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ENERGY EFFICIENCY STRATEGIES FOR BUILDINGS
Tallinn University of Technology, October 9-11 2013
SIMULATION TOOLS FOR THE DESIGN PROCESS
Microclimate in Urban Planning
Prof. Evyatar Erell
Desert Architecture and Urban Planning
The Jacob Blaustein Institutes for Desert Research
Ben-Gurion University of the Negev, Israel
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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Acknowledgements
Prof. Terry Williamson
Adelaide University
Prof. David Pearlmutter
Ben Gurion University of the Negev
Students: Daniel Boneh, Yannai Kalman
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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Outline of talk
 Application of climatology in urban planning
 The Canyon Air Temperature (CAT) model
 Application example 1: Albedo
 Application example 2: Density
 Future research
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Planning authorities (or why cities are like camels)
“a camel is a horse designed by committee…”
Sir Alec Issigonis (or VOGUE Magazine)
 modern architecture and urban
planning are carried out by groups of
professionals from diverse fields
 information from multiple and
sometimes conflicting sources must be
reconciled
 the problem is not to produce an
idealized plan derived from climatic
considerations
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Context
Asking the right questions is the
key to setting appropriate
objectives.
Academic research does not
necessarily focus on the ‘right’
questions (from the perspective of
the planner).
However, although planning
questions are typically ‘wicked
problems’ 1, we still expect
academic research to be the key
to answering them…
Image from Search Patterns by Peter Morville and Jeffery Callender
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Objectives
1. To create a planning framework for the urban area (or part of it) that
will allow optimal exposure of individual buildings so that they may
employ measures for improved thermal control, either to conserve
energy or to improve comfort in the absence of AC (although these aims
may be mutually exclusive!).

In accordance with the local climate

In accordance with the building’s function
2. To design public open space that supports pedestrian activity in a
comfortable environment (thermal & visual comfort, air quality)

In accordance with the local climate

In accordance with expected activities
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Process
1. Analysis of local climate
2. Analysis of life styles and requirements of the project’s occupants,
and identification of main environmental problems
3. Definition of planning objectives, with reference to
 spatial scale: urban/neighborhood/building
 elements dealt with: buildings/open space
 temporal scale, on the annual cycle (summer-winter) or diurnal
cycle (day-night)
4. Selection of appropriate design strategies
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Climatic planning strategies

Land use allocation (location)

Street orientation

Building density

Building typology (e.g. pavillion, row, courtyard)

Street cross-section

Vegetation

Colour (albedo?)

