The 6th International Conference on Sustainable Energy and Environment [Special Session: Urban Climate & Urban Air Pollution (UCUA)] 28-30 November 2016, Dusit Thani Bangkok Hotel, Thailand

1. 28-Nov-2016
Human thermal perception
and outdoor thermal comfort
under shaded conditions
in summer : A field study
in an institutional campus
The 6th International Conference on Sustainable Energy and Environment
Manat Srivanit1,* and Daranee Jareemit2
1, 2 Faculty of Architecture and Planning, Thammasat University
* Corresponding author, E-mail address: s.manat@gmail.com
Special Session: Urban Climate & Urban Air Pollution (UCUA)

2. CONTENTS
1. Background
2. Objectives
3. Methods in Outdoor Thermal
Comfort Study
 Micrometeorological
measurements and questionnaires
 Experimental design
 Thermal comfort index assessment
4. Results and Discussion
5. Conclusions
6. Recommendations
2

3. 1.BACKGROUND
 An institutional campus can be regarded
as a small city due to its large
educational buildings coverage,
population size, and various complex
activities, which may have serious direct
and indirect impacts on the
environment.
 Outdoor thermal conditions might affect
occupant’s thermal perception, who live
in these spaces. Therefore, one must
consider long-term thermal comfort
based on the thermal requirements and
characteristics of residents.
(Photo: Author, 2016)
3

4. (c) The monthly mean urban climatic variations during a
5-year period (from 2006 to 2010)
Source: Srivanit M. et al., 2013
Climatic conditions in the hot and humid tropical climate
of University campus
 During the summer, the highest mean monthly
of solar radiation was exceeded in April. These
large values of the average solar radiation and its
could affect a university campus’s environment
and quality of life.
4Source: http://solarchvision.com/?page_id=601
(d) Bangkok’s hourly solar direct radiation
(b) Sun path
in northern
hemisphere
(a) Components contributing to thermal comfort
Source: UC Berkeley Center for the Built Environment

5. 5
 How does the outdoor thermal
environment affect human thermal
comfort perception in university
campus?, And
 How do shading environments
influence on human thermal
comfort?
Understanding the characteristics of
outdoor microclimate environment and
the comfort implications for the people
using them opens up new possibilities
for the development of campus spaces.
Research questions:
5

6. The area of study:
 The study was conducted to
analyze the outdoor thermal
conditions on university campus in
Thammasat University’s Rangsit
Campus, which is located in the
suburb of Bangkok Metropolitan
Region (BMR). The campus
occupies 2.8 sq.km.
2.OBJECTIVES
(1) To determine whether their thermal comfort requirements
varied with two different environments (Outdoor and
Semi-outdoor conditions), and
(2) To examine the thermal effects of shading on outdoor and
semi-outdoor thermal comfort.
(Source: Jirawan Klaylee, 2016)
Geographical location: Lat. 14° 4.239´N, Long. 100°36.332´E 6

7. 7
(a) Micro-Climate
Measurements
(b) survey questionnaires
Air temperature
Air velocity
Humidity
Radiant temperature Thermal perception
Activity and clothing
insulation*
Psychological mechanisms
Experience
Expectation
Preferences
Thermal history
Socio-cultural
Transversal Method
(or True-experiments)
Human physiology
State of health
Step II. Input Conditions
& Field Survey
Calculation of thermal
comfort index
Contributing factors
RayMan
Model
Physiologically
equivalent
temperature
(PET)
Determination of
neutral and thermal
acceptable range
Recommendations
Examine the thermal
effects of shading on
outdoor and semi-
outdoor thermal
comfort
Food and drink
Body shape
Age and gender
Step III. Assessment of the thermal environment
Methods to determine mean
radiant temperature
(Using a globe thermometer)
Questionnaire design
(Structured
interviews)
Time periods of
field survey
(Summer season)
* ASHRAE 55, 2010. Thermal Environmental Conditions for Human Occupancy
Instrumentation set-up
(Including type of
equipment and accuracy)
Step I. Experimental design and Micrometeorological measurements
3. A general framework for a field study of outdoor thermal comfort
7
Time of day of survey
Geographic location
Fisheye-photo

