Row House in Hanoi and Some Climatic Design

High Density Housing in a Central District in Hanoi A Climatic Design Analysis

Le Lan Huong Lecturer Hanoi University of Civil Engineering

Abstract Climate is one of the important factors to be considered in planning and architectural design. In Vietnamese traditional architecture, open spaces such as garden, courtyard and light well are very necessary parts of the house, especially in a narrow and deep house, which has been a typical house in Hanoi for many decades. The main topics taken into consideration are the use of the open spaces in the tube house and their effect to the indoor climatic condition. In this study, simulations using DEROB-LTH, AIOLOS and Leso DIAL software were established to calculate the influence of the open space on ventilation, thermal comfort and lighting condition. The result is: i) a courtyard or a light well plays an important role in the indoor climate. ii) changing the height of light well directly affect to cross ventilation, so it makes a great influence to thermal comfort in the house. iii) changing the height of light well is less effect than adding a small backyard in both view of ventilation and lighting for the studied tube house.

Introduction Vietnam is a republic of Southeast Asia bordered by China on the north, by the South China Sea on the east and south, and by Cambodia and Laos on the west. Officially it is the Socialist Republic of Vietnam and its area is 331,690 km² with the coastlines of 3,444 km (excluding islands).

Vietnam has a population of 79,939,014 (2001), yielding a population density of 241 people per km². The southern part of the country is more urbanized than the northern part, but although urban development is proceeding, the majority still live in small villages, only 20 per cent of the population being urban. Most residents are ethnic Vietnamese, and Vietnamese is the common language.

Hanoi, capital city of Vietnam, is in the northern part of the country, about 140 km from the Gulf of Tonkin. The city is located on the west bank of the Red River, in the middle of the fertile river delta of the same name. Metropolitan Hanoi had a population of 3,056,146 in 1989.

Since the 1980s, rapid and uncontrolled migration into Hanoi from other areas of Vietnam and the arrival of numerous foreigners has created severe housing problems. Economic and social problems have also developed as Hanoi has tried to absorb poor migrants who seek employment in the city.

Much of the city is characterized by leafy boulevards and villas built by French colonialists, but Hanoi actually has been inhabited for about 1,400 years. Hanoi is a city in transition. Having sustained periodic bombing during the Vietnam War, the city now features high-rise office buildings and hotels in its outer districts. With the opening of Vietnam to joint-venture business and tourism, tourists more consider about Hanoi through architecture works in Old Quarters.

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Figure 1. Hanoi- a picture of the old and the new development.

Background Vietnam occupies the easternmost part of the Indochina’s Peninsula, a rugged, elongated S-shaped strip of mountains, coastal plains, and river deltas. Vietnam may be divided into four major regions. In the northwest is the mountainous southerly extension of China's Yunnan Plateau. To the east of the highlands is the Red River delta, triangularly shaped lowland along the Gulf of Tonkin. Hanoi is located in this region.

Geography Hanoi is located in the centre of north Vietnam, limited between 20°53 to 21°23 North latitude and 105o44 to 106o02 East longitudes. Most of the area of Hanoi is in the Red river delta with an average altitude from 5m to 20m.

Figure2. Map of Vietnam

Climate Hanoi has a tropical hot – humid monsoon climate with clearly four distinctive seasons. Hanoi has a high humidity, hot rainy summer and cold dry winter. The most distinctive characteristic of Hanoi’s climate is the fluctuations between the cold and the hot season.

Temperature In summer, from May to September, the weather is hot, average temperature during day is 30 –34oC with a great deal of sunshine. The air temperature reaches the highest values at the end of June and the early of July. In the winter, from November to January, waves of Northeast monsoons in every 7 –10 days bring in cold air, lowering the average temperature to 10 –15oC. (Figure 5)

Relative Humidity Hanoi is located near the sea and in the monsoon effect area, so the relative humidity is very high during most of the year. The average relative humidity of more than 70% occurs all the time, especially it reaches a high value in March and in the rainy season (from May to September). (Figure 5)

Wind

Figure 3. Prevailing wind in winter and summer Figure 4. Total wind

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High Density Housing in a Central District in Hanoi

In summer, the prevailing wind is South-eastern wind, coming from the sea. In the winter, prevailing wind is from North and Northeast with dry and cold air making the weather muggy and uncomfortable.

