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Unforbidden cities (part two)

A team from the University of California, Berkeley, took a hard look at Tianjin’s urban superblocks. Concluding a two-part article, Harrison S. Fraker Jr. describes some alternative design concepts and the obstacles in their way.
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We knew that Chinese gated superblocks comprise the largest part of China’s overall development efforts, which are among the most ambitious construction undertakings in the history of the world. The Chinese are building 10 to 15 gated superblocks every day, equal to 10 million to 12 million housing units per year (10 times the US average). The process benefits from a clear definition of roles.

The city builds the new system of arterial roads and then sells the superblock development rights to a developer, who is responsible for constructing a prescribed number of housing units at specific unit sizes. The developer is also responsible for providing all internal community facilities and infrastructure -- including commercial shopping and offices, schools, recreation facilities, parks and landscaping -- and all internal roads, sewage lines, water and power distribution. The process depends on the support of a centralised infrastructure of power plants (usually coal-fired) and electric power lines, sewage treatment plants (including sewer mains), and a sanitary water supply provided by the city or provincial utilities. The developer just “plugs in” to these services.

While highly efficient at providing housing, an array of negative consequences has emerged from China’s gated superblock model. With a single entry/exit, and barriers to those outside the immediate gated community, the pattern almost guarantees that people will be forced to use cars on trips that are now walked or bicycled by 80% of the residents. As vehicular traffic grows, streets will become congested, creating corridors of pollution similar to what we saw on our tour. This traffic pattern will also remove people from the pattern of streets and alleys that has supported the rich and diverse urban culture of traditional Chinese cities for millennia.

Preliminary calculations revealed that 30% of China’s CO2 emissions could be directly attributed to the construction, transportation and power generation required to build and operate these superblocks. The Berkeley team quickly realised that by developing principles and prototypes for transit-oriented neighbourhoods, it could address half the problems of the impact of the car.

But what if we thought bigger? What if our designs could also generate all the community’s energy by employing renewable sources on site, treat all wastes and provide most of the water? If China’s fundamental unit of development could become resource self-sufficient (i.e., carbon neutral) in its operation, and if it could replicate and spread throughout the world, this would be a major force in reversing global climate change.

With this larger goal in mind, the Berkeley team spent the semester creating an entire system – including (but beyond) transit-oriented neighbourhoods -- to consider all potential sources of energy and waste flows that might make the neighbourhood resource self-sufficient. First the team tackled the challenge of making the project transit friendly. They came up with a system of designated streets and blocks with mid-block greenways reserved for pedestrians and bicycles. These greenways connect to a network of parks leading directly to transit stops. In this way pedestrians and bikes are given a privileged, independent route to transit.

At the same time, all the streets are carefully designed to accommodate bikes and pedestrians; but by creating an independent system, the bicycle and pedestrian congestion at intersections is greatly reduced. With such a walking- and bicycle-friendly neighbourhood, dependence on the car as the primary mode of transit can be reduced and the vehicle miles travelled reduced, with CO2 emission reduced as well by 75%. Car ownership (an estimated 12,000 to 14,000 cars are being added to China’s streets every day) is not discouraged, but the car becomes a convenience for recreation and selected uses, rather than a necessity.

The team then focused on how to supply energy for a high-density, superblock community. Conservation and implementing designs that best responded to the climate appeared to be the most cost-effective strategy for reducing both energy consumption and demand. By careful application of passive solar-design principles and natural cooling (using shading and ventilation), we determined that heating loads could be reduced by 80% and cooling loads by 60%. The challenge became how to provide the back-up heating and cooling, and the electricity for lighting and appliances.

A combination of renewable strategies was discovered. By putting photovoltaic panels (PVs) on the roofs and also using them as sun shades for south-facing windows, we calculated we could deliver approximately 40% of the electric load to energy-efficient appliances. Adding wind-conversion machines atop tall buildings (approximately 20 to 30 per neighbourhood) would provide an additional 40% of the electric load. The balance of the electric load, plus gas for cooking and domestic hot water, could be provided by biogas generated from a combination of sewage, food wastes and green wastes from the local landscape, trees and urban agriculture. In this model, the high density of housing (150 units to the acre) became an environmental asset by providing the concentration of waste required to produce sufficient energy. An integrated system was also preferable, in that it could spread the workload and could be sized for optimum cost effectiveness; no energy storage was required.

In addition to transportation and energy, water supply and waste-water treatment were equally important to these newly designed communities. The buildings could collect all rainwater in cisterns for supply, and recycle “gray” water for low-flush toilets. Ground water would be either absorbed directly on site or collected for landscape irrigation; there is no storm-water runoff. Waste water produced when bacteria digest and decompose biological matter in an oxygen-free environment (producing methane as an energy source) is treated naturally and recycled, also for irrigation. This water system could provide as much as 75% of the needed water.

The team also restricted impermeable paving materials to the travel lanes of the streets. All parking areas, sidewalks and courtyards were proposed to have porous pavers. By absorbing storm-water run-off on site, the design eliminates the cost of storm-water piping, and, more importantly, it provides natural irrigation and soil aeration, making it possible to plant a more extensive “urban forest”.

