, as studied by Nakamura et al (1988), air temperature across the height of a urban canyon with an aspect ratio (H/W, average building height to street width) of 1 does not vary considerably (less than 1ยบC). Therefore outdoor thermal comfort studies depending solely on Ta are not adequate Jendritzky, et al (1981). Outdoor contexts where mean radiant temperature (Tmrt, which is the resultant of the average between the temperatures of near surfaces in direct interaction with a standing person), can be radically different from Ta, Tmrt is the deterministic factor that defines comfort levels, as also studied by Matzarakis, A. (1996). at the same time, under direct solar radiation, the variation between Tmrt and Ta, can be higher than 30ยบC, while areas under shadow a 16
Urban Canyons and Outdoor Comfort.
Improving Outdoor Comfort and Water Cycles
variation of 5ºC has been reported by Ali Toudert, F. (2005) in hot dry climates.Thus, shading and protection from excess of solar gains must be of priority. Reduction of air temperature and incremental wind speeds are not of primal importance because of their direct dependance on canyon form. Sky View Factor (SVF), which is the amount of visible sky in the spot analysed is another crucial factor in outdoor comfort analysis. Its values are located between 1 and 0 clear and obstructed sky respectively. SVF keeps a opposite relation with H/W ratio, which means that in mid-latitude locations, with a larger H/W ratio less solar radiation reaches the ground, therefore daytime Ta increases with decreasing H/W ratio and a larger SVF. In the case of tropical and equatorial locations this effect is significantly reduced because of the high solar altitude Errell, E. (2011). Although deep canyons can reduce the amount of direct solar radiation reaching the lower levels, the reflected and long-wave radiation might get trapped inside the canyon and reduce wind-driven cooling Pearlmutter, D.et al (2005). The main research conducted by Sharmin, T. et al (2013) involved the calculation of PET index with Rayman 1.2, and the simulation with ENVI-met Version 4 of the microclimatic characteristics of urban canyons in Dhaka City located at 23.24ºN, 90.23ºE with a tropical monsoon climate with a distinct warmhumid rainy season, a hot-dry summer and a short cold-dry winter season. Two different study areas were selected, one Baridhara, a medium density formal residential area with mostly uniform building heights and a regular street pattern while the second is a traditional mixed-use residential area with a combination of different building heights. PET was calculated for the periods analysed (Figure 3). The results show that the main factor controlling PET is the shading of near surfaces. At peak hot times of the day, PET values under direct solar radiation reach more than 58ºC, which obviously results on severe discomfort, areas under shade show values around 40ºC. Ali-Toudert, F. et al. (2004) summarized similar results of PET during high temperature periods. Areas under shade show a decrease of up to 20ºC. The impact of orientation and SVF upon PET is not clear in the figure as sun is very high at this time of the day in this location. Correlations showed to be weak on (Figure 3) because of high solar altitude .
Figure 3: PET calculations comparison at 14:00 hours and SVF/PET correlation. Sharmin, T. et al (2013)
After the analysis of the simulations the main findings can be summarized as follow: 1.SVF in deeper canyons causes lower air temperatures during the day. After sunset deeper canyons are found to be a little warmer than wider canyons. 2. Canyon orientation is not found to be related with to the air temperature inside it. 3. All urban canyons present higher air temperatures over 18 hour cycle simulations because of heat storage in the urban fabric. 17
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PET and mPET
4.Thermal comfort is largely affected by the presence of direct solar radiation. A difference of more than 35ºC in Tmrt values between areas under direct solar radiation and areas in shadow was detected in the study. At peak hot times of the day, Tmrt is at least 50ºC higher for areas under sun and 20ºC higher for shaded areas when comparing with air temperature. 5.Orientation has a significant influence on outdoor comfort for mid-lattitude areas because of the differences in shading observed through the day in each orientation. Although in the case of Mexico City and due to its altitude and the predominantly high solar angles the influence of this factor is significantly decreased. 6. Higher Tmrt was detected in deeper canyons when comparing the results of different canyons in different analysis point with different SVF values when shaded. Similar correlations where found when comparing all receptor points in areas under direct solar radiation because of the increased net radiation inside deeper canyons, as studied by Errell, E. (2011), Pearlmutter, D.et al (2005). The relationship between shade and H/W ratios have to be carefully studied to be able to understand the resulting Tmrt. Studies by Ali Toudert, F. (2005), and Tan, C. et al. (2013), presented results where Tmrt reduction was attributed to the reduction of SVF and the increase of H/W ratios. The study presented by Sharmin, T. et al (2013) shows the importance of shading strategies for achieving outdoor comfort. Higher H/W ratio increases shadowing between buildings and reduces Tmrt when compared with its values for sun exposed areas. Even when higher levels of shade might be obtained with higher H/W ratios due to the direct solar radiation access reduction at the level of the street, deeper canyons present increased levels of diffused short-wave radiation and trapped long-wave radiation from the building mass, more so if analysing a high density environment. Higher H/W ratios (higher density) could increase mutual shading between buildings, which can be valuable for the mid-latitude cities when the lower solar angles can produce this shadowing effect, although the solar angles have to be carefully analysed because at mid-day even deep canyons may not be able to avoid sunlight penetration. Furthermore, increasing density in this way results in a larger gain in net radiation, which will increase Tmrt even in the presence of shade. Sharmin, T. et al (2013)
3.3 PET and mPET For calculations of PET and mPET indices, considerations must be taken referring to wind speed. For yearly calculations weather data obtained from weather stations are measured at a height of 10m. A reduction factor proposed by Matzarakis, A. (20015) should be applied to those wind measurements since comfort is to be assessed at a height of 1.1m. Figure 4 shows the mentioned reduction factor depending on the site´s typology. For the case of the stairways in Mexico City the “Urban” case is to be applied.
Figure 4: Changes of wind speed (in %) from originally 10 m height to human-biometeorologicalheight of 1.1 m for different roughness lengths. Source: Matzarakis, A. (2015).
Figure 5: PET, mPET and UTCI comparison. Source: Matzarakis, A. (2015)
Figure 5 shows a comparison between PET, mPEt and UTCI indices. For this research mPET calculations will be used since activity represents an important factor in the comfort conditions of the study site. Some PET calculations will be done for comparison purposes. 18
Albedo
Improving Outdoor Comfort and Water Cycles
3.4 Albedo As described by Errel, E. (2012), the urbanization processes in cities affect the absorption and reflection of incoming solar radiation and long-wave radiation from the surface. This effect is due to the influence of urban geometry and the different surface properties of building materials as well as air pollution. The proportion of energy reflected by an urban surface back to the atmosphere and the proportion absorved by the materials in it, is defined by two factors: First; the albedo of individual materials, (determined by the angle of incidence and by the wavelength reflectivity of solar radiation) which on typical urban surfaces may vary from only 0.05 for a dark asphalt to about 0.8 for whitewashed roofs (Table 1). And second; the interaction of the individual materials with other materials inside urban canyons, due to high probabilities of multiple reflections and absorptions in the canopy-layer results in a low urban albedo.
Table 1: Albedo and thermal emissivity of natural and manmade materials.
As described by Errel, E. (2012), the effect of urban albedo upon urban geometry has been widely studied and can be described as follows: • In dense urban areas, a large proportion of solar radiation is reflected by rooftop surfaces, which in plain terrains can reduce the amount of reflections in the urban canyon. In very low-density scenarios it is high because the streets are wider and the buildings are lower, which reduces reflection. The lowest albedo values are registered in medium-density environments where streets width can be twice the width of the building blocks. • When buildings are higher and the streets narrower (deep canyons), mutual reflections between buildings lead to more solar radiation absorption by the building materials, reducing albedo and resulting on higher net radiation peak values during the day compared to shallow canyons. • In steep topographies, building rooftops can produce reflections on surrounding walls increasing solar radiation absorption on these surfaces. • The orientation of the roads does not seem to have significant impact on albedo, specially in regions with high solar angles that receive high levels of solar radiation in all orientations. Other studies by Zaragoza, A. (2012), and Álvarez, G. (2014), suggest the possibilities to reduce Urban Heat Island effects in highly urbanized cities by increasing the albedo of the rooftops of buildings all over the city. Especially in warm climates, rejecting unwanted solar gains from the buildings can reduce cooling loads during the summer without generating need for heating during the winter. Some other researchers, Errel, E. (2013), debate that, in outdoor spaces particularly urban canyons, the substitution of low albedo materials for more reflective ones has not demonstrated significant reductions in temperatures on the street level. As a result of increased reflections this substitutions could even affect negatively pedestrian comfort when the reflected solar radiation gets trapped in deep canyons. Barradas, V. (2014), states that mitigating UHI and climate change by augmenting the albedo in Mexico City is a rather difficult strategy to properly assess, but in simple numerical terms, the solar radiation which reaches the top layer of the atmosphere 19
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Vegetation :
is of about 1,366 Wm2 and from this, at noon, less than half reaches the city (around 600Wm2). So in a rough calculation, whitening the roofs, reducing in 50% the albedo of the surfaces would reflect 300 Wm-2. If in the road from the highest point of the atmosphere to the city surface the radiation got reduced to 766 Wm-2, it would be logical to expect the same reaction in the opposit direction. Possibly, the reflected energy would get trapped in the first layers of the atmosphere and in the first layers of the troposphere. So none of the reflected radiation would reach the outer space. In that case, the air would get hotter because it would absorb that radiation excess, increasing global warming. On the other hand, if this reflected radiation would find in it´s way a reflective surface like a cloud, it would be projected back to the earth´s surface. In cities like Mexico the difference between cold and hot seasons , could invalidate the proposal of whitening the roofs, because in the hot season it could decrease the temperature. But this would persist and probably would decrease more during the cold season, because the albedo increases with the lower solar rays. From that, it can be assumed that more energy would be necessary for heating. After considering the statements described, careful considerations must by taken during the design of outdoor spaces in terms of surface material selection as advised in the RUROS project “Design Principles and Applications”, developed by Chrisomallidou, N (2004), where it is warned that the use of light coloured and highly reflective materials may prevent surface overheating but may also cause glare and thermal reflection towards users and the surrounding surfaces. On the other hand dark surfaces can be used with discetion as long as they are carefully protected from direct solar radiation. Vegetated surfaces must be preferred as they prevent reflections and help cooling the air by evapotranspiration c. The use of “Cool” and “Heat Emitting” Walls is proposed by Lenzholzer, S. (2015). Cool Walls, constructed with lower mass materials, are able to reject the long-wave radiation, hence keeping low temperatures. Materials such as hollow building bricks, aerated concrete, insulated materials or even clay walls are suggested. For Heat Emitting Walls, south orientation must be preferred to ensure solar access. This type of wall can generate a warm microclimate around it, which can help provide comfort during cold seasons. In Mexico City´s context adequate shading control must be provided to these walls during hot seasons and peak solar radiation times to prevent excess of heat. Winter days when temperatures are lower but solar radiation is still high are the must suitable times for the implementation of this kind of strategy.
3.5 Vegetation : It is well known that Urban Vegetation is the most effective strategy for providing outdoor comfort and reducing Urban Heat Island effects, since it elevates humidity and helps decrease temperature due to its capacity to cool down its surroundings through evapotranspiration. Jauregui et al. (1997) through the data obtained from 16 urban/suburban and rural pan evaporation stations in Mexico city assessed the comparative evaporative characteristics of different areas in the city, finding significant increases in Heat Island intensity in the central and western parts of the city, for the period of 1967-88 linked to the accelerated urbanisation. They noticed on the contrary that in the western suburbs the re-vegetation in that time of a former lake surface of 9500 Ha reduced the pan evaporation in spite of the rapidly increasing UHI in the rest of the city. More recently Barradas (2013) found that in some urban parks studied in Mexico City, their vegetation composition can reduce air temperature up to 5ºC, noticing also that this difference increments rapidly as the size of the park increases, but reaches a point when the increase of this difference become meaningless. Unfortunately, the design of green spaces in Mexico City has only been assessed from the landscape perspective, without taking into consideration that vegetation is a dynamic element that interacts with the atmospheric environment and not only a aesthetic one. Without forgetting that vegetation also acts as a filter for soil and atmospheric pollutants. Barradas (2013) identifies the insertion of vegetation systems, including green roofs as the most efficient for the mitigation of high levels of solar radiation. These systems need to be carefully designed with knowledge on their natural processes. Lenzholer, S. (2015) gives guidelines for the selection of suitable species of trees and vegetation. Decidious trees should be selected for densely built areas, to prevent overshadowing, and also in any other places where shading is needed during summer and solar radiation access during winter. Evergreen trees should be picked according to size, density of the foliage and root growth, considering the shadowing need and the place where they are going to be located. Roots can present problems when trees are planted in small gaps between concrete slabs, or other solid materials. 20
Shading
Improving Outdoor Comfort and Water Cycles
Barradas (2013) analysed the evaporation rates of two of the most abundant trees in Mexico City the “hule” (Ficus elastica) and the “trueno” (Ligustrum lucidum) which have a evapotranspiration capacity of 0.2 L/h and a foliar area index of 10 meaning that during the day the leaves can loose enough water to maintain the temperature 7ºC under the temperature that a concrete area would reach. In this evapotranspiration process transpiration of water requires 312 W/m2 and if the net solar radiation is of 450 W/m2, the air temperature would be of 19.2 °C, without taking into account air velocity. Without this transpiration process air temperature would raise to 26.3ºC. The two species, could be used in the design of parks and green areas to provide comfort physiologically and psychologically.
