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PASSIVE DESIGN SEEN FROM SPATIAL OPENNESS AND AIRFLOW IN

CONTEMPORARY TUBE HOUSES OF HO CHI MINH CITY, VIETNAM

Article in Journal of Architecture and Planning (Transactions of AIJ) · April 2023

DOI: 10.3130/aija.88.1249

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 日本建築学会計画系論文集 第88巻 第806号, 1249-1258，2023年4月
【カテゴリーⅠ】 J. Archit. Plann., AIJ, Vol. 88, No. 806, 1249-1258, Apr., 2023
DOI https://doi.org/10.3130/aija.88.1249

PASSIVE DESIGN SEEN FROM SPATIAL OPENNESS AND AIRFLOW

INPASSIVE DESIGN SEEN
CONTEMPORARY TUBEFROM SPATIAL
HOUSES OF HOOPENNESS
CHI MINHAND AIRFLOW
CITY, VIETNAM
IN CONTEMPORARY TUBE HOUSES OF HO CHI MINH CITY, VIETNAM
ベトナム・ホーチミンの現代のチューブハウスにおける空間の開放性と風環境からみたパッシブデザイン
ベトナム・ホーチミンの現代のチューブハウスにおける空間の開放性と風環境からみたパッシブデザイン

Yen Khang NGUYEN TRAN, Mizuho UEYAMA, Ryo MURATA

Yen Khang NGUYEN TRAN ＊1, Mizuho UEYAMA ＊2 and Ryo MURATA ＊3

グェン トラン イェン カン ，上山 瑞穂 ，村田 涼

*1 *2 *3
グェン トランイェン カン，上 山 瑞 穂，村 田 涼

This study aims to shed light on the correlation between spatial composition and indoor airflow as a passive design used
in contemporary tube houses in Ho Chi Minh City (HCMC), Vietnam. In this constraint housing typology due to rapid
urbanization, the study clarifies patterns of the living room and bedroom for their architectural and environmental
characteristics such as room placement, spatial openness, airflow area and wind path. By revealing variable combinations
between spatial openness and airflow in terms of rooms pattern and houses pattern, the finding clarifies diverse design
methods responding to the environment in the contemporary tropical city.

Keywords: Spatial Composition, Openness, Wind environment, Tube House, Passive Design, Ho Chi Minh City
空間構成、開放性、風環境、チューブハウス、パッシブデザイン、ホーチミン

1. Introduction to the architecture of public buildings and institutions but also

1.1 Background and purpose evolved, transformed and continuously reinvented to be a part of
In the hot and humid climate of Vietnam, climate-responsive the urban housing design in this cityiii). Among all the typologies of
building solutions, routed in the way of the culture characterized urban housing in HCMC, the tube house is a fascinating example
by strong community connections and traditional lifestyles close of street houses, which existed since the 15th century and has
to nature, are essential. Although heavily influenced by different been retrofitted to adapt to different periods of urban development
cultures, transformations and adaptations through several periods since the Doi Moi policy in 1986. However, despite being the most
of colonization, the spatial planning of Vietnamese housing has popular type of housing in HCMCiv), the contemporary tube house
always tried to keep its unique traits. These are the characteristics is a challenge for architects in terms of preserving a comfortable
of open structure, the organic connection to the natural environment for urban dwellers and reducing energy consumption.
environment and the capacity for self-adaptation to the climate Hence, this context of high urban density and high impact of heat
conditions . Recently, these unique characteristics are going under
i)
islands in HCMC intrigue interest to understand the contribution
constant modification in the urban situation of Ho Chi Minh of housing design to enhancing the living condition of urban
City (HCMC), the densest city in Vietnam and one of the largest dwellers. This study aims to investigate how the design of tube
urban metropolis in Southeast Asia. As a recently developed houses in the contemporary era, with its unique characteristic of
metropolis, with fast-constructed urbanization via the economic spatial composition, could provide alternative solutions using the
boom with waves of scholars returned from abroad, HCMC has climate-responsive approach.
fostered its own architectural identity. The identity inspired by Besides, in the previous research on contemporary Vietnamese
modernism features an interplay of voids and enclosures that houses4), the authors investigated the light and wind environment
provides composite articulation for louvers and porosity blocks on of living spaces. The previous results clarify their composite
the building facades . These spatial compositions belong not only
ii)
characteristics of space and environment. However, how the

*1 ＊Assist.
1 Prof.,
Assist. Dept.Dept.
Prof., of Architecture Design,Design,
of Architecture ShimaneShimane
University, Dr. Eng.
University, *1 島根大学総合理工学部
島根大学 総合理工学部 建築デザイン学科
建築デザイン学科 助教・博士 ( 工学 )
助教・博士（工学）
Dr. Eng.
*2 Tohata architects & engineers, M.Eng. *2 東畑建築事務所・ 修士 ( 工学 )
＊2
Tohata architects & engineers, M.Eng. 東畑建築事務所 修士（工学）
*3 ＊Assoc. Prof., Dept. of Architecture, Tokyo Institute of Technology, Dr. Eng. *3 東京工業大学 環境・社会理工学院 建築学系 准教授・博士 ( 工学 )
3
Assoc. Prof., Dept. of Architecture, Tokyo Institute of Technology, 東京工業大学 環境・社会理工学院 建築学系 准教授・博士（工学）
Dr. Eng.

— 1249 —
composite characteristics of these environmental factors might in spatial composition as a part of the climate-responsive design
vary in different living spaces of the housing planning, such in the tropical climate. As lessons learned from the vernacular
as the bedrooms and living rooms with different time usage architecture, Dahniar12) studied the composition of open
and environmental conditions are not clarified yet. Also, for veranda during different historical periods as a climatic control
contemporary urban houses like the tube house, the passive device maintaining social life and identity of Indonesia’s social
design strategy is a challenge to be considered within the living interactions. Ichikawa13) was interested in the layout of the
condition of HCMC. Further, the outcome could contribute to the terraces as an extended semi-outdoor space between houses in the
design of contemporary tube house typology and offer different dense village of the Philippines for social gatherings and private
approaches to integrating passive solutions that enhance the uses with taking advantage of the natural wind flow. Le14) studied
dwelling environment in Vietnam. the flexibility and potential for expansion of the building envelope
1.2 Past studies and relevancy from traditional street houses to high-rise apartments, focusing
For the analysis methods focusing on passive design in detached on ensuring natural ventilation for cooling in Vietnam. These
houses seen from spatial composition, in addition to the continuity previous researches contributed to the quest to apply the passive
of previous research on contemporary Vietnamese houses4), the design strategy to building elements for contemporary housing in
following authors’ past studies mainly provide a base used in the tropical climate.
this research. Matsumoto5) clarified the intentionality towards By considering the above methods and positioning this study
environmental design in Yoshimura’s housing works through the from the past studies, this research clarifies the combinational
interpretations of spatial composition as a thermal and airflow characteristics of space and environment by simulating the indoor
design. Fujiwara highlighted the integrations and confrontations
6)
airflow of the rooms with different functions and investigating
inherent in the window composition of the seaward villas. These how these spaces are open to the outdoors in the contemporary
researches give significant references for the analysis methods in tube houses which is a critical urban house typology in Vietnam.
this study, especially for the opening ratio and wind path. Besides, The findings from this study would provide helpful insights for
concerning past research on Vietnamese tube houses, researchers future practices to improve urban housing. Further, the outcome
developed several directions considering the typology, spatial will contribute to finding solutions to enhance the quality of living
organization and environmental assessment. Firstly, the focus was according to sustainable design trends, especially in tropical cities.
to determine the conservation requirements for the traditional
typology of Vietnamese architecture, such as the study from 2. Methodology
To . Secondly, several studies focused on comparing traditional
7)
2.1 The environmental condition of HCMC
and modern typologies. To8) clarified the transformation of the The environment of HCMC is characterized by a tropical climate
traditional type to the modern type under the influence of rapid with key features such as high temperature, high humidity
urbanization after the 1986 Reform. Nguyen9) analyzed a large and long sunlight hours across most time of the year (see
sample of tube houses via different urban development periods Fig.1). Besides, the rapid urban expansion and the influence of
to determine the Isovist of green space ratio within the change in climate change are accelerating the vulnerability of the living
structure and organization. Thirdly, according to the recent rise condition of urban dwellings, resulting in an unsatisfactory
of interest in reducing energy consumption in housing design, indoor environment and increasing the use of air conditioning
there was a new wave of research on sustainable design strategies by households to reduce discomfort during the hottest month.
to understand the tendency of reinventing tube house typology. Considering these data, the simulation conducted in the following
For instance, Nguyen10) focused on improving energy efficiency in chapters of this research is set in April, which is at the end of the
tube houses via a survey on occupants’ awareness. While Dang 11)
dry seasons, coinciding with the period of highest temperature
took another approach through the comfort perception of urban and long sunlight hours while the precipitation stays among the
dwellers based on the simultaneous influences of temperature and lowest and wind speed is average with high humidity. In addition,
airflow by combining questionnaires and on-site measurements to reports on the use of air conditioning during this month stand at
justify the acceptable rate of wind velocity to enhance the indoor the highest during the period of daily activitiesv).
environment. Despite these previous researches contributing 2.2 Case studies of contemporary tube house in HCMC
to clarifying the diverse fields covering the broad topics of Tube houses are traditionally known as the urban townhouse,
Vietnamese tube houses, the relationships in the spatial and which evolved from the rural housing type into an indigenous
environmental characteristics through a scientific approach have urban context, initially with a narrow front for shops vi) and
not been investigated yet. the houses expanded longitudinally to accommodate housing
Also, on a broader scale of adaptation from the traditional to functions inside the street block. After the Reform in 1986,
modern housing design in Asia, several researchers are interested tube houses became the most dominant type in the urban

