Policies and technical guidelines for urban planning of high-density cities - air ventilation assessment (AVA) of Hong Kong.

In 2003, Hong Kong was hit by severe acute respiratory syndrome (SARS) from which many people died. The Hong Kong Government subsequently set up a Governmental Team Clean Committee to investigate possible urban design policies. Team Clean charged the task to the Planning Department, HKSAR. In 2003, it initiated a study titled: "Feasibility Study for Establishment of Air Ventilation Assessment (AVA) System." A number of focused studies were conducted. It eventually led to the technical methodology and guidelines of the air ventilation assessment (AVA) system. Unlike many countries with guidelines for dealing with gust wind problems, AVA is a guideline for weak wind conditions specifically designed to deal with congested urban conditions. The AVA system basically establishes a method for project developers to objectively assess their designs. In 2006, the government of Hong Kong officially adopted the system and required all major publicly funded development projects to undertake the assessment. The scientific and implementation processes leading to the AVA system are reported in this paper.