8. Experimental design and Micrometeorological measurements
 What is human thermal comfort?
“Human thermal comfort as the state of
mind that expresses satisfaction with the
surrounding environment.”
Defined by ASHRAE (The American Society of Heating,
Refrigerating and Air Conditioning Engineers)
(i) Measurement scale for the subjective perception of
thermal environments
Thermal sensation
surveys were conducted
between April and May
2015, over 20 days of
sampling in summer
season. The data
collection was
conducted on the dates
with clear sky condition.
(a) (b) (c)
(ii) The field survey procedures included both physical
measurements and questionnaire surveys.
(a) The mobile microclimatic measurements setup, (b) research assistants conducting surveys, and (c) the sample of fisheye
photograph taken from the survey location can be calculated the sky view factor (SVF) by the RayMan model. (Source: Author, 2016) 8

9. 4. RESULTS AND DISCUSSION
Table 4-1 Summary of the respondents
 A total of 600 questionnaires were collected
both in the outdoor (28.83%) and semi-
outdoor (71.17%) spaces during the survey.
 Most of the responses (74.67%) were clustered
on the warm side of the scale (TSV > 0).
 The majority of the respondents (100%) stayed
under trees or buildings shaded and cloudy
shade conditions
0
20
40
60
80
100
120
140
160
180
-3 (Cold) -2 (Cool) -1 (Slightly
cool)
0 (Neutral) +1 (Slightly
warm)
+2 (Warm) +3 (Hot)
Frequency
Outdoor
Semi-outdoor
0
50
100
150
200
250
Comfortable Slight
uncomfortable
Uncomfortable Very
uncomfortable
Extremely
uncomfortable
Frequency
Outdoor
Semi-outdoor
(a) Distribution of thermal sensation votes
(b) Overall comfort votes in the both spaces
Physiological Factors
All
(n=600)
Outdoor
(n=173)
Semi-outdoor
(n=427)
Age (year) Avg. 34.07 34.62 33.84
Std.D. 3.52 2.24 3.90
Weight (kg.) Avg. 57.92 58.77 57.58
Std.D. 11.91 12.65 11.58
Height (cm.) Avg. 165.32 166.35 164.90
Std.D. 7.93 8.54 7.63
Body mass index
(BMI) (kg m-2)
Avg. 21.08 21.09 21.08
Std.D. 3.38 3.38 3.38
Clothing (Clo)
Avg. 0.54 0.43 0.59
Std.D. 0.32 0.23 0.33
9
(4.1) Questionnaire data

10. (4.2) Thermal acceptability and thermal sensation vote
 The large percentage of “hot” votes made the summer season, the most
uncomfortable with a rate of 81.50% and 79.63% for outdoor and semi-outdoor
environments respectively.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
-3 (Cold) -2 (Cool) -1 (Slightly
cool)
0 (Neutral) +1 (Slightly
warm)
+2 (Warm) +3 (Hot)
Percentageofthermalperceptionvote(%)
(a) Outdoor
Comfortable Slight uncomfortable
Uncomfortable Very uncomfortable
Extremely uncomfortable
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
-3 (Cold) -2 (Cool) -1 (Slightly
cool)
0 (Neutral) +1 (Slightly
warm)
+2 (Warm) +3 (Hot)Percentageofthermalperceptionvote(%)
(b)Semi-outdoor
Comfortable Slight uncomfortable
Uncomfortable Very uncomfortable
Extremely uncomfortable
10

