An analysis of passive design and unique spatial characteristics inherent in vietnamese indigenous housing and their applications to contemporary high rise housing in vietnam

This thesis studies the application of passive design and special features in traditional and regional houses, i.e., the eco-elements and spatial composition of traditional folk houses a

공학박사학위 논문

베트남 전통주거건축에 내재된 자연형 디자인 및 공간구조의 분석과 현대 고층주거로의 적용에 관한

연구

An Analysis of Passive Design and Unique Spatial Characteristics Inherent in Vietnamese Indigenous Housing and Their Applications to Contemporary

High-Rise Housing in Vietnam

공학박사학위 논문

베트남 전통주거건축에 내재된 자연형 디자인 및 공간구조의 분석과 현대 고층주거로의 적용에 관한

연구

An Analysis of Passive Design and Unique Spatial Characteristics Inherent in Vietnamese Indigenous Housing and Their Applications to Contemporary

High-rise Housing in Vietnam

(Le Thi Hong Na)

이 논문을 티홍나 공학박사학위 논문으로 인정함

2011 년 2 월

An Analysis of Passive Design and Unique Spatial Characteristics Inherent in Vietnamese Indigenous Housing and Their Applications to Contemporary

High-rise Housing in Vietnam

Department of Architecture Engineering

February, 2011

The house is the major element of an artificial environment Vernacular houses reflect the lifestyles of the inhabitans, representing various cultures and societies This thesis focuses on traditional folk houses in countryside areas and street houses in urban Vietnam One of the main characteristics of traditional folk houses is that they have been designed with a deep understanding and respect for nature Unfortunately, this design-with-nature approach is no longer found in modern houses The street house is the most common type of housing in urban Vietnam Together with the flexible characteristic, this dwelling type has a good quality for living environment and becomes an identity of Vietnamese cities However, because its main

This thesis studies the application of passive design and special features in traditional and regional houses, i.e., the eco-elements and spatial composition of traditional folk houses and the diversity and flexibility of street houses to urban high-rise housing in Vietnam On-site survey, data collection, and detailed analysis to discover the specific values of traditional houses, street houses, and modern Vietnamese life style are conducted Based on the findings of this research, further proposals on using passive method principles for Vietnamese climate and designing new models for high-rise housing can be made.

This study significantly contributes to the creation of a new high quality living environment in urban Vietnam

TABLE OF CONTENTS

Title Page No

Abstract i

Table of Contents iii

List of Figures vi

List of Tables xiii

INTRODUCTION Previous Studies 1

Objectives 4

Organization 5

PART I: PEDAGOGICAL STUDY CHAPTER 1: PASSIVE DESIGN PRINCIPLES FOR A VIETNAMESE HIGH-RISE HOUSING DESIGN 1.1 Climate Data of Vietnam 11

1.2 Passive Design Method 19

1.3 Passive Design Principles for Vietnamese High-rise Housing Design 26

1.4 Rain Harvesting 40

1.5 Summary 46

PART II: RESEARCH & SURVEY CHAPTER 2: VIETNAMESE TRADITIONAL FOLK HOUSES 2.1 General view of traditional houses in different regions in Vietnam 48

2.2 Vietnamese family structure 52

2.3 Traditional folk houses in northern Vietnam 55

2.4 Traditional folk houses in middle Vietnam 60

2.5 Traditional folk houses in southern Vietnam 64

2.6 Traditional stilt houses in highlands of Vietnam 72

2.7 Summary 79

CHAPTER 3: FOLK HOUSES IN NORTHERN VIETNAM 3.1 Basic Configuration, Orientation, and Spatial Characteristics of the Traditional Folk Houses Typical in Northern Vietnam 81

3.2 Four Traditional Houses at Duong Lam Village in Northern Vietnam 91 3.3 Summary 108

CHAPTER 4: URBAN STREET HOUSES IN VIETNAM 4.1 Definition of Street Houses in Urban Vietnam 110

4.2 Evolution of Street Houses in Urban Vietnam 111

4.3 Diversity of Urban Street Houses 115

4.4 Flexibility of Urban Street Houses 121

4.5 Six Street Houses in Hanoi and Ho Chi Minh City 128

4.6 Summary 144

PART III: DESIGN APPLICATIONS CHAPTER 5: PROPOSED TYPOLOGY PLANS OF THE TRANSITION FROM TRADITIONAL FOLK HOUSES TO HIGH-RISE HOUSING 5.1 Two New Designs 156