Figure 5. Monthly climatic data graph

Architecture Concerning architecture, Hanoi can be divided into the following areas: the ancient and old streets, the old citadel, the residential areas and the new quarters.

Traditional Housing in Hanoi Traditional architecture has been developed through trial and error to suit the social needs of the inhabitants and the local climatic conditions.

Figure 6. A traditional house

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Orientation in a traditional house plays an important role in coping with the climate. Most traditional houses in the North delta are open to the South or Southeast to let sea wind in. Thick brick walls with very small windows facing East and West can restrict the direct radiation of the sun inside the house.

The roof shelters the occupants from the rainfall and the heat of solar radiation. The slopping roof drains off a big amount of rainfall. The deep verandah provides shading for the wall and prevent the rain splashing this wall.

The construction of the houses is wood frame structures made from timber or bamboo. The natural cross ventilation has been taken into account by using a permeable enclosure. The building materials of wall such as woven bamboo and wood board permit air movement indoors. Roof materials such as reed and clay tile, laid on bamboo frames give the possibility for air flowing through the splits.

Garden with many kinds of trees and plants surrounding the house is not only for providing fruit and vegetable but also for improving the indoor climate of the house. This garden plays a role as a buffer space of the house. Location and kind of these trees are also carefully considerate in the traditional houses.

Hanoi housing in the French colonial period In the early French colonial period (1874-1920) the built up area was largely confined to three sections of Hanoi’s old sector: Ancient Quarter, the Citadel Area and the French Quarter. In 1922, French Government decided to establish a new residential area (now it is called BTX area) to provide dwelling for Vietnamese officials as well as reduce the congestion in the overpopulated quarters of Hanoi.

Ancient Quarter Hoi An set apart, Hanoi is Vietnam's only city where ancient streets can be found. The houses still keep an appearance as they had at the end of 19th century. Prior to the French colonial period these streets had all the same appearance and laid out in an order similar to a chessboard; most of them were named after the goods manufactured or sold there. For instance, Hang Duong means "Sugar Street", Hang Bac "Silver Street"…

Figure 7. Ancient Quarter

Most of houses of these streets have the shape of tube and are called "tube houses". The house is like a tube with its narrow width and deep length; it is sometimes opened into another street, different from that of the entrance door of its front. All the houses have similar disposition with the front rooms serving as places where goods are manufactured or sold, small open courtyards to let in light, usually with ornamental rock works and little water-pools with gold fish, and adorned with ornamental plants and flowers. Back rooms serve as living sections with dining and bedrooms. Most of these houses are covered with small tiles with a characteristic feature: two walls of the gable are built so that they arc higher than the roof and evoke a staircase with two funny pinnacles.

Thus, "tube- like houses" are simple and narrow and mostly one-storey houses. They serve both as the place of manufacturing or of selling products and as the dwelling house of the family. In these streets, the shops are open all day long and even in the evening; the quarter is always lively, the street inhabitants help each other, having the same interests. This community of people share the same fate; they are united by feelings of solidarity.

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French quarter In 1886, the French Administration designed a master plan for the city's development. The Ho Guom area was reconstructed at first. In the second stage of reconstruction, ponds, lakes, waterways including the To Lich river were filled in, and the old citadel together with an earthen enclosure (1894-1896) destroyed. The ancient streets had their road straightened and were added with works of infrastructure. Some of the old houses were

Figure 8. A house with French and Asian architecture styles

their original architectural style being respected, others left the place to new houses built in Western style with 2 or 3 stories.

As the result, "Western" streets emerged, one to the south of Ho Guom Lake, and another on the place where the old citadel used to be, near the Concession Area which was built in the first days of the period of French colonialism.

These core buildings with "orthodox" architecture, with black stone roofs, surrounded by peripheral verandas. Most of the villas were built after the architecture of France: inclining roofs, smart and meticulous decorations over the door and on the roof. In these three above-mentioned quarters, in the 20s and 30s appeared buildings with European and Asian architectural styles.

Most of them result from previous research in architecture, particular in order to make the buildings more adapted to the traditional and natural environment.

The streets constructed during this period contribute to the architectural richness of Hanoi, a city with harmonious beauty enhanced by natural landscapes and cultural reminiscences.