Special landscaping elements
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Generating solutions (i)
Study existing settlement patterns typical of specific environments to
see which appears to be the most successful, and try to emulate the
main features in new design.
Drawbacks:
 The similarity between environmental conditions in the existing and
planned settlements may not be sufficient.
 The modern adaptation may differ critically in some aspects from the
traditional solution.
 The existing traditional solutions may not encompass the whole
range of possible plans.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
10
Generating solutions (ii)
Analyze the processes occurring in urban regions to develop a model
capable of predicting conditions in any given environment.
Drawbacks:
 Unless the model is complete and accurate, conclusions may be
misleading.
 Modeling the microclimate does not generate architectural form…
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Application of computer modeling
Required:
A model to predict the air temperature at a given point in the urban
canopy layer with sufficient accuracy to be a useful practical tool for
use in simulation of building energy or thermal comfort.
 The model should be simple to use
 It should require only publicly available inputs: standard
weather data and a simple morphological description of site
The CAT model deals with the intra-urban variations in canopy air
temperature, at a spatial scale that is smaller than the resolution of
meso-scale models.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Canyon Air Temperature (CAT)
Generates climate data for a typical
meteorological year (TMY) at an
urban site, based on measured data
from a reference station (rural,
airport).
Erell & Williamson, 2006
T_base
T_urb
T_urb
=
T_base
T_met
T_met
Simulates urban effects on temperature,
humidity and wind in a street canyon,
accounting for:
• Building geometry
• Surface cover
• Anthropogenic heat
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Methodology: Model flow chart
INPUTS
SENSIBLE HEAT FROM CANYON SURFACES
view factors
TURBULENT MIXING
canyon geometry
SW (solar) radiation: dir, dif, reflected
thermal (buoyancy)
LW radiation: sky, terrestrial
mechanical (wind)
reference site
canyon site
anthropogenic heat
mixing coeff.
weather file
heat storage
anthropogenic heat
wind speed & convection
DBT PREDICTION
moisture availability (advection)
sensible heat flux
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Validation
reference
N
Kent Town BoM
View of Adelaide Centre and measurement sites
urban canyon
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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CAT model validation - Adelaide
BoM
urban
observed
predicted
Absolute minimum
5.6
7.3
7.3
Mean daily minimum
9.5
10.5
10.2
Monthly mean
13.0
14.6
14.6
Mean daily maximum
17.1
17.3
17.8
Absolute maximum
22.0
22.0
22.3
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
CAT simulation
results for May 2000
application
CAT model
albedo
density
development
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CAT model validation (ii)
heat island
7
y = 0.71x + 0.48
R2 = 0.70
predicted UHI (K)
6
5
Williamson Degree of
Confirmation (D) = 0.58
4
3
2
D=0
if model results are no
better than the trivial
estimate (Tcanyon = Tref)
D=1
if model results give a
perfect fit with measured
data
D<0
if model results are worse
than the trivial estimate
1
0
-1
-2
-2
-1
0
1
2
3
4
measured UHI (K)
5
6
7
cool island
Williamson, 1995
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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CAT validation (iii): Gothenburg
Wind data in input file suspect
Williamson Degree of Confirmation: 0.52
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
Application example (i):
Albedo
The effect of albedo
modification on outdoor
thermal comfort
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
development
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application
CAT model
albedo
density
development
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Previous research
“The use of reflective coatings could improve building comfort and reduce cooling energy use, and at city scale it could contribute to the reduction of the air temperature due to heat transfer phenomena and therefore improve outdoor thermal comfort and reduce the heat island.”
“Large‐scale increases in albedo could lower ambient air temperatures by 2°C.”
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Reflective surfaces have lower temperatures
Air temperature: 32oC
49oC
37oC
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Objective and methodology
Objective: To evaluate the effect of high‐albedo materials on thermal comfort in public open space in warm climates.
Method: Run the Canyon Air Temperature (CAT) model to obtain inputs for estimating thermal comfort using the Index of Thermal Stress (ITS).
 Surface albedo (road and walls): 0.2, 0.45, 0.7
 Canyon aspect ratio: 0.1, 0.5, 1, 2
 Canyon direction: N‐S, E‐W
 Geographic locations and climate: Eilat, Adelaide, Singapore, Gothenburg
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
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Index of Thermal Stress (ITS)
Biophysical model based on radiative and convective exchange between a person and the environment (Givoni, 1963; Pearlmutter et al, 2007)
Calculated as the evaporation rate (sweat), in terms of equivalent latent heat, which is required to maintain thermal equilibrium.
Evaporation = (Metabolism + Work) + Radiation + Convection
Thermal stress (in watts) is correlated with thermal sensation on a scale from ‘comfortable’ to ‘very hot’.
Updated correlations for outdoor conditions were obtained using field data for Sde Boqer. Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
23