5.2 Summary 170

CHAPTER 6: PROPOSED TYPOLOGY PLANS OF THE TRANSITION FROM CONTEMPORARY STREET HOUSES TO HIGH-RISE HOUSING 6.1 Proposed Typology Plans of the Transition from Street Houses to High-rise Housing 172

6.2 Two New Designs 182

6.3 Summary 191

CONCLUSIONS AND SUGGESTIONS 193

REFRENCES 198

ACKNOWLEDGEMENTS 211

(Huan, 2007) 1.4 Average monthly sunhours in Hanoi and HCMC Figure redrawn by author

(Vietnamese Architecture Research Institute, 1997) 1.5 The 3-tier approach to the design of buildings environment

Vietnam; (b) Service cores on the hot sides of built form; (c)

Sun path and HCMC tower designed by Ken Yeang (2007)

Figure redrawn by author

1.12 (a) Vertical and cross ventilation model for the building

envelope; (b) Horiziontal ventilation and vertical

sun-screening on the South facade of the Moulmein Rise,

Singapore; (c) Controllable window (Chieu, 2006); (d)

Protruding balconies in the Newton Suites, Singapore

Figure redrawn by author; photo taken by author

1.13 (a) Shading by eaves; (b) Shading by transitional space Figure drawn by author

1.14 Master section showing recycled rainwater system Figure taken from

Yeang, K., 1998 1.15 Podium section showing rainwater systems through eco-cells Figure taken from

Yeang, K., 1998

2.1 Rate of family sizes in urban Vietnam Figure drawn by author 2.2 Number of generations in a household in urban Vietnam Figure drawn by author 2.3 Master plan of folk housing typical of northern Vietnam Figure redrawn by author 2.4 Traditional folk housing typical of northern Vietnam Figure taken from Hoang

H.T., 1996 2.5 A view of a traditional village, and a country lane in in

northern Vietnam

Photo taken by author and from internet 2.6 Front court and a pen for livestock in a traditional house in

Duong Lam Village

Photo taken by author and from internet 2.7 Altar in a living room of a traditional house in Vinh Phuc, and

typical interiors of old houses in Duong Lam Village

Photo taken by author

2.8 Some folk houses in northern Vietnam Photo taken by author

2.10 Bamboo screen infront of the main space, interior and the altar

in Ruong house

Photo taken from internet

2.11 Master plan of Hue garden house typical Figure redrawn by author 2.12 Garden around Hue garden houses Photo taken from internet 2.13 The Chau house in Cai Lay district Tien Giang province Figure taken from Giang

N.H, 2007 2.14 Master plan of the Chau house Figure taken from Giang

N.H, 2007 2.15 The main house of the Chau house Photo taken from Giang

N.H, 2007 2.16 Master section of the Chau house Figure taken from Giang

N.H, 2007

2.17 Chau house looking outside from the living room Photo taken from Giang

N.H, 2007 2.18 Living room in the Chau house Photo taken from Giang

N.H, 2007 2.19 Well-air wall and open door in the Chau house Photo taken from Giang

N.H, 2007 2.23 On the lower level of a Thai house, the family entertains

guests, cooks and weaves, and some stilt houses in southern

highland of Vietnam

Photo taken from internet

2.24 Tay ethnic minority's stilt house Figure taken from Hoang

H.T., 1996 2.25 Sections of Tay ethnic minority's stilt house Figure taken from Hoang

H.T., 1996 2.26 Xa pho ethnic minority's stilt house and Muong ethnic

minority's stilt house

Photo taken from internet

2.27 Dao ethnic minority's stilt house Main façade and master

N.T, 2010

3.1 Prevailing wind direction in northern Vietnam Figure redrawn by author 3.2 Folk house typical in Northern Vietnam Figure redrawn by author 3.3 Main part of a typical folk house Figure redrawn by author

