«CSAAR (7: 2010: Amman) Sustainable Architecture and Urban Development \ Edited by Steffen Lehmann, Husam Al Waer, Jamal AI-Qawasmi. Amman: The Center ...»
Vietnamese originally inhabited the basin of the Hong River Delta - Northern Vietnam, then moved south, taking cultural aspects of their housing construction to the new southern settlements. Archaeological evidence shows that primitive vernacular houses were constructed in the area with climatically appropriate built forms, materials, and spatial functions (Tran, 1999). Unlike the nomads in northern savannahs, the Vietnamese settled down and cultivated the land.
Housing typo\ogies evolved in the South to adapt to harsher tropical conditions Iike typhoons, humidity and flooding through trial and error.
Vietnamese vernacular architecture evinces both socio-cultural and environmentally responsive design. From a cultural perspective, Vietnamese hornes are where family members foster spiritual values, teach morallessons and care for each other. Horne owners, usually local peasants, took climatic patterns and regional conditions into account when constructing their buildings. The site planning, house layouts, and external gardens and landscapes work together to create a sense of place and community. Passive solar design significantly reduces indoor air temperature, induces natural ventilation, and protects the house from direct sunshine and rain. Locally available materials create robust structures that can stand up to natural disasters such as windstorms, typhoons and floods.
Applying Vietnamese vernacular housing principles to contemporary design could enable local inhabitants to preserve the regional traditions and socio cultural values as weil as to reduce negative impacts. Vernacular housing does not require resource-intensive methods and technologies in construction, operation, or maintenance. lndeed, the vernacular has, for thousands of years, been shaped by the natural context as weil as regional ordinances and cuItural norms. Therefore it can provide an effective model system for modern Vietnamese architecture.
2 Climate and Topography
Vietnam is a long S-shaped country stretching from 8°30' to 23°22' North with two primary climatic regions: Northern climatic region and Sorthern cIimatic region with the border on the latitude of 16 degrees north, which is located on the Hai Van Pass, Thua Thien Hue Province (Vietnam Ministry of Construction, 1985) (Fig.l). The regional temperature varies with the change of latitudes along the stretch of the country. Northern Vietnam has a humid and subtropical climate, while the South enjoys a tropical climate all year round with the two seasons, dry and wet. The whole country is influenced by seasonal monsoons which bring heavy rainfall to all regions. From November to April, the Northern region is affected by north-eastern monsoons which are cold and dry, while from May to Gctober, highly humid monsoons come from south-west direction influence the South ofVietnam.
Sustainable Architecture and Urban Development 289 The temperatures of the country range from 12 to 34 degrees Celsius and the mean temperature is always higher than 21 degrees Celsius. The North has a cold winter where the temperature sometimes drops down to 6 degrees Celsius, while the temperature in the South remains stable between 21 to 34 degrees Celsius.
The period of sunshine in the country annually is between 1400 and 2800 hours.
Relative humidity is rather high in all regions, and usually over 77 percent.
Rainfall is torrential with annual precipitation exceeding 1000 mm almost everywhere. Therefore, regional flora and rainforests are diverse, and have provided manY types of timber for building construction. Heavy rain fall usually combines with windstorms, causing floods in many areas ofVietnam.
Mountainous areas occupy three fourth of the country while the remaining are low-lying coastal plains and deltas. Some higher points of the north-west mountainous regions and the central highland have lower temperatures than other parts due to their higher altitude. The slope of the topography gradually decreases from west or north-west to east or south-east. Dwelling areas and vast rice farms are located on the eastern and south-eastern coastal plains and deltas.
The Hong River Delta in the North and the Mekong River Delta in the South are the two main 'granaries' supplying rice and agricultural products for domestic and export purposes.
Vietnamese inhabitants constructed adaptable houses that took these climatic and topographie conditions into account. The typical characteristics of Vietnamese housing, especially climatic features, can be identified in terms of site layout, passive design, material and structure.
Phuong Ly, Janis Birkeland &Nur Demirbilek
Figure I. Map ofVietnam. Image edited from Vietnamese Government Website (http://www.chinhphu.vn).
3 Vietnamese Vernacular Housing And Its Typical Characteristics Vietnamese vernacular architecture has evolved over thousands of years in South-east Asia and has adapted to its regional climate. Images of primitive vernacular houses were reflected on decorative motifs on the tympanums of ancient Dong Son bronze drums (including Ngoc Lu I bronze drum) (Fig.2), which are considered the physical evidence of Dong Son Culture, flourishing in the heartland of the Hong River Delta of Northern Vietnam from 2000 to 3000 years ago. The motifs show that the vernacular houses are an on-stilt structure, which has a saddle roof with two deep gables on two opposite elevation sides (Fig.2). This kind of housing is c\imatically-appropriate because of its heat resistant tall roof, elevated noor, shaded overhang and lightweight materials for preventing solar access, increasing natural ventilation, and reducing humidity.
Sustainable Architecture and Urban 291 Figure 2. A c1imatically-appropriate house redrawn from the decorative patterns on the tympanum ofNgoc Lu 1, one ofthe most known Dong Son bronze drums discovered in the Hong River Delta, Northern Vietnam. Photo ofthe Ngoc Lu I tympanum from Nguyen and Hoang (\ 975).