Inputs from CAT (i): Air temperature
40
ref
0.20
0.45
0.70
Difference in DBT between reference and canyon
30
3
25
0.20
0.45
2
20
0.70
15
24
3
6
9
12
15
18
21
time of day
DBT in N‐S canyon with H/W=2, for surfaces with different albedos (0.2, 0.45, 0.7)
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 T (deg C)
DBT (deg C)
35
1
0
-1
-2
-3
6
9
12
time of day
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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18
application
CAT model
albedo
density
development
24
Inputs from CAT (ii): Wind speed and RH
3.0
met stn 10m
open 1m
N-S canyon 1m
Measured RH at weather station and predicted RH at urban sites
2.0
70
1.5
met stn
60
1.0
0.5
0.0
24
3
6
9
12
15
18
21
24
time of day
Measured wind speed at weather station and predicted wind speed at pedestrian height in open area and in N‐S canyon with H/W=2.
relative humidity (%)
wind speed (m/s)
2.5
urban
50
40
30
20
10
0
24
3
6
9
12
15
time of day
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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21
24
application
CAT model
albedo
density
development
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Inputs from CAT (III): Surface temperatures
Surface temperatures simulated by CAT used as input for calculating ITS: reference meteorological station (‘ground’) and N‐S canyon.
'met stn'
ground
360
0.20
road
350
wall1
340
wall2
330
air DBT
surface temperature (K)
surface temperature (K)
360
320
310
300
290
350
0.45
340
0.70
DBT
330
320
310
300
290
280
280
24
3
6
9
12
15
18
21
24
24
3
6
12
15
18
time of day
time of day
surfaces of N‐S canyon with albedo = 0.2
9
road surface of N‐S canyon
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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application
CAT model
albedo
density
development
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Effect of albedo on pedestrian heat stress (open space)
Open space simulated by CAT used as input for calculating ITS: ‘canyon’ with H/W=0.1, for surfaces with different albedos (0.2, 0.45, 0.7)
0.20
1000
0.45
heat stress (W)
800
0.70
600
400
200
0
-200
6
8
10
12
14
16
18
time of day
N‐S “canyon” with H/W=0.1, for surfaces with different albedos (0.2, 0.45, 0.7)
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
27
Effect of albedo on pedestrian heat stress (deep canyon)
Canyon environment simulated by CAT used as input for calculating ITS: canyon with H/W=2, for surfaces with different albedos (0.2, 0.45, 0.7)
0.20
1000
0.20
1000
0.45
800
0.70
heat stress (W)
heat stress (W)
800
0.45
600
400
200
600
400
200
0
0
-200
-200
6
8
10
12
14
16
18
0.70
6
8
12
14
time of day
time of day
N‐S canyon (H/W=2)
10
open space (H/W=0.1)
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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application
CAT model
albedo
density
development
28
Effect of canyon orientation on pedestrian heat stress
Canyon environment simulated by CAT used as input for calculating ITS: canyon with H/W=2, for surfaces with different albedos (0.2, 0.45, 0.7)
0.20
1000
0.20
1000
0.45
800
0.70
heat stress (W)
heat stress (W)
800
0.45
600
400
200
600
400
200
0
0
-200
-200
6
8
10
12
14
16
18
0.70
6
8
time of day
N‐S canyon
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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12
time of day
E‐W canyon
14
16
18
application
CAT model
albedo
density
development
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Breakdown of external fluxes on a pedestrian
SW (reflected)
1000
1000
SW (sun)
800
LW (sky)
LW (sky)
convection
convection
600
600
flux (W/m2)
flux (W/m2)
SW (sun)
LW (terrestrial)
LW (terrestrial)
800
SW (reflected)
400
200
400
200
0
0
-200
-200
600
800
1000
1200
1400
1600
1800
600
800
time of day
N‐S canyon with H/W=2, albedo=0.45 (walls and floor)
1000
1200
1400
1600
time of day
E‐W canyon with H/W=2, albedo=0.45 (walls and floor)
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
1800
application
CAT model
albedo
density
development
30
Effect of albedo on external (incoming*) fluxes on a
pedestrian
external fluxes (W/m2)
1000
800
600
SW reflected
SW sun
400
LW terrestrial
LW sky
convection
200
0
-200
0.20
0.45
0.70
surface albedo
N‐S canyon with H/W=2 at noon, for surfaces with different albedos (0.2, 0.45, 0.7)
* External fluxes do not include LW radiation given off by the person or latent heat loss by sweat. Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
31
Scenario testing
What if urban scale albedo modification reduced air temperature by 2K (as some models suggest)?
1000
800
heat stress (W)
N‐S canyon, H/W=2
-2K
Base case: ‐ reference DBT not modified
‐ albedo of canyon surfaces = 0.45
base
600
400
200
‘‐2K’ case: 0
‐ reference DBT reduced by 2K
‐ albedo of canyon surfaces = 0.7 -200
6
8
10
12
14
16
18
time of day
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
32
Sensitivity of heat stress to wind speed and DBT
noon in an open square (H/W = 0.1), assuming global horizontal flux of 900 wm‐2, diffuse solar radiation 200 Wm‐2, and surface albedo = 0.45. WARM-HUMID (Adelaide, Nov. 25) vapour pressure ‐ 24.6 mmHg
(equivalent to DBT=31oC and RH=65%). HOT‐DRY (Eilat, July 22)
vapour pressure ‐ 15.0 mmHg (equivalent to DBT=37oC and RH=11%).
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
33
ITS vs. PET
1120
y = 26.70x ‐ 604.89
R² = 0.98
960
Correlation between the Physiologically Equivalent Temperature ‐ PET (Hoppe, 1999) and ITS for a pedestrian standing in an open space with ground albedo of 0.2 and 0.7. ITS (Watts)
800
y = 26.41x ‐ 576.22
R² = 0.91
640
480
320
160
Simulated values for Eilat (July 22) and Adelaide (Nov. 25). 0
-160
0
20
40
60
80
PET (deg C)
Eilat
Adelaide
PET calculated using SOLWEIG1D (Lindberg et al, 2008)
http://www.gvc.gu.se/Forskning/klimat/stadsklimat/gucg/software/download Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
34
Conclusions

The reduction in air temperature from local‐scale application of high‐albedo materials may be modest

Any improvement in thermal comfort due to the reduction in long wave radiation from cooler surfaces is offset by an increase in reflected short wave radiation

The net effect is an increase in thermal stress

Studies on the effect of the UHI on thermal comfort should be based on realistic values of all (inter‐related) environmental parameters in the specific canyon being evaluated
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
Image: http://www.petergreenberg.com
Application example (ii):
Density
Impact on Pedestrian
Comfort and Building Energy
Efficiency of Increasing the
Height of Tel Aviv Buildings
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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application
CAT model
albedo
density
development
36
Seismic vulnerability
 Israel lies along the Dead Sea Transform,
an active rift which caused ten
earthquakes of magnitudes between 6 and
7.2 in the region in the last thousand years.
Images: http://www.eitanot.co.il
 Much of the residential housing was built
before seismic building codes were
enforced in 1980.
 National Guideline Plan 38 incentivizes
their structural reinforcement by offering
building additions, typically the addition of
several floors to existing 2-4 story
buildings.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
37
Research objectives
We know that building density affects
microclimate in cities:
 Urban heat island
 Reduced wind speed
 Changes to humidity
QUESTIONS:
How will addition of several floors to
existing buildings affect:
1.
2.
Pedestrian thermal comfort
Building energy consumption
Maximum intensity of the nocturnal UHI
(Oke, 1987)
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
38
Methodology
Three models are used to simulate these effects:
Canyon Air Temperature (CAT):
Models effects to microclimates
CAT output is used to generate ‘urbanized’ inputs for
Index of Thermal Stress (ITS):
ENERGYui:
Calculates pedestrian thermal stress
Simulates building energy requirements
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
39
Accounting for moisture and surface cover
29
Temperature differences between
Tel Aviv and Bet Dagan (reference)
July (oC)
Temperature (oC)
27
25
23
daily
max
daily
avg.
daily
min
21
IMS data
1.90
0.10
-1.60
19
CAT prediction
0.11
-0.06
-0.52
17
0
3
6
9
12
15
18
21
24
time of day (hours)
Bet Dagan met stn
Data: Israel Meteorological Service, 1995-2009
http://www.ims.gov.il/
Simulated surface cover effects
Bet Dagan is 7 km inland: It is cooler at night and hotter by day than Tel Aviv.
CAT under-estimates both trends.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
40
CAT simulation (i): Dry bulb temperature
Simulated temperature difference relative to met station
5
8 stories
∆T canyon (K)
4
5 stories
3
2 stories
2
1
0
‐1
0
3
6
9
12
15
18
21
24
time of day (hours)
Intra-urban temperature variation due to geometry is largely a nocturnal phenomenon.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
41
CAT simulation (ii): Wind Speed
Simulated wind speed at 1.5 m height in streets
with different building heights
1.4
met stn.
6
1.2
2 stories
5
1.0
5 stories
8 stories
4
0.8
3
0.6
2
0.4
1
0.2
0
0.0
24
3
6
9
12
15
18
21
24
canyon wind speed speed (m/s)
met stn wind speed (m/s)
7
time of day
Height increase from 2 to 5 floors reduces wind speed at street level substantially.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
42
Thermal stress
1
2
3
4
5
6
7
8
6006
500
480‐640
400
400
320‐480
hot
640‐800
3005
300
160‐320
200
warm
500
Thermal Stress (W)
Thermal Stress (W)
600
East-West canyon
200
100
0‐160100
0
<0
‐100
‐200
04
‐100
comfortable
Floors
North-South canyon
‐200
0
3
6
9
12
15
18
21
24
0
3
6
time of day (hours)
2 stories
4 stories
9
12
15
18
21
time of day (hours)
6 stories
2 stories
4 stories
6 stories
Adding floors reduces thermal stress in N-S streets, but improvement in E-W streets is minor.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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application
CAT model
albedo
density
development
43
Pedestrian energy flux
2 floors
8 floors
900
NorthSouth
canyon
flux (W/m2)
700
500
300
100
-100
900 600
800 1000 1200 1400 1600 1800 600
time of day
800 1000 1200 1400 1600 1800
time of day
EastWest
canyon
flux (W/m2)
700
500
300
100
-100
600
800
1000 1200 1400 1600 1800 600
800
1000 1200 1400 1600 1800
time of day
time of day
Convection
LW Sky
LW Terrestrial
SW Sky
SW Reflected
Daytime changes to air temperature due to adding floors have a negligible effect on thermal comfort
– but changes to radiant exchange are extremely important!
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
44
 Building thermal simulation
interface for EnergyPlus.
 Designed to aid in
compliance with Israeli
Standard 5282 (green
building).
street
canyon axis
ENERGYui
 Occupancy, internal loads
and HVAC set points (20oC
winter, 24oC summer) are
fixed.
 Shading by adjacent buildings of
equal height was modeled by
adding non-conditioned extensions
to the building
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
45
Building energy loads
Simulated Annual Energy Demand
(kWh/sq.m)
40
Heating
35
Cooling
30
25
Average annual HVAC
load in 7-stories
building [W/m2]
20
1st floor
16.6
Middle floors
23.5
Top floor
43.0
15
10
5
0
North-South 1
story
North-South 3
story
North-South 5
stories
North-South 7
stories
Number of floors
In spite of increased air temperature, adding floors actually reduces average A/C loads
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
46
Conclusions
The CAT model confirms that adding floors will increase air temperature (at
night), and will reduce wind speed, BUT:
 Pedestrian Thermal Comfort (ITS)  Increasing building height improves pedestrian conditions in N-S canyons
(and to a much lesser extent in E-W canyons).
 This is due to changes to the radiation balance (which counteracts
modest changes to air temperature and wind speed).
 Energy Efficiency (ENERGYui)  Increasing building height reduces the average energy demand for
acclimatization.
 This is largely due to an increase in the proportion of intermediate stories,
which are more efficient than the upper floor which is exposed directly to
the sun, as well as through mutual shading between buildings.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
47
Final comments