3.4 3D Model of folk house typical in northern Vietnam Figure taken from Quang

N.M.L, 2010 3.5 3D Model of the main part of folk house typical in northern

Vietnam

Figure drawn by Quang N.M.L, 2010

3.7 Ventilation in the cross section and cross-ventilation through

two air-holes in the lengthwise section

Figure drawn by author

3.8 Planting green tree principle around house Figure drawn by author

3.11 Window with mobile bamboo screen in traditional house Figure drawn by author

based on on-site survey

N.M.L, 2010 3.14 Main façade, mobile bamboo screen, and verandah of the Vinh

house

Photo taken by author

based on on-site survey

N.M.L, 2010 3.17 Main façade, open doors, well area, and verandah of the Hung

house

Photo taken by author

3.18 Floor plan of the Huyen house Figure drawn by author

based on on-site survey

N.M.L, 2010 3.20 Gate, main façade, north façade of the shop, and shop of the

Huyen house from the inside

Photo taken by author

based on on-site survey

3.22 Floor plan of the individual house Figure drawn by author

based on on-site survey

N.M.L, 2010 3.24 Verandah, main façade, open doors, and a small window in the

rear of the Man house

Photo taken by author

3.25 Compositional layout of folk housing Figure drawn by author 3.26 Basic layout of the main part Figure drawn by author 3.27 Toilet location in a compositional layout Figure drawn by author 3.28 Green garden in traditional folk housing Figure drawn by author

4.1 Old street house Hanoi Old Quarter Photo taken by author 4.2 Old street house in Cho Lon area in Ho Chi Minh City Photo taken by author 4.3 Number of floors and lengths of street house in 5 periods Figure drawn by author 4.4 Typology of street house classified by morphology Figure drawn by author 4.5 Typology of street house classified by number of open sides Figure redrawn by author 4.6 Disordered Type of street house group’s layout - Mixed,

diverse module sizes and shape

Photo taken from Google earth; Figure drawn by author

4.7 Ordered type of street house group’s layout - Designed same

module size and shape

Photo taken from Google earth; Figure drawn by author

4.8 Street house in district 10, HCMC Photo taken by author 4.9 Sketch of a group façade in a busy street Figure drawn by author 4.10 Combined model of a street house group Figure drawn by author 4.11 Plans of a street house typical designed by Nha-Vui company Figure taken from Nha-

Vui company 4.12 Section of a street house typical designed by Nha-Vui

company

Figure taken from Vui company

Nha-4.13 Districted function and organized traffic sketch of a street

house typical designed by Nha-Vui company

Figure taken from Vui company

Nha-4.14 Section typical showing the diversity of room location Figure drawn by author 4.15 Smart expandable spatial composition Figure drawn by author 4.16 Section showing expansibility of street house by adding more

storey

Figure drawn by author

4.17 Diagram showing natural ventilation through inner courtyard

and staircase in street house typical

Figure drawn by author

4.18 Natural ventilation and illumination sketch of street house

typical designed by Nha-vui company

Figure taken from Vui company

Nha-4.19 Main Façade of the 86 Hang Dao House Photo taken by Luan

L.V.T, 2010 4.20 Plans of the 86 Hang Dao House Figure redrawn by author 4.21 Master Section of the 86 Hang Dao House Figure redrawn by author 4.22 Main Façade of the Truong House Photo taken by author

based on on-site survey 4.24 Master Section of the Truong House Figure drawn by author

based on on-site survey

N.M.L, 2010

based on on-site survey 4.27 Master Section of the Lien House Figure drawn by author

based on on-site survey

N.M.L, 2010 4.29 Master Section of the Tuan House Figure redrawn by author

based on on-site survey

based on on-site survey

D.D, 2010 4.32 Master Section of the Minh House Figure redrawn by author

based on on-site survey

4.33 Plans of the Minh House Figure redrawn by author

based on on-site survey

N.M.L, 2010 4.35 Master Section of the Hoang House Figure redrawn by author

based on on-site survey

based on on-site survey 4.37 Composition of street house Typical Figure drawn by author 4.38 Old street house’s eco-sufficient spatial composition - Plan,

and master section

Figure redrawn by author

5.1 Design solutions for the modern sky-window with horizontal

ventilation

Figure drawn by author

5.2 Vertical and cross-ventilation model for the façade and the

roof

Figure drawn by author

5.3 a Shading by eaves: b Shading by transitional space Figure drawn by author 5.4 Three basic unit layouts with a forecourt where a pond or a

