Impact of Urban Form and Design on Mid-Afternoon Microclimate … · 2016-07-14 · parking lot...
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1 Decision Center for a Desert City, Arizona State University, PO Box 878209, Tempe AZ 85287-8209 2 Department of Computer Science, University of Kaiserslautern, PO Box 3049, 67653 Kaiserslautern, Germany 3 School of Geographical Sciences and Urban Planning, Arizona State University, PO Box 875302, Tempe AZ 85287-5302 4 School of Letters and Sciences, Arizona State University Polytechnic, 6073 South Backus Mall, Mesa AZ 85212 4 Center for Geographic Information Systems, Georgia Tech, 280 Ferst Dr N, Atlanta GA 30332-0695 Impact of Urban Form and Design on Mid-Afternoon Microclimate in Phoenix Neighborhoods 1 2 3 4 5 Ariane Middel , Kathrin Häb , Anthony J. Brazel , Chris Martin , Subhrajit Guhathakurta Acknowledgements This research was supported by the National Science Foundation (Grant SES-0951366, Decision Center for a Desert City II: Urban Climate Adaptation; Grant BCS-1026865, Central Arizona-Phoenix Long-Term Ecological Research, CAP-LTER) and the German Science Foundation (DFG, Grant 1131) as part of the International Graduate School (IRTG 1131) at University of Kaiserslautern, Germany. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsoring agencies. Compact Highrise Scenario (CHS) NDV Calibration Runs 0 100 200 50 m Openset Lowrise Scenario (OLS) urban form urban form urban form urban form urban form mesic run mesic run mesic run mesic run xeric run xeric run xeric run xeric run xeric run Compact Lowrise Scenario (CLS) Compact Midrise Scenario (CMS) Openset Midrise Scenario (OMS) <= 40.30 40.31 - 40.60 40.61 - 40.90 40.91 - 41.20 41.21 - 41.50 41.51 - 41.80 41.81 - 42.10 42.11 - 42.40 42.41 - 42.70 42.71 - 43.00 43.01 - 43.30 43.31 - 43.60 43.61 - 43.90 43.91 - 44.20 44.21 - 44.50 44.51 - 44.80 44.81 - 45.10 45.11 - 45.40 45.41 - 45.70 > 45.70 2m air temperature [°C] 2m air temperature [°C] urban form ENVI-met simulations <= 41.30 41.31- 41.60 41.61 - 41.90 41.91 - 42.20 42.21 - 42.50 42.51 - 42.80 42.81 - 43.10 43.11 - 43.40 43.41 - 43.70 43.71 - 44.00 <= 41.30 41.31 - 41.60 41.61 - 41.90 41.91 - 42.20 42.21 - 42.50 42.51 - 42.80 42.81 - 43.10 43.11 - 43.40 43.41 - 43.70 43.71 - 44.00 44.01 - 44.30 44.31 - 44.60 44.61 - 44.90 44.91 - 45.20 45.21 - 45.50 45.51 - 45.80 45.81 - 46.10 46.11 - 46.40 46.41 - 46.70 > 46.70 44.01 - 44.30 44.31 - 44.60 44.61 - 44.90 44.91 - 45.20 45.21 - 45.50 45.51 - 45.80 45.81 - 46.10 46.11 - 46.40 46.41 - 46.70 > 46.70 Legend k k vegetation receptor 60m 122m 15m 23m 12m 9m 7m 6m 5m porch patio overhang building heights building features impervious pervious patio roof garage main street small path inorg. mulch parking lot walls flower bed grass CHS other scenarios urban form References [1] Ian D. Stewart, Tim R. Oke, 2012, Local Climate Zones for Urban Temperature Studies. Bulletin of the American Meteorological Society, 93(12):1879–1900. [2] Ariane Middel, Kathrin Häb, Anthony J. Brazel, Chris Martin, Subhrajit Guhathakurta, 2012, Urban form, landscape design, and microclimate in Phoenix, Arizona. 