Bui Thi Xuan (BTX) district - The study area The house chosen for this research is located in Bui Thi Xuan district. A mixture of Vietnamese tube houses and French villa styles can be found at this area. Around 1940, land lots in Hanoi were narrowed and the large- scale villas previously constructed were no longer feasible. This period established the strong architectural character of the local structure extending the fabric of the French Quarter in the form of a later and more domestic scale. Thus this combination style was sought and its houses perform to be appropriate with the climate and lifestyle of Hanoi people. The typical house in BTX area has a tube-like shape with 5-10meters wide and around 20 meters deep. It is divided into 2 or 3 parts by courtyards. The inner courtyard in this kind of houses plays very important role. The number of inner courtyards does not depend on the area of a lot, but rather on the depth of each house. A courtyard has several functions that are indispensable, particularly in the case of tube- like house.

Figure 9. A house in BTX area

The following are some of its function in order of importance – it serves as: A light well A part of the natural cross ventilation system A space for outdoor activities: washing, drying, and preparing food and

some cottage industry activities, decorative plants, a rocky garden, a goldfish bond and so on

A space for further development With regard to through ventilation, courtyards are very effective. With water

present in courtyard, the cooling effect is substantial. The difference between street temperature and indoor temperature is sometime 3 to 4 oC higher.

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Like houses in the Ancient and French Quarter, houses in the BTX area have thick brick walls (220mm) and slope tile roofs. Most of houses are one or two- storey houses with wood frame doors and windows. The high ceilings as well as high doors and windows make the natural cross ventilation better.

Modern Architecture During the period of 1960 - 1970, the State built a series of residential areas in the suburbs. These are prefabricated houses, rather small and of the same model, built in Kim Lien, Trung Tu, Giang Vo, Thanh Cong, Thanh Xuan Bac areas. Now most of them are on the downgrade and lack modern comfort.

The city has been expanded with various construction projects in which of new residential areas in the suburb. Over the last ten years, the city has been developing along the Giai Phong Road, Nguyen Van Cu, Lang Ha, Ngoc Khanh, Thai Ha and in

Figure 10. Some pictures of high block in Hanoi

the area of West Lake villas... Multi- storied buildings of governmental offices are built amidst private houses but the mushroom growth of these areas goes along without following any master plan.

In the near future, many urban-planning projects (South and North Thang Long Bridge areas, West Lake Tourism area...) will be carried out with the cooperation and investment of foreign companies.

It is not a long-term goal of the government to rely on small scale housing as a main source of housing in the urban area, but in reality small scale housing in Vietnam makes up about 80% of the housing fund. Usually people find a bit of land, typically about 4-6 m wide and 15-20 m long. The house then is constructed with or without an architect. Most new tube-like houses are 4 or 5 storey ones with the same way in spaces designing. In this kind of house, living areas such as bedrooms, living room, and dining room are expanded maximum. The area for courtyard decrease as an indispensable result. In some houses, there is no courtyard at all but small a light well above stair area only. Conditions of natural ventilation and day light in many rooms, especially room at the back of house are very poor. Moreover, people tend to build their houses with brick and concrete because of financial reason. Wood has become more and more expensive and impractical material.

Figure 11. A new tube house

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Problem Hanoi is now in a construction boom. Its architectural aspect changes everyday. Since the end of the 80s with the implementation of the renovation policy, economic life having been improved, commerce developed, many houses in the Ancient and BTX Quarter have been demolished, other repaired or rebuilt and often concrete 4- or 5- storied houses have replaced the old ones. The area of these streets has gradually lost the beauty of its traditional architecture.

Figure12. BTX area – Combination between old and new character.

In the view of climatic design, most of the new tube-like houses seem to have adverse effects on thermal comfort. It is now time to start taking carefully consideration in climatic design that makes a higher quality of living in the tube house.