water feature is located

Figure drawn by author

5.5 A few combinatory examples where different types of housing

units are combined

Figure drawn by author

5.6 Five proposed typologies of a high-rise apartment Figure drawn by author 5.7 Type 1 - 26-storey apartment model Figure drawn by author 5.8 Cross-ventilation of a plan and section Figure drawn by author 5.9 Type 1- Plans showing the flexible combination of apartment

types

Figure drawn by author

5.10 Apartment units typical of type 1 Figure drawn by author 5.11 Type 2 - 30-storey apartment model Figure drawn by author 5.12 Cross-section of the second type of housing Figure drawn by author 5.13 Type 2 – Plans showing the flexible combination of apartment

types

Figure drawn by author

5.14 Apartment unit typical of type 2 Figure drawn by author 5.15 Natural ventilation through two façade layers Figure drawn by author

6.1 Sections showing natural ventilation in the street house and in

the apartment unit

Figure drawn by author

6.2 Some proposed floor plans of apartment unit Figure drawn by author 6.3 A few combinatory examples where different types of housing

are combined

Figure drawn by author

6.4 Basic proposed typologies of a high-rise apartment Figure drawn by author 6.5 Basic proposed typologies with corridor added

6.6 Fourteen proposed typologies of a high-rise apartment Figure drawn by author 6.7 Models of two units combination Figure drawn by author 6.8 Plans of flexible combinations Figure drawn by author 6.9 Plans of typical apartment units Figure drawn by author 6.10 Type 1 - 26-storey apartment model Figure drawn by author 6.11 Type 1 – Cross-section of the first type of housing Figure drawn by author 6.12 Type 1 – Combinations of various units Figure drawn by author 6.13 Type 2 - 31-storey apartment model Figure drawn by author 6.14 Type 2 -Cross-ventilation of a section Figure drawn by author 6.15 Type 2 – Combinations of various units Figure drawn by author

Research Institute, 1997) 1.2 Average rainfall (mm) in Hanoi and Ho Chi Minh

City

Table redrawn by author (Vietnamese Architecture Research Institute, 1997) 1.3 Monthly mean sunshine hours (hours/day) in Hanoi

and HCMC

Table redrawn by author (Vietnamese Architecture Research Institute, 1997) 1.4 Monthly mean solar radiations (kWh/m2/day) in

Hanoi and HCMC

Table redrawn by author (Vietnamese Architecture Research Institute, 1997)

2.1 Comparison of characteristics of traditional houses

in different regions of Vietnam

Table drawn by author

2.2 Comparison rate of family size in urban Vietnam Table redrawn by author

(Thiem N.D., 2001) 2.3 Household structure divided according to aged

groups

Table redrawn by author (Thiem N.D., 2001) 2.4 Number of generations in a household in urban

5.1 Combined solutions of the forecourt in urban

high-rise apartment of urban Vietnam

Table drawn by author

5.2 Summarize of characteristics of proposal apartment Table drawn by author

6.1 Spatial composition models of New Designs Table drawn by author

Figure drawn by Quang N.M.L, 2010

6.2 Summarize of characteristics of proposal apartment Table drawn by author

INTRODUCTION

Previous Studies

Many researchers and scholars in Vietnam have given emphasis to the characteristics of Vietnamese traditional folk housing Nevertheless, there has been little discussion on how such characteristics of traditional folk housing may be adapted to the high-rise and high-density lifestyle in Vietnam Kinh (2004) studied Vietnamese traditional housing and showed the influences of natural and hot-humid elements on architecture Son (2006) researched on the Vietnamese traditional house and emphasized on its ecological elements Thang (2006) considered the Vietnamese traditional folk house as an ecological architecture However, these authors did not make any on-site survey and their studies were rather incomplete

Nevertheless, a number of similar studies have been conducted in other countries For example, Bay (2002 & 2004) investigated the Bedok Court Condominium project, which was an ideological re-invention of traditional

‘kampong’ living in Singapore By surveys of human response and of human thermal comfort, Bay demonstrated that the traditional open space as the forecourt is suitable for Singapore life style and contributes to encourage

the thermal comfort By using environmental performance modeling, Srivastar (2009) proved that the traditional passive strategies can be effectively adapted to modern design conditions and benefit the comfort conditions in dwellings of India Kamal (2006) recommended an adaptation design of the traditional Malay house to meet the requirements of comfortable living in modern houses but he did not give any design proposal