— 1250 —
 35 350
area due to their low-cost construction that can adapt to rapid

30 300
urbanizationvii), the influence of western living standards and a

25 250
recent rise in awareness of building design incorporated the idea
Temperature /

of sustainability. The tube house's features are characterized by

Wind speed

Humidity /
Sunlight /

200

Rainfall
20

15 150 a long and narrow form and segmented arrangement, usually

10 100 built on one to two storeys above ground with several voids across

5 50
the length of the building to maximize the porosity and provide

0 0 enough natural light and airflow for all the rooms. However,
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
since the mass production of tube houses between 1999-2009,
Avg. rainfall(mm) Avg.Humidity(%) Avg. Wind speed(m/s)
Average Temperature() Average Sunlight Hours/Day land coverage in HCMC can go up to 80-100% in a residential
*Source https://www.weather-atlas.com/en/vietnam/ho-chi-minh-city-climate neighbourhood of core districtsviii) and the original features also
*Data are collected from average temperature, average rainfall, average
humidity, average wind speed, average daylight/ sunshine hours and combined. transformed with more storeys and shorter lengths due to the
Fig.1 Climate condition of Ho Chi Minh city packed urban settings. These conditions make it extremely
Tab.1 List of case studies
No. House Year Architect Status difficult to ensure a comfortable environment for all rooms and
1 White House 2010 H.a a affect the dwellers' living conditions. Based on this context,
2 NA House 2011 Nature Arch Studio a
VTN Architects, SDA, this study analyses the tube houses designed after the mass
3 Stacking green 2011 a+b
NISHIZAWAARCHITECTS
4
production period, focusing on the relationship between airflow
Anh House 2013 S+Na Architects b

5
VTN Architects, SDA,
a+b
and spatial openness. Forty-seven case studies are selected from
Binh Thanh House 2013
NISHIZAWAARCHITECTS
6 Folding Wall House 2013 Nha Dan Architects a the architectural medium as the contemporary tube houses in
7 3×10 House 2014 DD concept a
HCMCix). They are built from 2010 onward (Tab.1), having three
8 B House 2014 i.House Archi. & Cons. a
9 The Gills 2014 Cong Sinh Architects a to six stories above ground, a depth-to-length ratio of two or more
10 Thong House 2014 NISHIZAWAARCHITECTS b
and only the narrow side of the house facing the road.
11 Vegan House 2014 Block Architects a
12 Breeze House 2015 Mel Schenck b 2.3 Structure of the analysis
13 HEM House 2015 Sanuki Daisuke Architects (SDA) b
14 House 304 2015 KIENTRUC O a
The analysis is structured in three steps corresponding to
15 Kaleidoscope 2015 Cong Sinh Architects a chapters 3, 4 and 5. Firstly, chapter 3 focuses on the space where
16 Micro Town House 4×8m 2015 MM++ Architects a+b
17 Saigon House 2015 a21 studio a the main activities of urban dwellers occur during the daytime
Townhouse with a and nighttime. The analysis extracts living rooms and bedrooms
18 2015 MM++ Architects a+b
Folding-up Shutter
19 Wasp House 2015 Tropical Space a in each case study as the targeted functional room. It examines
20 Bamboo House 2016 VTN Architects a how to open up these spaces to the outdoor environment in terms
21 Lee&Tee House 2016 Block Architects a
22 Nha Cua Tien 2016 23o5 Studio a of spatial composition via examination of room placement and
23 Quiin House 2016 23o5 Studio a spatial openness. Secondly, chapter 4 analyzes the potential of
24 Zen House 2016 H.a a
wind path and continuity of air movement within these rooms
25 / House 2017 Time Architects a
26 // House 2017 Time Architects a by using the simulations of indoor airflow during the dry season.
27 Backyard House 2017 AD+studio a
Finally, chapter 5 illustrates the variations of combinational
28 D House 2017 KIENTRUC O a
29 Giabinh.House 2018 AD9 Architects a patterns of spatial composition and airflow in each room.
30 House for a Daughter 2018 Khuon Studio a Further, the intentionality toward the passive design of each
31 Lantern House 2018 atelier NgNg a
32 Lien Thong House 2018 6717 Studio
house inheriting the spatial openness and tendencies of airflow is
a
33 The Rough House 2018 NELO DÉCOR a clarified. These analysis methods are shown through an analysis
34 ZAKK and MB'S House 2018 Sawadeesign a
example illustrated in Fig.2.
35 Breathing House 2019 VTN Architects a
36 Ha House 2019 VTN Architects a
37 k59 home& atelier 2019 k59 atelier a 3. Spatial composition by room placement and spatial openness
MM Tropical Suburd
38 2019 MM++ Architects a+b 3.1 Room placement
Townhouse
39 Pattern House 2019 MM++ Architects a+b The study extracted the living rooms and bedrooms as the target
40 Tan Phu House 2019 k59 atelier a
41 V House 2019 AD9 Architects a for analysis. The data collection retrieved 49 living rooms and 124
42 VOM House 2019 Sanuki Daisuke Architects (SDA) b bedrooms from the 47 case studies. As shown in Tab.2 and Tab.3,
43 VY ANH House 2019 Khuon Studio a
case studies with one living room (45/47) and multiple bedrooms
44 Floating Nest 2020 atelier NgNg a
45 HL House 2020 Chi.Arch a (45/47) are a majority. Then, the living rooms and bedrooms are
46 T House 2020 Acspace a investigated in terms of room placement in Tab.4 and Tab.5.
47 THD House 2020 AD9 Architects a
*a = Vietnamese local architect, b = foreign architect based in HCMC,
The analysis examines their position on the building side, their
a + b = local and foreign collaboration level at the building height, and the orientation of their windows.