A recent paper by Yaghoobian and Kleisel (2012) suggests that high‐albedo pavements may increase cooling loads in summer (because reflected solar radiation offsets the reduction in sensible heat)

High‐albedo roofs are always desirable in warm climates!
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
48
Shading and air movement
Effective microclimate modification in small, well-defined urban spaces:
Raffles Hotel, Singapore
Clarke Quay, Singapore
7th Ave. Mall, Beer Sheva
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
49
Layered building facades
Arcades provide shade
(and protection from rain):
Israel (left), Portugal (above).
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
50
Challenges in modeling complex street cross-sections
basic street canyon
recessed colonnades
street with overhangs
street with pergolas
street with sidewalk trees
boulevard with center trees
Simulate each with respect to - air flow; temperature; thermal comfort; air quality; visual
comfort; acoustics… for different aspect ratios, wind speed and direction etc.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
51
A cascade of models at appropriate scales
global climate change
X
regional resolution
urban effects
 Spatial scales
street canyons
thermal comfort
 Time scales
 1-way vs. 2-way coupling?
buildings
 Processes (physical, chemical etc.)
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
application
CAT model
albedo
density
development
52
Final thoughts on computer modeling and simulation
 There is much to be learned from models of different kinds at different
scales (in time and space) – but care must be taken to avoid drawing
the wrong conclusions from inappropriate use of any particular model.
 Formulating the question appropriately is the first step
 Building energy simulation must take into account the effects of the
surrounding urban environment.
 The problem is complex, but the analysis needs to address all relevant
factors: Focusing on one, e.g. air temperature, risks erroneous
conclusions.
 How do atmospheric models link to models employed by other
disciplines (e.g. transport)?
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
53
Thank You
Prof. Evyatar Erell
Desert Architecture and Urban Planning,
The Jacob Blaustein Institutes for Desert Research,
Ben Gurion University of the Negev
Sde Boqer Campus, 8499000
ISRAEL
Tel: +972 8 6596878
E-mail: [email protected]
Website: www.bgu.ac.il/CDAUP/evyatar-erell.html
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
54
References and additional reading

Erell, E. and Williamson, T. (2006). Simulating air temperature in an urban street canyon in all
weather conditions using measured data at a reference meteorological station, International
Journal of Climatology, 26, 1671-1694.