3.6 Shading Mexico City has an altitude of more than 2400m above sea level. It is clear that shading is an elemental strategy for achieving comfort due to its high solar angles and radiation levels. In the area of study, vegetation as a mean of shade is difficult to provide. Big trees cannot be placed in most canyons due to reduced space and, root growth can cause problems in the pavements in the sloped canyons. Therefore, the design of shading devices might solve this problem. The main challenge for this is the understanding of solar trajectories and the selection of spaces to be shaded. On this topic, Hwang, R. et al. (2010) concluded after the calculation of PET for a ten year period in some areas of Taiwan that thermal comfort conditions can vary substantially between seasons, so then, shading levels should also vary depending on them. A space with proper shading in spring and summer might feel cold in winter. Therefore shading devices that can be used in the warm seasons and removed during cold periods can be useful. Even more so if the users can control them.
3.7 Water Water management is one of the most pressing problems in the area of study. High precipitation levels and the mixing of black and gray waters overflow the system causing floods. At the same time, water shortages are common even during rain season due to failures in the supply system. Rodriguez et al. (2014) analysed the insertion of water bodies in the urban fabric of Mexico City and its effect on the City´s microclimate. Three different zones (urban centre, urban north and ravine west), were studied using data obtained from Mexico´s National Meteorological System (SMN), Meteonorm, Envi-Met and Rayman to obtain the Tmrt, to assess human thermal comfort using PMV and PET. Results show that evapotranspiration can be used to improve urban comfort by inserting water bodies in public spaces as long as the water is in constant movement and present during hot periods so the evaporation process can actually take place. The most significant improvement in terms of urban comfort detected by the research was inside flat urban canyons in the centre of the city, where the prescence of water moving in low depth canals produced a reduction of approximately 26K in the Tmrt and of 2K during the peak temperature hours reducing heat stress for the users. Then the introduction of BioSwales in streets demonstrated the posibility to evaporate 32% of the received rainwater under sunny conditions and the remaining 68% can be infiltrated to recover underground water reservoirs. For the case of the ravines a terraced rainwater retention system was proposed mainly for water re-infiltration. It was then concluded that a total of 293.65million-m3 of rainwater could be recovered every year by the reinsertion of water in differet parts of the city. This total is distributed in 94million-m3 through infiltration and 165 million-m3 collected every year. With the recovery of this rainwater volume, yearly energy savings of 1.54TWh could be achieved. In the stairways studied in this dissertation, provision of comfort through evapotranspiration would be difficult to achieve. The slope of the terrain produces high speed runoffs of rainwater, reducing the possibilities for the water to evaporate inside the canyons. Even though, the water management problem that exists in the area makes viable the proposal of a Bio-swale system. Not with the purpose of retaining and re-infiltrating rainwater but instead for its filtering, storage and use by th community.
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Urban Heat Island
3.8 Urban Heat Island Urban Heat Island Effects caused by the predominance of impervious surfaces with low albedos and the lack of vegetated spaces has been identified in most highly urbanized cities around the world. In Mexico City, Jauregui (1993) analysed the UHI by comparison of urban/rural monthly mean maximum and minimum temperatures since the first time it was possible to obtain these kind of data. At the beginning of the 20th century, when Mexico City was smaller, just a pair of stations were installed. Back then, the UHI magnitude was of 2ºC. During the 1930´s the difference grew with the city to 6ºC until the 80´s where it was calculated at 9ºC. Along with this there has been a constant presence of daytime “cool” islands observed at Tmax time, but it is unclear if it is due to the effect of contrasting urban/rural thermal inertia or to the placement of warm air mass towards the south during morning hours. It is possible that the processes leading to the formation of daytime UHI´s depends on the urban morphology of the surface that directly affects the partitioning of incoming solar radiation rather than on the long-wave radiative exchange. Figure 6 shows the maximum and minimum temperatures for Mexico city in 1980.
A
B
Figure 6: Maximum and minimum temperatures for Mexico city in 1980. Source: Jauregui (1993)
In more recent periods the extent of Mexico´s Urban Heat Island were studied also by Cui, YY et al. (2012) found by comparing land surface UHI (UHIskin ) obtained satellite data and near-suface UHI (UHIair ) from air temperature measurements obtained through two automatic meteorological stations 2m above ground one 6.3 km southeast of the city centre and one 25.1km northeast, it was found that during day time strong UHIskin is present during the wet season (May-October) and considerably less strong UHIskin was found during dry season (March-April, November-February) in Mexico City, with evidence of urban cool slands happening relatively frequently. During night time UHIskin was observed to be high through the year lessened during wet season. UHIair was lower than UHIskin at night following the same wet season decrease. The most significant difference between UHIskin and UHIair was identified during daytime when UHIskin presented low values for the dry season and high values for the wet season while UHIair values remained low with very little seasonal variation. Multiple regression analysis and simulated surface heat fluxes suggest that during the day UHIskin is a function of the difference in vegetation fraction between the urban and rural areas. At night, however, UHIskin is mainly linked to the strength of nighttime surface inversion layers that are due to radiative cooling. In more recent years the UHI was reassessed by Ballinas et al. (2011) confirming that urban sprawl that generates drastic land uses where between 1980 and 2010 the population increased from 14,052,263 to 20,137,152 inhabitants and in the urban area from 1,156 to 1,627 km2 according to INEGI. The Urban Heat Island (UHI) is actually an intense phenomena in Mexico City. Jauregui (1998) reported that in November 1981 the intensity between the urban area (Plateros) was up to 8 ºC higher than the rural area (Texcoco) (Tu-r ) at the time of the minimum Tu-r was 6 ºC. The warm midtown was located in the area surrounded by Circuito Interior (≈ 112.7 km2 ).#
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Climate Zones in Mexico City.
Improving Outdoor Comfort and Water Cycles
Figure 7: Air temperatures. Source: Ballinas (2011).
Figure 7 shows that the actual heat island in Mexico City is distributed in almost all the urban area with a warm centre among the stations ENEP-Acatlån, Villa de las Flores, San Agustin, Cerro de la Estrella and Plateros mainly occurring late in the night. However, unlike the traditional UHI, it is also established in the daytime, with intensities of up 7 °C (TU-R).
3.9 Climate Zones in Mexico City. Estrada, F. et al. (2009) studied using multivariate analysis the spatial variability in the climate of Mexico City. They took thirty years of meteorological data from 37 stations located within the city. Although the city has a relatively small area, the contrasts in topography and land use in its territory create various microclimates. This study also confirms the influence of orography and urbanization on climate in cities. They found two main climatic regions defined by topography (Figure 8) and four sub regions with similar climatic characteristics: low altitude suburban, low altitude highly urbanized, urbanized mountain base and higher elevation with forest, Three climate indices were also defined. The three indeces are related to: temperature and precipitation; to days with fog and with electrical storms and to days with hail and low temperatures.
A
B Figure 8: Main climatic regions found in Mexico City (A). Microclimatic sub-Regions of Mexico city. (B). Source: After Estrada, F. et al. (2009)
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3.10
Hypothesis
The initial hypothesis for this research project, based on the learnings from the initial research is established from three starting points: The altitude of Mexico City makes solar radiation the prevailing factor affecting the outdoor comfort, especially in the site of study in Magdalena Contreras municipality in southern part of the city located on hilly terrains reaching more than 2800m above sea level. Even though the climate in Magdalena Contreras is classified as Temperate sub-humid, the micro climatic conditions that stepped canyons present depend largely on the heat exchanges between the surfaces of the urban canyons while exposed to high levels of solar radiation. Pedestrian comfort in the stairways is also influenced by physiological (metabolic rates of the users going up and down the stairs, clothing, sex, weight, etc.) And physiological conditions (mood, aesthetic conditions of the canyons, possibilities to control their immediate environment, etc.). It is then believed that the design of a system that can integrate shading and water management inside the steeped canyons can provide first; comfort to the users, more so if provided with control of those devices. And second; reduce flooding in the lower parts of the site while collecting rainwater for communal use reducing the dependance on the existent water distribution system thus saving energy.
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Hypothesis
Context and Precedents
Improving Outdoor Comfort and Water Cycles
4. Context and Precedents 4.1 Mexico City Mexico City, (Figure 9A) was established in the year 1325 when as the legend tells, the Aztecs found an eagle devouring a snake on top of a cactus in a lake located in a closed basin surounded by mountains, and a volcano. The region is now known as “Valle de Mexico” (the valley of Mexico). The city slowly evolved through the centuries from an Aztec Temple city to a Spanish colony in 1519 until the early 20th century, when it started to grow exponentially in every direction. In 1900 according to INEGI, Mexico city had 700,000 inhabitants, nowadays approximately 20 million people live in the metropolitan area of 4250 km2 formed by the conurbation of the states of Mexico, Morelos and Mexico City itself. The city rests on heavily saturated clay and has seismic activity risk, also continuous extraction of underground water generates sinking problems in it’s centre and flooding on the lower zones. Almost a third of the population of the metropolitan area is living in areas susceptible to flooding, one million live in areas of landslide risks, and five million live without access to basic services Baker, J. (2012). The growth of the city exhausted the available space for urbanization. The massive migrations of people looking for job opportunities during the second half of the 20th century generated a floating population in need of housing, forcing them to occupy the rural outskirts of the city. Illegal settlements were established without any urban planning strategies, or quality public space. Through time, households in the area got consolidated by self-construction. Large numbers of people living there, the lack of regulation, and rampant corruption made virtually impossible the implementation of any urban strategies. Until now serious problems of security, public services and accessibility persist, particularly in the south of the city where the topography is steep because of the hills and mountains that form the valley.
4.2 Area of Study. Magdalena Contreras. The area known as “Cerro del Judio” (Hill of the Jew) or “Mazatépetl Hill” in the South-West limit of Mexico City (Figure 9B) part of the Magdalena Contreras municipality, is definitely one of the most representative examples of the described phenomenon. The area was part of a conservation zone reforested with endemic species of cedars, pines and eucalyptus that covered 670 Ha but was gradually occupied by illegal settlements until only 30 Ha were left on top of the hill, that area is now closed to the public to prevent further invasion. Ruins of a small aztec temple remain inside the forested zone. The rest of the hill got urbanized without planning following the rough topography of the terrain generating a organic urban fabric with very limited mobility through the site. River Magdalena is the last river opened to the sky in Mexico City, every other river has been intubated. Even though River Magdalena has alarmingly high pollution levels. Public transport systems have limited acces to the site. Predominant winds in the area come from South-East.
A
B Figure 9: Mexico City’s (left) and Cerro del Judio’s (right) location. Source: Google Earth Pro Software.
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Climate
4.3 Climate 4.3.1 Mexico City’s Climate. Mexico City, is located at 19°23’N, 99°10’W, 2309 m. The country has a humid subtropical mild summer climate with dry winters and mild rainy summers. (Köppen-Geiger classification: Cwb). The mean temperature is 16 degrees Celsius. Average monthly temperatures vary by 5 °C. In the winter time, records indicate temperatures by day reach 21.7°C on average falling to 5.3°C overnight. In spring time temperatures climb reaching 26.3°C generally in the afternoon with overnight lows of 8.7°C. During summer average high temperatures are 24°C and average low temperatures are 11°C. Come autumn/fall temperatures decrease achieving average highs of 22°C during the day and lows of 8.7°C generally shortly after sunrise. The total annual Precipitation averages 709 mm which is equivalent to 709 Litres/m². On average there are 2598 hours of sunshine per year. (Figure 10) Shows sunlight conditions over the year. (www.mexico-city. climatemps.com/sunlight.php. visited.: 13/08/2015).
Figure 10: Monthly sunlight situation of Mexico City. Source: www.mexico-city.climatemps.com/sunlight.php. visited.: 13/08/2015.
Figure 11: Mexico City’s monthly climate. Source: Meteonorm
28
Climate
Improving Outdoor Comfort and Water Cycles 4.3.2 Magdalena Contreras monthly weather data.
Figure 12: Mexico City´s weather graph for year 2100. Source: Meteonorm.
Figure 11 shows the monthly weather data for a weather station at Ciudad Universitaria near the Magdalena Contreras municipality In general the weather follows the patterns described for the entire Mexico City. In green dotted lines the adaptive comfort band calculated after ASHRAE EN 1525. Comfort levels seem to be achieved only by peak temperatures throughout the year, This temperatures peak ocurr mainly between mid-day and 3 pm. That is directly related to the solar radiation levels which have a maximum peak during March, April and May but are still high during the rest of the year. High solar radiation periods are identified in the graph with yellow bars. During the summer solar radiation levels are still high because of higher solar angles, but as seen in Figure 10 more cloudy periods are registered. Interactions of hours of sun per day, sky conditions and solar angles normalize the effects of solar radiation for most of the year. Relative humidity levels do not reach more than 80% during the summer wet season and register values under 60% the rest of the year. Wind speeds are shown as measured by the weather station at a height of 10m. Figure 12 shows the weather graph for Magdalena Contrearas in the year 2100 as calculated in Meteonorm from the same weather station of the present state graph. Air temperatures are expected to increase by 1ºC to 3ºC. This temperatures are already reached during hot periods in the area. Even though with these predictions temperatures seem to be closer to comfort their interactions with solar radiation need to be analysed to calculate PET and mPET. 4.3.3 Magdalena Contreras Microclimate Classification.
Figure 13 presents the micro-cllimatic classifications of the different regions of Figure 13: Magdalena Contreras micro-climates. Magdalena Contreras. The area of study (defined Source: INEGI. with a yellow dotted line), has a Template subhumid classification. As defined by Estrada, F. et al. (2009), Mexico City has 4 different micro climates defined by the topography and land use. The site is located on the “Urbanized Mountain Base” zone, which presents increased precipitation levels due to the influence of the Urban Heat Island effect present in the highly urbanized centre of the city. Many factors (solar radiation, urban geometry, materiality, orientation, wind, etc.) Influence the specific micro-climate characteristics of any site. Considering that, on-site measurements are to be analysed to establish the microclimate of the canyons studied in this research project.
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Site Demography.