By comparison of traditional and some modern samples, Yilmaz (2008) analyzed low energy passive strategies in building design for five different climatic zones of Turkey Yilmaz proved that designers that they should take lessons from the traditional samples through implementation of their strategies with new materials and technologies in new building design Yeang (1996) wrote extensively about the systemic technology of the eco-skyscraper Yeang’s work is exemplary in the use of passive and mixed bio-climatic strategies, as well as in the use of clean means of reducing building inputs and outputs

The old street house has been extensively studied in previous studies The modern street house, despite its dominant appearance in contemporary urban fabrics of Vietnamese big cities, has not been adequately studied so far, even though it is sometimes criticized in Vietnamese architectural and urban debates Kien (2008a) researched on how to preserve and restore the old

street houses in Hanoi Based on the results of numerous surveys, Kien highlighted specific characteristics of the old street house in detail Apart from that, a comparison between the typology and the characteristics of old street house and that of the modern street house in Hanoi to outline the weaknesses of the modern street house and highlight the outstanding advantages of Hanoi old street house In this study, there is a need to analyze and compare plans for the preservation and conservation of the old street house Dan (2005) analyzed the social factor in street house alleys in

Ho Chi Minh City However, he only showed the problems and did not offer any solution Tam (2000) gave an overview of the history and the development of street houses in Vietnam and presented a spatial composition about it in brief

Meanwhile, Chon (2007) briefly discussed the characteristics of the old street house in Hanoi and Chinese shop-houses in Ho Chi Minh City Then,

he made a comparison between the old street house and the Chinese houses in terms of spatial composition and construction Song (2004) made observations on the typo-morphology of deep and narrow lots in the Old Hanoi area and showed the relationship between it and historical, economic, and social elements In short, previous studies published about Vietnamese street houses typically focused on the characteristics of the traditional street house or considered the historical and social issues regarding street house

shop-living environment However, there are only a few studies on special elements of the contemporary street house and the connection between them and modern housing design

Moreover, Chieu and Khai (2006) studied the principles applied in housing design in Vietnam Nevertheless, they focused more on the ecological concept than the proposed special solutions In his master thesis, Huan (2007) proposed a design method for high-rise housing in Ho Chi Minh City, under micro-climatic and energy-efficiency conditions He also gave emphasis on the importance of lessons learned from traditional housing design However, he did not recommend how to apply them to modern high-rise housing

eco-Conducting research on the special features of indigenous houses and applying them to urban high-rise housing in Vietnam is necessary because

of the lack of related study on this subject matter

Objectives

This study focuses on the application of the special features of indigenous houses to urban high-rise housing in Vietnam We conducted on-site surveys, collected data, and analyzed the specific values of indigenous

dwelling and modern Vietnamese lifestyle in detail The basic principles on passive design have been suggested for high-rise housing designs In addition, a number of new high-rise apartments have been proposed

The following tasks are intended to achieve the above goals The first task is

to investigate the spatial characteristics of the traditional folk house and Vietnamese lifestyle in the countryside; to select and develop the advantages

of traditional housing, and apply them to high-rise housing designs; and to propose new typologies in modern high-rise housing designs The second is

to research on the characteristics of the street house and Vietnamese urban lifestyle; to find out and develop the advantages of the street house, apply them to high-rise housing designs; and to propose new typologies in modern high-rise housing designs

Organization

This dissertation is organized as follows Part I focuses on the “Pedagogical Study” and includes one chapter The basic principles of passive design for high-rise housing are outlined in Chapter 1 At first, climatic data of Vietnam is given Basic passive design method is concerned Then, basic

principles of passive design for tropical high-rise housing in Vietnam are outlined Rainwater harvesting is discussed at last

Part II focuses on the “Research and Survey” and includes three chapters Chapter 1 provides an overview of Vietnamese traditional folk housing Special characteristics of traditional houses in the north, the south, central, and the highlands are introduced

Traditional folk housing in northern Vietnam is analyzed in Chapter 2 According to a survey in 2008, traditional houses in Vietnam, particularly in the Duong Lam Village (one of the oldest villages in Vietnam), can be classified into four different typologies; these have been included in this study The features of those typologies, such as composition, eco elements, and construction materials, among others, are examined Finally, the particular characteristics in the spatial composition of traditional folk housing are discussed