— 1251 —
 No.43 VY ANH House Chapter 3 Spatial Composition
No.43 VY ANH House Chapter 3 Spatial Composition As a result, all the living rooms are lifted from the street level
(photograph of Khuon Studio, 2019) Room placement
(photograph of Khuon Studio, 2019) Room placement
No.43 VY ANH House Chapter
Room No.3 SpatialL1 CompositionB1 and located on the ground floor (30/49) or middle floors (19/49).
(photograph of Khuon Studio, 2019) Room No. L1 B1
No.43 VY ANH House Room
Side placement
Chapter 3 Spatial Street Back
Composition
Side No.
Room Street Back Concerning their position on the building sides, the majority
Levelplacement
Room L1
Middle B1
Low
Level
Side Middle
Street Low
Back of the rooms is facing either the street side or the backside of
Orientation W E
Room No.
Orientation L1
W B1
E
Level
Spatial openness Middle Low
Side
Spatial openness Street Back the building (26/49). Both situations are mostly with the south
Orientation
Open surface No.
Level W L1-1 Low E
B1-1
Middle L1-1 2 B1-1 2
Open surface
Windowopenness
Spatial size
No. orientation. Concerning their level at the building height, about
Orientation W3.0 m22 3.8E m2
Window
Open size No.
surface 3.0
L1-1 3.8 m2
m B1-1
Window/wall
Spatial openness ratio 39% 39% 80% of the bedrooms are on the middle level (94/124). In this case,
Window/wall
Window size ratio L1-1 39%m2 3.839%m2
Attached
Open surface No. 3.0 B1-1
Open None the placements are mostly on the street side (55/124) and backside
Attached
elements
Window/wall ratio 39% 39%
Window
elements size Open None
3.0 m2 3.8 m2
Wind speed distribution Composite
Wind speed distribution Attachedratio
Window/wall
Composite
opening ratio Open 39%SS LS
39% (51/124). Also, these placements are toward only one side of the
Wind opening elementsratio SS None LS
floor
floor

Wind Attached Open None

Wind speed L1distribution speed Composite building. Regarding the orientation of windows, the most common
1st11stfloor

Configuration
L1 (m/s) elements
speed opening ratio
Configuration
pattern
SS
Multiple LS
Single
Multiple Single
st

Wind speed distribution (m/s)

Wind S S
NN > 0.4 Composite
pattern is the south in cases of rooms on the street side and the east in
floor

speed
= opening ratio SSS LSS
N L1 > 0.4 Configuration
Chapter 4 Airflow
L1
floor

= 0.4 Chapter 4 Airflow Multiple Single

floor

B1 (m/s)
Wind < pattern cases of rooms on the backside (21/55 and 18/51).
floor

< 0.4 Configuration

st

B1 velocity Room No. L1

Multiple B1 S
S Single
1

N
0 = >
1 0.4
2m pattern
Room No. L1 B1 S
G

S Wide
GG

0
(m/s)1 2m Chapterarea
Airflow 4 Airflow Wide
G floor

B1
Chapter 5 Spatial compositionB1 & airflow < 0.4 Airflow area Wide Wide 3.2 Spatial openness
Chapter 5 Spatial composition & airflow > 0.4 Chapter
Room path
No.4 Airflow L1 B1
Room No. L1 B1 0 1 2m Wind
Bedroom
ii iv
Bedroom < 0.4 Room Wind No.
Airflow
path
area
ii
L1 iv
B1 The spatial openness of living rooms and bedrooms is analysed
Room No. L1 B1 Open group Indoor air Wide Wide
Chapter 5 Spatial composition &Open airflow
bgroup Airflow Indoorpath
air Presence None
Room pattern
Chapter 5 Spatial ii compositioniv & airflow movement
Wind area Wide
ii
Presence Wide
iv
None
Room pattern
RoomAnalysis
Fig.2 No. L1ii
example B1iv Bedroom
b movement considering the open surface, which is the combined
RoomAnalysis
Fig.2 No. L1
example B1 Open group Wind
Bedroom Indoorpath
air ii iv
Room Number
pattern of living ii iv Open movement Presence None
Tab.2 room bgroup
Tab.3 Number
Indoor of air
bedroom Exist None characteristics of windows in terms of the window's size and the
Room
Fig.2 pattern
Tab.2Analysis
Number example ii room
of living iv Tab.3
b Number of bedroom
movement
Number of One Multiple Number of One Multiple
Fig.2
Number Analysis example
One Multiple Number One Multiple structure of layers using attached elements such as louver,
Tab.2 perof
room Number houseof living 1 room 2 room
Tab.3 per of
Numberhouseof bedroom
1 2 3 4 5 6 7
Tab.2
room per Number
house of living 1 room 2 Tab.3
room per Numberhouseof bedroom1 2 3 4 5 6 7
Number
Numberof of houses One
ofhouses 45 Multiple
One 2
Multiple Number of
Number houses One
of houses One 2 24 13Multiple 7 0 0 1
Multiple porosity blocks or planters. Firstly, the analysis extracts the open
Number
room
livingper house
room/house 45 22 Number
room perof
bedroom/house house 112 24 22 1333 47 50 6012471
Total number of rooms 11 492 Total number of rooms
Total number of rooms Total number
Number of rooms
of houses
works 13 77 00 0012411
surface from all the living rooms and bedrooms. It is defined as
Number
Number ofhouses
of works 45
45 49
22 Number of 22 2424 13
Tab.4 Placement of living room
Number
Tab.4
Total number of living
Placement rooms
of living 49
room Number of bedroom 124 illustrated in Fig.3, which is the wall consisting of the window
Side of roomsStreet (18) 49 Middle Total(2) number Backof rooms(3) Across 124(26)
Level Placement
Tab.4 Side of living(18) roomMiddle (2) Back (3) 0 Across (26)
Level PlacementStreet
Tab.4 of living 0
room 0 0
Level Side
TopSide Street (18) 0 Middle (2)0 Back (3) 0 Across (26)0 facing the outside air. The collection counts 75 open surfaces in the
Top N Street
S E (18)W N-S
Middle
0 N-S E-W0 N S E W (2)
E-W N Back
S E(3) W0 N-SAcross E-W(26)
Level (0)
Top N S E W N-S E-W0 living rooms and 153 in the bedrooms. In Fig.4 and Fig.5, the
(0) 0
N 0 0
S 0 0
E W 0 0
N-S 00 N
E-W 0 0 E 0 00 0 0 0
(0)
Top 0 0 0 0 0 S 0 0 W 0 N-S0 E-W0
N0 S0 E 0 10 W0 N-S 0 E-W0 0 N 0 S 0 E 0 W 2
0 N-S0 0 7
E-W
(0)
Middle N 0S 0E 10
10 0 2 7 medians for window sizex) are found to be 8m2 for windows in the
Middle
Middle 0N S E W
W
0 N-S
0
N-S 0 0 0N 0S 0E W
E-W 2
0 N-S
0 0 7
E-W
(19) E-W N S E W N-S E-W7
(19) 3 3 1 10
3 3 1
3
3
0
0
0 0 1 0 0 21
0 1 0 0 1
7
7
0
0 19
living room and 4.9m2 for the one in the bedroom. Regarding these
Middle 8 2 N S E W 1
(19)
N S E W 8 N-S
8
E-W2
2 N S E W 1
1
N-S E-W19
19
Ground
Ground
Ground N
3
N 3S
S E
1
E W
W3 N-S
0
N-S E-W
E-W0 1N 0S 0
E W1 N-S
7
N-S E-W
0
E-W open surfaces' size, the window-to-wall ratio (WWR) was also
(30) E-W E-W
(30)
(30)
N
4 S
4 1 E
1 1 W
1 2 N-S
82 0
0 22 N
2 0 0
0 S
0 1 E
1 W 10
0 N-S
9
9 1119
11
Ground 4 1 1 2 0 2 0 0 1 0 9 11 examined (see Fig.3). The majority of open surfaces show more
Tab.5
Tab.5 Placement
Placement N ofof bedroom
S bedroom
E W N-S E-W N S E W N-S E-W
Tab.5 Placement
(30) of bedroom
Level Side
Side 4 1
Street 1
(55) 2 0
Middle (12)2 0 0
Back 1
(51) 0 9 Across
Across 11
(6) than 50% of WWR, which are from 56 living rooms and 81
Level Placement Street (55) Middle (12)2 Back (51) Across (6)
Tab.5
Top of bedroom 8 2 10
10 1
1
TopSide N S E W 8 2 10 bedrooms. This result indicates a tendency for both types of rooms
(21)
Top
Level N Street
S E (55)W N-S N-S
MiddleE-WE-W
(12) N S
S (51)
N Back E
E W W N-S
N-SAcrossE-W
E-W(6) 1
(21) 4 S
N 1 E 1 W 2 0
N-S E-W2 1
N 4 S 3 E W 2 1
N-S 0
E-W
(21) 4 1 1 47 82 0 2 102 1 4 3 10 2 1 0 1 to have large windows to provide natural light.
Top
Middle 4 1 1 47 2 0 2 10 1 4 3 32 2 1 0 5
(94)
Middle NN SS E E W W N-S N-S E-W E-W NN S S E E 32 W
W N-S
N-S E-W 5
E-W
(21) 47 10 32 5 Secondly, the attached elements, which are installed parallelly
Middle 4N
(94)
8 20 S E
N 1S 1E W
8 11 W2 N-S
02
N-S 28
E-W
E-W
N 9
17 S 12
N 4S 3E W
E W 24 N-S
15
N-S
E-W
00
E-W
(94) 8 20 8 11
470 2 8 0 7 9 12 9
4 5 0 0
Ground 8N 20 S 8 E 11 W 2
N-S E-W8 10 N S E W
32
N-S E-W 5 outside the windows, were classified by the characteristics of open
Middle
(9) N 0 0 7 S 9 12 4
9 5 0 0
Ground
(94) 0 S0 E 0 W 0
N-S
0 E-W
E-W
0 0 N 4 2 E 3 W 0
9
N-S0 E-W
0 0
E-W
Ground N
8N 20 S E W N-S
2 8 N S E W N-S or closed (Tab.6). The majority of these elements are the open type
(9) S 8E 11 W N-S E-W 7N 9S 12 E W 4 5
N-S 0
E-W
(9) 0 0 0 0 0 0 4 2 3 0 0 0
Ground N 0 0 0 00 0 0 0 4 2 3 90 0 0 0
axonometry S E W E-W
N-S front view N S E W N-S E-W in both living rooms and bedrooms (22/75 and 67/153), which
(9) 0 0 0 0
0 0 0 0 4 2 3 0
open surface × % = Window-to-wall ratio always allow light and air to flow through, such as porous blocks or
open
(WWR)
window surface window nets. Then, the ratio between the openable window and to open
openable openable × % = Opening ratio
window surface is defined as the opening ratio. Also, the ratio between the
window
attached attached × % = Composite opening ratio openable window's area, excluding the area blocked by attached
50 element element
50 Window-to-wall ratio (WWR) 100% elements, was defined as the composite opening ratio (see Fig.3).
) ))