Method Parametric Model DEROB-LTH Derob- LTH was originally developed at Numerical Simulation Laboratory of the school of Architecture, University of Texas at Austin. The Derob- LTH modules are further developed to suit the local needs at the Department of Building Science at Lund Institute of Technology. Derob is a powerful software for calculation the indoor climate and thermal simulation of building. The simulation result is given as hourly values of volume, surface, operative temperature, solar radiation, heating and cooling requirement, energy flow, and as summary for each month and the whole simulation period. However, it may not be a complete tool for hot and humid climate, as it does not take humidity condition into consideration. AIOLOS Aiolos software focuses on the calculation of airflow rate in natural ventilation. It is a good tool for calculation of air change per hour and airflow rate through each volume at specific time. The result is used as in put for Schedule of HVAC in Derob. LESO DIAL Leso-DIAL gives architects relevant information regarding the use of daylight at the beginning of the building design process. Leso Dial is lighting simulation software for many kinds of building such as school, factory, and museum… The result is daylight sufficiency and daylight factor for each volume calculated.

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Method and tool

Method Purpose Tool - To derive a comfort zone for Hanoi habitant - To compare indoor temperatures of final case with the Hanoi comfort zone.

Givoni chart Literature application

- To have general design criteria which can be used as suggestion of Mahoney Table

Mahoney Table

Parametric Modelling

- To study the Base case and understand problems. - To study other developed cases, from which find out the best solutio .

DEROB-LTH AIOLOS Leso DIAL

nTable 1. Method and tool

Traditional Tools

Givoni Chart

0

1000

2000

3000

4000

0 5 10 15 20 25 30 35 40 45Temperature (°C)

Vapo

ur P

ress

ure

(Pa)

janfebmaraprmayjunjulaugseptoctnovdec

100% 90% 80% 70% 60% 50%

40%

30%

20%

10%

C

V

I

DH

INV

EC

IG

HAC

AC: CoolingC: ComfortDH: DehumidificationEC: Evaporative CoolingH: HeatingI: High InertiaIG: Internal GainsINV: High Inertia and Night VentilationV: Ventilation

Figure 13. Givoni chart As can be seen from the Givoni chart, the comfort area for Hanoi is ranged from

16oc to 25oC with humidity from 22% to 80%. In summer, when the temperature is much higher, ventilation plays an important role to make thermal comfort in Hanoi building better.

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Mahoney Table Table 2. Summary result of Mahoney Table for Hanoi climate Topic Variation Suggestion Geography Orientation North and South (long exit is east-west)

Spacing Opening spacing for breezing penetration Air movement Room single banked, permanent provision for air

movement Opening Medium opening (25-40%)

Ventilation

Position of opening

In north and south walls at body height on windward side

Shading Protection of openings

Excluded direct sun light

Walls Light walls, short time-lag Walls and floors Light, low thermal capacity

Building properties

Roofs Light, insulated roofs Rain Rain protection Protection from heavy rain necessary

Case study The studied house is a typical house built in 1990s in BTX area. It is a four-storey house 5.8 meters wide and 22 meters deep. There is a small courtyard that provides daylight and natural ventilation for the house, especially for rooms in the back.

Figure 14. Plans, main section of house No66 Trieu Viet Vuong Street

Figure 15. Some interior picture of house No66 Trieu Viet Vuong Street

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Data Input Input for DEROB-LTH Base Case Description This study is concentrated on the ground floor of a typical tube house in the BTX area. Base case is developed from the existing house mentioned before with certain assumption and modification in order to run DEROB-LTH. - 4-storey house with 3 common walls, which are considered as adiabatic walls. - A unique external wall orientated to South, according to Mahoney suggestion. - A light well- vertical block from ground floor to top for. The height of this space is changed in Case 01 and Case 02. Base on the analysis of climatic data for the whole year, climatic data of two significant months (January and July) have been selected to run cases. Figure 16. Baseline case model (Only ground floor structure, the rest of building excluded)

Table 3. Baseline case description

External wall Volume Function Dimensions Door Window

1 Living room

5.8x6.5x4 3.0x2.2

2 Bedroom 4.2x5.5x4 3 Light well 5.8x4.5x17* 3.3x0.6(2) 4 Kitchen 5.8x 5.5*x4 5 Corridor 1.6x11.5x4 1.0x3.0 Note. * The value will be changed in the developed cases Material Properties Description Table 4. Building Material Kinds Layer Thickness

(mm) Name Conductivity

(W/mK) Wall Material Normal wall

1 2 3

15 220 15

Cement mortar Brick in humidity condition Cement mortar

0.93 0.96 0.93

Adiabatic wall

1 2 3

500 110 15

Mineral Wool Brick in humidity condition Cement mortar

0.04 0.96 0.93

Roof Material Normal roof

1 2 3

10 15 10

Burnt clay tile Cement mortar Burnt clay tile

0.8 0.93 0.8

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Corridor (Vol.5)