Chapter 3 is an investigation of the urban street houses in Vietnam Special characteristics of contemporary street houses are examined in terms of their diverse and flexible typologies Definition and development of the street house in Vietnam urban are presented An old street house in the Hanoi Old Quarter and five contemporary street houses in Ho Chi Minh City are reviewed Finally, the composition of street house is presented

Part III focuses on “Design Applications” and includes two chapters Chapter 5 proposes the typology plans for the transition from traditional folk house to high-rise housing Chapter 6 presents the typology plans for the transition from contemporary street house to high-rise housing

A summary of this research, as well as key observations, are made in the latter part of the study This part identifies future research needs This study hopes to contribute significantly in helping reshape urban living in Vietnam

PART I PEDAGOGICAL STUDY

CHAPTER 1 PASSIVE DESIGN PRINCIPLES FOR A VIETNAMESE HIGH-RISE

HOUSING DESIGN

Passive systems are designed to improve conditions without using any electromechanical systems Examples of passive design strategies include adopting appropriate building configurations and orientation, in relation to the local climate, and a suitable façade design Passive design does not preclude the use of mixed mode or productive mode devices, although they are considered as last options in the creation of optimal comfort levels in a building The passive design requires an understanding of the climatic conditions of a locality As such, designs are not just meant to synchronize a building’s design in relation to the climate, but to optimize the ambient energy of the locality into the design, and thereby improving internal comfort conditions As such, an improved level of comfort remains even during an electrical power failure (Yeang K., 2007)

The maximum utilization of natural energy such as solar or wind energy is the most efficient way of saving energy The passive design generates power through the utilization of natural forms of energy, and not through any mechanical system Properly designed and constructed passive houses bring many benefits, such as low energy bills; high economic returns and greater financial independence; greater thermal comfort, less reliance on noisy mechanical systems; reduced maintenance costs; increased day-lighting or higher quality of lighting systems; and reduced energy usage and reliance on fossil fuels (Xu F et al., 2006) The significance of passive design is very important to high-rise housing, which consumes considerable energy This means that architects and designers need to understand and consider the environment, geography, and the climate during the design and planning phase Thus, the design should have thermal insulation, natural ventilation, and should be shaded from sunlight

Despite the development of industry, commerce, finance, and the rapid increase in urban population, there is no increase in land resources In this context, high-rise apartments are developed because of their huge economic value In recent years, simple but mediocre glass and concrete box buildings, with fully glazed façades, have become popular among Vietnamese architects However, the designers are usually insensitive to local climatic conditions when designing buildings in Vietnam, often resulting in

unnecessary discomfort and energy waste Natural ventilation and illumination are not carefully considered The core is usually closed and located in the center In many cases, a solid form with a huge rectangle or square is what comes out in their designs There is no method to prevent the negative influence of direct solar radiation on houses (Chieu H.D and Khai V.T , 2006) Additionally, there is no high-rise building using solar energy nowadays Although high-rise buildings help conserve land resources, their negative impacts on the environment have become more serious due to the consumption of a large amount of natural resources and energy Passive design should become a national strategy in Vietnamese architecture to reduce building maintenance costs, protect the environment and human health, and develop high-rise buildings in a sustainable way (Huan G.N., 2007)

In this chapter, the basic principles of a passive design method for high-rise housing in relation to the local climate of Vietnam are investigated First, a study on the climate data of Vietnam is conducted to outline the recommendations for suitable design principles Second, the three-tier approach to building design to control its internal environment is introduced with emphasis on the passive design method Third, the five main points that must be considered during the design process are discussed: (1) configuration and orientation, (2) building envelope, (3) natural ventilation,

(4) day-lighting, and (5) passive solar heating, cooling, and thermal storage Finally, the rainwater harvesting is discussed in the last section

1.1 Climatic Data of Vietnam

This part reviews the climate data of Vietnam The correct climate assessment helps create buildings suitable to the external environment The fundamental reason for developing a building is to provide shelter from various climate conditions, such as cold, heat, wind, and rain The climate of

a building is the set of environmental conditions surrounding a building; it affects the internal environment through heat transfer

Climate has important effects on the energy performance of buildings in both winter and summer, and on the durability of the building fabric Climates that are favorable to energy use and durability also make the external environment of a building attractive and useful for recreation Although the overall features of a climate are beyond our control, the design

of a building can have a significant influence on the climate behavior of a building (Randall M., 1993)

