THE INFLUENCE OF URBAN DENSITY ON POTENTIAL OF NATURAL VENTILATION AND URBAN AGRICULTURE INTEGRATION IN RESIDENTIAL DISTRICTS

Abstract

Because of the continuous increase of urban population, urban planners tend to apply high plot ratios to current residential projects to meet the requirement of accommodation. This dissertation intends to provide a point of view for urban planners on the decision making regarding urban density in future residential projects. With a question of high urban density may sacrifice other necessary urban needs in residential zones, this dissertation tries to explore the relationship between urban density (represented by plot ratio), Natural Ventilation Potential (NVP) and urban agriculture. A hypothesis is made that high plot ratio will reduce Natural Ventilation Potential and food production. In order to prove or disprove the hypothesis, three models of different plot ratios are made and evaluated on their potential of natural ventilation and urban agriculture integration. Calculations based on assumptions are carried out to evaluate food production and Computational Fluid Dynamics is used to evaluate wind condition. The hypothesis was proved to be only partially correct. The calculation result shows that self-sufficiency (defined in the dissertation) can be achieved under a plot ratio of as high as 4.5. The simulation result shows that at high levels, the wind condition is better in high plot ratios than lower ones. It is explained by that at high levels, the influence of height on NVP overtake that of urban density. Though the hypothesis is not fully correct, the evidences in this dissertation cannot end the discussion on the role of plot ratio in urban design trends because there are a lot other factors involved in the issue such as air temperature, economy, land restriction, requirement of open spaces and so on. Studies on these factors should be carried out to give a more completed view on the issue.