4.4 Site Demography. Magdalena Contreras has a total population of 239,086 as shown in (Table 2) 52% of which are women and 48% men (Figure 14), with a median age of 30 years. The population profile shows an almost even distribution of people between newborn and 59 years while only 10.20% are elder adults above 60 years old (Figure 15), this could be explained by the lack of accessibility to the area. Public transport has a very limited access to the site because of its rough topography. The fact that most settlements were established illegally and without proper urban planning generated serious problems of connectivity. This is a constant problem in the entire municipality,. Accessibility to disabled people is extremely difficult. Elder people with mobility problems, and visually impaired people live in the stairways studied. Even daily shopping becomes an enormous challenge for them. Housing is the predominant typology in the municipality, by 2010, 62,703 private households (Table 3) were registered by the national census carried out by INEGI (Instituto Nacional de Estadistica y Geografia). These households have an average occupancy of 4 people (Figure 16). In many cases multinuclear families construct their houses room by room as they obtain enough resources to do so. More storeys are added as the family grows. Houses with up to five or six storeys can be seen in the site. This contributes to the bad image of the area, since no architects, or designers are involved in the process in most cases. These illegal settlements have been there for more than 50 years and were constructed before any kind of infrastructure were placed in the site. During the decade of 1980, ownership of the plots was legally given to the dwellers. This event forced the government to construct the basic infrastructure around the already developed housing schemes which results on regular miss functions than can deprive the area from services for weeks at a time. Housing
Magdalena Contreras
Distrito Federal
Occupied private housing, 2010
62,703
2,388,534
Average occupancy in private dwellings inhabited, 2010
3.78
3.6
Households with TV
61,358
2,337,884
Households with a fridge
55,577
2,165,900
Households with computer
28,507
1,171,631
Table 3: Area of study demographic analysis. Source: INEGI (2010)
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Population
Magdalena Contreras
Mexico City
Total population, 2010
239,086
8,851,080
Median age, 2010
30
31
Table 2: Demographics Mexico City and Magdalena Contreras. Source:INEGI (2010).
Total population 2010
48%
52%
men, 2010
women, 2010
Figure 14: Gender of the population of Magdalena Contreras. Source: INEGI (2010).
Percentage of population 2010 0 to 14 years
10.20% 29.30%
15 to 29 years 35.10%
30 to 59 years 25.40%
60 or more years
Figure 15: Population age groups Magdalena contreras. Source: INEGI (2010).
Occupied private housing 2010 2% With 1-4 occupants
27%
With 5-8 occupants
71%
With 9 and more occupants
Figure 16: Number of inhabitants per household. Source INEGI (2010).
Public and Green Spaces.
DELEGACIÓN
Improving Outdoor Comfort and Water Cycles
% green Total green % of green Área Km² areas with areas km² areas trees
Tree area % green areas Green area / per with grass and inhabitant m² inhabitant bushes m²
% of city population (2000)
Magdalena Contreras
14.08
1.82
16.20
27.10
72.90
10.30
2.80
20.80
Distrito Federal
632.66
128.28
20.40
55.90
44.10
15.10
8.40
100.00
Table 4: Public Space and potable water. Source: INEGI.
Public space
Magdalena Contreras
Mexico City
Child playgrounds 2011
8
569
Urban Surface km2 2005
15.05
12,633.97
Urban Surface km2 2005
18.20
22,940.50
Households with potable water
27,564
1,123,522
Table 5: Green spaces. Source: INEGI.
Figure 17: Green
areas in the site.
4.5 Public and Green Spaces. Public and green spaces in urban environments in Magdalena Contreras are scarce. The majority of this spaces are located in the outskirts of the site. A high percentage of Magdalena Contreras municipality comprises environmentally protected areas that elevate the official indices presented by government institutions (Table 4). Although in the study site, green spaces are almost nonexistent, trees can be seen through the stairways, but in most cases they do not present optimal conditions (Figure 17) as they are not well suited for narrow spaces. Green areas are also present in the outskirts of river Magdalena but there is no access to them. Children have very few recreational areas which do not receive maintenance. Figure 18 and Figure 19 show two children playgrounds found in the area. Their deteriorated conditions and the insecurity of the area keep them empty. Users of the stairways where asked during surveys if they considered that public spaces were needed in the area. 81.1% of the subjects answered “Yes”, while 18.9% said “NO”. Most of the “No” responses where given by people living near the football fields in the northern part of the site. There are still many illegal households established on river Magdalena´s outskirts. Must of them do not have potable water or sewage services as seen in Table 5. This households are constructed with scrap materials and are located in places in constant risk of landslides and flooding. Even in this kind of settlement social inequality is clearly perceptible.
Figure 18: Children playgrounds in the site.
Figure 19: Children playgrounds.
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Water Management.
4.6 Water Management. As stated before, the area receives high levels of rainfall during Summer. Many clandestine sewage outlets go directly to the river. Even the main sewage system gets overflowed and generates floods in the lower parts of the municipality (Figure 21). Mobility in the area is dangerous especially during rain season for the inhabitants that have to cross river Magdalena. Extremely unsafe bridges also shown in Figure 21 let them avoid walking more than 3km to find a proper street to cross. Vegetated areas on the sides of the river are blocked by fences and walls to prevent the dissipation of odours generated by the pollution. Cleaning this areas and opening them as public space could enormously increase the quality of life of the community. Education on environmental topics is needed considering that most of the pollution is generated by the inhabitants . In recent years the government started the regeneration of some stairways in the site. Concrete canals were constructed on the sides of the canyons to evacuate rain water, they are connected to the main sewage system and mix rainwater with black waters. Unwanted results due to poorly designed projects are seen inFigure 22. Poor construction material quality generates ruptures of concrete slabs and steps. Root growth of trees is not planned properly. The walls designed to enclose them are destroyed easily. This can lead to the fall of trees on houses or even pedestrians.
Figure 20: Flooding.
4.7 Security The stairways present a big challenge for the inhabitants and the government of the area. Narrow canyons with no vegetation showed to be preferred for illegal activities. After sunset many teenagers and young adults can be seen consuming drugs in the hidden corners. Many inhabitants expressed concerns because of regular burglary in canyons lacking proper illumination during the night. When asked if they felt safe in the area, 30% of the subjects of the survey conducted said “No”. Subjects who responded “Yes” were asked why they felt safe. Most of them responded “I´m used to the site .
Figure 21: River pollution and risk for near houses.
Wider canyons, and canyons in better aesthetic conditions seem to offer a sense of community that a normal street can not. The inhabitants of the spaces know and protect each other. Much higher rates of satisfaction on living in the area and sense of security were expressed by the inhabitants of these canyons. To complement these observations, some success cases in Latin American countries will be analysed next. Learning from these precedents will provide guidance for the design strategies to be proposed. Figure 22: Root growth.
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Precedents
Improving Outdoor Comfort and Water Cycles
4.8 Precedents Considering the lack of research in sustainability and pedestrian comfort conditions, in this kind of spaces the projects next analysed implemented strategies to reduce waste and make more efficient construction processes. 4.8.1 Vertical Gymnasiums in slums in Venezuela. Latin American cities share urban sprawl and illegal settlements similar to the conditions present in the area of study, through the years many urbanists, architects, researchers and many other professionals, have developed projects for the regeneration of this communities, although, the complexity of the issues they present requires an interdisciplinary approach were all the parties involved (communities, government and designers) take part in to the planning and decision making.
Figure 23: Vertical Gymnasium. La Cruz. Venezuela. Source: http://www.u-tt.com/projects_ChacaoVG.html. Visited: 03/08/2015.
Regeneration projects developed by Urban Think Thank, initially for Venezuelan cities, were developed also in Brazil and other countries with similar problems. On a first stage this projects involved the design of a Vertical Gymnasium at Barrio La Cruz (Figure 23), Venezuela. This building transformed the site of a former soccer field into a fitness complex with several sport facilities. The scarce availability of space forced the designers to stack the uses instead of spreading them out. The area has use through days and nights now, with an average of 15,000 visitors per month. Post occupancy studies say that it has helped lower the crime rate in this barrio by more than 30 percent since its opening. (http://www.u-tt.com/projects_ChacaoVG. html. Visited: 03/08/2015).
Figure 24: Grotão – Fábrica de música’, by Urban-think tank, São Paulo, Brazil. . Source: http://www.designboom. com/architecture/urban-think-tank-grotao-fabrica-de-musica/ Visited: 03/08/2015.
Another gymnasium was then designed for the Grotão community at the heart of the Paraisópolis favela of São Paulo, Brazil, (Figure 24) basic infrastructure was proposed. Water, sewage networks, lighting, services, and public space were the priority. Basic human needs are covered by the architectural program. Even though the area is quite central it is only connected by one road, very similar to Mexico City´s slums, effectively segregated from the rest of the city. Many places in this area are in high risks of landslides . Because of this, many house had to be demolished in the site generating available spaces for development. This vacant spaces were used to propose the much needed public space, Infrastructure was used to create social cohesion. Helping to reduce erosion in the way. Several cultural facilities including a music school are stacked in the building along with transport infrastructure. Mixed uses are introduce 33
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Precedents
in the building, commercial spaces regenerate the public life in the ground floor. The houses in danger which have to be demolished where given new plots at the top of the new development . The open plan in the first floor keep a continuous connection with the sloped terrain that also serves as a water management system. (http://www.u-tt.com/projects_Grotao.html. Visited: 03/08/2015).
This project also includes environmental performance strategies (Figure 25) such as a combination of Cross-natural ventilation using the cool winds coming from the South and using the natural slope of the hill to block the warm northern winds. Stack effect is used to direct the warm air to the top of the building where a ventilation chimney regulates its release when necessary, also solar and wind electricity generators support an air conditioning system that works only during peak heat periods. The concrete slabs of the intermediate floors are cooled by a hydronic piping system embedded in the structure. A shading system for the East and West facades helps avoiding unwanted heat gain during hot periods. A Water management model was designed for the project (Figure 26). The hill is used as a terraced public park, permeable surfaces along the terrain allow the reinfiltration of the excess of storm water, while the contours of the design direct the water to the bottom part of the hill reducing off site discharge, terraced wetland gardens are situated on each side of the slope to collect water and naturally filter contaminats and particles to enhance air quality, and lower ambient temperature through evapotranspiration, along with creating habitat niches to attract birds. The treated water from the wetlands is the stored in underground tanks and then pumped to the building, filtrated through rapid sand filters for reused in bathrooms and irrigation of planted areas, excess water can then be discharged to the public sewage system.
Building systems 1. natural ventilation chimney combination of stack, solar and wind supported ventilated system 2. hybrid photovoltaic panels electricity during the day IR-Emission of water during the night 3. air conditioner 4. shading protects against solar exposure along the east and west facade 5. slab cooling tempering the concrete structure with embedded hydronic piping 6. hybrid ventilation natural ventilation in should seasons AC operation in humid season 7. cross ventilation wind from south direction provides fresh air, warm winds coming from north direction are blocked by the hill cooling water cycle 8. heat rejection from air conditioner 9. heat sink during the day 10. heat emission during night by lunar collector on roof 11. chilled water to air conditioner
Figure 25: Grotão – Fábrica de música’, by Urban-think tank, São Paulo, Brazil. . Source: http://www.designboom.com/architecture/ urban-think-tank-grotao-fabrica-de-musica// Visited: 03/08/2015.
Water model 1. runoff cascades over permeable surfaces, absorbing excess stormwater and increasing water oxygen levels
This water treatment system offers interesting possibilities for the later development of design strategies to be applied in the area of study of this research project in Magdalena Contreras in Mexico City, the similar conditions shown and the fact that the site is located in the outskirts of the city where precipitation levels get increased because of the influence of the Urban Heat Island generated in it´s centre, F. et al. (2009) make the proposition of water management strategies a suitable solution for the reduction of the amounts of water discharged to the local sewage system which as described before gets dramatically overloaded during the wet season 34
2. site contours direct the water inward to minimize off-site discharge 3. runoff is collected into terraced wetland water gardens to trap contaminants and particulars. the system is a natural filter that enhances air quality, lowers ambient temperatures by evapotranspiration, and introduces habitat niches that attract foraging birds 4. treated overflow from the wetlands is collected into an underground cistern for storage and later reuse 5. stored water is treated to local quality standards with rapid sand filtration and pumped to elevated tanks for reuse 6. water is lifted during dry periods to provide irrigation in planted areas 7. treated water is available for non-potable uses, such as toilet flushing 8. minimal stormwater is discharged to the public sweage system
Figure 26: Water management model. Fábrica de música’, by Urban-think tank, São Paulo, Brazil. . Source: http://www. designboom.com/architecture/urban-think-tank-grotao-fabrica-demusica/. Visited: 03/08/2015.
Precedents
Improving Outdoor Comfort and Water Cycles causing floods in the lower parts and land slides on the margins of River Magdalena that put in grave danger several poorly constructed buildings that invade this path. (http://www.designboom.com/architecture/ urban-think-tank-grotao-fabrica-de-musica// Visited: 03/08/2015.) In general the building and it´s outdoor spaces are designed to integrate the community through social interaction, sport, and commercial activities while providing aesthetically pleasing environments than would enhance this processes. Environmental considerations are crucial to the viability of the project reducing maintenance costs that could jeopardise its survival through time. Along with the Vertical Gymnasiums, a cable car system (Figure 27) was constructed in Caracas to improve mobility inside the community, placing cultural and recreational infrastructure in each station. The project has proven prominently successful.
Figure 27: Metro Cable project. Caracas,Venezuela. Source: http://www.u-tt.com/projects_Metrocable.html. Visited: 03/08/2015
Figure 28: Stairways in Venezuela. Source: (http://lindahagberg.com/Barrio-Stairways, Visited: 04/08/2015)
4.8.2 Water Collection System. A graduate project developed by Hagberg, L. (2010, http://lindahagberg.com/Barrio-Stairways, Visited: 04/08/2015) also for the Venezuelan community of La Ceiba, near the location of the Metro Cable project already described, is shown in Figure 28. The project involved the design of a water collection and irrigation system to be implemented on stairways on very similar conditions to the study site in Mexico City. The system involves the collection through gutters of rainwater from the roofs of the houses in the site and it´s storage in concrete tanks connected to a series of plant beds for hydroponic vegetable production, that get irrigated by gravity depending on the availability of water in the tank giving preference to the plants that need more water (Figure 29).