Fig 3.
40Definition of openratio
surface 100%
2 22

Window-to-wall
> 50% 56/75 (WWR)
(m

>
(m

40 = =
> 50% 56/75
For each open surface, the above ratios are calculated, and the
) (m

50 < =
< 50% 19/75
size

30 Window-to-wall ratio (WWR) 100%

size

30 50< 50% 19/75 50%

size size

40
2

>
20 = 50% 56/75 100% 50%
(m

Window-to-wall ratio (WWR) combinations of these two are classified as the pattern of composite
Window
Window

20 50% 19/75
Window size (m2)

<
30 40 >50% 56/75
Window

10 50% 8.0 m22

10 30 <50% 19/75 Median opening considered in each living room and bedroom. As shown in
200 Median 8.0 m2
Window

50%
100 20 0 10 20 30 2 40 50 m2 60 Fig.6 and Fig.7, the medians of the opening ratio are 50% in the
0 10 20 surface30
Open size (m22) 40Median 8.0
50 60
0 Open surface size (m )
Fig.4 Window
10 0 size and WWR
10 WWR of of living room
20living room30 40Median 8.0
50 m2 60
living rooms and 33% in the bedrooms. The medians of the
Fig.4 Window size and Open surface size (m2)
50 0
50 Window-to-wall ratio (WWR) 100% composite opening ratio are 27% and 15%, respectively, indicating
) ))

Fig.440Window0 size and10 WWR of20living room

30 40 50 60
2 22

Window-to-wall ratio (WWR) 100%

(m
(m

40 => 50% 81/153

= Open surface size(m2)
) (m

50 > 50% 81/153

=
30 Window-to-wall that the attached elements halve the openness overall in both
size

< 50% 72/153 ratio (WWR)

size

Fig.4 100% 50%

30Window
< 50% size and WWR of living rooms
72/153
size size
2

40 50%
(m

> 50% 81/153

20 50
= room types. In addition, the majority of the composite opening
Window
Window

20 Window-to-wall ratio (WWR) 100%

30 < 50% 72/153
Window size (m2)
Window

10 40 > 50% 81/153 50% 4.9 m22

Median
10
20 Median 4.9 m2 patterns are LL and SS in both room types. For instance, 28/75
0 30 < 50% 72/153
Window

100 0 10 20 30 40 50 2
50% 4.9 60 and 26/75 are found in living rooms, while 55/153 and 54/153 are
0 10 20 surface30size (m2) 40Median
Open
2
50 m 60
20 Open surface size (m2)
Fig.5 0
Window size and WWR of bedroom in bedrooms, respectively.
0 10 20
Fig.5 Window size and WWR of bedroom 30 40 50 60
10 Open surface size (m2)
Median 4.9 m2 Finally, combinations of the composite opening pattern and the
Fig.5 Window size and WWR of bedroom
0
0 10 20 30 40 50 60
Open surface size(m2)
Fig.5 Window size and WWR of bedrooms

— 1252 —
presence of attached elements were examined and classified into Tab.6 Types of attached element
Open Open-close Close
four configuration patterns in terms of opening surface (Tab.7). In (22,67) (4,1) (15,33)
both living rooms and bedrooms, the majority of combinations are
the type of layers using attached elements. Also, the most common
Louver Porous block Net Planter Low wall Door High wall
configuration pattern of opening surface is ④ Multiple layers・S (5,15) (4,26) (8,11) (5,5) (0,10)
(31/75 for the living room and 63/153 for the bedroom). However, in Composite opening ratio median 27% Composite opening pattern
Small Large
the case of the living rooms, ① Single layer ・L also has an almost 100
(37) (38) Large Composite
80 opening ratio Large Small
(39) Opening ratio