Vietnamese vernacular housing has evolved through trial and error to changing conditions of settlement, climate, eeology and culture over time. For example, houses with straight simpler roofs have been preferred over the previous saddle ones to enable quicker construction with limited IocaI materials and skills.
Likewise, the on-pile form of houses in the mountains was transformed into ground-Iying structures on the plains (Nguyen et al., 2007). As a result, the vernacular was an improved structure to optimise regional c1imates and to provide comfort for occupants. In Northern Vietnam, the traditionaI horne became a self-contained economic unit within its village that retlects cultural values. In fact, using natural means in construction to provide health and well being for house owners is the most important fimction that the Vietnamese vernacular achieved.
Vietnamese traditional housing has adopted principles for designing building in the hot and humid tropics which, according to Lauber et al. (2005), induce maximum natural ventilation and prevent intensive solar heat loads in building living areas. In this paper, typical vemacular houses throughout the country are selected to exemplif)r their environmentally responsive characteristics. The characteristics are identified in houses located in both rural and urban Vietnamese regions. The houses all use numerous natural means of c1imatic controL However, common features are the strategies of organising the site, integrating passive solar design, using locally available materials and using appropriate structure.
292 Phuong Ly, Janis Birkeland &Nur Demirbilek
3.1 Site planning
Depending on available land, rural houses optimize all parts of the site while urban houses, which are usually built on small and constrained plots, integrate with nature through site layout. Vemacular housing in Northem Vietnam is typical of Vietnamese rural houses, which were transferred to other southem areas of the country over the centuries. The rural houses are usually slted on a sufficient large plot that the appropriate orientation the south in Vietnam can be selected. Integral exterior design elements such as courtyard, ponds, and vegetation are integrated with the house. In urban houses located on a limited area plot, intemal solar courtyards are oriented to induce breezes and to provide naturallighting. Both the rural and urban vemacular designs are adapted to each specific context to facilitate amenity and well-being for occupants.
The rural houses in Northem Vietnam incorporate many common elements such as main housing blocks with auxiliary blocks, sheds for poultry and animals, ponds, a courtyard, an open-air worship place, and vegetation (Fig.3).
The compound is weil organised so that energy from the sun and wind are optimised to control the house's climate. For instance, the main blocks of housing are usually designed with their long main fac;:ade tacing south and linked with auxiliary blocks to form a courtyard in the middle. As the heart of the compound, the courtyard induces air flow to living spaces and captures sunlight for drying rke, cereals and clothes. The water ponds are located adjacent to the main blocks to provide cool air for the whole site during hot summers, and treat wastewater with aquatic plants. Fish, poultry, animals and vegetables provide on site food. Indoor and outdoor pI aces for worshiping the God of land, Buddha, or owner's ancestors reinforce the spiritual values ofthe occupants.
Water for household use is derived from different sources and treated by traditional methods. Water from ground-wells, rivers or lakes can be stored in containers for depositing and then filtered by tanks that contain layers of charcoal, sand, and grave. Most vemacular Vietnamese houses use rainwater harvesting system to provide water for cooking and drinking. Rainwater is also treated in the same method. After being filtered, water is boiled or baked under sunlight to e1iminate bacteria.
In ancient urban areas such as Hoi An - the World Heritage Site in Central Vietnam - most vemaculars have a form of townhouses which have a unique to response to the environment. Located on a small rectangular plot, which is quite narrow on one side and very long on the other, the townhouses serve a dual function of both a shop and a shelter comprised of two or three main timber blocks, single- or two- storey, and solar courtyards between the blocks. Due to facing astreet for trading, the selection of the optimal orientation for Hoi An houses is less important, but inside courtyards enable ventilation, lighting and air flows from the interiors to courtyards and vice versa via timber balusters and opening vents. With this type of architectural layout, the urban townhouses are cool and comfortable for residents.
Sustainable Architecture and Urban Development 293 Figure 3. An example of a vernacular compound in Northern Vietnam. Image redrawn from Nguyen and Nguyen (I 995).
3.2 Passive design solutions While appropriate orientation and integrated layout are the two most distinctive organisational features when planning a traditional housing site, passive designs show ski II in creating climate responsive housing. The house designs reduce the impacts of solar radiation, wind and rain on their living spaces. Typical solutions in the Vietnamese vernacular include solar courtyard, mediating space, envelope shading device, air vent, and surrounding greenery. Some archetypical passive means can be found in the housing model ofNorthern Vietnam (Fig.4).
The solar courtyard plays an important role in capturing sufficient natural lighting and cool breezes into rooms. The courtyard is necessary in a rural house.
In fact, it is more indispensable in the urban house, which is usually located on a confined plot with surrounded boundary (Fig.5 & 6). As a leeward element, an internal courtyard orients natural air movement into the interiors from all wind directions, and thus cools the house. In rural regions, occupants are able to use the solar access from the courtyard to dry their cultivated rice and cereals. The courtyard provides a place of working and entertaining, and a sense of family identity. It is also a place where ritual activities are conducted.
Janis Birkeland &Nur Demirbilek
Figure 4. Climate responsive means of a typical vemacular house in Northem Vietnam: verandah, shading overhang, openings and air vents, and appropriate material use ofthe envelope.
Image redrawn from Nguyen and Nguyen (1995).