8th International Conference on Urban Climate (ICUC8), August 2012, Dublin, Ireland. Simulation Results Methodology We simulated near-ground air temperatures for typical neighborhoods in Phoenix using the three-dimensional microclimate model ENVI-met. The model was calibrated using the CAP LTER North Desert Village (NDV) landscape experiment at Arizona State University's Polytechnic campus. This site is an ideal test bed to determine the model's input parameters, since it is a controlled environment recreating four prevailing residential landscape types in the Phoenix metropolitan area (mesic, oasis, xeric, and native). After calibration, we designed five urban form scenarios that represent a realistic cross-section of typical residential neighborhoods in Phoenix. The urban form scenarios follow the Local Climate Zone (LCZ) classification scheme after Stewart and Oke [1]. We then combined the urban form scenarios with mesic and xeric landscape designs and simulated microclimate conditions for these neighborhoods in ENVI-met for June 23, 2011, a typical summer day. Model Calibration Results For a detailed discussion of calibration results, see [2]. Key Findings l The hierarchy of landscaping scenarios reflects the magnitude of the respective latent heat flux. l The diurnal spatially averaged air temperature is highest for the CHS, but mid-afternoon air temperatures are lowest. The daily air temperature amplitude for the CHS is relatively low. l Air temperatures in the midrise scenarios are higher than in the lowrise scenarios. l Air temperatures in the openset scenarios are lower than in the compact scenarios, whereas wind speed is higher in the openset scenarios. l Advection is important for the temperature distribution in the urban form scenarios. For example, in the CMS, the building to the west has a shielding effect, keeping high temperatures away from the courtyard. This is also reflected in the spatial variation of air temperatures, which is highest for this scenario. l There is a relatively high correlation between surface temperatures and incoming short-wave radiation. It ranges from 0.42 for the xeric OMS to 0.73 for the highrise scenario. l Shading patterns and surface materials impact surface temperatures and can be used to influence local temperatures. Introduction Over the past decades, many cities have been warming due to urban heat island effects, induced by changes in land cover and built forms. Those local climate variations can lead to a higher demand for air conditioning and increased human discomfort in the summer, especially in This study investigates the impact of urban form and landscaping on the mid-afternoon microclimate in Phoenix, Arizona. The goal is to find the most effective urban form and design strategies to ameliorate temperatures during the summer months and, consequently, to reduce residential energy use and increase human comfort. arid and semiarid environments. calibration run calibration run NDV: mesic site NDV: xeric site 0 50 100 25 m shrub succulent tree local weather station soil main street grass walkway building garage patio Legend Modeled vs. Observed <= 0.5% 0.6% - 2.0% 2.1% - 4.0% 4.1% - 6.0% 6.1% - 10.0% 10.1% - 15.0% 15.1% - 25.0% 25.1% - 52.0% Legend 2m Air Temperature [°C] xeric OMS mesic OMS xeric CLS mesic CLS xeric Calibration mesic Calibration xeric CMS mesic CMS xeric OLS mesic OLS xeric CHS 38.5 39.0 39.5 40.0 40.5 41.0 41.5 42.0 42.5 43.0 43.5 44.0 44.5 45.0 45.5 46.0 46.5 47.0 47.5 48.0 48.5 49.0 49.5 50.0 Scenario Snapshots of the air temperature distribution at 2m height and wind vectors for each combined urban form and landscaping scenario for June 23, 2011, 15:00h Landscaping Scenarios mean air temperature [°C] Native 36.13 Xeric (w/o CHS) 35.84 Oasis 35.42 Mesic 33.52 Urban Form Scenarios air temperature [°C] at 15:00h Urban Form Scenarios mean air temperature [°C] OMS 44.90 35.61 CMS 44.74 35.43 OLS 43.88 35.05 CLS 43.71 34.82 CHS 40.74 36.07 Histogram for 2m air temperature distribution in each scenario: For each scenario (rows), the occurrence of temperatures (rounded to 0.5 °C) in percent (columns) is mapped.