Ratio (%)
equal number (28/75). This configuration is a Large and Single 60 Opening ratio
40 median 50% Large LL LS
opening surface facing the outdoor air without any attached 20 Small 28/75 11/75
(36)
element. In the case of the bedrooms, there is a similar quantity of 0 SL SS
Open surface Small
Opening ratio Composite opening ratio 10/75 26/75
the configuration ③ Multiple layers・L (37/153). This configuration
Fig.6 Composite opening pattern of living room ’s open surface
is also a Large opening surface, but there are Multiple openings Composite opening ratio median 15% Composite opening pattern
Small Large Composite
using layers of attached elements. These results suggest a 100
(76) (77) opening ratio Large Small
80
Large Opening ratio

Ratio (%)
confrontation between the spatial openness and the layers of the 60 Opening ratio (77)
40 median 33% Large LL LS
outer surface of the windows. 20
55/153 22/153
Small
0 SL SS
Open surface (76) Small
Opening ratio Composite opening ratio 22/153 54/153
4. Wind environment by airflow area and wind path Fig.7 Composite opening pattern of bedroom’ s open surface
4.1 Settings of wind simulation for airflow Tab.7 Configuration patterns of open surface
Attached None (34,53) Presence (41,100)
The natural airflow in the rooms was investigated by element
Composite LL SL LS SS LL SL LS SS
Computational Fluid Dynamics (CFD) and used climate data from opening
pattern (19,23) (9,17) (0,1) (6,12) (9,32) (1,5) (11,21) (20,42)
WEADACxi) with the settings for the simulation model detailed Confi- Single L Single S Multiple L Multiple S
guration
in Fig.8. The average wind condition in Aprilxii) (cf. Chapter 2.1) pattern
of opening
was defined as the input values for the analysis model according surface
(28,40) (6,13) (10,37) (31,63)
to the most significant period concerning activities in each type
Software (STREAM ver.2021.1) Climate WEADAC
of room. The wind speed was calculated from the hourly average Turbulence model: Standard k-ε Location HCMC, Vietnam
Boundary cond.: All surfaces smooth. Season: April
of the chosen period in each room type, at 4.0 m/s and 1.7 m/s, for Root block:
-Standard length is x,y,z=1m Living room Bedroom
the living rooms and bedrooms, respectively. The wind direction -Limit width: x,y,z=0.01m Time 17:00 - 20:00* Time 0:00 - 5:00*
-Surface roughness classification: III Orientation: S-S-E Orientation: S-S-E
was South-South-East, found in both room types . The targeted
xiii)
-Power index:α=0.2 Wind speed 4.0m/s Wind speed 1.7m/s
Analysis surface Modelling of surrounding buildings
building was modelled with some considerations in spatial Analysis surface Target buiding
forms, such as including stairs, and built-in furniture. Also, all Buildings on the
other side of the Adjacent
0.5m Floor level front road buildings
the windows and doors are open considering a condition for the to property
0.5m from the floor to calculate the limit of
maximum potential of natural airflow. The surrounding buildings wind speed relative to human height** target
H=10m

Modelling of target building building

were modelled as an assumed urban environment of medium-rise All openings (doors, windows, 0.5 m step back
skylight) are open. from property limit
and high-density conditions, with simple building shapes without Include stairs and built-in furniture. Surrounding buildings are modeled as
eavesxiv). A setback of 0.5m between buildings on the sides and Not include vegetations. simple shape without eaves.
*The time for simulation in living room and bed room are chosen
at the back are defined for all surrounding buildings, taking into according to the period when these rooms are most used during the day.
**The height correspond to the posture of sitting and lying on bed.
account the rapid urbanization of HCMCxv). Fig.8 Settings of simulation for airflow
4.2 Airflow area Median 74% Narrow Wide Narrow Wide Median 25%
Living room

20 (24) (25) (62)

50 (62)
For both room types, a distribution plan of wind speed defined at
Bedroom

15 40
10 30
the height of 0.5m from the floor level is set to show the behavior of 5 20
10
0 0
natural airflow inside the rooms according to human height. Then,
~100
~10
~20
~30
~40
~50
~60
~70
~80
~90

~10
~20
~30
~40
~50
~60

~100
~70
~80
~90

Ratio of airflow area(%) Ratio of airflow area(%)

the ratios between the airflow area to the floor area in each room
Fig.9 Airflow area in living room Fig.10 Airflow area in bedroom
were calculated, by defining the range of wind speed for airflow Tab.8 Wind path
Presence of wind path
area from 0.4 m/s and faster, which is the range of airflow people
In depth direction In transverse None
could feelxvi). As shown in Fig.9 and Fig.10, the medians of airflow Wind path With side direction No side direction direction

area ratio are 74% in the living rooms and 25% in the bedrooms,
indicating that strong velocity in the living rooms tends to cover a Living room 4/49 (4) 24/49 (14) 4/49 (4) 17/49
large airflow area, while it tends to be limited in the bedrooms. Bedroom 1/124 (1) 36/124 (31) 10/124 (10) 77/124
Tab.6, 7 Note: The numbers indicate the quantity of rooms (living room,
4.3 Wind path bedroom), in which contains the type of attached element.
Tab.8 Note: The numbers in ( ) indicate the quantity of rooms which
Next, the analysis examines the shape of the airflow area in have the wind path continuing to the adjacent indoor space.

— 1253 —
each room, called the wind path, which is an airflow area crossing that the spatial connection between different indoor spaces would
between adjacents and opposites walls. Further, the presence create airflow between spaces, even though these room types tend
and the shape of wind path, considering factors such as the depth to locate at the end of long narrow buildings.
or the direction, characterize the wind paths into four types, as
illustrated in Tab.8. In the case of the living rooms, the majority 5. Passive design seen from spatial openness and airflow
(32/49) have a wind path, while in the case of bedrooms, it is only This final chapter examines the correlation between the spatial
about 40% (47/124). This result shows a difference in the tendency openness and the indoor airflow in the living rooms and bedrooms,
of wind path between the two room types. Regarding the directions which are results from the previous chapters, investigating
of wind path, in the case it existed a wind path, results show the variations in terms of the passive design for each house.
highest quantity in the depth direction with no side direction 5.1 Combination of open pattern and wind path in each room
(24/49 for living rooms and 36/124 for bedrooms). Especially in First of all, in the configuration pattern of the opening surface,
the living rooms, wind paths in transverse directions are limited. the [Single] layer with no attached element and the [Large]
Furthermore, the wind path continuing to the adjacent indoor composite opening ratio could be understood as the components
space was examined (see Tab.8 note). In the case of the bedroom promoting spatial openness. Hence, a combination of these
with the presence of wind path (i, ii, iii), the result shows that 90% components in windows was examined in all room types and
(42/47) have this continuous airflow crossing in the indoor spaces classified into four open patterns. Further, the combination of
through the internal opening on the wall. This result indicates these open patterns and the wind path is considered the room
Tab.9 Combinations of open pattern and wind path
Orientation & Room 28-L1 S M - - 8 N
32
- 25-B4 M T - - - 56 W
Continuity