Figure 29: Water collection system. Source: (http://lindahagberg.com/Barrio-Stairways, Visited: 04/08/2015)
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Precedents
In terms of water management systems, many American cities are implementing Bio-swale, and Bio retention systems. Its main purpose is to reduce water runoff in streets and public spaces. Bio-swales are best suited for flat terrains that can hold water for longer periods. Proper insulation should be provided to avoid humidity transmittance to neighbouring buildings. Dense vegetation has to be planted to filter pollutants from the water along with different substrates in different sizes. Under drains evacuate excess water to the swage system. (Figure 30)
Figure 30: Bioretention system. Source:
36
Fieldwork
Improving Outdoor Comfort and Water Cycles
5. Fieldwork 5.1 Delimitation of the area of study The fieldwork for this research was undertaken during 5 days from the 1st of July of 2015 to the 6th of July, excluding Sunday the 5th because of the complicated access to the site. The fieldwork was focused on the North side of “Cerro del Judio” between the natural conservation area described in the introduction of this document and a series of football fields located under high voltage electricity lines further north. This two sites are located on top of hills and form a canyon that contains the Magdalena river in its lowest part. The first part of the fieldwork comprehended a general walk through the site to visit the stairways previously identified using Google Earth Pro software as valuable for research. Typology, materiality and orientation, were the main selection parameters for the canyons to study. The lack of connection from the South side to the North side of the Magdalena River crossing the site also influenced this selection.
Figure 31: Case studies definition. Source: Google Erth Pro software.
(Figure 31) shows the final selection of this areas. For descriptive purposes the stairways will be named from now on by its orientation axis from lowest to highest elevation. In the figure, yellow dotted lines represent stairways were spot measurements were taken at different times of the day on a non sequential way during the first days of work. The blue lines represent two stairways studied on the 3rd and 6th of July at mid-day. The first one (1a Cerrada Paraiso) oriented on a SE-NW axis. The 2nd one, (2a Cerrada Paraiso and Calle Alcatraz) also SE-NW. Finally the red dotted line shows (Andador Granada) where measurements were obatined during the 3rd, 4th and 6th of July two times each day, this stairway was selected as the most representative case to be studied, The climatic conditions at the site during the period of study presented a predominantly overcasted sky with intermittent periods of rain, a∫∫nd periods of sunny clear sky on the 3rd and 6th of July. Each spot measurement here shown states its respective sky condition at the moment. As identified in the Mexico City’s weather graph (Figure 2) March, April and June are the months which receive the most solar radiation, and therefore they are assumed as the most uncomfortable months of the year. Even though the fieldwork period had to be carried out at the beginning of July during the wet season. Regardless of this fact solar radiation proved to be the mos influent factor in therms of comfort.
39
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Fieldwork
After the study area selection, spot measurements were taken using a 3 in 1 Testo 410-2 tool to measure air temperature, relative humidity, and wind speed. A Surface temperature meter Testo 810, a Luxmeter Testo 540. A Data Logger Tinytag plus2 with an attached metalic probe and a ping-pong ball painted in black matte paint inserted in the tip of the probe to measure globe temperature with a 5 minute stabilisation wait on each measurement. Along with this, an infrared FLIR camera was used to take infrared pictures of floor, walls and vegetation. All this data was recorded at each point measured, expecting to create a representative enough database to assess the micro-climatic conditions of the area. It is important to point out that the data logger used to measure the globe temperature (Gt) presented a failure during some measurements showing temperatures of -47 ยบC. This measurements were omitted and Mean Radiant Temperature (Tmrt) was calculated using Rayman Pro software to substitute the missing values in (Figure 39 and Figure 40). Tmrt was calculated for all the spot measurements taken and compared with the globe temperature data obtained on the graph presented in (Figure 32). The temperatures seem to follow the same fluctuation patterns but with constant differences of 7.5 ยบC on average but reaching to up to 22.35 ยบC when surface temperatures increased and cloud cover was calculated as 0 octas. It was also observed, the influence of the direct solar radiation on the globe temperature measurements that stay constantly below the air temperature measurements until the measurements under direct solar radiation are shown. After this, Pet and mPET, Mayer, H. et al. (1987), Matzarakis, A. et al. (2014). were calculated and compared in the graph shown in (Figure 33) making evident the difference that the inclusion of the metabolic activity and clothing makes on the mPET model, which is crucial to the assessment of the overall comfort conditions of the site, since the stairways users are under heavy metabolic rates when going up and down,. The metabolic rate assumed for the calculations is 200W, and the clothing as 0.7, as observed during the surveys done as part of the research.
Temperatures 50
45
40
35
ยบC
30
25
20
15
10
5
0 0
20
40
60
80
Spot Measurements Ta
Tmrt
Figure 32: Spot measurements temperature comparison.
40
Gt
St
upper limit
lower limit
100
Case Studies.
Improving Outdoor Comfort and Water Cycles
PET/mPET comparison 45
40
35
30
ยบC
25
20
15
10
5
0 0
20
40
60 PET
80
100
mPET
Figure 33: Spot Measurements PET/mPET comparison. Source: Mayer, H. et al. (1987), Matzarakis, A. et al. (2014).
5.2 Case Studies. 5.2.1 Andador Granada. Andador Granadas a Stepped Canyon oriented on a N-S axis with an average width of 6.5 meters with houses in both sides. It is constructed with reinforced concrete structures and cement blocks or mud brick for the walls, some of them rendered and painted in different colours, some others just rendered and the rest exhibiting just the nude blocks or bricks. The roofs are mostly constructed with reinforced concrete slabs without any insulation and predominantly covered with red waterproofing paint in the rooftops. The canyon of Andador Granada has an inclination of 12ยบ. It is divided into three sections, the lower one with the presence of large trees with concrete walls surrounding them and steps that almost half of the width of the stairway. On the surveys done in this part of the stairway, inhabitants of the houses with access through this stairway expressed their concerns because of the rupture of the concrete walls caused by the roots of the trees. Their concern related to the possibility of the trees falling at any time on the houses walls or into the canyon representing a severe safety risk for both inhabitants and users of the stairway. It was observed that the shading provided by the trees was not as effective as one might expect due to their height, relatively small crown and their low leaf density alongside with the difficulty of their maintenance. This observation lead to the hypothesis of trees not being the best strategy to provide shading in the stairways unless a thorough analysis of their root development and the ways to securely implement them in the site. Simulations of its future growth and the shadow they will provide would be needed. The mid section of the stairway has the same architectural configuration but with recently planted small trees. Finally the upper section is reduced in width to 3.5m and has no significant vegetation, inside the canyon. Some trees are present in the interior patios of the houses. Spot measurements were taken in three spots: low, mid and high parts of Andador Granada, during three days, twice a day (Figure 34 to Figure 38).
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Fieldwork
0.062 SVF
0.054 SVF
Figure 34: Andador Granada location and Sky View Factor of spots measured.
14:45 Ta: 21.9 ºC WS: 0.4 m/s PET: 18.3 ºC Lux: 3568 Gmax: 878.5 W/m2
Overcast Gt: 17.75 ºC RH: 46.4 % PMV: 0.8 mPET: 25.5 ºC 03/07/2015
14:30 Ta: 22.3ºC WS: 0.6m/s PET: 19.2 ºC Lux: 3884 Gmax: 909.2 W/m2
Overcast Gt: 20.6ºC RH: 50.5 % PMV: 0.9 mPET: 26.4 ºC 03/07/2015
Figure 35: Spot Measurements Andador Granada between 14:00 and 15:00.
17:15 Overcast 17:00 Overcast Ta: 20.2 ºC Gt: 17.68 ºC Ta: 20.4ºC Gt: 19.66ºC WS: 0.5 m/s RH: 65.9 % WS: 0.0m/s RH: 66 % PET: 16.9 ºC PMV: 0.6 PET: 21.7 ºC PMV: 1.1 Lux: 2108 mPET: 24.3 ºC Lux: 4423 mPET: 26.5 ºC Gmax: 408.9 W/m2 03/07/2015 Gmax:466 W/m2 03/07/2015 Figure 36: Spot Measurements Andador Granada between 16:00 and 18:00.
42
0.08 SVF
14:15 Ta: 23.1 ºC WS: 0.8 m/s PET: 19.9 Lux: 8498 Gmax: 936.2 W/m2
Overcast Gt: 22.1 ºC RH: 45.2% PMV: 1 mPET: 26.7 ºC 03/07/2015
16:45 Ta: 20.9 ºC WS: 0.0 m/s PET: 20.4 ºC Lux: 2093 Gmax: 466 W/m2
Overcast Gt: 17.15 ºC RH: 56 % PMV: 0.9 mPET: 25.6 ºC 03/07/2015
Fieldwork
11:30 Ta: 22.7 ºC WS: 1.0 m/s PET: 17.4 ºC Lux: 16790 Gmax: 971.2 W/m2
Improving Outdoor Comfort and Water Cycles
Overcast Gt:17.77 ºC RH: 51.9 % PMV: 0.8 mPET: 24.6 ºC 04/07/2015
11:10 Ta: 22.7ºC WS: 0.4 m/s PET: 19.7 ºC Lux: 27590 Gmax: 942.3 W/m2
Overcast Gt: 19.26ºC RH: 53.4 % PMV: 1 mPET: 26.2 ºC 04/07/2015
10:50 Ta: 20.9 ºC WS: 0.7 m/s PET: 17.3 ºC Lux: 12702 Gmax: 906.6 W/m2
Overcast Gt:19.35 ºC RH: 53.6 % PMV: 0.6 mPET: 24.9 ºC 04/07/2015
16:20 Ta: 25.1 ºC WS: 0.5 m/s PET: 26.1 Lux: 66900 Gmax: 610.1 W/m2
Sunny Gt: 30.04 ºC RH: 43.6% PMV: 1.8 mPET: 31.5 ºC 04/07/2015
Figure 37: Spot Measurements Andador Granada between 10:00 and 12:00..
17:10 Ta: 26.0 ºC WS: 0.5 m/s PET: 21.8 ºC Lux: 3419 Gmax: 428.4 W/m2
Sunny Gt: 19.49 ºC RH: 44.4 % PMV: 1.3 mPET: 28 ºC 04/07/2015
17:00 Ta: 27.1 ºC WS: 0.0 m/s PET: 24.4 ºC Lux: 19089 Gmax: 466.3 W/m2
Overcast Gt: 20.64 ºC RH: 40 % PMV: 1.6 mPET: 29.5 ºC 04/07/2015
Figure 38: Spot Measurements Andador Granada between 16:00 and 17:30.
(Figure 34) shows the plan view of Andador Granada and the Sky View Factor calculated using Skyhelios and Rayman Pro, Matzarakis, A. et al. (2014). SVF values decrease gradually from the lowest to the highest section. (Figure 35 and Figure 36) show the spot measurements taken on the 3rd of July between 14:00 and 15:00 and between 16:00 and 18:00, with a overcast sky. Air temperatures are between the comfort zone, higher than the globe temperature measured in all the measurements. With wind speeds and relative humidity between 45 and 66%. PMV, PET, and mPET were calculated for each point showing apparent comfortable scenarios, but mPET always higher due to the consideration of 200W for the metabolic rate of the subjects going up or down the stairs, and 0.9 clo value as observed in their clothing. Solar radiation values obtained from Rayman Pro are also presented, resulting on approximately 900W/m2 for (Figure 35) having considered 3octas of sky cover from observation, and around 450W/m2 for (Figure 36) with 7 octas considered. (Figure 37) with spot measurements taken on the 4th of July show the same temperature behaviour as the day before, (Figure 38). On the other hand brief sunny periods show a fast temperature change once solar radiation is present. Important differences were detected in the lowest, widest section measured at 16:20. There, globe temperature reached 30ºC with the data logger exposed to the direct solar radiation. The narrower upper canyon remained at 19.49ºC due to obstruction, confirming the influence on temperature of the H/W ratio, 2.42 for the narrow one and 1.3 for the wider. 43
Narrow stepped caNyoNs iN mexico city
10:50 Ta: 24.7 ºC WS: 0.0 m/s PET: 27.9 ºC Lux: 12355 Gmax: 905.8 W/m2
Overcast Gt: 28.2 ºC RH: 48 % PMV: 1.9 mPET: 31.8 ºC 06/07/2015
10:30 Ta: 25.1 ºC WS: 0.0 m/s PET: 26.6 ºC Lux: 23750 Gmax: 863.6 W/m2
Fieldwork
Overcast Gt: 25.7 ºC RH: 46 % PMV: 1.8 mPET: 31.1 ºC 06/07/2015
10:20 Ta: 24.4 ºC WS: 0.4 m/s PET: 30.5 ºC Lux: 14560 Gmax: 840.1 W/m2
Overcast Gt: 39.2 ºC RH: 49.1 % PMV: 2.3 mPET: 33.7 ºC 06/07/2015
14:10 Ta: 28.0 ºC WS: 0.9 m/s PET: 35 ºC Lux: 75760 Gmax: 945.1 W/m2
Sunny Gt: 47 ºC RH: 36.7% PMV: 2.9 mPET: 34.4 ºC 06/07/2015
Figure 39: Spot Measurements Andador Granada between 10:00 and 11:00..
