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Heat. Humidity. Monsoon rains. Intense sunlight. Air stagnation. Historically, the urbanism and architecture of Southern Vietnam has responded to the tropical climate of the region. Imperial and even colonial-era architecture was sensitive to the challenges of the climate. However, over time, context specificity was foregone in the name of globally recognised ‘development’ and the irresistible attraction of modern comforts supported by technological innovations. Today, the country is rapidly urbanising and its middle class is growing, the consequences of which lead to more impermeable surfaces, (air-conditioned) buildings, exponentially growing (carbon-based) mobility and massive investments in infrastructure all of which dramatically increases greenhouse gas emissions and exterior temperatures. Fortunately, in recent decades, there has been a new wave of urbanists and architects who are successfully reviving age-old vernacular practices and experimenting with creating new urban-nature relations and innovative construction methods.

In 2020, Southern Vietnam, including the Southeast (Ho Chi Minh City (HCMC) and surroundings) and the Mekong Delta, accounted for approximately 35% of the nation’s population (97.5 million) and double the average population density (779 people/km2 in the Southeast and 424 people/km2 in the Mekong Delta). It has a tropical climate with a dry season (December-April) and a wet season (May-November), which supports rainforests, lush vegetation and remarkable biodiversity. The region is strongly influenced by the southwest monsoon and witnesses an average temperature of 27ºC; its relative humidity exceeds 70% year-round. The measured average temperature increase in Southern Vietnam, between 1958-2018, was 1ºC; the IPCC predicted change in average temperature in the region in 2046-65 ranges from 1.2-1.9ºC and in 2080-2099 from 1.6-3.5ºC, depending on the province, season and scenario RCP 4.5 or 8.5. The increase is already palpable and there is an urgent need to adapt measures.

It should come as no surprise that there is a growing contingent of urbanists and architects working in the region who are designing new morphologies and typologies. Numerous strategies that offer protection from the scorching heat and sun while mitigating the effects of relative humidity cleverly recontextualise vernacular and colonial climate-sensitive architecture and urban design.


Fig. 1: Exemplar type of traditional rural housing in the Mekong Delta


Fig. 2: Tree-lined boulevards and activated waterways defined old Saigon, as shown in the former Bai Sau Canal, District 6


Strategic Citing, Local Materials and Screen Walls

Historically, in the dispersed agro-urban landscape of the preindustrial world, settlement as well as individual building configuration and site orientation were strongly related to cosmo-magical and worldview notions. Various earth gods and spirits were revered and had the role to secure human livelihoods by ordering their connections with the natural world, and popular beliefs placed great emphasis on the veneration of ancestors, associated with particular places. Additionally, phong thuy (Vietnamese feng shui, the science of wind and waters) — the auspicious citing of ‘everything under the heaven’, of built structures (from houses to tombs to entire cities) in the landscape — figures strongly throughout history. Joseph Needham defined it as the art of adjusting the features of the cultural landscape to minimise adverse influences and derive maximum advantage from favourable conjunctions of form. He proclaimed that feng-shui’s ambition was to structure the relationship between the natural and social environment and that its symbolism was not merely ritualistic but led to a minute appreciation of the topographical features of any locality.

The explicit use of the locational assets such as small tributaries, terraces and small plateaus remains evident when studying older urban and rural settlement morphologies. Buildings were raised on piles or sat atop slightly higher land cushions, all linked to an ingenious system of communally built and managed canals/ponds, and favourably oriented to prevailing winds for cross ventilation. In the preindustrial area, buildings were not necessarily the sole (or even most important) element of the dwelling environment. The open space of housing, communal houses and temples opened onto paths, courtyards and collective spaces. Clusters of buildings — from housing to social infrastructure — were consciously (and auspiciously) arranged in relation to the local context, where the micro-topography and vegetation were carefully choreographed. In that sense it is telling that not one drawing of rural housing typologies in Southern Vietnam, assembled for the Ministry of Construction, is without the prominent presence of at least one tree (Fig. 1). The daily dwelling environment is as much (if not more) outside than inside and trees and water were the main components of micro-climatic manipulation — of shadow, cooling water surfaces, light and breezes; low-vegetation was avoided since it obstructs cross ventilation (and attracts unwanted pests and parasites).


There is a growing contingent of urbanists and architects working in the region who are designing new morphologies and typologies


Secondly, at the scale of buildings themselves, vernacular traditions relied on locally available, perishable and light materials (wood, thatch, bamboo, palm leaves, jute, etc.) that have a low thermal capacity. Fastening of materials used various methods of weaving, tying, pegging and notching; historically, vernacular structures used no metal. Long eaves protected walls and windows from sun and torrential rains. Buildings were raised above the group to reduce the entry of pests and allow air circulation and were incredibly open, with non-load bearing walls under timber roofs supported on columns. The use of textiles in verandahs tempered bright light and dust. Roofs controlled solar isolation, while walls — often of woven panels — allowed for natural ventilation. According to Roxana Waterson, the houses of Southeast Asia should be considered ‘living,’ since they are embedded in processes of active vitality and dynamic change related to everyday social practices while simultaneously being deeply imbued with symbolism.