Light well (Vol.3)

Kitchen (Vol.4)

Bedroom (Vol.2)

Livingroom (Vol.1)

Internal wall Door Window 1.0x2.4

1.0x2.4 2.0x2.2 1.0x2.4 2.0x2.2 1.0x3.0

Spec.heat (Wn/kgK)

Density(Kg/m3)

0.29 0.2 0.29

1800 1800 1800

0.24 0.2 0.29

50 1800 1800

0.24 0.29 0.24

1900 1800 1900


4 5 6

15 100 15

Cement mortar R.Concrete in high humidity Cement mortar

0.93 2.0 0.93

0.29 0.25 0.29

1800 2400 1800

Adiabatic roof

1 2 3

500 50 15

Mineral Wool R.Concrete in high humidity Cement mortar

0.04 2.0 0.93

0.24 0.25 0.29

50 2400 1800

Floor Material Ground floor

1 2 3 4 5

20 15 100 150 500

Granite Cement mortar Concrete Sand Earth

3.5 0.93 1.7 0.4 1.4

0.25 0.29 0.24 0.24 0.22

2700 1800 2300 1700 1800

Door and window material Door 1 40 Wood 0.16 0.66 700 Window 1 Single glass Input for AIOLOS Table 5. Infiltration and Internal load for cases

Baseline Case Case 02 Case 03 Vol Hour Summer ach.

Winter ach.

Summer ach.

Winter ach.

Summer ach.

Winter ach.

Inter. Load

V1 01-07 13.4 5.6 14.5 1.6 13.4 1.5 0 08-11 22.5 6.75 18 2 16 2 150 12-16 13.5 6.4 14.5 2 13 2 150 17-19 13.3 6.8 15.5 2 12 2 0 20-24 13.8 7 15.3 2.1 12.5 2. 0 V2 01-07 13.4 5.6 14.5 1.6 13.4 1.6 150 08-11 22.5 6.75 18 2 16 2 105 12-16 13.5 6.4 14.5 2 13 2 150 17-19 13.3 6.8 15.5 2 12 2 105 20-24 13.8 7 15.3 2.1 12.5 2.1 150 V3 01-07 40.4 40.5 38 10 40 14 0 08-11 35 35.2 32 8 35 10 100 12-16 39 39.2 36.5 15 39 16 100 17-19 36 36 32 15 36 16 100 20-24 49 49 42 21 47 23 0 V4 01-07 5.14 2.4 5.14 1.2 35 2.5 0 08-11 5.75 2.5 5.75 1.2 40 2.6 150 12-16 5 3 5 1.5 42 3 250 17-19 5.3 1.3 5.3 0.6 38 2 600 20-24 2.6 1.6 2.6 0.8 36 0.6 0 V5 01-07 13.4 5.6 14.5 1.6 13.4 1.6 0 08-11 22.5 6.75 18 2 16 2 0 12-16 13.5 6.4 14.5 2 13 2 0 17-19 13.3 6.8 15.5 2 12 2 0 20-24 13.8 7 15.3 2.1 12.5 2.1 0 Note: Summer and winter infiltration (ach.) values in the baseline case are copied from Phan Thanh Truc- AEE Program 2000. Values for other cases are based on the changing rate between cases in the researcher’s own simulation on AIOLOS. Input for Leso DIAL Table 6. Required illumination Kind of work Required luminance level Corresponding activities “Rough” work 100 – 200 lux Storage, circulation, etc… “Ordinary work” 300 – 500 lux Reading, writing, screen

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work, etc… “Delicate” work 500 – 1000 lux Design, work on plants,

technical works, etc… “Very delicate” work > 1000 lux Precision work, quality

control, colour control… In the case study of housing, 250 lux is suitable lighting condition and it used for all cases as required luminance level.

All cases are base on the same building materials. Light colour floor, wall and very light colour ceiling are chosen for simulation. Windows are made of single glass with the medium frame.

Results Result from Baseline Case simulation Baseline Case in summer In July, both cases with and without passive ventilation are simulated. The comparison between these two cases directly dedicates the influence of ventilation to inner temperature of the house.