15:00 Ta: 27.3 ºC WS: 0.7 m/s PET: 34.3 ºC Lux: 57280 Gmax: 845.3 W/m2
Sunny Gt: 45.3 ºC RH: 39.1 % PMV: 2.8 mPET: 34.5 ºC 06/07/2015
14:20 Ta: 27.8ºC WS: 0.9 m/s PET: 35.8 ºC Lux: 49530 Gmax: 928.4 W/m2
sunny Gt: 47.9 ºC RH: 39.5 % PMV: 3 mPET: 34.5 ºC 06/07/2015
Figure 40: Spot Measurements Andador Granada between 14:00 and 15:30.
(Figure 39) show measurements taken on the 6th of July. It has to be noted that values of Gt in all of this measurements are substituted by Tmrt values calculated by Rayman Pro due to the failure in the datalogger. This values are presented in the graphs as 0ºC only for descriptive purposes. Although in (Figure 39) values of Gt (Tmrt) are higher than the air temperature this might be because of the differences noted between Gt and Tmrt already discussed. In (Figure 40). the influence on solar radiation can be noted even considering this differences, also noting that for clear sky situations (0 octas) the high solar angle of the site allows solar access even in the narrowest canyon. 5.2.2 2a Cerrada Paraiso. 2a Cerrada Paraiso is an urban canyon constructed with reinforced concrete slabs on the floor, in the mid and top sections, stone bricks on the floor of the bottom section, and concrete structure with cement blocks for the houses on its sides, mostly rendered and painted. The three sections have an average width of 8m, but the mid and top sections show a better state of conservation, since the bottom part has irregular heights on the steps, cracks and irregularities in general that can make it dangerous. 44
Fieldwork
Improving Outdoor Comfort and Water Cycles
0.025 SVF
0.034 SVF
Figure 41: 2a Cerrada Paraiso location and Sky View Factor of spots measured.
0.021 SVF
11:45
Overcast/Sunny
11:30
Overcast/Sunny
WS: 0.0 m/s
RH: 54.5 %
WS: 0.5 m/s
RH: 52.7%
Ta: 23.9 ºC
PET: 30.2 ºC Lux: 36500
Gmax: 988.5 W/m2
Gt: 20.86 ºC PMV: 2.2
mPET: 32.8 ºC 03/07/2015
Ta: 21.5 ºC
PET: 23.1 °C Lux: 38950
Gmax: 971.4 W/m2
Gt: 18.65 ºC PMV:
mPET: 29.3 ºC 03/07/2015
Figure 42: Spot Measurements 2a Cerrada Paraiso between 11:00 and 12:00..
18:45 Ta: 21.6 ºC WS: 0.4 m/s PET: 17.7 ºC Lux: 1473 Gmax: 58.7 W/m2
Overcast Gt: 16.19 ºC RH: 64.8 % PMV: 0.7 mPET: 24.7 ºC 03/07/2015
18:30 Ta: 22.2 ºC WS: 0.5 m/s PET: 18.2 ºC Lux: 2560 Gmax: 113.7 W/m2
Overcast Gt: 17.21ºC RH: 65.1 % PMV: 0.8 mPET: 25.2 ºC 03/07/2015
18:15 Ta: 20.5 ºC WS: 0.4 m/s PET: 17.3 °C Lux: 3663 Gmax: 231.6 W/m2
Overcast Gt: 17.39 ºC RH: 66.7% PMV: 0.6 mPET: 24.6 ºC 03/07/2015
Figure 43: Spot Measurements 2a Cerrada Paraiso between 18:00 and 19:00..
45
Narrow stepped caNyoNs iN mexico city
12:40 Ta: 24.1 ºC WS: 0.0 m/s PET: 22.9 ºC Lux: 13215 Gmax: 1016.6 W/m2
Overcast Gt: 19.66 ºC RH: 46.6 % PMV: 1.3 mPET: 27.9 ºC 04/07/2015
12:30 Ta: 23.7 ºC WS: 0.4 m/s PET: 19.7 ºC Lux: 11056 Gmax:1015.5 W/m2
Fieldwork
Overcast Gt: 17.86 ºC RH: 49.8 % PMV: 1 mPET: 26.2 ºC 04/07/2015
12:20 Ta: 23.6 ºC WS: 0.0 m/s PET: 22.1 °C Lux: 7703 Gmax: 1012.7 W/m2
Overcast Gt: 18.68 ºC RH: 45.7% PMV: 1.2 mPET: 27.2 ºC 04/07/2015
Figure 44: Spot Measurements 2a Cerrada Paraiso between 12:00 and 13:00..
12:20 Ta: 25.3 ºC WS: 0.5 m/s PET: 23.3 ºC Lux: 96830 Gmax: 1012.5 W/m2
Sunny Gt: 24.12 ºC RH: 41.7 % PMV: 1.5 mPET: 29.4 ºC 06/07/2015
12:40 Ta: 27.5 ºC WS: 1.3 m/s PET: 27.3 ºC Lux: 39000 Gmax:1016.6 W/m2
Sunny Gt: 32.67 ºC RH: 43.2 % PMV: 2.1 mPET: 32.3 ºC 06/07/2015
12:50 Ta: 26.4 ºC WS: 0.6 m/s PET: 33.3 °C Lux: 97520 Gmax: 1015.9 W/m2
Sunny Gt: 44 ºC RH: 38.7% PMV: 2.7 mPET: 34.3 ºC 06/07/2015
Figure 45: Spot Measurements 2a Cerrada Paraiso between 12:00 and 13:00..
(Figure 41) shows the plan view of and the 2a Cerrada Paraiso´s Sky View Factors, with higher values than Andador Granada as it is wider (8m) with a H/W ratio of about 1.06. (Figure 42 and Figure 43) show the spot measurements taken on the 3rd of July, with an overcast/sunny and overcast sky respectively, with temperatures in comfort range, following the same pattern as Andador Granada when overcast, although on the measurements taken at 11: 30 and 11:45 were considered with a sky cover of 3 octas, which elevated tmrt values and therefore PET and mPET. (Figure 44) shows the same overcast path while (Figure 45) with a sunny condition presents a gradual increment in Gt (12:50 Gt measurement suffered the same datalogger problem described before and was substituted by calculated Tmrt, this measurement also showed the highest surface temperature registered, of 40ºC on stone brick floor).
46
Surveys
Improving Outdoor Comfort and Water Cycles
Age
5.3 Surveys
8%
5.3.1 Responses Analysis.
9% 0-20
During the period of development of the fieldwork 90 subjects were asked to answer a 10 question survey. Basic data starting by age (Figure 46) was obtained showing the majority of subjects between 31-50 years old and a stronger presence of women when analysing gender distribution of the sample (Figure 47) which might be explained by the surveys being carried out mostly during week days. There was also a strong presence of retired elder people some of them with mobility problems and one subject with visual disability that expressed his necessity of going up and down the stairways three times a day. Most elder women also expressed the accessibility problems that the poor design and construction quality of the stairways represent to them, and how it limits the number of times they go out of their houses to the minimum necessary. (Figure 49) illustrates the percentage of the number of times that the subjects go up and down the stairs per day, being two times the majority but going up until 60 times for a construction worker transporting sacks of cement. Most subjects spotted this as the factor that makes them most uncomfortable on their daily routines, even though overall responses of the thermal sensation experienced at the moment (Figure 50) were inclined towards neutral for 37% of the cases, while the hot side of the scale received a 31% of added responses and the cold side a 27%. In terms of clothing (Figure 48) the majority of people was wearing trousers and sweaters at the time of the survey because of the intermittent rain falling and cloudiness of the sky (Figure 51) during the days of the sample. The survey format can be found on page 79 of the appendix of this document.
19%
27%
31-50 51-70
2% 1%
2%
2% 1% 1%
Gender
Figure 46: Age distribution of sample. Source: survey. 1%
31%
Female Male 68%
Dress
1% 2% 2% Coat
8%
Jacket 27%
Sweater Sweatshirt T-shirt
27% Thermal sensation
Vest
Figure 48: Clothing of sample subjects. Source: survey. 2% cold
12%
17%
cool
9%
hot neutral slightly cool slightly warm warm
37%
1
Sky condition
Figure 50: Thermal Sensation of subjects. Source: survey.
4
5%
5
8% 27% 12%
6
15%
4%
13% Overcast
7 8
9%
10
6%
12 23%
Shirt
33%
0
3
Male Disabled
Figure 47: Gender distribution of sample. Source: survey.
13%
2
1%
74-80
37%
10%
Use of stairs (times a day)
21-30
15
Overcast Overcast/Sunny Raining 68%
Sunny
60
Figure 49: Use of stairways. Source: survey.
Figure 51: Sky condition at the moment of the sample. Source: survey.
47
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Surveys
Surveys 60
50
40
30
20
10
0 0
10
20
30
Ta 째C
Ts 째C
40 Tmrt 째C
50
Gt
upper limit
60
70
lower limit
Figure 52: Survey spot measurements graph.
act
Sky condition
clo
Hot or Cold State at
PMV
PET
mPET
-1 3 0 3 0 0 2 -2 0 0 2 3 0 -2 1 0 0 1 0 -2 1 0 0 3 -1 2 1 2 1 2 -1 0 -1 0 2 3 2 3 3 3 3 3
0 0.5 0.7 1.5 1.8 1.3 1.3 0.8 0.8 1 1.7 1.3 1.2 0.7 1.8 1.5 1.6 1.7 1.7 1.3 1.7 1.1 1.5 2.2 1.7 1.8 1.7 1.3 2 1.2 1.2 1.8 2.4 1.7 1 1.7 3.7 3.3 3.2 3.8 2.8 3.3
16.9 21.2 20.5 24.7 25.9 24.1 25.5 21.3 20.5 22.1 26.2 22.6 22 17.5 25.8 24.5 23.8 25 24.2 21.9 24.4 20.2 23.3 29.9 24 25.6 23.6 21.5 26.7 22.1 20.8 25 30.2 25.3 20.4 25.7 39.2 36.8 36.7 41.3 34.5 38.7
24.8 25.9 27.7 30.8 31.9 30.7 29.8 28.2 27.8 26.8 30.9 27.5 27 24.8 31.3 29.2 29.9 31 30 28.3 30.4 27 29.4 33.3 30 30.6 29.6 27.8 31.9 26.9 27.1 30.7 33.5 31 27.6 31.4 37.5 36.5 36.3 38.5 34.8 36.8
act
sky condition
clo
Raining
T-shirt Sweatshirt
the moment
T-shirt
Vest
Sweater Overcast
Going up
Sweatshirt
Jacket Coat Shirt Overcast/Sunny
Sweater Sweatshirt T-shirt
Sunny
Shirt Sweatshirt
A
PMV
PET
mPET
0 0 0 -1 2 -2 0 2 -1 0 0 -2 0 0 0 -3 0
0.3 0.1 0.5 0.1 0 1.1 0.8 1.6 0.7 1.1 1.3 2.6 1.6 2.9 2.9 3.3 2.2
21.2 17.5 22.1 21.7 19.8 25.2 22.5 26.9 20.6 23.1 25.7 35.1 27.4 36.4 36.3 39.1 31
25.1 22.3 26.2 23.7 24.4 27 26 29.6 24.7 26.4 27.7 33.3 29.9 33.9 33.7 34 31.7
1 -2 0 -2 0
-0.9 -0.7 -0.3 -1.5 1.7
22.8 19.1 21.7 18 30.7
21.3 18.2 20 17.1 27.1
-3 0 -2 -2 -1 -1
-0.8 0.2 0.7 0.5 0.6 1.4
18.2 22.1 24.6 24.3 25.8 29.8
18.8 21.7 23.9 23.7 25.7 28.2
0 2
0.4 1.1
18.8 22.7
26.1 29.1
the moment
T-shirt Vest
Overcast Going down
Sweater
Overcast/Sunny
Vest Sweater T-shirt
Sunny
Sitting
Standing
Working
Vest Sweatshirt T-shirt Sweater
Overcast
Sweatshirt Sunny
Sweatshirt
Raining
Sweatshirt Sweater
Overcast Overcast/Sunny Sunny
Sweatshirt Sweatshirt T-shirt
Overcast
T-shirt
Going up
200 W
Going down
150 W
Standing
80 W
Working
80 W
Sitting
60 W
Coat
0.9 clo
Raining
0 Octas
Sweater
0.8 clo
Overcast
0 Octas
Sweatshirt
0.7 clo
Overcast/Sunny
3 Octas
Vest
0.6 clo
Sunny
7 Octas
Shirt
0.5 clo
T-shirt
0.4 clo
B
Table 6: Survey answers comparison with PMV, PET and mPET calculations, and Rayman Pro inputs.
48
Hot or Cold State at
Surveys
Improving Outdoor Comfort and Water Cycles
5.3.2 Responses Comparison with Spot Measurements. Along with the described questions, spot measurements where taken for most subjects (72 out of the total 90) to assess the relations between their answers and the actual environmental conditions at the moment, the graph of (Figure 52) shows the temperatures comparison taken by spot measurements and Tmrt calculated with Rayman Pro. Alongside (Table 6 A) shows the relations between the thermal sensation expressed by the subjects during the survey on the “Hot or Cold State at the moment� column, with the observed conditions of activity, sky condition, and clothing, organized by hierarchy. It can be observed that in terms of activity, going up (even considering the uneven distribution of the number of responses between the different activities), has the most warm-hot responses 2-3 respectively, possibly showing the influence of the activity in the comfort sensation. When looking at the sky condition, Overcast/Sunny and Sunny as expected have the most warm/hot responses of the sample still on the Going up part, although a pattern like that would be difficult to identify for the rest of activities due to the significantly reduced number of responses received for them. On the other hand clothing does not seem to influence at the same extent the thermal condition of the subjects.
