Modelling the urban microclimate effects of street configurations on thermal environment in the residential townhouseof bangkok

Presentation of the 1st International Conference on Recent Advances in Science and Technology - Kuala Lumpur - Malaysia during 20-22 Feb. 2019

1. ICORAST-1308
Modelling the Urban Microclimate
Effects of Street Configurations
on Thermal Environment
in the Residential Townhouse
of Bangkok, Thailand
International Congress on Recent Advances in Sciences and Technology
Manat Srivanit
1,*
and Daranee Jareemit
2
1, 2
Faculty of Architecture and Planning, Thammasat University
* Corresponding author, E-mail address: [email protected]
ICORAST2019: Feb. 20-22, 2019 Kuala Lumpur, Malaysia

2. OUTLINE
1.Introduction
2.Objective
3.Material and method
Conceptual framework
Case study
Methodological framework
Experimental design
4.Result
5.Conclusion
6.Recommendation
2

3. 1. INTRODUCTION
3
Bangkok, the capital of Thailand, is in a hot
and humid region. Most people in several
parts of the country move into Bangkok to
find better work and living quality.
People suffer from hot and extreme
outside air condition as a result they prefer
and spend most of their time indoor
especially during the hot summer.
(a) Variation in yearly mean temperature
in large Asian cities
(b) Effect of
urbanization on
Land-Surface
Temperature (LST)
(Kataoka et al., 2009)
(Estoque et al., 2017)

4. 4
Bangkok's recent growth has occurred outside
the city, in suburban (and exurban) areas.
Between 2000 and 2010, the city grew by 30%,
while the suburban provinces grew more than
twice as quickly, at 66%. The city's population
growth was 1.9 million, while the suburban
provinces added 2.5 million population.
The expansion of Bangkok, 1850–2002 (Angel et al., 2011)
http://www.newgeography.com

5. The location of townhouse
development projects are typically
found in the north of Bangkok
which the location have good road
infrastructure and are located
along the national railway line in
the Rangsit area. (Thaitakoo &
Takeuchi, 2018)
Rangsit Area
(Modified from http://www.as-p.com/projects/project/zukunftsstudie-bangkok-21-91/show/)
5
(Agency for Real Estate Affairs, 2018)
Townhouse market which make 32% of the
remaining supply, grow by 14%
•35,456 Newly launched units in 2017,
increased by 14% from last year
•62,571 Remaining units in 2017,
increased by 15% from last year
•27,547 Sold units in 2017,
increased by 14% from last year
Market trends by house types in 2017
Typical townhouses in Rangsit area

6. The average long-term meteorological data for RangsitArea*
(b) Maximum temperatures(a) Average temperatures and precipitation
(c) April will be the year’s hottest month, with a summer perpendicular position on April 26 of Thailand
6
Source: APICHART JINAKUL
Remark: * Thai Meteorological Department (TMD) at PathumThaniStation (14.116 °N, 100.621 °E)
Source: http://www.bangkokpost.com

7. 2. OBJECTIVE
This study aims investigating the design of residential
townhouse configurations, which promotes more
outdoor thermal comfort in Bangkok city.
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Study area and climate conditions
The suburban of Bangkok in the Rangsitarea (a city in
PathumThaniProvince) was selected as a specific case of
this study.
Townhouse configurations are performed via using an
urban microclimatic simulation model (ENVI-met Model),
which run for a summer perpendicular position on April 26
in hot-humid climate of Thailand.

8. 3. RESEARCH METHODOLOGY
8
Townhouse form and design
configurations
Street canyon orientation
Aspect ratio or H/W ratio
Urban
microclimatic
simulation
model
Investigate the effect of
street configurations on
thermal environment
Understanding the
characteristics of outdoor
thermal environment and
comfort implications for the
development of townhouse
design.
Building Control Act
B.E. 2522 (A.D. 1979)
of Thailand
3.1 Conceptual Framework
Gives suggestions for urban planners
and policy makers to improve urban
thermal environment
Input
Output
Outcome
Feedback Findings
Summer perpendicular
position on April
Climatic Conditions

9. 3.2 Case Study
Mobile microclimate instruments >
Model domain (yellow outline) Street canyon and pedestrian zones
Fisheye lens image and SVF of the measurement location
diagram showing the shading position of a cubic 3x3x3m (XYZ) at different
times for a perpendicular position on April 26.9
Based on the Building Control Act,
B.E. 2522 (A.D. 1979) of Thailand,
typical townhouses in Thailand has
following qualifications;
1 –4 stories,
a block of townhouses width
not over 40 meters and 16
meters long,
minimum width and length per
unit being 4 and 24 meters,
respectively,
minimum open space being
30% of land size, and
set back in the front and back of
building being 3 and 2 meters,
respectively.

