CARE2022 Hong Kong Conference

55 • Air Ventilation Assessment (AVA) The introduction AVA in mid-2000’s had met with strong reservation, even objection, from certain developers and practitioners due to worries on constraining development potential and design of buildings, Now, AVA has become the norm in site planning and building design. The Urban Design Guidelines incorporated in the Hong Kong Planning Standards and Guidelines (HKPSG) – has helped to maintain important breezeways within the urban area to achieve cooling without affecting the development potential of the sites concerned. b) Cooling Hong Kong – warnings on heat A series of Hong Kong heat-health studies have been conducted. The first study on heat and health found that more consecutive hot nights (HNs, with daily minimum temperature >= 28ºC) contributed to higher mortality risk, while the number of consecutive very hot days (VHDs, with daily maximum temperature >= 33ºC) did not have significant association with excess mortality.5 Following the first study, local researchers conducted a further study and found that significant associations with raised mortality risks were observed for a single HN, while stronger associations with mortality were observed as significant for five or more consecutive VHDs/HNs. Three thresholds (5VHDs, 5HNs, 2D3N) were determined to be representative of identical types of Extreme Hot Weather Events (EHWEs) in Hong Kong. Females and older adults were also determined to be relatively more vulnerable to all defined EHWEs.6 These thresholds are being considered by HKO for alerting the public to prolonged heat situation. These studies sought to better understand the heat risks, measures for mitigating these risks, enhancement of weather warning system, as well as using urban planning and design to mitigate high heat in Hong Kong. The third study on the spatial pattern of extreme hot weather conditions in Hong Kong found a significant spatial variation in the extreme hot weather conditions of Hong Kong in both day-and-night times. This indicates that the spatial variation of land use configurations must be considered in the risk assessment and corresponding public health management associated with extreme hot weather.7 Built on the third study, local researchers developed a spatiotemporal hazardexposure-vulnerability assessment of the extreme heat risk in Hong Kong and found that the risk was spatially variant, and high-risk spots were identified at the community scale for both daytime and nighttime, with high risks mainly occurring in the core urban areas.8 Based on the above research findings, HKO enhanced the precautions associated with the Very Hot Weather Warning in September 2021, which better suit the health needs of the elderly and persons with chronic medical conditions. 5 Preparedness and Resilience FIGURE 5.20 Air ventilation assessment introduced by PlanD in 2006 Source: PlanD ORIGIN Technical Circular No. 1/06 – Air Ventilation Assessments was promulated in 2006 subsequent to a reserach comissioned by the Planning Department to understand the design and planning of the city fabric for better natural air ventilation and cooling FIGURE 5.19 Proactive conservation policy to be adopted for the Northern Metropolis Development Strategy Source: