To address the environmental impact and challenges that often accompany high-density urban housing, researchers have been conducting exploratory studies to conceptualise sustainable housing typologies and designs for future high-density developments in ecologically sensitive areas.
In 2016, Singapore University of Technology and Design (SUTD) carried out a research study to explore various ecologically sensitive housing typologies on a hypothetical 60-hectare site which has natural assets such as mangrove forest and a nature park.
The team conducted three community design workshops involving 75 participants, with the demographics of the participants being representative of Singapore’s population. “These workshops ensure that ideas for new typologies are aligned with the needs of the community,” says Dr Thomas Schroepfer, the study’s lead researcher.
From photographs that depict various urban typological features, each participant was asked to choose a single feature they would most like to see in their neighbourhood presently. Participants were then asked to select a different feature — one that they would most like to see in the future neighbourhood as they age. This helped the research team conceive typologies that could potentially meet both present and future citizen needs.
The workshops also included moderated, open-ended discussions where participants were asked to describe their daily lives and envision a residential neighbourhood in the year 2040. Based on their input, the team listed the following key considerations to guide their conceptualisation of housing typologies on the study site:
• Shared, flexible spaces where work, play and social activities can occur should be provided to complement residential spaces
• Housing configurations should come in a greater variety than what is currently available
• Amenities for community events should be situated along blue and green corridors, referring to pathways and public spaces enhanced by aquatic and arboreal features respectively
• High-rise housing blocks should ideally be mixed with low-rise residential typologies to create civic areas that provide vibrant streetscapes and a sense of space at human scale
The workshops also revealed that vertical greenery features were popular overall, but seniors preferred them to be closer to the ground and favoured natural vegetation. As such, the team arrived at two conclusions:
• High-density housing typologies should incorporate green spaces at various heights
• Typologies should seek to preserve and leverage natural features in their original form at ground level
Dr Schroepfer also proposed that blue and green corridors of the study site should not be seen as an isolated network, but should link up with rivers, harbours and natural reserves in the vicinity to form a larger, island-wide green and blue network. Connecting these assets first necessitates an in-depth ecological study to detail the topography and natural water cycle of the study site.
Creating and enhancing blue and green corridors also allows them to function as social linkages between the study site and surrounding neighbourhoods. In conceptualising typologies for the site, the research team proposed that typologies bordering existing estates should have physically unimposing forms with multiple connections to “maintain a sense of openness and encourage human traffic flow”. Where key blue and green corridors are located, the team sought to incorporate ample public space within specific typologies. The aim, Dr Schroepfer says, is for the study site to “draw in” the wider urban community by leveraging its ecological corridors and, in the process, maximise the positive social effects of the site’s natural assets.
Dr Schroepfer emphasised that there is no one-size-fits-all urban housing typology for the study site, which the team further divided into sub-parcels of land for the study: “A typology should be designed as a calibrated response to the specific parcel of land it sits on.”
Taking into consideration their own findings, which include extensive topographical and environmental variations throughout the study site, the team formulated a number of housing typologies — each with a distinctive form and purpose. For each typology conceptualised, extensive computational modelling tests using real-world data were conducted. From the tests, adjustments to building form were made to ensure that the team’s ideas would be feasible in the real-world environment.
One of the housing typologies created, the Interchange, addressed urban environmental concerns of noise and air pollution. Meant for a parcel of land along a main traffic corridor at the edge of the study site, the Interchange was conceived as a high-density, low-rise typology with the following features:
• Linear open-air green spaces designed to filter noise and air pollution from the arterial road and elevated expressway
• Underground connections act as social linkages to funnel adjacent communities into the precinct
• A stepped-down low-rise form to create a pleasant visual transition to the study site, preserve the vistas of existing housing blocks across the road, and meet the expressed public desire for vibrant streetscapes designed around low-rise typologies
A graphical overview and cross-section of the Interchange typology. Image credit: SUTD
Similar in form to the Interchange typology, the Horizontal Tower runs on both banks of a waterway that serves as the study site’s primary blue corridor. Instead of using greenery to mitigate pollution, the tiered, leaf-and-branch form of this low-rise typology contains green surfaces to achieve visual and spatial continuity on both sides of the building with respect to its surrounding landscape. The form also offers residents greater frontage to an ecological asset while acknowledging citizen preference for communal areas that provide a sense of space at human scale.
A graphical overview of the Horizontal Tower typology. Image credit: SUTD
Another typology, the Sky Hive, takes the form of high-rise, high-density residential blocks designed and modelled to maximise the efficiency of rainwater collection. Rainwater is filtered through green surfaces on each floor and is eventually collected in a tank beneath the building. At the same time, the green surfaces satisfy citizens’ desire for vertical greenery and enable the entire high-rise building to function as an ecologically significant component of a green corridor.
A graphical overview and cross-section illustration of the Sky Hive typology. Image credit: SUTD
The research team proposed seven Sky Hive towers across the study site. Combined, the towers can help augment the sustainable water cycle within the precinct by channelling filtered greywater to nearby pond gardens. As Dr Schroepfer points out, this could in turn minimise runoff-related drainage problems faced by many high-rise buildings in the city.
Complementing the ecologically-sensitive characteristics of the Sky Hive, the Horizontal Tower and the Interchange is the Urban Landscapism typology, which was conceptualised for a land parcel near an existing hill and a conserved two-storey colonial mansion. This typology was designed by the research team to address the issue of building on uneven terrain without having to compromise the uniqueness of existing topography and valuable natural and man-made assets.
A graphical overview of the Urban Landscapism typology. Image credit: SUTD
Designing and building on existing terrain is also an important part of preserving a site’s natural water cycle, says Dr Schroepher. “When developing typologies, natural terrain should be preserved instead of relying on cut and fill techniques,” he says. “Doing so can help cities preserve valuable ecosystems and prevent loss of biodiversity.”
The typologies proposed by the research team for the study site have one thing in common: they seek to optimise the ecological function of a housing block in the design stage of the project through the design of its form and façade. Doing so minimises the need for downstream solutions that could negatively impact the environment, such as external cooling systems that emit waste heat and greenhouse gases.
The SUTD study underscores the importance of developing typologies as an informed and calibrated response to both immediate and extended environments. To achieve ecologically sustainable outcomes, high-density urban housing typologies can form parts of a larger green and blue network that also promote mobility and social exchange.
In conceptualising site-specific, ecologically-sensitive urban housing typologies, the study also highlights the importance of retaining and enhancing existing natural features. Doing so could help preserve, restore or enhance valuable natural systems and create ecological opportunities such as mitigating negative urban effects and conserving scarce resources such as fresh water.