Room configuration Airflow Pattern 16-L1 AM - - - 55 N - 11-B2 S T - - - 62 W

Level

Single layer
pattern (4,9)
pattern of area (%) 36-B3 S M - 10 N -
Side

21-B2 B M - - - 27 W -
pattern

no. open surface

Wind

Open

41-B3 B T - - 42 W -
path

iv 25-B2 M M - - - 46 W
N S E W Ratio Avg. 46-B3 S M - - - 11 N - 4-B1 B G - - 40 W
32-B1 BM - - - 0 N 24 - (2,7)
15-B6 M M - - - 44 W 55 ii
25-L1 S M - - 91 W i (2,0) - - - 9 N -
- - 96 46-B1 S M 7-B2 S M - - - 91 W (4,14)
8-L1 S M 100 W - - -
8-B1 BM 26 W 7-B1 S M - - - 91 W
5-L2 AM - - 94 W - - - - -
43-B1 B G 70 W 22-B1 B M - - - 31 W
5-L1 AM - - 95 W -
12-L1 A G - - 98 W 44-B3 S M - - - 52 W
4-L1 S G - - - 67 N -
17-L2 S M - - 100 W 40-B2 M M - - - 81 W
18-L1 S G - - 69 N
87 1-L1 AM - - 94 W - 44-B2 S M - - - 73 W
42-L1 S G - - 73 N
3-L1 AM - - 74 W - 33-L1 M G - - - 66 N
17-L1 MG - - - 100 W
22-L1 AG - - 93 W - 20-L1 AM - - 87 W 82
- 32-L1 A G - - - 64 N 65
21-L1 A G - - 71 N - 30-B2 S T - - - 24 N iii
31-L1 S M - - - 94 W
35-L1 S M - - - 58 N 6-B1 B G - - - 60 W (2,4)
38-L1 AG - - - 98 W
4-B2 S M - - 50 W - 15-L1 A G - - 77 W -
ii 37-B3 B M - - 37 W 43
4-B4 AM - - 80 W -
ii 19-L1 S G - - - 82 W 37-B2 B M - - 51 W
(9,12) 40-L1 S M - - - 82 W (10,8) 13-L1 S M - - 6 N -
36-B2 S M - - - 26 N

Small pattern (13,49)

10-B2 S M 98 W -
Large pattern (22,31)

- - 34-L1 A M - - - 24 N -
1-B1 S M - - - 55 W
42-B1 S T - - 35 W 12-B1 S M - - 43 W 7-L1 A G - - - 99 W -
25-B3 S M - - - 75 W 12-B4 BM - - 30 W 41-L1 A G - - - 61 N 41 -
5-B3 A T - - 55 W - 44-L1 A G - - - 38 N -
6-B2 S M - - - 48 W 54 58
11-B1 S M - - - 42 W 20-B2 AM - - - 73 W 45-L1 B M - - - 16 N -
15-B1 S M - - 36 W 1-B3 B T - - - 86 W 9-B3 M M - - - 0 N -
38-B3 B T - - - 88 W 39-B2 S M - - - 28 W 18-B3 M M - - - 0 N -
15-B2 BM - - - 30 W 41-B2 S T - - - 50 W 47-B2 B M - - - 3 N -
38-B2 BM - - - 84 W 39-B3 BM - - - 21 N 21 iii (0,1) 18-B1 M M - - - 0 N -
4-B3 BM - - 0 N 39-B1 B G - - - 0 N -
Large pattern (10,35)

36-L1 S G - - 55 N -
62

Multi layer
20-B1 AM - - - 16 N 37-B1 B M - - 38 W -
Single layer

30-L1 AG - - - 69 N -
1-B2 S M - - - 55 W 39-B4 B T - - - 0 N - 9-B2 B M - - - 0 N -
18-B2 S M - - - 48 W
iii 12-B3 BM - - - 33 W - 17-B2 B T - - - 16 N -
28-B2 AM 63 W (2,5) 5-B2 S M - - - 41 W - 24-B2 M M - - - 0 N -
- - - 56
12-B2 BM - - - 0 N - 9-B1 B M - - - 0 N -
33-B2 BM - - - 64 W
3-B1 B G - - - 0 N - 24-B1 M M - - - 0 N -
33-B3 B T - - - 51 W
10-B1 S M - - - 8 N - 25-B1 M M - - - 0 N -
37-L1 S G - - 39 N -
30-B1 S M - - - 0 N - 47-B1 S T - - - 8 N -
11-L1 AG - - 66 N -
47-L1 AG - - 64 N - 3-B2 AM - - 0 N - 15-B4 M M - - - 22 N 11 - iv
2-B2 S M - - - 0 N - 31-B3 B M - - - 8 N - (6,30)
2-L1 AG - - 60 N -
16-B2 S M - - - 6 N 12 - 26-B2 B M - - - 0 N -
9-L1 S M - - 59 N 60 -
35-B2 S M - - - 7 N - 29-B2 S M - - - 0 N -
46-L1 AG - - 81 W - iv
2-B1 S M - - - 50 W - 45-B2 S M - - - 15 N -
24-L1 AG - - - 50 N -
(0,26)
5-B1 B G - - - 27 W - 23-B1 B G - - - 67 W -
26-L1 AG - - - 62 N -
16-B1 S M - - - 4 N - 26-B1 B M - - - 0 N -
29-L1 S G - - - 61 N -
34-B1 S M - - - 0 N - 29-B1 B G - - - 0 N -
41-B1 BM - - 0 N -
35-B1 S M - - - 15 N - 31-B1 B M - - - 9 N -
6-B3 BM - - - 16 N - iv
19-B2 S M - - 0 N - 46-B4 B T - - - 21 N -
33-B1 S M - - - 16 N -
(9,14) 8-B3 S T - - 9 N - 14-B2 S M - - - 20 N -
17-B1 S T - - 14 N -
19-B1 S M - - 11 N - 31-B2 S M - - - 14 N -
6-B4 S M - - - 27 N -
15-B7 B T - - - 28 W - 32-B2 S M - - - 4 N -
27-B2 S M - - - 96 W -
13-B1 B G - - - 10 N - 46-B2 B M - - - 25 N -
21-B1 S M - - - 28 W 25
-
45-B1 S M - - - 25 N - 14-B1 S M - - - 30 W -
27-B1 S M - - - 0 N -
15-B5 BM - - - 31 W - 40-B1 B M - - - 19 N -
28-B1 S M - - - 31 W -
-
15-B3 S M - - 35 W - 29-B3 B T - - - 0 N - 44-B1 S M - - - 0 N
23-B2 BM - - - 63 W - 14-L1 B G - - - 93 W 93 i Notes [Level] *Configuration patterns
8-B2 BM - - 7 N - 36-B1 BM - - 83 W 83 (1,1) T Top of open surface are ,
45-B3 BM - - - 12 N - 27-L1 BM - - - 88 W [Side] M Middle , , from Tab.7
22-B2 S T - - - 2 N - 10-L1 A G - - - 98 W S Street G Ground * Continuity of air
6-L1 AG - - 94 W 94 i (1,0) 23-L1 S G - - - 97 W 95 M Middle movement,resulted from
43-L1 S M - - - 95 W B Back [Airflow area] Tab.8 as
39-L1 AG - - 88 W 88 - ii
42-B2 B T - - 51 W 13-B2 BM - - 48 W A Across N Narrow presence of continuity
28 (1,2) 18-B4 M T 27 W W Wide - no continuity
38-B1 S M - - - 6 N - - -