11. y = 0.1508x - 3.7797
R² = 0.8043
y = 0.1263x - 3.3368
R² = 0.739
-3
-2
-1
0
1
2
3
15 20 25 30 35 40 45 50
MTSVs
PET (Celsius)
Outdoor (n=173)
Semi-outdoor (n=427)
The neutral temperature of
outdoor environments is slightly
lower than semi-outdoor
environments with a difference
of 1.36 °C.
Environments Simple linear regression
Neutral temperature
(°C PET) (MTSVs=0)
1. Outdoor MTSVsOutdoor= 0.1508PET – 3.7797 25.06
2. Semi-outdoor MTSVsSemi-outdoor= 0.1263PET – 3.3368 26.42
(4.3) Thermal sensation and neutral temperature
11
Table 4-2 Comparing the neutral temperature in difference spaces
Where: PET = Physiological Equivalent Temperature (°C), and MTSVs = Mean thermal sensation votes

12.  The results found that the upper
boundary is obtained at 35.2 °C PET for
outdoor environments and 37.3 °C PET
for semi-outdoor environments.
 It indicates that the respondents, who
stay in outdoor environments, are
psychologically intolerant against the
summer conditions more than those
living in semi-outdoor environments.
y = 0.2593x2 - 12.842x + 150.76
R² = 0.8144
y = 0.2084x2 - 12.407x + 192.74
R² = 0.486
0
10
20
30
40
50
60
70
80
90
100
10 15 20 25 30 35 40 45 50
Percentageofthermalunacceptable(%)
PET (Celsius)
Outdoor (n=173)
Semi-outdoor (n=427)
Environments
Thermal neutrality (°C PET) Thermal
acceptable
ranges *
(°C PET)
Thermal
uncomfortable
rages
(°C PET)
Simple linear
regression
Quadratic
polynomial
Differential
1. Outdoor 25.06 24.77 -0.29 14.33-35.20
(range=20.87)
<14.33 and
>35.20
2. Semi-outdoor 26.42 29.76 +3.34 22.20-37.33
(range=15.13)
<22.20 and
>37.33
(4.4) Comparing linear regressions of thermal sensation and thermal acceptable
ranges for the respondents voted in different environments
Table 4-3 Comparing linear regressions of thermal sensation and thermal acceptable ranges
Remark: * ASHRAE Standard 55 corresponded with minimum standard of 80% acceptability (or 20% unacceptability)
12
20% Unacceptability Line

13. City/ Country Location
climate classification a
Neutral
temperature
[◦C PET]
Upper limit
of neutral
temperature
[◦C PET]
Climate Group
Rome, Italy
(F. Salata et al., 2016)
41.5◦N,
12.3◦E
Mediterranean Csa 26.9 29.2
c
Cairo, Egypt
(A.H.A. Mahmoud, 2011)
31.0◦N,
31.3◦E
Hot desert BWh 27.04 30.0
c
Guangzhou, southeastern China*
(K. Li et al., 2016)
23.1◦N,
113.3◦E
Humid subtropical Cfa n.a. 34.03
b
Taiwan
(T.P. Lin and A. Matzarakis, 2008)
24.1◦N,
120.7◦E
Humid subtropical Cwa 25.6 35.4
b
Hong Kong, China
(V. Cheng et al., 2012)
22.3◦N,
114.2◦E
Humid subtropical Cwa 25.0 32.0
Thammasat University Rangsit
Campus** [present study]
14.1° N,
100.6° E
Tropical wet and dry Aw 25.1 35.2
b
Singapore, Singapore*
(W. Yang, N.H. Wong, S.K, 2013)
1.4° N,
103.8° E
Tropical rainforest Af 26.5 31.7
Sydney, Australia
(J. Spagnolo & R. de Dear, 2013)
33.9◦S,
151.2◦E
Humid subtropical Cfa 22.9 n.a.
Remark: * whole year survey, ** under shaded conditions,
a Köppen climate classification
b by assuming the ASHRAE Standard 55 corresponded with minimum standard of 80% acceptability (or 20% unacceptability)
c by assuming the comfort range was the interval +0.5 of the ASHRAE 7-point scale
Table 4-4 The neutral PET and comfort ranges of summer in other studies.
13