Baseline Case - July - Indoor Temperature (All doors and windows are closed)

2628303234363840424446

1 3 5 7 9 11 13 15 17 19 21 23

Hour

Tem

pera

ture

Out_TempVol1_Temp Vol2_TempVol3_TempVol4_TempVol5_Temp

Figure 17. Baseline case indoor temperature in July in situation without ventilation.

Baseline Case - July - Operative Temperature

26272829303132333435

1 3 5 7 9 11 13 15 17 19 21 23

Hour

Tem

pera

ture

Out_TempVol1_TempVol2_TempVol3_TempVol4_TempVol5_Temp

Figure 18. Baseline case temperature in July in situation with passive ventilation. Observation In situation without ventilation, indoor temperatures in the ground floor volumes are extremely high, especially in volume 3. Temperature is ranged from 31oC to 35.5oC

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in volume 1,2 and volume 5. In volume 4, the indoor temperature even reaches higher value in whole day because this volume has only one wall having opening to light well. Volume 4 average temperature is 1oC higher than volume 2 during daytime and 2oC higher at night. Volume 3 seems to be a heat trap with large glass area above; therefore, the indoor temperature has been the highest number, from 38 to 43oC. With passive ventilation, thermal condition in all volumes has been improved remarkably. As can be seen from the below figure, in simulation with passive ventilation, average operative temperatures in volume 1, 2 and volume 5 are approximately 3oC lower than in case without ventilation. There is a significant change in volume 3 – a light well space. In volume 3, the average indoor temperature is cut down from 41oC to 31oC when passive ventilation is set into the house. The temperature change in volume 4 – the kitchen is the smallest. The operative temperature of volume 4 reaches the highest value in most time in comparison with others. In this volume, thermal condition is quite corresponding with air change flow derivate from AIOLOS (ach value of volume 4 is about 30% ach value of other volumes). This result implies the configuration of this volume may restrict natural cross ventilation. 45

40

35 30 25

20

15

10

0

5

Vol1 Vol2 Vol3 Vol4 Vol5

Without ventilationPassive ventilation

Figure 19. A comparison of average indoor temperature in baseline case between simulations with and without passive ventilation. Baseline Case in winter re

atu

per

em

T

Baseline Case - January - Indoor Temperature (All doors and windows are closed)

1314151617181920

1 3 5 7 9 11 13 15 17 19 21 23

Hour

O_TempVol1_TempVol2_TempVol3_TempVol4_TempVol5_Temp

Figure20. Baseline case indoor temperature in January

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e

r

atu

per

em

T

Baseline Case - January - Operative Temperature

13

14

15

16

17

18

19

20

1 3 5 7 9 11 13 15 17 19 21 23

Hour


Figure 21. Baseline case operative temperature in January In the winter, operative temperatures in volume 1, 2 and volume 5 are range from 15 to 18.5oC. In the volume 4, the operative temperature is slightly higher (about 0.5o-C). The season behind is may be a high thermal maintain of volume 4, the space without external wall. Contrast to summer, ventilation is not an optimum solution to improve thermal condition in the house in the whole day. Opening is the result for temperature increasing during daytime but it makes the house cooler at night and in the early morning, especially from 2am to 10am. Day-light Condition In the aspect of lighting, this study is concentrated on the volume 4, which has a worst daylight condition. To derive daylight sufficiency and daylight factor of this volume, DIAL programme is used. The result implies that for the required illuminace 250 lux, the mean daylight sufficiency is low (only 26%). The illuminance distribution is quite heterogeneous (only 2.2%) in this volume. Baseline Case Problems In all-sided consideration of temperature, ventilation and lighting condition in the baseline case, there are some problems, following by

In the summer, operative temperature in all volumes is rather high in comparison with Givoni comfort zone.

In volume 4, cross ventilation effect is not remarkable, so thermal condition is bad also in the summer.

In the winter, operative temperatures of all volumes seem to be slightly low at night and in the early morning.

Daylight condition in volume 4 is quite under an acceptable level. Case Development Base on dedicated problems of Baseline case; 3 more cases have been established to solve the problems step by step.

