Building to alleviate pollution

Much has been made of Hong Kong’s atrocious air. Ajay Shamdasani looks into what can be done to improve the situation.

Hong Kong’s skyline is obscured most days, and perhaps more obtrusively hot air traps fumes at street level, making it unpleasant to venture outdoors. The question is whether or not intelligent urban planning can alleviate, or at least ease, the situation.

According to Sylvester Wong of Hellmuth, Obata and Kassabaum (HOK), a US-headquartered company that focuses on design and analysis for constructed environments, “The worst circulation is generally at ground level, where its impact on pedestrians is also the highest. Gaps in a city’s building composition generally help, but we also see high street-level wind generated by tall buildings. So every city situation is different, partly due to unique microclimate conditions.”

Computer modelling of wind flow, used to study the impact of wind at ground level, will reveal different solutions for every project and city. But regardless of the locale, Wong believes it is essential not only “to consider scenarios in changes to the building skyline, but also the built condition of the first few storeys of the city”.

Wong’s views dovetail with those of Hong Kong University of Science and Technology Professor of Urban and Environmental Planning, William Barron, who says, “The most basic thing is more space between buildings; to be more sophisticated there are options for airflow studies as was done for the government headquarters building on the site of the former HMS TAMAR, in Central.” This building, aptly nicknamed The Door, has been designed with a large hole or doorway at its base to allow air to flow through it.

It would seem that tall buildings can, through proper design, allow for natural ventilation. Furthermore, in Wong’s opinion buildings over 10 storeys only marginally affect airflow - therefore “having fewer tall buildings would block less airflow than more shorter ones”.

Building up, the experts believe, is the best way to encourage natural breezes, even in a place as crowded and congested as Hong Kong. “Most gains can be made in the first steps of a project, in smart design decisions regarding location, orientation and scale,” says Wong. “This intelligent urban design makes easier the intelligent building design of structures to achieve even more gains.”

Many things can in fact be done in this regard, and not all of them are state of the art. The few colonial buildings left in Hong Kong, with their facades, setbacks and overhangs, facilitate freer airflow than many of the new glass-encased tower blocks.

“Stanley’s Murray Building is much more efficient than is, say, the Bank of China Building,” says Barron. The HSBC Building, with its wide ground floor opening, also comes to mind for circulating air at street level.

The prognosis need not seem so bleak if the aforesaid solutions and improvements are implemented. The net result might mean more pleasant breezes, plus somewhat cooler, fresher air for all those who call Hong Kong home.

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