During the French colonial (1887-1954) and American occupation periods (1954-75), urban architecture prevailed, including its insertion into small towns and villages throughout the Southeast Region and the Mekong Delta. The French developed what Gwendolyn Wright dubbed as assimilationist architecture, where local devices and styles were incorporated into French-styled buildings. Screen walls and brise soleil were widely utilised for their role in sun shading as well as natural ventilation (that from the beginning of the 20th century was complemented by electric fans).


Fig. 3 A, B, C: A number of strongly vegetated urban tissue samples were developed which interweave road and water systems as warp and woof


Dominant roofs with large overhangs were also widely employed to block the sun and direct the rain away from buildings. And, since the tropics were historically framed as hot, impoverished and pestilential regions, largely unsuitable for white settlement, it was not long before mechanical air-conditioning became commonplace in American-era buildings, particularly hotels, hospitals, diplomatic and military structures. Air-conditioning was a paradigm shift: from attenuating one way or another comfort (and by extension health) to artificially replacing heat by coolness (and where the lush environment became transformed into a techno-scientific sterile one). By the 1980s, Japan and Singapore invested in significant research on air-conditioning for tropical regions. Over time, the ubiquity of air-conditioning accelerated parallel to the widespread availability of cheap fossil fuel. For anyone regularly visiting Southern Vietnam (and other parts of the tropics), both the over-cooling and over-reliance on air-conditioning is abundantly evident. Since the 2000s, there has also been an abundance of shopping malls. They have become more than beacons of consumerism and are public spaces as well since they are cool in all senses: air-conditioned and appealing to the expectations of modern (civilised) life.

For over a decade, Jiat-Hwee Chang has been researching the socio-cultural histories and techno-politics of air-conditioning and climate change in urban Asia. Chang reveals how climate control was not a neutral scientific discourse but loaded with cultural and methodological biases that were part and parcel of the West’s civilising agenda; he reveals the complex entanglements between climate and economy, comfort and development, and nature and culture. He critically dissects the reductive understandings of thermal comfort proponents of mid-20th century bioclimate, ‘tropical architecture’ by researchers such as Britain-based George Atkinson and Otto Koeningsberger. For Chang, the techno-scientific approach to thermal comfort complicates the universal call for a return to climatic design and its low energy passive means of cooling. Andrew Cruse further nuances the arguments of Chang by focusing on Ho Chi Minh City. He develops the notion of Southern Vietnam’s historical hybrid approach to thermal comfort as a process of negotiation and “… entanglements between natural and artificial, open and sealed, the technical and the social… comfort as a process of negotiation between climate, building and occupant within a socio-political context.” He critically documents fixed, binary notions and norms and offers the concept of pluralistic ‘tropical comforts.’


Fig. 4: Top- The Bình Thanh House’s façade of precast concrete screen walls alternates with vegetal balcony spaces
Middle - The section clearly articulates the alteration of mechanically air-conditioned spaces and living spaces open to the environment 
Bottom - The air- conditioned spaces can also be opened to the tropical climate, allowing inhabitants to finely tune their comfort


Trees in the City and Tropical Cities of Tomorrow

At the scale of cities, climate-responsive design was also historically developed. In urban areas, trees were systematically planned and constructed at the national scale, first organised directly by emperors and later by central and municipal governments (Fig. 2). Typically, cities were a configuration of dramatically oversized and systematically tree-planted boulevards that frame large allotments of gardens (with trees) in which relatively small buildings were positioned. Canals, with their sensory refreshing effect, complement the boulevard system. The landscape structure (tree systems, garden patchworks, water, etc.) rather than the built itself made the monumentality of the colonial city and was the main climatic adaptation measure. The city became a constructed vegetal environment.

With hindsight, one can understand that this ‘landscape construction’, regardless of whether Vietnamese or colonial, constituted the core of the tropical urbanism of Southern Vietnam and that trees were a key component. This is for obvious reasons: the hot and humid climate. Trees are essential to make the deltaic quagmire that constitutes most of Southern Vietnam liveable. They stabilise the water-sick land and generate a micro-climate. A tree canopy (thickly overgrown or light) makes a world of difference when under the shadow of a tree or in the radiant sun. And the archetypical architectural elements of the south, including the veranda and large screen walls remind one of being outside under a canopy, in a shaded place — they modulate the radiant heat and harsh sunlight. Dwelling in the tropical environment became an interplay between being in a building (with its gradients of exposure to sun and light) and staying outside under a variety of canopies, thin and dense, filtering light, generating gradients, shade and breezes. People seek tree-canopied spaces and/or cooling bodies of water (ponds, lakes, riversides or canals). The landscape construction, usually through cut and fill, defines ‘higher’ land, that is stabilised and sanitised through tree planting and making water bodies.


Both the over-cooling and over-reliance on air-conditioning is abundantly evident


In 2020-21, RUA/IUPSD designed the small settlement of Can Giouc in HCMC’s periphery into a city to accommodate a population of 40,000-70,000 on 910 hectares. The low wetland (formerly with mangroves) has been witnessing a new major wave of radical transformation through rampant urbanisation and agricultural modernisation. A countermodel was developed to the surrounding large developments, by Vietnam’s large developers like the Vin Group and the Sun Group, by avoiding blanket land-leveling by filling and the creation of tabula rasa. It rather exploited the ‘as found’ condition.