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Table 7. Baseline Case and Case development steps. Model Description Purpose Used

program BASELINE CASE (summer + winter)

Ground floor of a typical 4 storey house, 4m height ceiling. - Volume 1: living room (5.8mx6m) - Volume 2: bed room (4.2mx4.5m) - Volume 3: light well (5.8mx17m) - Volume 4: kitchen (5.8mx6m) - Volume 5: corridor (1.6mx11.5m)


CASE 01 (summer + winter) Baseline case but

13m height for Volume 3 (equivalent 3 storey house)

-To improve daylight inner rooms.

Leso DIAL

CASE 02 (summer + winter)

Baseline case but - 8m height for Volume 3 (equivalent 2 storey house) - Decreasing of opening time in winter

- To test temperature & ventilation changes in summer - To increase operative temperature in winter. -To improve daylight inner rooms.


CASE 03 (summer + winter)

Baseline Case + Backyard added

- To improve thermal condition through ventilation changes - To improve daylight inner rooms.


CASE 04 (In the Future) A combine between

Case02 and Case03 - To get the best microclimate condition.


Table 8. Further input for Leso DIAL in developed cases

Volume Size (m) Opening Atrium height Case Width Height Depth No Size (m)

Over-hang No Height (m)

Baseline Case

5.8 4 5.5 1 2

2.4 x 2.2 1x3

0 0

1

17

Case 01 5.8 4 5.5 1 2

2.4 x 2.2 1x3

0 0

1 13

Case 02 5.8 4 5.5 1 2

2.4 x 2.2 1x3

0 0

1 9

1 2

2.4 x 2.2 1x3

0 0

1

17

Case 03 5.8 4 4

3 2.4x2.2 2.4x0.7 2 13

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Results of Simulations Thermal condition Figure 22. Case 1 and Case 2 operative temperatures in July and January

ature

1 23


Case 03 - July - Operative Temperature

262728293031323334

1 3 5 7 9 11 13 15 17 19 21 23

HourT

emp

erat

ure


erature

1 23


Case 03- January- Operative Temperature

13

14

15

16

17

18

19

20

1 3 5 7 9 11 13 15 17 19 21 23

Hour

Tem

per

atu

re


Case 02- January - Operative Temp

13

14

15

16

17

18

19

20

1 3 5 7 9 11 13 15 17 19 2

Hour

Tem

per

atu

re

Case 02- July - Operative Temper

25

27

29

31

33

35

1 3 5 7 9 11 13 15 17 19 2

Hour

Tem

per

atu

re

Case 02 In case 2 simulation in summer, operative temperature in volume 1, 2, 3, and 5 is

slightly changed in comparison with baseline case. In contrast, the operative temperature decreases in volume 4 are significantly decreased in both day and night (the former is 0.5oC and the latter is about 1.5oC). When the light well has been lower, the vertical air movement in the light well is cut down, so more air change into the volume in the back. That is why cross ventilation in volume 4 raises.

In the winter, when opening time is restricted (most door and windows open only 3 hours per day), passive ventilation is come down; operative temperatures in all volumes are raised.

Case 03 In summer, it is clear to see from the above figure that, operative temperature in

volume 4 is evidently decreased, first and foremost at night. In case 2, volume 4 average temperature is 2oC lower than in Baseline case. With changing of back wall from adiabatic wall to external normal one, volume 4 seems to escape from heat-trap status, so thermal condition is quite better.

Figure 22 shows the comparison of operative temperature in volume 1, 2 and volume 4 between cases. Volume 3 (the light well) and volume 5 (the corridor) are not mentioned because of less important areas. Obviously, while operative temperature in volume 1 changes slightly, temperature in volume 4 cut down rapidly.

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Figure 23. Comparison of operative temperature between cases

Vol.1, Vol.2 and Vol.4 Operative Temperature of all Studied Cases in July

28.5

29

29.5

30

30.5

31

31.5

32

Base case Case 02 Case 03

Vol.1Vol.2Vol.4

Output of Leso DIAL Lighting simulation was run for only volume 4, which has the worst daylight condition in the house. Leso DIAL was used to calculated daylight sufficiency and daylight factor of the studied volume.

Daylight factor (DF) is the ratio of the daylight quantity (illuminance) available on the outside and inside.

DF = Ep Ehz (%)

Typical daylight factor reaches the moderate level from 2 to 4% and average level from 4-7%. In this range of daylight factor, the studied volume is probably suitable for normal living activities.