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Materiality
5.4 Materiality The observations of materiality within the site of study made evident that this is one of the most relevant factors able to cause discomfort to the users of the stairways, whenever high levels of solar radiation are present, because of the high thermal absorbance of the detected materials. First, a thermal image (Figure 53) of a overall perspective of the site, taken during a short sunny period of the 1st of July at 14:00 hours shows that surface temperatures of the facades and roofs of the buildings can reach 35 °C even shortly after presenting an overcast sky for most of the day. Differences in surface temperature can be seen in (Figure 54) which shows the palette of construction materials of the area, thermal images of sunny and overcast periods are shown for vegetation, stone blocks and concrete, showing differences of 4.8ºC for vegetation, 30.4ºC for stone blocks and 16.6ºC for concrete, the substantial difference of the stone block proved to greatly affect the mean radiant temperature (Tmrt) as can be seen in spot measurement number 92 of the graph shown in (Figure 55)
Figure 53: Infrared photo showing the surface temperature of a section of the site seen from a street in the hill in front. Compared with a photograph taken at the same moment.
Vegetation
Stone brick
Concrete
Red roof
Concrete block
Stone
Figure 54: Materiality.
Surface temperatures under direct solar radiation compared to the same material under shadow, by canyon element and material are shown in graphs. (Figure 55) concrete blocks, stone for the floors. (Figure 56) reinforced concrete, for the structure, stone, concrete blocks or red brick for the walls either nude, rendered , rendered painted or just painted. (Figure 57) as for vegetation, grass, a variety of plants and trees were measured wherever they were near at the time of the measurement either directly on the stairway or inside the houses but reachable for the measurement tool. 50
Materiality
Improving Outdoor Comfort and Water Cycles
St by material - Floor 40
35
30
Concrete
25
Concrete Wet Stone
20
Stone Brick 15
10
5 1
4
7
10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97 100 St Floor Under Shadow
St Floor Under Sun
Figure 55: Surface temperature analysis of spot measurements taken on the floor by material. St by material - Wall 40
Brick
35
Brick Rendered 30
BrickPainted Stone
25
Concrete 20
Soil
15
10
5 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 St Wall Under Shadow
St Wall Under Sun
St Wall Material
Figure 56: Surface temperature analysis of spot measurements taken on the walls by material.
St by material - Vegetation 30
25
Grass Plant 20
Vine Tree
15
Soil
10
5 1
3
5
7
9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 St Vegetation Under Shadow
St Vegetation Under Sun
Figure 57: Surface temperature analysis of spot measurements taken on the vegetation by material.
51
Analytic Work
Improving Outdoor Comfort and Water Cycles
6. Analytic Work The research done so far has identified solar radiation, materiality and low wind speeds as the main thermal discomfort causes for the users of the stairways. The analytic work here presented includes a series of parametric studies that will help define the adequate strategies to solve this problems.
6.1 Andador Granada. Wind and solar radiation analysis. Low wind speeds and high solar radiation incidence are detected on the rearch for this project. A CFD simulation using Ecotect and a 3d model of Andador Granada (Figure 58) comfirms this data. Roughnes of the terrain and the tight urban fabric reduce the wind to speeds to values not higher than 2m/s inside the canyon. Yearly cummulative values of solar radiation incidence are shown in (Figure 60). Roofs have a higher exposure level. Eventhough the slope of the terrain produces reflections from this roofs to the houses avobe them, increasing surface temperatures inside the canyon.
Figure 59: Andador Granada Model. Source: Sketchup.
Figure 58: Wind study. Andador Granada. Source: Ecotect.
Figure 60: Solar radiation study. Andador Granada. Source: Ecotect.
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Base Case Definition
6.2 Base Case Definition A base case is defined next based on the fieldwork’s most representative case “Andador Granada”. A model of a typical section of a stairway was drawn to assess the possible solutions to the presented problems. The canyon (Figure 61) has a width of 6.50m, 65m in lenght, with houses of varied heights on both sides. On the left side (coloured in red) a rainwater concrete drain 0.50m wide runs through. Steps 3m wide are alternated with resting spots made of slabs of concrete where the entrances of the houses are located and platforms constructed with brick walls and concrete floors or grass. At some points this platforms are used to hide the registries of the sewage system. The Sky View Factor of the canyon was calculated (Figure 62) using Skyhelios software Matzarakis, A. et al. (2014), with a value of 0.175. After that yearly mPET values were calculated for present and for the year 2100 (Figure 63 and Figure 64) using hourly data obtained via meteonorm from the weather station Ciudad Universitaria, close to the study site. The “Urban” reduction factor (50%) propposed by Matzarakis, A. (2015) was applied to the wind speed values. mPet results for the present scenario show a comfortable condiciton for most of the year. This can be because the weather data obtained form meteonorm is taken of the weather station situtated on a university campus whit many open areas. The fieldwork conducted for this research showed temperatures below and reaching comfort while under claudy skyes and rainy periods, but going well above comfort when exposed to a clear sky. Results for the year 2100 scenario show that an increase of 1ºC - 3ºC in temperature would considerably increase the amount of time in the year when comfort conditions would not be achived. The fieldwork also demonstrated that this temperatures and even higher can alreaby be reached inside the canyons while exposed to direct solar radiation. Figure 65 shows the topography and obstacles modelled in Rayman Pro and used as input for the calculations of Tmrt and mPET. Also an Metabolic activity of 200 W was considered for all calculations and adaptive clothing for mPET was used.
Figure 61: Base Case
Figure 62: SVF of the Base Case (0.175). Source: Skyhelios software.
56
Base Case Definition
Improving Outdoor Comfort and Water Cycles
100%
90%
80%
70% 31-‐+
60% %
26-‐30 50%
21-‐25 21-‐20
40%
11-‐15 6-‐10
30%
0-‐5
20%
10%
0% January
February
March
April
May
June
July
August
September
October
November December
Monthly mPet Values Figure 63: mPEt values yearly analysis. Present. 100 90 80 70
%
60 31-‐+
50
26-‐30 21-‐25
40
16-‐20
30
11-‐15 6-‐10
20
0-‐5
December
November
October
September
August
July
June
May
April
March
February
0
January
10
Monthly mPET values 2100
Figure 64: mPEt values yearly analysis. Future (20100).
Figure 65: Topography and Obstacles used for mPET calculations. Source: Rayman Pro
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Base Case Shadow Analysis.
6.3 Base Case Shadow Analysis. Shadow analyses were run using Autodesk Ecotect 2011 for the South-North (Figure 67), NorthSouth (Figure 68), West-East (Figure 69) and EastWest (Figure 70) orientations for Spring equinox, Summer solstice and Winter equinox at 10:00, 12:00 and 15:00. For the South-North orientation, the west facing walls are sunlit during the morning, the floor is sunlit at mid-day and the East walls in the afternoon. The North-South wall solar angles and slope keep the canyon in shadow at the morning and the afternoon in spring and winter. At mid-day the floor is sunlit all the year, the West wall receives sunlight in the summer mornings and the East walls in the summer evenings. Figure 67: Shadow analysis for the S-N orientation. Source: Ecotect 2011.
The West-East simulation shows Finally the East-west oriented canyon is overshadowed in the afternoons, the floor is sunlit at morning and midday, the north walls in the morning and midday in spring and winter and the south walls in the morning and midday in the summer. (Table 7) shows a summary of this findings.
S-‐N
N-‐S
W-‐E
E-‐W
Figure 68: Shadow analysis for the N-S orientation. Source: Ecotect 2011.
Figure 69: Shadow analysis for the E-W orientation. Source: Ecotect 2011.
58
W wall E wall Floor E wall W wall Floor S wall N wall Floor N wall S wall Floor
Spring
Summer
Winter
morning midday a7ernoon
Table 7: Sunlit spaces summary.
Figure 66: Shadow analysis for the W-E orientation. Source: Ecotect 2011.
Base Case Solar Radiation Analysis.
Improving Outdoor Comfort and Water Cycles
6.4 Base Case Solar Radiation Analysis. Solar radiation annual, cumulative results are shown in Figure 70 to Figure 73, fot the South-North, North-South, East-West and West-East respectively. The simulations were run with no obstuctions rather than the buildings on the sides, to assess the radiation levels received by the canyon surfaces. As expected, the South-North orientation receives more radiation through the year, 1395kWh per year on average, The North-South case suffers from self obstruction but still receives an average of 820 kWh a year. The West-East case shows an average of 1272kWh per year with overshaded south walls and the East-West case with an average of 11700kWh receives less radiation than the West-East case.
Figure 70: Solar Radiation Analysis on the S-N axis.
The patterns here described will be useful for selcting the placement of the shadow devices to be designed. As stated in the literature review, overshadowing has to be avoided in winter, so adaptable shading devices are to be proposed. Next the effectiveness of the posible solution strategies will be assessed on the same model.
Figure 71: Solar Radiation Analysis on the N-S axis.
Figure 72: Solar Radiation Analysis on the W-E axis.
Figure 73: Solar Radiation Analysis on the E-W axis.
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Shading with trees.
6.5 Shading with trees. Trees with high trunks and wide crowns are placed in the base case model to assess their impact in the shading of the canyons. Results show similar effectiveness in all orientations, reducing considerably the solar incidence in the canyon surfaces, as can be seen in Figure 74 to Figure 77. Although the literature review and the fieldwork proved the problems that trees may bring to this particular context.
Figure 74: Tree influence on solar Radiation on the S-N axis.
Many of the stairways are of recent construction, and eventhough spaces for vegetation are included in the new schemes, this are very small. Bringing grown trees would not be viable due to high costs, and planting new ones would mean several years without any shading benefit. As seen in Andador Granada building infrastructure around old trees can generate several safety problems. The patterns of root growth and the reduced space for them inside the canyons make difficult the provision of shade by trees. Although in cases where the canyons are wider and allow the planting, careful considerations must be taken. Evergreen trees should only be used for South-North oriented canyons which receive more solar radiation at higher angles throughout the year. Descidious trees should be preferred for all other orientations to ensure solar access during the cold periods. Plants with big leafs can also help provide shading, but most importantly the prescence of vegetation in the canyons is needed to provide psychological comfort
Figure 75: Tree influence on solar Radiation on the N-S axis.
Figure 76: Tree influence on solar Radiation on the E-W axis.
60
Figure 77: Tree influence on solar Radiation on the W-E axis.
Shading Devices.
Improving Outdoor Comfort and Water Cycles
6.6 Shading Devices. A shading device design controllable by the user is tested in Figure 78 to Figure 81. The main idea involves a free-standing openable upsidedown umbrella that could also serve as a rainwater collector when open. Three possible scenarios are tested in each orientation. At the bottom, a free-standing closed case. In the middle two half umbrellas hang from the walls of the canyon. and at the top a free standing open umbrella. The closed case provides solar acces during cool periods and nights. The half umbrellas provide shadow more effectively in the West-East and East-West orientations in the North and South oriented walls respectively. In the SouthNorth orientation the open umbrella provides defined shadows that would generate cool spots during hot periods. The North-South orientation presents larger shadows.Giving control of the devices to the users could prevent overshadowing.
Figure 78: Solar radiation analysis on umbrellas proposal S-N axis.
The relatively mild weather conditions of the site make necessary the provision of control and adaptavility of the devices to the users. This will also increase confort on a psychological basis.
Figure 79: Solar radiation analysis on umbrellas proposal N-S axis.
Figure 80: Solar radiation analysis on umbrellas proposal E-W axis.
Figure 81: Solar radiation analysis on umbrellas proposal W-E axis.
61
Research Outcomes and Design Applicability
Improving Outdoor Comfort and Water Cycles
7. Research Outcomes and Design Applicability 7.1 Lessons from Research, Fieldwork and Analytic Work. After the studies conducted during this dissertation, the findings from research, the fieldwork done in Magdalena Contreras municipality and the analytic work carried out can be summarized as follow: Solar Radiation plays the most influential role in outdoor comfort in the site. High solar angles ensure solar access for all orientations at mid-day. Variations at morning and afternoon are seen for walls facing East and West. Because of the reduced space in the canyons, evaporative cooling could be difficult to achieve. Eventhough, a water management system which includes Bio-swales as a system to filtrate, store and reuse rainwater would be beneficial for the improvement of water cycles and the reduction of floods. Aesthetics of the canyons also impact significantly outdoor comfort. Users of canyons in better aesthetic conditions express higher rates of satisfaction.
65
Narrow stepped caNyoNs iN mexico city
Shading Device.
7.2 Shading Device. Once the problems have been analysed. A system is proposed to provide outdoor comfort and enhance water management. First, a user controllable shading device based on the concept of an upsidedown umbrella is presented in (Figure 82). The use of outdoor resistant materials is suggested. Users can open or close the umbrella whenever they consider it necessary. The provision of shade will generate cool spots underneath in conjunction with an appropriate material selection for the floors. Light coloured concretes can be used, but stone and clay should be preferred. Materials with high heat storage capacity should be avoided unless they are properly shaded during most of the hot periods. A PV panel is located on top of the structure, lamps then will be provided with the required energy to transform the shading device in to a lamp at night. Charging spots for cellphones and lap tops can be procured for the users. This would enhance the appropriation of the devices and the social interaction around them. Then, water will run through a separate tube isolated from the PV panel electrical parts, down to a water collection tank buried underneath the resting spots already present in the stairways. (Figure 83). In the area, this umbrellas can become a unifying element to give the community more security and encourage the preservation of natural resources.
Figure 83: Umbrella section.
66
Figure 82: Shading device design.
Possible Shading Device
Arrangement.
Improving Outdoor Comfort and Water Cycles
7.3 Possible Shading Device Arrangement. Views of possible location of the umbrellas inside the canyons are presented in (Figure 84). An overall re-design and change of materiality of the surounding surfaces will be needed. Solar exposure analysis should be carried out to propose adequate materials. Following the general guidelines provided by the analytic work. the umbrellas should be located in the canyons to provide cool spots for resting and relaxing. For that, benches will be constructed preferably of brick or clay tiles. Vegetation should also be added to the design. Vines and broad leaf plants are to be selected. In terms of materiality, stone brick (adoquin) should only be used where appropriate shading by the umbrellas is provided for most of the warm season (April-May) and during summer. Concrete is already the predominant material throughout the area, but lighter colours are to be preferred. Walls should be painted in light colours but white should be avoided to prevent excessive reflections towards the pedestrians
Figure 84: Possible views of the umbrellas. Open-Closed.