Based on existing topography, explicit degrees of wetness were created to accommodate different vegetation, from mangroves to riverine forests to orchards and urban forestry. Fingers of urban development penetrate the countryside where (wet and dry) natural areas alternate with aqua and agricultural lands. Waterways are systematically interwoven into the urban morphology and allow for systematic water transport. The partially re-naturalised, east-west Mong Ga River centres a predominantly wet natural area with lakes, marshlands and islands that can embed exclusive leisure and educational programmes. The existing agricultural area in the south is upgraded into a sustainable high-tech agri/aquacultural park. Each of the three areas accommodate patches of settlement with a variety of densities, different in form and qualities, as well as forms of (urban) forestry. Interweaving water, forest and settlement structures is seen as essential for the tropical city in the making (as it was historically) (Fig. 3).


Fig. 5: Top - The rich section reveals the blurred boundaries of openness/closedness, light/shadow, shared/private, plant/ construction material 
Fig. 6: Middle - Thickened facades modulate light and accommodate vegetation, complemented by outdoor workspaces
Bottom -Tropical vegetation colonises the front and back of the building


Contemporary Vernacular and Return to Climatic Design

Since the 2000s, there has been an intense resurgent interest in the vernacular, particularly in relation to its low-energy passive design for cooling in lieu of the over reliance on energy-intensive active cooling of mechanical air-conditioning. Already in 1997, Singaporeans William Lim and Hock Beng Tan spoke of a Southeast Asian ‘contemporary vernacular’ as “a self-conscious commitment to uncover a particular tradition’s unique responses to place and climate, and thereafter to exteriorise these formal and symbolic identities into creative new forms which reflect contemporary realities including values, cultures and lifestyles.” And, as global warming imposes itself as an important sociopolitical agenda, an interpretation of the vernacular is becoming an integral part of a new tropical architecture.

In Southern Vietnam, there has been the innovative development of a contemporary vernacular across building types and scales which prioritises vegetation, natural light and ventilation. Responses to climate and heat have been primary drivers for the experimentation. Some of the most rigorous testing has been in Ho Chi Minh City, where architects deliberately weave two different nature-culture relations: one more traditional, largely with local materials and open to the vagaries of the climate and another artificial and tempering the climate with mechanical equipment and modern materials. In the widely published Bình Thânh House (2013) (Fig. 4), Shigru Nishizawa (then working at Võ Trong Nghia), accommodated two different lifestyles for an extended family — one contained within three, airconditioned floating volumes wrapped by pre-cast concrete pattern blocks (60cm wide by 40cm high) and another of the in-between spaces, open to the exterior, in which water elements and vegetation are key components. It is not surprising then that the section is the most revealing drawing and, indeed, the house and many others like it are designed in section.

Waterways are systematically interwoven into the urban morphology and allow for systematic water transport


The k59 atelier of Phan Lâm Nhat Nam and Trân Câm Linh similarly developed a house/office (2019) (FIG. 5) for themselves and their extended family. The small plot (4 x 16m), nestled between two typical ‘hem’ (urban alleys), has a flow-through ground floor with collective spaces and upper floors that have airconditioned, private space volumes (bedrooms and bathrooms) connected via bridges to various spaces that engage with the exterior through folding, sliding and rotating doors and windows interwoven with carefully chosen and maintained plants (and that butterflies and birds are attracted to them). The affordable concrete block structure and floor contrasts with a reflection/cooling pool on the ground floor, the warm wood of the staircases and bridges and lush vegetation on the façade, the roof and throughout the interior. Although most experimentation with the contemporary vernacular has been developed at the residential scale, there is an emerging body of work in the education, hospitality and office sectors. Nguyen Hoàng Manh and his MIA Design Studio developed their office (2019-20) (Fig. 6) in the rapidly urbanising District 2 of the city as an open plan volume literally wrapped in lush foliage. The corner building, across from a city park exploits visual and physical access to vegetation to its fullest. The façade and interior workstations are designed to control the glare of tropical sunlight yet frame views to the building’s own garden and the park. Garden spaces include meeting tables and workspaces.

Heat. Humidity. Monsoon rains. Intense sunlight. Air stagnation. All are going to intensify in the coming years, combined with other phenomena including the increase and intensity of storms and long droughts. Fortunately, there has been a re-emergence of climate-attentive contemporary Southern Vietnamese urbanism and architecture. It is an urbanism and architecture that radically rethinks the tropical city and therefore rechoreographs the life of the street and the life of the building as elements of a heavily vegetated urban landscape. As well, there is a renewed specific role for water bodies that have an important impact on the sensation of thermal comfort. It explicitly designs a fluid and ambiguous relationship between a techno-scientific and traditional lifestyle, built and natural environment. Cool respites to increasing heat is achieved by banishing tried-and-true universal standards and embracing a range of thermal comforts that are created by a variety of mineral and vegetated spaces, water elements and trees.



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