Erell E., Soebarto V. and Williamson T. (2007). “Accounting for urban microclimate in computer
simulation of building energy performance”. In Wittkopf S. and Tan B. K. (Eds.) Sun, Wind and
Architecture, Proceedings of PLEA 2007, 24th International Conference on Passive and Low
Energy Architecture, Singapore, November 22-24, 2007, pp. 593-600.

Erell E. (2008). “The application of urban climate research in the design of cities”, Advances in
Building Energy Research, 2:95-121.

Erell E., Pearlmutter D. and Williamson T. (2010). Urban climate: Designing Spaces Between
Buildings. Earthscan/James & James Science Publishers, London, 266p.

Givoni B (1963). Estimation of the effect of climate on man — development of a new thermal
index. PhD thesis, Technion-Israel Institute of Technology.

Mills G., Cleugh H., Emmanuel R., Endlicher W., Erell E., McGranahan G., Ng E., Nickson A.,
Rosenthal J. and Steemer K. (2010). "Climate Information for Improved Planning and Management
of Mega Cities (needs perspective)". Procedia Environmental Sciences, 1:228-246.

Oke, T. R. (1987). Boundary Layer Climates. London & New York, Methuen.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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References and additional reading

Pearlmutter D., Shaviv E. and Berliner P. (2007). "Integrated modeling of pedestrian energy
exchange and thermal comfort in urban street canyons", Building & Environment, 42:2396-2409.

Pearlmutter, D., Dixin, J. and Garb, Y. (2011) “The index of thermal stress as a predictor of
subjective thermal sensation in a hot-arid urban environment,” Proceedings of the 19th International
Congress of Biometeorology, Auckland New Zealand, December 4-8, 2011.

Ritchey, Tom (2005). "Wicked Problems: Structuring Social Messes with Morphological Analysis“.
Swedish Morphological Society, www.swemorph.com.

Williamson, T. J. (1995)."A confirmation technique for thermal performance simulation models",
Building Simulation '95, Madison, Wisconsin, U.S.A.

Williamson T. and Erell E. (2008). “The Implications for Building Ventilation of the Spatial and
Temporal Variability of Air Temperature in the Urban Canopy Layer”. International Journal of
Ventilation, 7(1):23-35.

Williamson T.J., Erell E. and Soebarto V. (2009). "Assessing the error from failure to account for
urban microclimate in computer simulation of building energy performance". In Building Simulation
2009, Proceedings of the 11th International IBPSA Conference, Glasgow, Scotland, July 27-30,
2009, pp. 497-504.

Yezioro, A., Shapir, O. and Capeluto, G. (2011). A simple user interface for energy rating of
buildings. Proceedings of Building Simulation 2011, 12 IBPSA Conference, Sydney, 14-16 Nov.
2011, p. 1293-1298.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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‘wicked problems’
Ritchey, 2005
In social studies, a ‘wicked problem’ is a problem that is difficult or impossible to
solve because of incomplete, contradictory, and changing requirements that are
often difficult to recognize.
1. There is no definitive formulation of a wicked problem (defining wicked problems is itself a wicked
problem).
2. Wicked problems have no stopping rule.
3. Solutions to wicked problems are not true-or-false, but better or worse.
4. There is no immediate and no ultimate test of a solution to a wicked problem.
5. Every solution to a wicked problem is a "one-shot operation"; because there is no opportunity to
learn by trial and error, every attempt counts significantly.
6. Wicked problems do not have an enumerable (or an exhaustively describable) set of potential
solutions, nor is there a well-described set of permissible operations that may be incorporated into
the plan.
7. Every wicked problem is essentially unique.
8. Every wicked problem can be considered to be a symptom of another problem.
9. The existence of a discrepancy representing a wicked problem can be explained in numerous ways.
The choice of explanation determines the nature of the problem's resolution.
10. The planner has no right to be wrong (planners are liable for the consequences of the actions they
generate).
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
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Williamson degree of confirmation
Cs  U (m, v)  U (e, m)
U(m,v) is the Theil inequality factor between the measured
value and the trivial guess
U(e,m) is the Theil inequality factor between the estimated
value and the measured one
U (m, v)  U (e, m)
D
U (m, v)
The Williamson degree of confirmation (D) is the confirmation
factor Cs normalized by the likely magnitude of the error,
represented by the Theil inequality factor between the measured
values and the trivial guess.
Evyatar Erell, Ben‐Gurion University of the Negev (2013)
Williamson, 1995