67
Narrow stepped caNyoNs iN mexico city
Shading analysis
7.4 Shading analysis Figure 85 shows the different possibilities of arrangement for the umbrellas. At the bottom the closed case, in the middle half umbrellas fixed to the walls on both side walls and at the top the open case. It can also be seen how cool spots would be crated inside the canyon. This spots should be designed to create pleasant environments. Figure 86 and Figure 87 show shadow ranges from 10:00 to 15:00 analysed using Ecotect. This studies are to be used to propose the adequate materials underneath the umbrellas. Materials with higher thermal capacities can be placed in the areas that would be in shadow when the umbrellas are closed. Then during cold dry periods when the umbrellas are closed those materials can become sources of heat to balance temperatures when cloudy skies are present.
7.5 Water Management System. A water management system is proposed integrating the shading devices already described (Figure 88). In the area of study, practically all roofs are flat and rarely used. Rainwater is channelled to the general sewage system and mixed with the black waters. This roofs already have effective drainage systems but that connection is the problem. By connecting the roof drains to the tanks underneath the umbrellas (Figure 89), all that rain water can be collected, filtered and stored for later use. Simple overflow systems can channel excess of water to the next tanks and at a last instance to the river. In the river much bigger Bio-swale systems can be constructed for reinfiltration, and at the same time they could become sources of public space. The implementation of this systems could act as a trigger for the further improvement of the site. Heat Emitting Walls are also proposed in Figure 88. Adoquin can be used there under the half umbrellas and be exposed to solar radiation in the winter. Users will have to be properly informed of the properties and possibilities of adaption of this strategies in order to provide the adequate comfort needed in the stairways. Water outlets will be located on each rainwater collection tank so the users can make use of the collected and filtered water for irrigation of the vegetation. Vine vegetated walls are to be proposed whenever possible since it is the most effective strategy to reduce surface temperatures and reflections in the walls. 68
Figure 85: Arrangement possibilities.
Figure 86: Shadow range 10:00 to 15:00 on a wall covered by a half umbrella. Source: Ecotect 2011.
Figure 87: Shadow analysis of an open umbrella. Source: Ecotect.
Shading analysis
Improving Outdoor Comfort and Water Cycles
Figure 88: Representative longitudinal section of the water collection system proposed.
The aesthetic of the stairways is a crucial factor for the success of the strategies proposed. Generating a sense of appropriation and well being by the design of a pleasant environment for the users would determine the protection of the devices against vandalism. The solar panels can also be used to provide electrical outlets at the ground level so the users can use the space to recharge their phones and even work on their computers. This would be attractive for kids and teenagers to the site. These strategies can also generate different commercial uses inside the stairways, at present small grocery stores can be seen in many corners of the site. But by creating a better ambiance coffee shops and all kinds of little businesses can be placed in the site to improve the economical activities and generate job opportunities. ONG´s should be involved in the first stages of the implementation of the strategies being aware of the possible objections that governmental institutions could have in terms of economical resources destined to them.
Figure 89: Representative transversal section of the water collection system proposed.
69
Conclusion
Improving Outdoor Comfort and Water Cycles
8. Conclusion Outdoor comfort has been widely overlooked in Latin-American cities. Relatively mild weather conditions often miss lead designers which results in poorly performing public spaces. The focus of this research demonstrates the intervention possibilities in complex urban environments. The provision of comfortable spots in the stairways studied can improve the overall conditions of the area. Not only in terms of outdoor comfort but also assessing problems of water management and insecurity, Multipurpose shading devices that can be adapted by the users depending on the seasonal weather conditions might seem as a modest strategy to give solution to a rather complex problematic. Although in combination with simple systems to filter, store and reuse rainwater can also be beneficial to reduce water runoff and flooding throughout the site. The use of solar panels on top of them and led lamps, will also provide proper illumination to the stairways at night to improve security. Careful considerations must be taken by designers to propose further interventions in the site. Materiality has a very important part in microclimatic performance inside the canyons. Materials like asphalt and dark coloured concrete should be avoided. Other materials like stone bricks can reach high temperatures when exposed directly to solar radiation during hot periods. But if shaded properly in this times could provide comfortable conditions as heat emitting walls during winter time permitting exposure. The aesthetics of the site play a very important role in the quality of life of the inhabitants. Satisfaction levels increase when a pleasant ambiance is created. To help this, vegetation is a fundamental strategy to be implemented. But, if trees are to be used for shading; professionals with deep understanding of the life cycles, vulnerabilities and growth must be involved to avoid problems. Plants and walls covered with vines or other kinds of vegetation are to be preferred in narrow canyons once provided with shading devices. Quantification of energy consumption and the possibilities of reducing it, are not between the reach of this research. Although it is logical to deduce that users who are in comfort at the moment they arrive to their house are less likely to make use of electric fans or portable heating devices. Finally, the implementation of the proposed strategies must be accompanied by a bigger plan for the insertion of cultural, sport and recreational facilities for the community as the study cases showed successful projects in Venezuela.
73
References
Improving Outdoor Comfort and Water Cycles
9. References Ali Toudert, F. (2005) Dependence of outdoor thermal comfort on street design in hot and dry climate. Universitätsbibliothek Freiburg. Zaragoza A. Muñoz, C. (2012). Albedo Effect and Energy Efficiency of Cities, Sustainable Development - Energy, Engineering and Technologies - Manufacturing and Environment. Available from: http://www.intechopen.com/books/sustainable-development-energy-engineering-andtechnologiesmanufacturing- and-environment/albedo-effect-and-energy-efficiency-of-buildings Baker, J. L. (2012). Climate change, disaster risk, and the urban Poor: Cities building resilience for a changing world. World Bank Publications. Ballinas, M. Barradas, V. (2011) ‘The actual Urban Heat Island in Mexico City’: Instituto de Ecología, Unam. Presentation. Barradas, V. (1991) ‘Air temperature and humidity and human comfort index of some city parks of Mexico City’, International Journal of Biometeorology, 35:24-28.” Barradas, V. (2013) ‘La Isla de Calor Urbana y la Vegetacion Arborea’: Oikos, No. 7:17-19. “Barradas, V. (2014) ‘Entre techos blancos y azoteas verdes: cambio climático urbano’, Oikos, No. 11:8-9.” Chrisomallidou, N. Chrisomallidis, M. Theodosiou, T. (2004) ‘Design Principles and Applications’, “Designing Open Spaces in the Urban Environment: A Bioclimatic Approach”, Centre for Renewable Energy Sources (C.R.E.S.),37-41. Cui, YY; de Foy, B (2012). Seasonal Variations of the Urban Heat Island at the Surface and the Near- Surface and Reductions due to Urban Vegetation in Mexico City. JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY, 51(5), 855-868. Erell, E., D. Pearlmutter and Williamson, T. ,(2011)Urban Microclimate: Designing the Spaces Between Buildings: Earthscan. Estrada, F. Martinez-Arroyo, A. Fernandez, A. Luyando, E. Gay, C. (2008) “Defining climate zones in Mexico City using multivariate analysis”. Atmosfera 22(2), 175-193 Givoni, B. (1994). Passive Low Energy Cooling of Buildings, Wiley. Grotao – Fábrica de música’, by Urban-think tank, São Paulo, Brazil. (2010). Available at: http://www.designboom.com/architecture/urban-think-tank-grotao-fabrica-de-musica/ (Accessed: 13/08/2015). “Höppe, P., (1999): The physiological equivalent temperature - a universal i ndex for the biometeorological assessment of the thermal environment. Int. J. Biometeorology. 43, 71-75.” 77
Narrow stepped caNyoNs iN mexico city
References
Hwang, R. Lin, T. Matzarakis, A. (2010) ‘Seasonal effects of urban street shading on long-term outdoor thermal comfort’, Building and Environment, 46 (2011), 863-870. Jauregui, E. (1993) Ernesto Jauregui: Mexico City’s urban heat island revisited. Germany Erdkunde. Band 47/1993 . Jauregui, E. (1998). Long-term association between pan evaporation and the urban heat island in Mexico City. Atmosfera 11, pp 45-60 Marciotto, E. Oliveira, A. Hanna, S. (2010) ‘Modeling study of the aspect ratio influence on urban canopy energy fluxes with a modified wall-canyon energy budget scheme ‘, Building and Environment , XXX, 1-9. Marciotto, R. Amauri P. Steven R. (2010). “Modeling study of the aspectratio influence on urban canopy energy fluxes with a modified wall-canyon energy budget scheme“. Building and Environment xxx)1e9. Matzarakis, A. (2015) Application of RayMan and SkyHelios model for architects’ Lecture, AA SED, London, 17/06/2015. “Matzarakis, A., Mayer, H., Iziomon, M., (1999): Applications of a universal thermal index: physiological equivalent temperature. Int. J. Biometeor 43, 76-84.” “Matzarakis, A., Rutz, F., Mayer, H., (2007), Modelling radiation fluxes in simple and complex environments - Application of the RayMan model. International Journal of Biometeorology 51:323-34.” Mayer, H., Höppe, P.R. , (1987): Thermal comfort of man in different urban environments. Theoretical and Applied Climatolog, 38, 43-49. National Census. (2010). Available at: http://www.inegi.org.mx/ (Accessed: 13/08/2015). Pearlmutter D, Berliner P, Shaviv E.. (2005) Evaluation of urban surfaceenergy fluxes using an open-air scale model. Journal of Applied Meteorology 2005;44:532–45. “Rodriguez, Z. Dietrich, U. Velasco, G. Dickhaut, W. (2014) ‘Mexico City adaptation: water- and energy-creating microclimates ‘, The Sustainable City IX, Vol. 2, 1213-1224. “ Sharmin, T. Steemers, K. (2013) ‘ Effect of Canyon Geometry on Outdoor Thermal Comfort: A case-study of high-density, warm-humid climate’, 29th Conference, Sustainable Architecture for a Renewable Future, 2013. Stairways in Venezuela. (2010) Available at: http://lindahagberg.com/Barrio-Stairways (Accessed: 04/08/2015). Vertical Gymnasium. La Cruz. Venezuela. (2010) Available at: http://www.designboom.com/architecture/urban-think-tank-grotao-fabrica-de-musica/ (Accessed: 13/08/2015). 78
Appendix
Improving Outdoor Comfort and Water Cycles
9. Appendix
Figure 90: Survey.