To design a building that is appropriate to its location, the climate of the site needs to be studied and predicted The following climate factors can be considered: temperature, humidity, precipitation of rain and snow, wind

speed and direction, sunshine hours and solar radiation, and atmospheric pollution

Vietnam is located in a tropical and temperate zone at the heart of Southeast Asia between 23.22° and 8.30° N, lying in the eastern part of the Indochina peninsula It is characterized by a strong monsoon influence, a considerable amount of sunny days, and a high rate of rainfall and humidity

There are two main climatic regions in Vietnam, the north and the south (Hoang H.T., 1996); the climate parameters between these two regions vary Hanoi experiences the typical climate of northern Vietnam, where summer

is hot and humid, and winter is relatively cool and dry The weather changes follow the four seasons, contributing to the diversified feature of Hanoi’s climate In contrast, Ho Chi Minh City (HCMC) experiences the typical climate of southern Vietnam, which is a tropical climate with two distinct annual seasons: the dry season and the rainy season Some of the most commonly used climate data of Hanoi and HCMC are described in the following sections

Temperature

In Hanoi, the minimum winter temperature can dip to as low as 6–7 °C, excluding the wind chill, whereas the summer can get as hot as 38–40°C

The average annual temperature is 23.2 ºC (73.7 ºF) The average temperature in winter is 17.2 ºC (62.9 ºF), whereas the average temperature

in summer is 29.2 ºC (84.6 ºF) July is the hottest month, whereas January is recorded as the coldest month

HCMC has the so-called subequatorial climate, with a high and stable temperature The yearly mean temperature is about 27.96 ºC April has the highest average monthly temperature (30.5 ºC), whereas December has the lowest temperature (26 ºC) The highest temperature can reach as high as

39 °C around noon in late April, whereas the lowest temperature may fall below 16 °C in the early mornings towards the end of December

Table 1.1 Average temperatures (0C) in Hanoi and Ho Chi Minh City

The average temperature statistics for Hanoi and Ho Chi Minh City are presented in Table 1.1 (Vietnamese Architecture Research Institute, 1997)

Rainfall and Humidity

Hanoi has an average rainfall of around 1,800 mm per year On average, there are 146 days per year with more than 0.1 mm of rainfall (precipitation)

or 12.2 days of rain, sleet, snow, etc per month Heavy rainfall occurs

during summer (1,682 mm per year) The winter months are relatively dry, although spring often brings light rain The rain becomes more intense with the monsoons in winter

HCMC has an average rainfall of around 1,934 mm per year or 151 mm per month The rainy season, with an average rainfall of about 1,800

mm annually (150 rainy days per year), begins in May and ends in late November Heavy rains usually occur in a short duration and diminish towards the end of the day; however, it can continue throughout the day sometimes The dry season is from December to April next year The average rainfalls in Hanoi and HCMC are given in Table 1.2 (from the Internet) The average annual humidity is 79% in Hanoi and 75% in HCMC

Table 1.2 Average rainfalls (mm) in Hanoi and Ho Chi Minh City

Two diagrams presenting average temperature and rainfall in Hanoi and Ho Chi Minh City are shown in Figure 1.1 Average temperature and rainfall in

Ho Chi Minh City are higher than those in Hanoi although Hanoi has a very high rainfall in winter months

Figure 1.1 Average temperature and rainfall in Hanoi and Ho Chi Minh City (from left to right)

Wind data

The direction of the wind affects both the structural design and the thermal design of a building The wind direction data can be diagrammatically presented by a “rose” of arms around a point, which represent the frequency

of wind blows from each direction The wind rose, which indicates the wind speeds in Hanoi and HCMC from different directions, is shown in Figures 1.2 and 1.3 (Huan G.N., 2007)

In Hanoi, the prevailing cool winds in summer comes from the south-east

In addition, Hanoi is influenced by the monsoon coming from the north and the north-east in winter season In HCMC, the prevailing cool winds in the dry season come from the southeast, whereas the prevailing cool winds in the rainy season comes from the west and the south-west (Vietnamese Architecture Research Institute, 1997)

8.8

> 3m/s 2-3m/s 1-2m/s 10%

Figure 1.2 Directional wind rose of wind speeds in Hanoi

> 3m/s 2-3m/s 1-2m/s 10%

Dry season (Mar, Apr, May) Rainy season (Jul, Aug, Sep) Figure 1.3 Directional wind rose of wind speeds in Ho Chi Minh City

