Out of the three main pillars of sustainable development for Singapore (figure 1), a major part of environmental sustainability in terms of the built environment comes from the BCA Green Mark Scheme as well as the ABC Waters Programme by PUB (Public Utilities Board).
The Green Mark Scheme by Building Construction Authority (BCA) focuses on sustainability in terms of a building’s construction stage, its form and functions with respect to energy efficiency, water efficiency, landscaping functions and passive or active design strategies for thermal comfort (figure 2). BCA has successfully grown the number of green buildings in Singapore from just 17 in 2005 to more than 2,100 today (BCA, 2014).
Under the ABC Waters Programme  by Public Utilities Board (PUB), design features for buildings can be categorized under the following building elements: Rooftop, sky garden or terrace, balcony, planter box, ground level greenery and green wall or vertical green (figure 3a).
Other than enhancing the aesthetics of buildings, these green elements perform primarily climatic roles of cooling the surrounding air temperature, reducing ground level runoff and to cleanse and treat stormwater runoff through natural purification processes before reaching the ground level (figure 3b).
Apart from having greenery that serves as climatic strategies and systems that deal with energy efficiency and resource wastage, concepts and proposals of integrating vertical farming with high-density buildings (figure 4) have emerged in recent years, adding on another dimension of how buildings can be environmentally sustainable . Specifically, ‘vertical farm’ that uses hydroponics and aquaponics methods can allow vegetables and fruits to be grown indoors within buildings in contrast to traditional methods of growing on arable land. Often, vertical farming is combined with rainwater and wastewater purification systems to create a sustainable closed loop system that has several advantages , making vertical farming much more sustainable than traditional green buildings. In the words of Dr. Dickson Despommier, a leading pioneer of the concept of vertical farming, vertical farms located in urbanized city areas can offer the perfect solution to the main crises the world is facing today, such as deforestation, population increase, climate change, pollution, land scarcity, dwindling ecology, decreasing food supplies, and urban heat island effect (Despommier, 2010).
Case Study 1: EDITT Tower, Singapore by Architects T R Hamzah & Yeang
In Singapore, EDITT Tower is a similar proposal that attempts to integrate greenery and sustainable energy systems into a vertical building. EDITT Tower is an ecological green vertical tower (figure 5a) proposed by Architects T R Hamzah & Yeang in 2008. Planted facades and vegetated terraces consisting of organic local vegetation are designed to wrap around the façade of the 26-storey building in a continuous manner. The vegetation areas constitute 3,841sqm, which is a ratio of 2:1 of gross useable area to gross vegetated area. Carefully selected indigenous plant species ensure that there is no competition with existing species of the locality (figure 5b). Overall, the tower is designed to show how bio-diversity can be enhanced despite being situated in a highly urbanized environment.
A crucial urban design issue in skyscraper design is poor spatial continuity between street-level activities with those spaces at the upper-floors of the city’s high-rise towers. This is due to the physical compartmentation of floors inherent in the skyscraper typology. In this design, landscaped ramps are lined with street-activities (stalls, shops, cafes, performance spaces, viewing-decks etc.) all the way up to first 6 floors (figure 5c). This creates a continuous spatial flow from public to less public as a vertical extension of the street, thereby eliminating the problematic stratification of floors inherent in all tall buildings typology.
The tower’s green credentials continue inside the tower with ecological features including water self-sufficiency through rainwater-collection and grey-water reuse for both plant irrigation and toilet flushing at over 55% (figure 5d). The design also optimizes recovery and recycling of sewage waste through the creation of compost and bio-gas fuel. The tower also aims to achieve almost 40% energy self-sufficiency through a system of solar panels (figure 5e). The tower will be constructed using many recycled and recyclable materials, and a centralized recycling system will be accessible from each floor (figure 5f).
Pushing the boundaries further, what if vertical farming is to be integrated with high-density residential living? In this case, residential planning has to be entirely redefined into a new housing typology that is able to maintain a symbiotic relationship between its occupants and farming systems. This mode of living is perhaps the most idealized version of sustainable living, where food is grown and consumed at an arm’s length, cultivating farm-to-table culture at the most personal level. Even though such a typology has not yet been realized, there do exist bold visions and proposals that display similar strands of thoughts .
