In the rush to build, Hong Kong must keep cool
Florence Lee says Hong Kong must reconsider its push to pack ever more flats into already dense urban areas, as the costs to health and the environment may outweigh the benefits
The government is planning to increase the plot ratio by 20 per cent or more in some densely populated areas such as Kai Tak and Tun Mun East to boost housing supply.
Earlier this year, Secretary for Development Paul Chan Mo-po said raising the plot ratio for several sites at Kai Tak would provide an additional 6,850 flats and raise the population capacity by 20,000 to more than 110,000. He also mentioned maximising the development density of the Tuen Mun East land plot, allowing for 8,000 new homes - or eight times the original plan.
These numbers and statistics seem positive. However, as with any large urban planning project, they also hide some complex realities and negative consequences. Such initiatives need more scrutiny and environmental assessment.
As a small city with an already high population density, any expansion plan will need to be thoroughly evaluated. What will the effect be on quality of life if building density and height increases substantially? Will there be adverse environmental and climatic effects? More importantly, what are the implications of a higher, denser Hong Kong for future generations' health and livelihoods?
Arguably, the biggest environmental impact of increasing plot ratios will be a bigger temperature difference between urban and rural areas - the "urban heat island" effect. It is not surprising to learn that Hong Kong's high-rise buildings already cause the city centre to heat up dramatically. High-resolution thermal satellite images from 2007 showed that our urban areas are up to 7 degrees Celsius warmer than open land - and it is getting worse. Scientists fear the difference could be as much as 10 degrees by 2050.
This temperature variation has many adverse health and environmental effects. First, retained heat worsens the air quality of the surrounding environment. In areas with lower building densities, heat and exhaust fumes are released into the surrounding air and rise up above the cooler, heavier air on the ground. As air moves upwards, pollutants and dust are lifted up.