Solar radiation

Table 1.3 Average monthly sunshine hours (hours/day) in Hanoi and HCMC

is estimated to be 122.8 Lcal/cm2

HCMC has an average of 2,000–2,600 hours of sunshine per year There is

an average of 2,299 hours of sunlight per year, with an average of 6.3 hours

of sunlight per day Average sunlight hours in HCMC ranges between 4.9 hours per day in August and 8.1 hours per day in March The average monthly sunshine reaches 160–270 hours

Figure 1.4 Average monthly sunhours in Hanoi and HCMC (from left to right)

The average monthly sunshine hours (hours/day) and the average monthly solar radiations (kwh/m2/day) in Hanoi and HCMC are presented in Tables 1.3 and 1.4, respectively As shown in Figure 1.4, the average monthly sun hours in HCMC are higher than those in Hanoi (Vietnamese Architecture Research Institute, 1997)

Thus, there is a dominant demand for cooling throughout the year in both Hanoi and HCMC, but a small amount of heating is required in Hanoi, which is estimated to be around 20% of the entire period The amount of cooling in degree hours (above 25 °C) in HCMC is almost double than that

in Hanoi In both cities, there is a significant demand for dehumidification (Tuan D.V., 2006)

The following weather conditions are also a matter of concern The high humidity accelerates rotting, rusting, and the growth of algae and molds With heavy clouds covering the high water vapor content in the air, direct solar radiation is filtered In summer, the prevailing cool winds mainly come from the south and the southeast (Figures 1.2 and 1.3) The winds are generally of low-variable speed Strong winds can occur with the rains February and March have persistent, light, and drizzling rain The rainy months are August, October, and November Rains become more intense with the monsoons in the winter Vegetation growth is sometimes difficult

to control given the country’s atmospheric condition, moderate heat, and high levels of rainfall Air flowing across any surface creates friction The wind spreads are higher in elevated areas and are lower near the ground, where there are many obstructions The relatively high percentage of reflected solar radiation from the sea, sky, and beach requires the use of glare controls in houses Occasional strong winds that occur during the monsoon season may pose serious hazards to both houses and inhabitants

1.2 Passive Design Method

In this section, the definition of passive design and related concepts will be outlined

Figure 1.5 The 3-tier approach to the design of buildings environment control

First, the three-tier approach to building design to control the internal environment is presented in Figure 1.5 In the first tier, designing the building envelope, which serves as the thermal envelope for keeping warm and staying cool, is necessary In the second tier, environment-friendly technology should be integrated to the basic building structure Both the first and the second tier are passive control methods The system capacity of the passive control method can help reduce the capacity of the active control method Hence, the total cost of making, using, maintaining, and demolishing the building should be considered in every process when constructing a green building (Suh S.J., 2009)

The passive and active control methods are presented in Figure 1.6 The climate and microclimate conditions in the locality should be studied carefully Based on this climate data, the basic building design is formed

(tier 1) The building orientation, form, and envelope in this basic design are designed to ensure thermal comfort The control systems are integrated into the basic building design in the passive control method (tier 2) The active control systems are used to gain the thermal comfort zone and to overcome the disadvantages of the passive control method

Figure 1.6 Passive and Active Control methods

If the building is to have a symbiotic relationship with nature and become part of ecological systems, the technical strategy must be consistent with this goal by using the passive control method This harmony is more important than the other aspects of the building design, and the design pattern should be determined by the quantitative analysis Accordingly, the construction of preeminent environmental buildings is raised as an urgent concern Ensuring that the technical strategy is in harmony with the environment and uses new or renewable energy will help make these

buildings become green The most ideal green buildings are those that do not leak energy and have preeminent environmental features using the passive control method All these are necessary to operate the building system

Figure 1.7 Environment-friendly building and Energy Load Reduction technologies

Figure 1.7 shows the relationship of an environment-friendly building and energy load reduction technologies As shown in the figure, the level of effort and relative energy load should be reduced when designing a green building The energy load reduction can be achieved depending on the effort and cost spent However, efforts should be made to reduce the energy load with low effort and low cost Accordingly, line A is the most economical technology when considering effort and cost It is followed by line B and