Case Study 2: Stacking Green, Vietnam by Vo Trong Nghia
In Saigon, one can frequently see and find potted plants and vegetation planted by local residents in their balconies, courtyards and along the streets. Overtime, this gradually became the character and custom of Saigon. In designing a typical tube house (4x20m wide) for a couple and their mother, Architect Vo Trong Nghia draws inspiration from this custom, resulting in a vertical garden façade at the front of the house (figure 6a).
Automatic irrigation pipes fitted inside the planters allow for easy watering and maintenance.
Spatial design of the interiors also revolves around the central concept of the vertical garden façade, in which there are few partition walls in order to maximize views of the green facades and to encourage ventilation. In addition, the green façade and roof top garden protect its inhabitants from direct sunlight, street noise and pollution (figure 6e).
Even though the main intents of integrating rows of greenery into the tube house are mainly for climatic purposes and to form a distinctive green façade, this case study has shown how greenery need not be spatially disconnected from the interiors of the living domain, but can have a considerable impact on how interior spaces are planned and configured. Therefore in envisioning a new housing typology that integrates vertical farming with high-density living, greenery need not merely be placed along external corridors and balconies, but greater spatial integration can further enhance how occupants view the functions of the green and how integral they are to their lifestyles.
On the whole, the above two case studies auger well for the future of green living, as the former reflects the technological ability of vertical farming and energy systems to be integrated within vertical buildings, while the latter leads one to envision further possibilities of how greenery can be integrated with the residential domain.
 Launched in 2006, ABC Waters Programme harnesses the full potential of Singapore’s water bodies to improve the quality of waters and to integrate drains, canals and reservoirs with the surrounding environment in a holistic way to create ‘Active’, ‘Beautiful’ and ‘Clean’ (ABC) waters for all. See more at: http://www.pub.gov.sg/abcwaters/Pages/default.aspx
 Advantages of the vertical farm include: year-round crop production, no weather-related crop failures, no agricultural runoff, allowance for ecosystem restoration, no use of pesticides, herbicides, or fertilizers, use of 70-95% less water, greatly reduced food miles, no more control of food safety and security, new employment opportunities, purification of grey water to drinking water, animal feed from postharvest plant material (Despommier, 2010, p.145-6)
 See other projects at: http://www.inspirationgreen.com/vertical-farms
 See: http://blakekurasek.com/rethinkingtheverticalfarm.html
References and Bibliography
- Arch Daily. (2012, January 20). Stacking green / Vo Trong Nghia Architects. Retrieved 21 December 2015, from http://www.archdaily.com/199755/stacking-green-vo-trong-nghia/
- Building Construction Authority (BCA). (2014). 3rd Green Building Masterplan. Retrieved 21 December 2015, from http://www.bca.gov.sg/Newsroom/pr01092014_3GBM.html
- Chalcraft, E. (2012, July 9). Stacking Green by Vo Trong Nghia. Dezeen magazine. Retrieved 21 December 2015, from http://www.dezeen.com/2012/07/09/stacking-green-by-vo-trong-nghia/
- Despommier, D. (2010). The vertical farm: Feeding the world in the 21st century. New York: Thomas Dunne Books/St. Martin’s Press.
- Divisare. (2008). T. R. Hamzah & Yeang: Editt Tower. Projects. Retrieved 21 December 2015, from http://divisare.com/projects/17296-t-r-hamzah-yeang-editt-tower
- Kain, A. (2008, October 15). Singapore’s Ecological EDITT Tower. Inhabitat. Retrieved 21 December 2015, from http://inhabitat.com/editt-tower-by-trhamzah-and-yeang/
- Kurasek, B. (2009, June 1). Rethinking the Vertical Farm. Vertical Farming. Retrieved 21 December 2015, from http://blakekurasek.com/rethinkingtheverticalfarm.html
- Livesey, J. (2008, October 25). Ecological tower brings natural life back to urban site. World Architecture News. Retrieved 21 December 2015, from http://www.worldarchitecturenews.com/project/2008/10548/tr-hamzah-yeang-sdn-bhd/editt-tower-in-singapore.html
- Ministry of the Environment and Water Resources Ministry of National Development (MEWR). (2014). Sustainable Singapore Blueprint 2015. Retrieved 21 December 2015, from http://www.mewr.gov.sg/ssb/files/ssb2015.pdf
- Public Utilities Board (PUB). (2014). ABC Waters Design Guidelines. Retrieved 21 December 2015, from http://www.pub.gov.sg/abcwaters/abcwatersdesignguidelines/Documents/ABC_DG_2014.pdf