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1Decision Center for a Desert City, Arizona State University, PO Box 878209, Tempe AZ 85287-8209 2Department of Computer Science, University of Kaiserslautern, PO Box 3049, 67653 Kaiserslautern, Germany
3School of Geographical Sciences and Urban Planning, Arizona State University, PO Box 875302, Tempe AZ 85287-53024School of Letters and Sciences, Arizona State University Polytechnic, 6073 South Backus Mall, Mesa AZ 85212
4Center for Geographic Information Systems, Georgia Tech, 280 Ferst Dr N, Atlanta GA 30332-0695
Impact of Urban Form and Design on Mid-Afternoon Microclimate in Phoenix Neighborhoods1 2 3 4 5Ariane Middel , Kathrin Häb , Anthony J. Brazel , Chris Martin , Subhrajit Guhathakurta
AcknowledgementsThis research was supported by the National Science Foundation (Grant SES-0951366, Decision Center for a Desert City II: Urban Climate Adaptation; Grant BCS-1026865, Central Arizona-Phoenix Long-Term Ecological Research, CAP-LTER) and the German Science Foundation (DFG, Grant 1131) as part of the International Graduate School (IRTG 1131) at University of Kaiserslautern, Germany. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsoring agencies.
Compact Highrise Scenario (CHS)
NDV Calibration Runs
0 100 20050 m
Openset Lowrise Scenario (OLS)
urban form
urban form
urban form
urban form
urban form
mesic run
mesic run
mesic run
mesic run
xeric run
xeric run
xeric run
xeric run
xeric run
Compact Lowrise Scenario (CLS)
Compact Midrise Scenario (CMS)
Openset Midrise Scenario (OMS)
<= 40.30
40.31 - 40.60
40.61 - 40.90
40.91 - 41.20
41.21 - 41.50
41.51 - 41.80
41.81 - 42.10
42.11 - 42.40
42.41 - 42.70
42.71 - 43.00
43.01 - 43.30
43.31 - 43.60
43.61 - 43.90
43.91 - 44.20
44.21 - 44.50
44.51 - 44.80
44.81 - 45.10
45.11 - 45.40
45.41 - 45.70
> 45.70
2m air temperature [°C]
2m air temperature [°C]
urban form
ENVI-met simulations
<= 41.30
41.31- 41.60
41.61 - 41.90
41.91 - 42.20
42.21 - 42.50
42.51 - 42.80
42.81 - 43.10
43.11 - 43.40
43.41 - 43.70
43.71 - 44.00
<= 41.30
41.31 - 41.60
41.61 - 41.90
41.91 - 42.20
42.21 - 42.50
42.51 - 42.80
42.81 - 43.10
43.11 - 43.40
43.41 - 43.70
43.71 - 44.00
44.01 - 44.30
44.31 - 44.60
44.61 - 44.90
44.91 - 45.20
45.21 - 45.50
45.51 - 45.80
45.81 - 46.10
46.11 - 46.40
46.41 - 46.70
> 46.70
44.01 - 44.30
44.31 - 44.60
44.61 - 44.90
44.91 - 45.20
45.21 - 45.50
45.51 - 45.80
45.81 - 46.10
46.11 - 46.40
46.41 - 46.70
> 46.70
Legend
kk vegetation
receptor
60m
122m
15m
23m
12m
9m
7m
6m
5m
porch
patio
overhang
bu
ildin
g h
eig
hts
bu
ildin
g fe
atu
res
imp
erv
iou
sp
erv
iou
s
patio roof
garage
main street
small path
inorg. mulch
parking lot
walls
flower bed
grass
CHS other scenarios
urban form
References[1] Ian D. Stewart, Tim R. Oke, 2012, Local Climate Zones for Urban Temperature Studies. Bulletin of the American Meteorological Society, 93(12):1879–1900.[2] Ariane Middel, Kathrin Häb, Anthony J. Brazel, Chris Martin, Subhrajit Guhathakurta, 2012, Urban form, landscape design, and microclimate in Phoenix, Arizona. 8th International Conference on Urban Climate (ICUC8), August 2012, Dublin, Ireland.