— 1254 —
 Both room - Open group (24) Living room - Open group (10)
No.5 No.35 a Each room has wind path (3)
No.36 Binh Thanh House Breathing House 18 Townhouse with a
Ha House Folding-Up Shutter NS
25 / House NS
40 Tan Phu House -
B3
Wind B3 b Living rooms have wind path (1)
L2
B2 B2 31 Lantern House -
B2 B1 c Bedrooms have wind path (1)
L1 L1
Wind L1 37 k59 home& atelier -
d Each room has no wind path (5)
Wind
9 The Gills NS
24 Zen House -
a Each room has wind path (14)
26 // house -
1 White House NS 29 Giabinh.House -
4 Anh House - 47 THD House NS
5 Binh Thanh House NS
6 Folding Wall House NS No.37
12 Breeze House NS k59 home& atelier
15 Kaleidoscope EW Bedroom - Open group (10) Wind
20 Bamboo House - B3
21 Lee&Tee House NS B2
22 Nha Cua Tien EW B1
30 House for a Daughter N
36 Ha House - B1
L1 L1
38 MM Tropical Suburb -
Town House Wind
39 Pattern House NS No.43
42 VOM House NS VY ANH House
a Each room has wind path (2)
b Living rooms have wind path (5) 10 Thong House -
3 Stacking green NS 33 The Rough House -
8 B House EW b Living rooms have wind path (4)
17 Saigon House NS
23 Quiin House -
19 Wasp House -
27 Backyard House -
35 Breathing House S
32 Lien Thong House -
c Bedrooms have wind path (2) 43 VY ANH House W
11 Vegan House NS c Bedrooms have wind path (2)
28 D House - 13 Living
HEM House NE
Both room - Open group (24) room - Open group (10)
d Each room has no wind path (3) 41 V House -
No.5 No.35 a Each room has wind path (3)
2 NANo.36
House Binh Thanh House Breathing- House d Each room has no wind
18 Townhouse path
with a (2)
Ha Town
16 Micro HouseHouse 4×8m S 34 ZAKKFolding-Up
and MB'S House
Shutter S NS
46 T House EW 45 HL25 House
/ House - NS
40 Tan Phu House -
B3
LegendWind B3 Bedroom
Living room b Living
Both room - Closerooms
grouphave
(3)wind path (1)
L2 NS
1 White House B2 B2 b Living31 room have wind
Lantern Housepath (1) -
B2 B1 14 House 304 have wind path (1)
c Bedrooms -
L1 Same
L1 direction of
Wind open surface in L1 c Bedroom 37 have wind path
k59 home& (2)
atelier -
Case study Project Combination of patterns the living room 7 3×10 House
d Each room has no wind path (5) E
No. name in ascending order Wind
and bedroom 44 Floating Nest W
9 The Gills NS
Fig.11 Correlation of spatial openness and airflow in each house 24 Zen House -
a Each room has wind path (14)
26 // house -
1 White House NS
patterns (as Housein Tab.9). As a result, patterns Ⓐ , Ⓑ , Ⓒ - and this47
shown 29 Giabinh.House
pattern corresponds to all living rooms. In these cases, -
4 Anh THD House NS
5 Binh
include many Thanhlayer
[Single] Houseand [Large] composite opening ratios, NS the orientation of the open surface is majority on the opposite
6 Folding Wall House NS No.37
and they 12 Breeze
tend to be open to the outdoor. Among them, Ⓐ Single NS sides, like N-S, which is along with the input windk59
House home& atelier
direction in
15 Kaleidoscope EW Bedroom - Open group (10) Wind
layer・Large pattern
20 Bamboo has the same quantity of components as - simulation, and the wind path continuing to the adjacent indoor B3
House
21 Lee&Tee House NS B2
[Single] 22
layer
Nhaand
Cua [Large]
Tien composite opening ratio, and they EW space is also the majority. From this result, it could be that B1
30 House for a Daughter N
mainly have
36 HaaHouse
simple form of a large window area without - the placement of the open surface and the B1 continuity of airflow
L1 L1
38 MM Tropical Suburb -
attached elements,
Town Housewhich are found a majority in the living room between the indoor spaces Wind are related. This relationship tends to
39 Pattern House NS No.43
(22/49). On House hand, Ⓑ Single layer pattern has more NS enhance the airflow across the depthVY
the other
42 VOM ANH House
direction while including the
a Each room has wind path (2)
[Single]blayer
Livingthan
rooms have wind
[Large] path (5)opening ratio, and Ⓒ Large
composite composite 10characteristic
Thong House of the windows using attached elements. -
3 Stacking green NS 33 The Rough House -
pattern has8 Bmore
House[Large] composite opening ratio than [Single] EW In the b case of Ⓓ Multi layer・Small pattern, all the open surfaces
Living rooms have wind path (4)
17 Saigon House NS
layer. In 19
both living rooms and bedrooms, the quantity of room - are ④ Multiple・S. 23 Quiin House This is the tendency of the open pattern -
Wasp House
27 Backyard House -
35 Breathing House S
patterns is the smallest in the Ⓑ Single layer (4/49, 9/124), and to be closed
32 Liento the
Thongoutdoors.
House More than 30% of each room type -
c Bedrooms have wind path (2) 43 VY ANH House W
the quantity in the
11 Vegan HouseⒸ Large pattern (10/49, 35/124) is more NS corresponds to this
c Bedrooms classification
have (13/49 and 49/124).
wind path (2)
28 D House - 13 HEM House NE
than twice Ⓑ . From this result, it could be that when one of the
d Each room has no wind path (3)
Furthermore,
41 V House the average airflow area in the room pattern -
components 2 NApromoting
House openness is dominant, the tendency of - shows dthat Eachtheroomwind area
has no windinpath
both(2)room types becomes smaller,
16 Micro Town House 4×8m S 34 ZAKK and MB'S House S
spatial openness
46 T House is to increase the window size while adjusting EWranging from 45 HLi House
to iv, where the wind path decreases in the depth -
by layers of the attached element, rather than making a small
Bedroom
direction. In the living rooms,
(3) this attenuation from i to iv is
Legend Living room Both room - Close group
NS
window without
1 any attached
White House element. This tendency leads to similarbregardless
Living roomofhave
the wind
openpath (1)
patterns. On the other hand, for the
14 House 304 -
enhancing the composite characteristic of the windows.Same direction of
open surface in bedrooms without wind path (wind
c Bedroom have wind path (2) path iv), the mean value of the
Case study Project Combination of patterns the living room 7 3×10 House E
In addition, case of theinⒸascending
No. in the name Large pattern,
order only ii
andconsists
bedroom airflow area Ⓐ and Ⓑ is more than twice that of Ⓒ and Ⓓ .W
ratio of Nest
44 Floating
of a combination with
Fig.11 Correlation the wind
of spatial pathand
openness in airflow
the depth direction,
in each house This result suggests that the adjusting by layers of the attached