10. 10
3.3 Methodological
framework
Parameter
settings
Model geometry
setting
ENVI-met output (Simulated)
Model verification
(Regression analysis)
•Air temperature (Ta)
•Relative humidity (RH)
•Globe temperature (TG)
•Wind velocity (Va)
•Fisheye lens image
Estimated mean radiant
temperature (MRT) using a
black-globe thermometer
method
Reliable the ENVI-met model
that accurately represents
the on-site environment
Parameterization of thermal
condition by Tmrt
Identify the most suitable
configurations within the
townhouse street
Measured mean radiant
temperature (Measured Tmrt)
•Air temperature
•Relative humidity
•Wind speed and direction
•Sky-view factor (SVF)
•Mean radiant temperature
(Simulated Tmrt)
Sky-view factor (SVF)
Knowledge on the effects of townhouse configurations and gives suggestions
for urban planners and policy makers to improve urban thermal environment
RayMan
Model
ENVI-met Model
Input
On-site measurement
Apr 26
th
, 2016
Yes
No
Model adjustment
Output
Schemes of the
townhouse configurations
Input
Outcome
•Street canyon orientation
•Aspect ratio or H/W ratio

11. Schemes of the simulated townhouse’s street
configurations
(a)Streetcanyonorientation
(b) Aspect ratio of building height and street width (H/W ratio)
3.4 ENVI-met model validation and design scenarios
Model validation is required for simulation
analysis to affirm the reliable of model
setting in a hot summer (April 26, 2016).
Table:Verified ENVI-met model simulation settings
Size of grid cells 2×2×3 m
Number of grid cells 129×129×30
Nesting grids 25
Soil profiles in nesting gridsLoamy soil (LO)
Initial temperature of
atmosphere
34°C
Air temperature and relative
humidity
Hourly data within a
24h cycle in April
Wind speed and direction
(degree) (0=from North)
5.3 m/s (180 degree)
Roughness length at reference0.01
Specific humidity in 2500m7 g/kg
Solar adjustment factor 1.0
Cloud cover 0 oct.
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Example of street canyon of base case (H/W = 0.9)

12. (a) (b)
Street canyon and pedestrian zones of
measurements (red outline)
Simulated of MRT values across
N-E street orientation with H/W=1.1
Example of the ENVI-Met simulation result
pedestrian zone
Left
12

13. 4. RESULTS
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Examples of (a) the simulated MRT at a street crayon of N-S orientations with H/W = 1.1,
and (b) Box-plot distributions of hourly MRT in street canyon of a 16 street configurations
for a perpendicular position on April 26.
(a) (b)
A B
A B

14. Fig . Distribution of MRT at street and pedestrian paths of four orientations.
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15. 5. CONCLUSIONS
Street canyon orientation and increasing aspect ratio significantly
improve thermal condition in street canyon, except E-W orientation.
In this study, locating street canyon in N-S orientation with aspect
ratio of 0.9 provides lower mean radiant temperature than other
configurationswhile E-W oriented canyon has a critical situation.
Even though the aspect ratio is increased to 1.1, the mean radiant
temperature rarely reduces.
The thermal condition in street canyons oriented NW-SE and NE-SW
have the same performance.
The right pedestrian path typically has higher thermal condition than
those in the left path since it exposes to the maximum amplitude of
solar radiation.
15

16. 6. RECOMMENDATIONS
To mitigate the critical thermal condition in E-W oriented
canyons (or uncomfortable solar orientation),
implementation of more techniques should be investigated.
Furthermore, it’s could determine the best uses for a
townhouse street according to its diurnal thermal behavior
in different periods during the year for further tests.
In addition, streets are paved and fully lacking of shading
elements, which increase thermal stress in summer. Thus,
sunshine eliminating design strategies can effectively
increase outdoor thermal comfort.
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17. Sunshine eliminating design strategies in street canyon
Note: All schematic street configurations of aspect ratio with the same for H/W ratio = 1.0
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18. END
Thank you for your attention
Q&A
International Congress on Recent Advances in Sciences and Technology
ICORAST2019: Feb. 20-22, 2019 Kuala Lumpur, Malaysia