overlapped city



Year: 2012
Size: 40,000 ha
Type: research
Location: West Houston, Texas, USA

Partner in charge: Chen Chen



Energy production in the post-fossil era will be dominated by renewables. Even though renewable energy has a low power density that requires dramatically larger areas to meet our cities demand, it is more compatible with urban conditions and more flexible with spatial application than fossil-fuel-based systems. Furthermore, renewable energy production can take place at various scales and its distributed production pattern can take advantage of the micro-grid, a more efficient and resilient distribution mode.

Traditional cities, which are solely energy consumers, are facing both the challenge and the opportunity of accommodating energy production within their footprints. This challenge will be even bigger with the ambition of managing urban growth in more compact models of development. Historically, political, religious and geographic agents have defined our cities. In the new era, the logic of energy production and distribution will start having a significant impact on the spatial organization of the urban growth. This project explores the morphology of resilient post-fossil cities across three scales: redefining urban boundaries and urban clusters, energy infrastructure framework and a new set of urban codes. Our proposal tries to generate spatial synergies between energy and other urban parameters in the three scales.

The testing site is in West Houston, the fastest growing urban area in the US, with a rich potential for renewable energy production. Parametric tools help recognize the different energy potentials associated with various massing strategies. A series of dynamic relationships links the traditional parameters of density and height with the energy productivity of each block, as a way to motivate developers to maximize their local energy production. The design of urban typologies is articulated following the concept of “overlapped city”: maximizing active surfaces and overlapping multiple programs in compact urban areas.

A policy of inter-block energy balance incentivizes the citizens to maximize their local energy production and reduce their reliance on the centralized energy supply, making the new city work as a resilient ecosystem. In such context, different degrees of flexibility can be allowed in order to adapt to the market economy. New patterns of energy specialization arise, defining the blocks that are more prone to production and the ones that are more prone to consumption. Through a system of energy “trading” a cluster meets its overall energy production target through the compensation among the different blocks and the creation of additional energy sources within the green corridors. As a result of the new urban code, some new interesting and highly diverse spatial conditions and relationships arise, disclosing the potential of this approach to create new paradigms of urbanization. Thus a variety of radically different scenarios are generated, tested and evaluated.

后化石能源时代的能源生产将会被可再生资源所主导。和化石能源相比,可再生能源的生产显然需要占据更大的面积才能产生足够的能量以满足城市需求,但可再生能源与城市环境更加相互协调、更能灵活地适应各种用地。另外,可再生资源分散式的传输模式能够利用更高效、更灵活的微电网而有效节能。

传统城市仅仅是是能源的消费者,在新能源时代,从城市内部解决部分供能问题成为可能,这既是挑战,也是机遇。若以紧凑且高密度的模式组织城市扩张,这种挑战将会更加艰巨。历史上,传统城市多由政治、宗教以及地理因素所定义。在新能源时代,能源的生产与配置将会深刻地影响城市空间布局及其扩张蔓延的模式。该课题研究在三个尺度层次上张开,探索后化石能源时代城市的形态:重新定义城市边界与城市组群[宏观]、能源基础设施的规划框架[中观]和一套新的城市空间规划导则[微观]。我们试图从设计前期就将能源规划的逻辑加入到传统城市规划的考虑中来。

我们选取了美国休斯敦西面的新区作为实验场地,这是美国人口增长最快的地区,并分布着丰富的太阳能和风能,具有巨大的可再生能源生产潜力。参数化的分析设计方法允许我们把城市建筑形态和不同能源的生产潜能联系起来。我们建立了这样一种激励机制:每块用地的开发者需要在用地内进行能源生产为自身提供一定比例的功能,由此在传统城市设计中诸如限高、容积率等参数与新能源的生产率间建立了一种复杂而动态的联系。建筑类型的设计体现了“重叠城市”的概念,即最大化功能性表面,使同一紧凑地段可兼顾城市活动和能源生产的多重功能。

我们提出街区间的能源平衡措施,促使市民最大化能源生产,并降低对集中式能源供应的依赖,使得新城市称为一个弹性的生态系统。为避免僵化的能源目标规划,形成灵活互动的能源市场经济,我们允许街区间存在互补的差异化:城市中将产生不同属性的区块,一些相对耗能,一些相对产能。区块之间可交易能源,以实现城市总体能源目标。此外,城市还可结合绿化空间创造一些以产能为主的区块以弥补总体产能的不足。这一套基于能源逻辑的城市导则将可能催生出新的空间关系与体验,展开一种与以往不同的城市化模式。我们还假设了城市发展的不同场景,并对其相应的城市形态进行测试、分析和评估。