79
Narrow stepped caNyoNs iN mexico city
Survey
Date
Time
Age
Gender
1 2 3 4 5
July 1st July 1st July 1st July 1st July 1st
13:00:00 13:10:00 13:20:00 13:25:00 13:30:00
38 40 24 52 41
Dress
Ac5vity
Sweatshirt Going up Shirt Going up Sweatshirt Going up Sweater Going down T-‐shirt Going up
General state Good Good Regular Good Regular
References
Distance Use of stairs walked per Likeness of (5mes a day) the zone day 4 2 Km No 2 3 Km Yes 1 3 Km Yes 4 1 Km Yes 6 0.5 Km Yes
Reason
Safety
Dirty Quite Quite Quite Quite
No Yes Yes Yes Yes
Need of Hot or Cold Hot or Cold green space State at the Preferred state Sky condi5on moment No 7 4 Overcast Yes 7 4 Sunny Yes 7 4 Sunny Yes 6 6 Overcast Yes 4 4 Overcast
Ta
Gt
ST floor
ST wall
WS
RH
Lux
27 27.3 25.8 25.2 24.8
25.3 28.4 28.4 24.65
27 27.1 32 29.3
24.4 24.4 23.7 26.9
0 0 0.7 0.5 0.9
40 42.3 46.1 46.2 48
83003 82580 88220 42430
6
July 1st 13:35:00
44
Female Female Female Female Female Male Disabled
Sweater
Going up
Good
4
1 Km
Yes
Quite
Yes
No
5
5
Overcast
25
30
25
40
7
July 1st 13:40:00
26
Female
Sweater
Si_ng
Good
4
2 Km
Yes
Quite
Yes
Yes
2
4
Overcast
26.1
8
July 1st 13:45:00
42
Male
Sweater
Regular
4
2 Km
Yes
30 Years living there
No
Yes
4
4
Overcast
24
19.49
30
25
1
48
9 10
July 1st 14:00:00 July 1st 14:15:00
27 22
Female Male
T-‐shirt T-‐shirt
Going up Vision problem Going up Si_ng
Good Good
3 10
1 Km 1 Km
Yes Yes
Quite Quite
Yes Yes
Yes Yes
6 5
6 4
Overcast Overcast
24 23.7
19.2884 19.4904
16.4 18.2
15.8 16.7
0 0.4
51 48
93333 9453
Quite
Yes
Overcast
23.5
19.0279
18.2
17.3
0.6
51.2
2858
24.5
22.66
14.7
18.7
0.6
45.8
22650
25.6 29.6 29.4 28.3 25.7 27.8 27.9 28.3 27.9 25 25 24.2 24.1 26.8 24.5
no 24.21 24.65 22.46 20.92 no 17.15 17.15 21.88 23.1 19.29 17.24 17.24
20.6 18.1 16.2 16.2 11.8 15.4 13.5 13 13.5 18.2 17.8 15
18.8 17.1 13.95 16.6 12.9 16.6 11.8 11 11.8 14.3 16.7 13.3
0.5 0 0.4 0.4 0.9 0.4 0.7 0 0.8 0.4 0.4 0.4 0.8 1 0.5
45.8 39.4 39.7 38 41.9 37.5 45 41.9 44.2 45 46 45.4 49.1 45.8 52.2
29700 8373 12833 702 6635 2450 3071 2445 2200 2270 2170 12348 5016 4780
11
July 1st 14:30:00
29
Male
T-‐shirt
Going up
Good
5
1 Km
Yes
Yes
2
4
12
July 1st 15:55:00
42
Female
Sweater
Going up
Bad
4
0.5 Km
Yes
Used to it Some5mes
Yes
4
4
13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 1st July 2nd July 2nd July 2nd July 2nd
16:00 17:50:00 17:00:00 17:00:00 17:20:00 17:35:00 18:13:00 18:15:00 18:20:00 18:25:00 18:30:00 18:30:00 18:35:00 18:40:00 18:45:00 19:40:00 19:45:00 11:00:00 11:10:00 11:15:00 11:20:00
36 17 36 15 55 31 22 24 47 35 37 39 28 74 38 25 22 66 65 58 21
Female Male Female Female Male Female Female Female Female Female Female Female Female Male Female Female Male Male Female Male Female
Sweatshirt Standing Sweatshirt Si_ng Sweatshirt Going down T-‐shirt Standing T-‐shirt Going up Coat Going up Sweatshirt Going up Sweatshirt Going up Sweatshirt Going up Sweatshirt Going up Sweatshirt Going up Sweatshirt Si_ng Jacket Going up Sweater Going up Sweater Going up Sweatshirt Going down T-‐shirt Standing Sweatshirt Going up T-‐shirt Going up Sweatshirt Going up Vest Going down
Good Good Good Bad Good Good Good Regular Good Good Tired Regular Good Good Regular Good Stoned Regular Good Good Regular
5 3 3 7 6 4 2 4 5 2 6 1 2 2 2 2 3 4 8 3 2
0.5 Km 1 Km 2 Km 3 Km 1 Km 1 Km 3 Km 4 Km 2 Km 0.5 Km 2 Km 5 Km 1 Km 3 Km 2 Km 2 Km 3 Km 1 Km 1 Km 2 Km 1 Km
Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes No Yes Yes Yes No No Yes Yes Yes
Quite Used to it Quite Used to it Unsafe Used to it Quite Quite Quite Unsafe Quite Unsafe Quite Quite Quite Unsafe Ugly Used to it Quite Quite
Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes
2 4 4 3 4 4 3 6 4 5 6 4 3 2 2 5 4 2 4 5 4
4 4 4 2 4 4 2 4 4 5 4 4 5 4 2 4 4 2 4 5 4
Sweatshirt Going down
Regular
Yes Yes No Yes Yes No No Yes Yes Yes No Yes No Yes Yes Yes No Yes Yes Yes Yes
Overcast/ Sunny Overcast Sunny Sunny Sunny Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast
34
July 2nd 11:25:00
45
Female
Unsafe
No
Yes
5
1
Overcast
35
July 2nd 11:40:00
52
Female
Regular
6
2 Km
Yes
Quite
Yes
Yes
4
4
Overcast
36 37 38 39 40 41 42 43
July 2nd July 2nd July 2nd July 2nd July 2nd July 2nd July 2nd July 2nd
11:45:00 11:46:00 12:00:00 12:05:00 14:40:00 15:00:00 15:20:00 15:55:00
40 40 53 56 33 18 46 75
Female Female Male Male Female Male Male Female
Sweatshirt Going up Good Sweatshirt Going up Regular T-‐shirt Going down Good Sweater Standing Regular Sweatshirt Standing Regular Sweatshirt Going down Stressed Vest Going up Regular Vest Going up Good
5 5 3 3 4 2 2 2
3 Km 2 Km 1 Km 5 Km 1 Km 0.5 Km 4 Km 5 Km
Yes Yes Yes Yes No Yes Yes Yes
Used to it Quite Used to it Quite Unsafe Quite Quite Quite
Yes Yes No Yes No Yes No Yes
Yes Yes Yes Yes Yes Yes Yes Yes
4 4 6 4 1 4 4 4
4 7 5 4 4 2 4 4
23.6 24.9 23.4 23.6 21.1 19.1 20
18.09 18.09 17 17 16.07 14.6 no
16.6 16.6 15.2 14.1 8.4 13.8 15.1
15.1 16.3 15.4 13.6 9.1 13.9 15.3
1.2 0.5 0.9 0.4 0.6 0.4 0
50 49.6 49.1 50.6 57.1 64.9 64.3
12879 7788 7401 4559 3007 1914 3989
44
July 3rd 11:30:00
32
Female
Sweatshirt
Standing
Good
4
1 Km
Yes
Quite
Yes
Yes
3
2
22.1
18.65
19.9
15
0.6
56.1
38710
45
July 3rd 12:00:00
23
Female
Sweatshirt
Going up
Regular
3
3 Km
Yes
Unsafe
No
Yes
7
3
22.9
22.7
18.9
14.1
0.8
51.7
41500
46
July 3rd 12:05:00
76
Male
Sweater
Gardening
Good
5
2 Km
Yes
Quite
Yes
No
3
3
47 48 49 50 51 52 53 54 55 56
July 3rd July 3rd July 3rd July 3rd July 3rd July 3rd July 3rd July 3rd July 3rd July 3rd
14:40:00 16:30:00 16:45:00 16:45:00 16:50:00 16:55:00 17:00:00 17:15:00 17:15:00 17:30:00
76 54 35 62 62 70 20 20 55 51
Female Female Female Male Male Female Female Male Male Female
Good Tired Good Good Good Regular Bad Good Good Bad
0 2 3 2 4 4 4 2 4 15
0.5 Km 3 Km 1 Km 4 Km 1 Km 1 Km 0.5 Km 1 Km 0.5 Km 2 Km
Yes Yes No Yes Yes Yes Yes Yes Yes No
Quite Quite Dirty Used to it Quite Quite Quite Quite Quite Used to it
No Yes Yes Yes Yes Yes Yes Yes Yes No
Yes No No No No No No Yes Yes No
3 7 3 4 6 4 6 3 3 2
6 7 4 6 6 4 3 4 3 6
Overcast Overcast Overcast Overcast Raining Raining Overcast Raining Overcast/ Sunny Overcast/ Sunny Overcast/ Sunny Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast
22.3 21.3 20.9 20.4 20.2 20.3 19.2
20.06 17.21 17.15 19.66 17.68 17.68 17
17.3 16.3 15.9 17.3 14.3 17.5
21.7 15.4 16.3 17.3 14.9 18.4
0.6 0 0 0 0.5 0 0.4
50.5 57.6 56 66 65.9 60.6
3884 1284 4423 2093 2611
57
July 3rd 17:45:00
30
Female
T-‐shirt
Going up
Good
5
1 Km
No
Unsafe
Yes
No
3
1
Overcast
19.3
17
17.5
18.4
0
50
3045
58 59 60
July 3rd 18:20:00 July 3rd 18:30:00 July 3rd 18:40:00
24 76 76
Female Female Male
T-‐shirt Sweater Sweater
Sweeping Standing Si_ng
Good Regular Good
2 3 4
0.5 Km 2 Km 0.5 Km
No Yes Yes
Unsafe Used to it Used to it
No Yes Yes
Si Yes No
4 2 2
1 2 2
Overcast Overcast Overcast
22.2 21.68
16.19
15.5 13.8
11.8 13.2
0.5 0.4
65.1 64.8
4572 2650
Sweater
Going up
Sweater Going down Sweater Going up Sweater Going up Sweater Standing Sweater Standing Sweater Going up Jacket Going up T-‐shirt Going up T-‐shirt Going down Sweater Going up
5
4 Km
No
61
July 3rd 18:45:00
58
Female
Sweater
Going up
Good
2
0.5 Km
2
2
Overcast
62
July 4th 12:40:00
39
Female
T-‐shirt
Going up
Regular
5
2 Km
Yes
Quite
Yes
Yes
4
4
Overcast
23.9
19.66
15
17.4
0.8
48.5
10950
63 64 65 66 67 68 69 70
July 4th July 4th July 4th July 4th July 4th July 4th July 4th July 4th
12:50:00 12:55:00 13:00:00 13:05:00 14:05:00 15:20:00 15:25:00 15:20:00
34 33 78 59 56 32 18 27
Female Female Female Female Female Male Male Female
Good Bad Regular Regular Bad Good Tired Good
2 4 2 1 12 4 6 3
1 Km 2 Km 0.5 Km 0.5 Km 3 Km 1 Km 3 Km 2 Km
Yes No Yes Yes No Yes No No
Quite Ugly Quite Used to it Sickness Safe Unsafe Dirty
Yes Yes Yes No Yes Yes No No
Yes Yes Yes Yes No Yes Yes No
4 4 2 2 2 7 6 5
7 4 2 7 5 5 2 4
Overcast Overcast Overcast Overcast Overcast Overcast Overcast Overcast
24.3 24.4 23.7 26.8 26.1 25.9
19.03 20.52 20.52 21.79 21.79 21.79
16.2 17 16.3 16.4 24.7
17.8 19.98 17.2 17.7 19.9
0.4 O.6 0 0.4 0 0.4
48.3 45.9 53.4 43.2 40.1 34.7
16858 15858 8917 43040 44060 29030
71
July 4th 15:20:00
38
Male
Good
2
1 Km
No
Stairs
Yes
Yes
4
6
Raining
23.4
24.43
14.8
15.6
0.4
51.7
1358
72
July 4th 15:30:00
56
Female
Sweater Going down
Regular
2
2 Km
No
Yes
4
4
Overcast
24.8
18.2
19.9
0
47.5
14069
July 4th 16:20:00
62
Male
Sweater
Disabled
8
3 Km
Yes
Yes
Yes
2
4
Overcast
25.1
21.46
24.6
23.4
0.5
43.6
66900
2 Km
Yes
Unsafe Wants a street Quite
No
73
Yes
Yes
2
5
Overcast Overcast/ Sunny Overcast Overcast Overcast Overcast/ Sunny Overcast/ Sunny Sunny Sunny Sunny Sunny Sunny Sunny Sunny Overcast Overcast/ Sunny Overcast
20.4
16.85
16.4
15.6
Sweater Going down T-‐shirt Going down Vest Going down Sweater Going up Sweater Going up T-‐shirt Going up Vest Going up Sweater Going up T-‐shirt
Going down Standing
74
July 6th
9:50:00
37
Female
Sweatshirt
Si_ng
Bad
75
July 6th 10:00:00
55
Female
Sweater
Going up
Regular
4
3 Km
No
Unsafe
No
Yes
6
4
76 77 78
July 6th 10:05:00 July 6th 10:10:00 July 6th 10:20:00
68 55 32
Female Female Male
Sweater Sweater T-‐shirt
Going up Going up Worrking
Good Good Good
2 6 60
1 Km 3 Km 3 Km
No Yes Yes
Unsafe Safe
No Yes Yes
Yes Yes Yes
4 4 6
6 4 4
Sweater Going down
79
July 6th 10:35:00
68
Female
80
July 6th 11:40:00
74
Female
81 82 83 84 85 86 87 88
July 6th July 6th July 6th July 6th July 6th July 6th July 6th July 6th
12:50:00 14:35:00 14:45:00 15:10:00 15:15:00 15:20:00 15:25:00 15:25:00
14 50 30 19 22 33 26 13
Female Male Female Female Male Female Male Male
89
July 6th 15:30:00
31
Female
Shirt
90
July 6th 15:35:00
40
Female
Sweatshirt
Figure 91: Surveys.
80
Vest
2
Good
6
2 Km
Yes
Quite
Yes
Yes
4
2
Regular
5
0.5 Km
Yes
Used to it
No
Yes
2
4
Good Good Good Good Good Good Good Good
3 1 2 3 5 2 4 15
2 Km 1 Km 0.5 Km 2 Km 4 Km 1 Km 0.5 Km 4 Km
Yes No Yes Yes Yes Yes Yes Yes
Yes No No No Yes Yes Yes Yes
Yes Yes Yes Yes Yes Yes Yes Yes
7 6 1 7 7 4 4 4
4 3 4 4 3 4 4 2
Going up
Good
10
4 Km
Yes
Going up
Good
4
2 Km
Yes
Quite Drugs Drugs Interes5ng Quite Quite Quite Quite Doesn´t flood Quite
Going down
Sweatshirt Going up T-‐shirt Going up Vest Going down T-‐shirt Going up T-‐shirt Going up T-‐shirt Going down T-‐shirt Going down T-‐shirt Going up
No
Yes
3
4
Yes
Yes
5
2
1.1
55.5
19.6
19.6
17
1
55.9
79080
23.4 25.4 24.4
16.8 17.9 17.2
16.9 16.7 17
0 0.4 0.4
50 52.4 49.1
20500 17751 14560
17599
24.4
17.8
13.5
0.5
47.5
30030
27.6
22.1
20.4
0
45
83410
26.9 30.7 30.5 28.6 28.8 28.8 28.8 28.5
32.67
40 17.5 36.9 15.7 15.7 15.7 15.7 24
26.4 34 27 17.3 17.3 17.3 17.3 17.2
0.6 0 0.9 0 0 0 0 1.3
38.7 26.1 36.9 42.5 40.6 40.6 40.6 35.6
97520 84640 84450 17259 17259 17254 17289 10598
27.7
25.4
22.8
0.8
39.5
10380
27.7
25.4
22.8
0.8
39.5
10380
References
Improving Outdoor Comfort and Water Cycles
Figure 92: Flat canyon South-North axis. For comparison w/ base-case.Source: Ecotect.
Figure 93: Flat canyon North-South axis. For comparison w/ base-case.Source: Ecotect.
Figure 94: Flat canyon North-South axis. For comparison w/ base-case.Source: Ecotect.
81
Narrow stepped caNyoNs iN mexico city
References
100 90 80 70
%
60
31+ 26-‐30
50
26-‐30 40
16-‐20 16-‐20
30
6-‐10
20
0-‐5
Monthly PET values 2100
Figure 95: PET frequency. 2100.
Figure 96: Shading device design alternative.
82
December
November
October
September
August
July
June
May
April
March
February
0
January
10