Simulation Results
MethodologyWe simulated near-ground air temperatures for typical neighborhoods in Phoenix using the three-dimensional microclimate model ENVI-met. The model was calibrated using the CAP LTER North Desert Village (NDV) landscape experiment at Arizona State University's Polytechnic campus. This site is an ideal test bed to determine the model's input parameters, since it is a controlled environment recreating four prevailing residential landscape types in the Phoenix metropolitan area (mesic, oasis, xeric, and native). After calibration, we designed five urban form scenarios that represent a realistic cross-section of typical residential neighborhoods in Phoenix. The urban form scenarios follow the Local Climate Zone (LCZ) classification scheme after Stewart and Oke [1]. We then combined the urban form scenarios with mesic and xeric landscape designs and simulated microclimate conditions for these neighborhoods in ENVI-met for June 23, 2011, a typical summer day.
Model Calibration ResultsFor a detailed discussion of calibration results, see [2].
Key FindingslThe hierarchy of landscaping scenarios reflects the magnitude of
the respective latent heat flux.
lThe diurnal spatially averaged air temperature is highest for the CHS, but mid-afternoon air temperatures are lowest. The daily air temperature amplitude for the CHS is relatively low.
lAir temperatures in the midrise scenarios are higher than in the lowrise scenarios.
lAir temperatures in the openset scenarios are lower than in the compact scenarios, whereas wind speed is higher in the openset scenarios.
lAdvection is important for the temperature distribution in the urban form scenarios. For example, in the CMS, the building to the west has a shielding effect, keeping high temperatures away from the courtyard. This is also reflected in the spatial variation of air temperatures, which is highest for this scenario.
lThere is a relatively high correlation between surface temperatures and incoming short-wave radiation. It ranges from 0.42 for the xeric OMS to 0.73 for the highrise scenario.
lShading patterns and surface materials impact surface temperatures and can be used to influence local temperatures.
IntroductionOver the past decades, many cities have been warming due to urban heat island effects, induced by changes in land cover and built forms. Those local climate variations can lead to a higher demand for air conditioning and increased human discomfort in the summer, especially in This study investigates the impact of urban form and landscaping on the mid-afternoon microclimate in Phoenix, Arizona. The goal is to find the most effective urban form and design strategies to ameliorate temperatures during the summer months and, consequently, to reduce residential energy use and increase human comfort.
arid and semiarid environments.
calibration run
calibration run
NDV: mesic site
NDV: xeric site
0 50 10025 m
shrubsucculenttreelocal weather station
soilmain streetgrasswalkway
buildinggaragepatio
Legend Modeled vs. Observed
<= 0.5%
0.6% - 2.0%
2.1% - 4.0%
4.1% - 6.0%
6.1% - 10.0%
10.1% - 15.0%
15.1% - 25.0%
25.1% - 52.0%
Legend
2m Air Temperature [°C]
xeric OMS
mesic OMS
xeric CLS
mesic CLS
xeric Calibration
mesic Calibration
xeric CMS
mesic CMS
xeric OLS
mesic OLS
xeric CHS
38
.5
39
.0
39
.5
40
.0
40
.5
41
.0
41
.5
42
.0
42
.5
43
.0
43
.5
44
.0
44
.5
45
.0
45
.5
46
.0
46
.5
47
.0
47
.5
48
.0
48
.5
49
.0
49
.5
50
.0
Scenario
Snapshots of the air temperature distribution at 2m height and wind vectors for each combined urban form and landscaping scenario for June 23, 2011, 15:00h
Landscaping Scenarios mean air temperature [°C]
Native 36.13
Xeric (w/o CHS) 35.84
Oasis 35.42
Mesic 33.52
Urban Form Scenarios air temperature [°C] at 15:00h
Urban Form Scenarios mean air temperature [°C]
OMS 44.90 35.61
CMS 44.74 35.43
OLS 43.88 35.05
CLS 43.71 34.82
CHS 40.74 36.07
Histogram for 2m air temperature distribution in each scenario: For each scenario (rows), the occurrence of temperatures (rounded to 0.5 °C) in percent (columns) is mapped.