Providing extensive tree coverage for the streets, sidewalks and parking areas has a triple environmental benefit. First, the shade in the summer reduces the “heat island” effect by as much as 3 to 10 degrees; not only making the public realm more comfortable but also reducing air conditioning loads by 10 to 15%. Second, by selecting appropriate species of trees and planting and harvesting them in sequence, all the CO2 generated on the site can be absorbed. Finally, the trees, clippings and prunings provide additional biomass for the biogas digesters. One of the most important parts in the whole system is the role of the streets, courtyards, greenways and parks -- the landscape -- in enhancing environmental quality. By employing the most advanced “green” design principles, only 40% of the land is covered by buildings; the rest, 60%, is public and semi-public open space.

While the streets, sidewalks and parking areas constitute a fifth of the land coverage, the remaining mid-block courtyards, greenways and public parks are double that figure. Half of the larger landscape can be used for recreation and at least half of it for local, organic community gardens, providing as much as 30% of the produce needs of the neighbourhood. As with the “green” streets, the green wastes from the urban agriculture and urban parks contribute significant biomass to the biogas digesters. By conceiving of the landscape, infrastructure and buildings as a whole-system design, the neighbourhood becomes as self-sufficient as possible.

As the project progressed, the Berkeley team became more and more excited by the potential for the whole-system design concept to be a real breakthrough, to be a reproducible model for sustainable development throughout China and the developing world. The buildings are platforms for producing energy from renewable sources, such as wind and sun. Sewage is not treated and dumped, but processed into energy, fertiliser and water for irrigation. The landscape is more than eye-pleasing; it is a multi-functional contributor to the systems. There is little or no waste, and all energy is generated on site. Most importantly, the neighbourhood becomes essentially a self-sufficient unit, a circular system. It does not require the construction of expensive new power plants, new sewage treatment and water supply outside the system.

But just as the team became more convinced that the design made environmental sense, difficult challenges emerged.

The new design requires a radical transformation in the development process. In addition to constructing housing units, the developer has to build a comprehensive, on-site utility system of energy production, water supply and sewage treatment, which is beyond the developer’s traditional scope of work. It requires getting approvals through government agencies that are narrowly proscribed and not accustomed to thinking across their jurisdictions. Most importantly, it requires design and construction professionals to share responsibility and to work collaboratively -- to which they are unaccustomed. It requires paying 15 to 20% of the costs up front.

Even though the life-cycle costs are significantly less than the cost of constructing new centralised utilities, the question becomes: Who owns, operates, and maintains the system, and how are they compensated for the service? Some models exist for funding and operating on site systems, but none is as comprehensive and integrated as the one proposed. (Since China is behind in providing centralised infrastructure, many developers have had to provide selected utilities, usually sewage treatment, on site). Despite these institutional and bureaucratic challenges, the economic and environmental benefits of the proposed system offer creative business opportunities for the neighbourhood and the city.

Still, the design team realised that the hardest obstacle to overcome would be the social and cultural demand for a “gated” identity. The concept of a gated community is ingrained in Chinese consciousness by the Forbidden City, the emperor’s own gated community. The traditional Chinese courtyard house, the hutong, is a form of gated community for families, with its walled precinct, gated entry and assembly of buildings around the courtyard.

We’ve tried to provide a similar gated identity, but not at the superblock scale, nor at the scale of individual units, but at an intermediate, urban-block scale. The system has the advantage of keeping select streets open and walkable to transit and services while creating semi-private, gated courtyards in the middle of blocks. The concept has a further advantage. The blocks can be designed to accommodate between 100 and 300 families, a scale that sociologists argue is a manageable size for knowing your neighbours and promoting a sense of community.

Even though the challenges are daunting, the inherent qualities in the design provide many opportunities and rationales for overcoming them. The upside potential -- economically, socially and, especially, environmentally -- is almost irresistible. What is needed is proof that such an integrated design can work.

Fortunately, the Gordon Moore Foundation has recognised this fact. It has made a multi-year, multimillion-dollar grant to Berkeley’s Institute for the Environment (B.I.E.) to enhance worldwide capacity for sustainable urban development. The Sustainable Neighborhood Project is part of the grant.

With a workable prototype, China’s unique top-down/bottom-up planning and development process has the capacity for rapid deployment of such a model. The central bureau of planning and reform would approve the model as fulfilling the goals of China’s 11th Five Year Plan for conversion to a “circular economy”. The ministry of construction would promulgate the detailed design guidelines, creating a standard template for design approval. Finally, the mayors, who are evaluated each year by the party, would be measured in part by how extensively they had applied this basic unit of development.

Through this process, the potential for replication is almost unlimited. Currently, several cities are vying for the opportunity to build one of these prototypes, resource-self-sufficient, transit-oriented neighbourhoods. Paradoxically, while China is presently the source of some of the planet’s most serious environmental problems, it also has the greatest capacity for change.


The author: Harrison S. Fraker Jr. is dean of the College of Environmental Design at the University of California, Berkeley.

Reprinted with permission from California magazine

Homepage photo by Photocapy

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匿名 | Anonymous



Looking forward to the greener future~

Great ideas there!! Indeed, China is urgently in need of a specially tailored sustainable urban form in order for 'green communities' to be replicated in a massive scale. At this initial experimental stage, however, the success of a demonstration project will largely rely on the governmental support at both national and local level. Working with a developer who has a special interest or a good track record in sustainable construction is also critical in making it work. Last but not least, i believe potential residents need to be well-educated enough and be environmentally conscious to adapt to the green lifestyle. For instance, seperation of domestic refuses according to their recycleability is rarely practiced in Chinese families nowadays.
All in all, for the development of a replicable type of sustainable community to become a reality, the government, the developer, the general public and many others need to be convinced and closely involved.