— 1255 —
elements causes significant effects on the airflow area. tendencies according to the room types in both the horizontal and
5.2 Correlation of spatial openness and airflow in each house vertical arrangements. Examining the spatial openness by the
Furthermore, the combination of room patterns and wind paths window size and layers of attached elements, the results
was examined in each of the case studies of tube houses (Fig.11). illustrated that both room types have mostly the opening surface
The distribution of the room patterns was classified into the open- consisting of Multiple layers and Small opening combined.
oriented pattern ( Ⓐ , Ⓑ , Ⓒ ) and the close-oriented pattern However, there was a confrontation between openness and layers
( Ⓓ ). By assembling these patterns, four groups of living rooms- of attached elements. Secondly, the simulation analysis of the
bedrooms are defined: the Both rooms - Open group, in which indoor airflow considering a significant wind condition during the
living rooms and bedrooms have the majority of Ⓐ , Ⓑ , Ⓒ ; the hottest season resulted that the living rooms tend to have larger
Living room - Open group, in which only the living room has a airflow areas and wind paths mainly crossing in the depth
majority of Ⓐ , Ⓑ , Ⓒ ; the Bedroom - Open group, in which only direction, while these movements of airflow tend to be limited in
the bedrooms have a majority of Ⓐ , Ⓑ , Ⓒ ; and the Both rooms - the bedrooms. Finally, the correlation between spatial openness
Close group, in which living rooms and bedrooms have only Ⓓ . As and airflow, considering all room types and all case studies of tube
a result, Both rooms - Open group is the most common, while Both houses, was examined. The classification of room patterns showed
rooms - Closed group is the least common. Also, the quantity of a tendency to increase the windows' size and to adjust it by using
Living room - Open group and Bedroom - Open group are equal. the attached elements when one of the elements promoting
In each group, regarding the combination with wind path, [a] is openness was predominant.
the majority for Both rooms - Open group. Among the case studies, Furthermore, the combination of room patterns and wind path
No.36 has different room patterns ranging from Ⓐ , Ⓑ , Ⓓ with was examined in all case studies. The majority showed in the
all types of wind paths ranging from i to iv. This combination group where both rooms are mainly open-oriented, while each
contains the most variation in spatial openness and airflow. room mostly has a wind path. On the other hand, about 40% of the
Besides, No.5 has only Ⓐ in the living room and only Ⓒ in the case studies limited these open-oriented room patterns to either
bedroom, though this is in the same category. From this result, the living rooms or the bedrooms. These combinations create
it could be that both of these tube houses have large windows diverse relationships between the houses' living environments and
but adjust them using either a single layer or multiple layers the outdoors and would suggest various possibilities in passive
of attached elements depending on the function of the rooms. design using airflow for HCMC contemporary tube houses.
This tendency allows the winds to flow across the space in each These findings clarify the variations of the passive design
room. On the other hand, the majority of case studies in [b] have approach concerning spatial openness and indoor airflow, which
only the open pattern Ⓒ . Also, in all the rooms, while there is present the opportunity to address the current challenges of
a homogeneity of having open patterns with large windows, the urbanization and enhance the living environment for urban
wind paths are different according to the function of the rooms. dwellers in HCMC. Hence, it would showcase the diversity of
Besides, in the Living room - Open group, the proportion of wind solutions integrating a passive approach from local architects to
path [d] increases, and these living rooms all have large windows, find solutions working with spatial composition and airflow to
but the area of wind path is limited. On the other hand, in the enhance the dweller's living conditions and preserve the inherited
Bedroom - Open group, the category [b], which is Living room has knowledge and cultural identity of southern Vietnamese
wind path, is the most common. For instance, in the case of No.43, architecture. Though several tendencies of correlation between
the living room is connected to the corridor leading to the staircase spatial openness and airflow are found in this research, it is clear
with skylightxvii), creating a wind path. that not all of them can be applied to the diverse climate regions in
Vietnam. Further investigations are needed to explore the richness
6. Conclusion in terms of climate-responsible solutions for Vietnamese housing.
This research examined the contemporary Vietnamese tube Also, this research scope only focuses on the significant typology of
houses in HCMC. By analyzing the spatial composition of the tube houses within the most recent period to demonstrate the
living rooms and bedrooms in terms of room placement and diversity of approaches that integrate design methods responding
windows' characteristics, and further defining the patterns in to the environment in contemporary Vietnamese architecture,
which they open up to the outdoors as spatial openness. Then by especially in HCMC. The insight collected from this study is
correlating these patterns with the potential of the indoor wind beneficial for future research on housing in tropical climates like
environment via simulation analysis in terms of airflow area and HCMC, which gain knowledge from passive design principles to
wind path, the results clarify some tendentious characteristics of respond to environmental threats and uncertainties. Finally, this
passive design in terms of spatial openness and airflow. paper is an improved study of the research17),18) on contemporary
Firstly, the analysis of the rooms' placement showed different tube houses in HCMC by further modifications.

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Notes periods for each room type are applied.
i) In reference 1), the authors clarify how the devices found in vernacular xiv) In addition to the surrounding building models as an assumed urban
dwellings of three distinctive regions in Vietnam adapt to the local environment of middle-rise and high-dense situation, the surface
climate conditions and ensure comfort for its inhabitant. roughness classification is selected, taking into account effects for wider
ii) In reference 2), Schenck identifies the vernacular modernism style areas as continuous building blocks with a middle-rise and high density.
of southern region architecture through terms such as articulation xv) The local regulation allows housing owners to build directly on the
(relationship of in and out through openings and protrusions in the property limit with exterior walls touching neighbors. If having windows,
facade) and brise-soleil (sun-blocking elements and ventilation screens) the setback is regulated at a minimum of 2 meters (Article 178 of the
with a high level of complexity for the quest of harmony. Civil Code 2015) [from https://www.luatvietnam.vn/dan-su/bo-luat-dan-
iii) Being relatively young, architecture in HCMC doesn't have many su-nam-2015-101333-d1.html (accessed on 2022.09.01) (in Vietnamese)].
traditional-style buildings except community halls, religious buildings Besides, according to the National Standard TCVN 9411:2012 for
and the colonial style of French institutions. Hence, in reference 2), it is adjacent housings[from https://www.vanbanphapluat.co/tcvn-9411-
assumed that the development of urban dwellings in HCMC is inspired 2012-nha-o-lien-ke-tieu-chuan-thiet-ke (accessed on 2022.09.01) (in
by these styles fusing past patterns and local climate adaptation. Vietnamese)], design standard 6.4.3 mentioned that if the street block
iv) According to Reference 3), the most dominant type of HCMC urban adjacent is still not constructed, even if the distance between 2 houses
settlement is the row houses, mostly built between 1999 to 2009. This is less than 2 meters, the owner can install openings if there is no
category is called "tube house", concerning self-constructed units for the complaint. In current practices, tube houses are built with high density
low and middle-income population. based on these regulations and neighborhood negotiations. Hence, for
v) Following the report on the rise in electricity consumption for HCMC the simulation model settings in this research, considering the situation
from Vietnam Electricity (EVNHCMC) between 2017 to 2019, the when urban street blocks are filled up and only the minimum distance is
increase in energy consumption reached 36.43% in 2020 compared to kept to allow the installation of an exhaust fan between adjacent houses,
the previous year. The majority was due to the increase in the use of air- a distance of 0.5m is set as their general situation.
conditioning. Data retrieved from https://www.plo.vn/do-thi/dien-luc- xvi) In reference 16), 0.35m/s is used as a lower threshold of wind speed
tphcm-ly-giai-hoa-don-tien-dien-tang-cao-904947, (accessed 2022.3.25) to investigate the thermal comfort in a hot temperature condition. By
vi) According to reference 8), the settlement of rural housing typology referring to this value, it is simplified to be 0.4m/s in this research
developed with a front shop to sell products in the popularized urban simulation as the lowest threshold for wind speed.
areas. The feudal government started to tax the size of the front width, xvii) Among 47 case studies, 32 cases contain skylights which can open
which led to the form of a tube house that extended toward the inward of above the staircases.
the street blocks while keeping the front facade as narrow as possible.
vii) According to reference 8), the period between traditional and modern References
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Hour 12 13 14 15 16 17 18 19 20 21 22 23 Japanese Villas, Journal of Architecture and Planning (Transactions of
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WV 3 3 3 3 4 4 4 4 4 3 3 3
紀 , 村田 涼 , 湯淺 和博 , 安田 幸一 : 現代日本の別荘における海に臨む室の
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 AIJ), Vol.73, No.624, pp. 457-463, 2008.2 (DOI: https://doi.org/10.3130/ 和文要約
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本研究は、高温多湿な気候の下、近年、経済発展により高密中層
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に着目し、これらの現代住宅にみられる空間の開放性と風環境の関
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11) Thanh-Hung Dang, Adrian Pitts: Simultaneous Influences of 味したレイヤー状の複合的な開放性から検討した。さらに、乾期の
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Layout of the Terraces for Comfortable Wind Flow and Various Uses in
る。一方、リビングと寝室の開き方に差異をつくる事例も全体の約
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2022.9

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