14. (4.5) Examine the thermal effects of shading on outdoor and
semi-outdoor thermal comfort
PET(Celsius) Shaded Conditions
the upper acceptability limit of outdoor
the upper acceptability limit of semi-outdoor
the neutral temperature of outdoor
the neutral temperature of semi-outdoor
25.06
26.42
35.20
37.33
AirTemperature(Celsius)
Shaded Conditions
MeanRadiantTemperature(Celsius)
Shaded Conditions
(a) (b)
Different conditions of shade categorized
The label represent:
(1) tree shade
(2) building shade
(3) both tree and building
shade
(4) cloudy shade
 It is found that occupants living in
semi-outdoor environments for all
shade characteristics are satisfied
their environment, which the PET
values are within the thermal
acceptable range with the upper
acceptability limit of 37.3 °C.
 Some of occupants living under
tree shades and both tree and
building shades for outdoor
environment feel slightly hot.
14

15. 5. CONCLUSIONS
 The neutral temperature is 25.06 °C and 26.42 °C PET for outdoor and
semi-outdoor environments, respectively. The neutral temperature of
outdoor environments is slightly lower than semi-outdoor environments
with a difference of 1.36 °C and the results indicated that occupants of
semi-outdoor environment was more tolerant regarding thermal comfort
than occupants of outdoor environments.
 The acceptable range of thermal comfort for respondents living in semi-
outdoor environment is from 22.2-37.3 °C PET, which is higher than the
range of 14.3-35.2 °C PET for the occupants living in outdoor environment.
The results indicates that the acceptable range of outdoor context wider
than the semi-outdoor context due to different expectation and this
contradiction could be due to the method of calculating the acceptable
temperature range. Another reason for the contradiction could be due to
the special tropical climate context of outdoor. Thus, it is reasonable to
find big differences among the semi-outdoor and outdoor conditions in
terms of acceptable temperature range for tropical climate.
15

16. 6. RECOMMENDATIONS
 The calculated PET values for each shading environment
varies, which were influenced by local air temperature and
mean radiant temperature. Shading is the key strategy for
promoting outdoor thermal comfort in tropics because it
leads to a reduction of air temperature and mean radiant
temperature and hence to a cooler thermal sensation.
 Therefore, in a hot-humid tropical region such as Thailand ,
the configuration of buildings in relation to the sun or
shadow is important, as is the strategic placement of
elements that provide shade, such as planting and street and
garden furniture, and applied with sunshine eliminating
design strategies can effectively increase occupant thermal
comfort and further increase their utilization rate of these
spaces in the summer. 16

17. (a) Sun path of Bangkok, Thailand
Influencing sun and
shade in tropical northern
hemisphere
(b) Shadow diagram of a cubic form measuring 3x3x3m (XYZ)
17
(a) Summer solstice [20 June]
(c) Equinox [21 March and 23 September]
(b) Perpendicular position [26 April and 16 August]
(d) Winter solstice [22 December]
Note: Shadows are calculate for a location at Bangkok, Thailand in SketchUp (Latitude 13.7563° N, Longitude 100.5018° E).
(Source: Author, 2016)

18. Dimensions and spacing of buildings affect outdoor thermal environment
by shading back into space at different hours
18
Summer solstice (20 June)
Equinox (21 March and 23 September)
Perpendicular position (26 April and 16 August)
Winter solstice(22 December)
Note: Shadows are calculate for a location at Bangkok, Thailand in SketchUp (Latitude 13.7563° N, Longitude 100.5018° E).
(a) N-S axis: H/W=1.0 (b) NE-SW axis: H/W=1.0
(Source: Author, 2016)

19. 19
Shading Design Options to Improve Outdoor Thermal Comfort
Implementation of shading design such as passways, arcades, and activity spaces for the student
Trees and other plants help cool the environment by providing shade and through evapotranspiration
19

20. 20
Artificial shading facilities can also create a good shading effect
20

21. END
Thank you for your
attention.
The 6th International Conference on Sustainable Energy and Environment
Special Session: Urban Climate & Urban Air Pollution (UCUA)
Organizers:
28-30 November 2016, Dusit Thani Bangkok Hotel, Thailand.