Performance Based Planning for High Density Urban Habitation

In Hong Kong, about 22% of the total territoryis area can be classified as built-up area and potential development area. Only 6% of this area is allocated to district and local open space for the 6.8 million populations, i.e. 2m2 per person. Sensible planning of the limited area to enhance the livability and environmental quality hence become a challenging issue for quality urban living of the mass population. However, considering the dynamic relationship of the different performance criteria in the hyper-dense urban environment, one needs to assess various environmental criteria to carry out a balanced planning. Meanwhile, effective tools to evaluate and manage the inter-relationship of these criteria, or indexes for integrated issues indication are not readily available that a reasonable planning is not always easy to achieve. In this paper, the “openness ratio” concept is introduced for open space planning to provide an integrated index for early stage of planning and design. The new index is expected to provide a comprehensive rating system in considering the environmental performance of open area. It helps to highlight the potential problems in planning or site layout and support the integrated thinking of the four key components: visual sensitivity, urban wind, urban noise and solar heat gain. The concept has shown to be feasible on simple massing study which is applicable in the preliminary planning stage