Baseline case (26%)

Case 01 (28%)

Case 02 (30%)

Case 03 (41%)

Figure 24. The daylight sufficiency comparison of all cases As can be seen from the above figure, the mean daylight sufficiency in Baseline case is quite low for the required illuminance of 250 lux. The day-light sufficiency in the room is slightly improved in case 1 and case 2 while it is noticeable changed in case 3. It is dedicated that changing the light well height is much less influence on lighting condition than setting other window.

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Le Lan Huong

In case 3, the mean daylight sufficiency reaches the value of 41%, the average value for housing illuminance requirement. However, daylight distribution in this case is less than in the case 02 because the rate between min and max illuminace is less (only 0.2).

Baseline case

Case 01

Case 02

Case 03

Figure 25. Daylight factor comparison in all studied cases The below table shows the summary of all daylight elements and some comments for all studied cases.

Result Case Daylight Sufficiency (%)

Daylight Factor (%)

Min /Max illuminace

Diagnosis

Baseline Case

26 2.2 0.2 - The mean daylight Suff. is LOW- The illu. distribution is quite heterogeneous

Case 01 28 2.4 0.2 - The mean daylight Suff. is LOW- The illuminance distribution is quite heterogeneous

Case 02 30 2.8 0.3 - The mean daylight Suff. is LOW- The illuminance distribution is slightly heterogeneous

Case 03 41 2.8 0.2 - The mean daylight Suff. is AVERAGE - The illuminance distribution is quite heterogeneous

Table 9. Daylight sufficiency and day-light factor in all studied cases

Conclusions In the tube-like house, open-spaces such as courtyard, backyard and light well always play an important role in improving microclimate condition. These spaces directly influence on many aspects, concluding thermal comfort, ventilation and daylight condition.

Ventilation and thermal condition 1. In the summer, ventilation seems to be the best strategy to reduce indoor

temperature for rooms in ground floor, where wall and roof insulation have not great influence. In this season, the chance of good cross ventilation

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should be elevated in rooms, especially for the room in the back of the house.

2. In the ventilation view for the studied house, changing the height of light well is less effect than adding a backyard.

3. With the same effect, ventilation also reduces temperature in winter. Therefore, in the winter, it is necessary to restrict opening time of doors and windows to keep the house warm, especially at night and in the early morning.

Lighting condition 1. With a room having no external wall, openings orient towards light well or

atrium, the height of light well directly effect to daylight quality of the room. In this study, when the height of light well is gradually reduced (Case 01 and Case 02), both the daylight sufficiency and daylight factor raise up one by one. Moreover, the rate between min and max illuminance increase also. The illuminance distribution is become better.

2. In the case adding an atrium in opposite side is available, the daylight sufficiency goes up remarkable. However, if the height of existing light well is remained high (Case 03), the illuminance distribution is still quite heterogeneous.

In general, the rate between dimensions of the courtyard or light well should be

carefully considered in all terms of ventilation, indoor temperature and lighting condition.

References AEE 2001 Course material Housing, Climate and Comfort. DEROB-LTH manual Thermal property of Building material compiled by Erik Johanson

Architectural Research Institute Architecture and Tropical climate in Vietnam. Ministry of Construction, Vietnam

Bo Adamson Design for Climatisation;

Houses in Warm- humid climate.

Hans Rosenlund 2001 Climatic Design of Building Using Passive Techniques

Lund University

Pham Duc Nguyen, Nguyen Thu Hoa and Tran Quoc Bao 1998 Cac giai phap kien truc khi hau Vietnam, (Climatic Design Tools in

Vietnamese Architecture). Hanoi.

Pham Hai Ha 2000 Nghien cuu hieu qua ve vi khi hau cua mot so giai phap kien truc trong nha ong Ha Noi. (Research on climatic effects of architectural design in Hanoi

tube houses). Hanoi

Acknowledgements This paper could not be done without the help of HDM department, Lund University and SIDA organization. I would like to thank Professor Hans Rosenlund and other lecturers for the knowledge in Climatic design they have provided to me in the AEE2001 course and all support they have given for my completion of my study. I specially thank to Laura Liuke, my tutor, for her advice and guideline. I am gratefully to all of the staff in HDM, Lund University.

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Documents

Row House in Hanoi and Some Climatic Design