The wall effect has recently risen to prominence in popular debate about development. The blocking of sea breezes and light by the siting and design of buildings has been a negative feature of our city's urban planning for decades. Now, this has reached the stage where people have begun to sit up and take notice. A judge's decision, in one case, that such matters are for the government rather than the courts is a setback of sorts to activists. But as one door shuts another is prised ajar.
Environmental and residents' groups will be heartened by today's report that a government corporation and one of our biggest developers, the Kowloon-Canton Railway Corporation, is not deaf to what they are saying. The KCRC proposes significantly reducing the scale of major developments along the West Rail that have the potential to add to the wall effect.
In one case, at Nam Cheong station, it wants to remove one of 10 high-rises originally planned on a closely packed site. A study of the development's impact on air ventilation is said to have shown that this will be a positive move for the local environment.
At Tsuen Wan West, it wants to slash 10 storeys off one of three development sites consisting of 11 residential towers that form walls. A research team is studying how to make both places more people-friendly. The corporation is reviewing three other projects with a total potential development area of 60 hectares.
Hopefully its argument that at the end of the day these are win-win proposals for the community, the developers and the government will be convincing enough to persuade officials to accept a potential loss in land premiums.
Lack of regard for air flow is, however, to be found in the city's older developed areas as well as in new projects designed to maximise the return to the developer from the plot ratio. When some of this land was originally partitioned, a past generation probably envisaged bungalow-style housing, rather than wall-to-wall blocks that rose ever higher over time.
The case for finding ways to scale down density to minimise the wall effect on fresh-air circulation is now evident. Even with consensus on reining in the height of new buildings, however, we would still be left with the wall effect where it matters most - at street level. Thanks to the Hong Kong preference for podium-based development, low-rise ground-level blocks supporting towers are often responsible for a mini-wall effect.
The government should introduce planning rules for newly developed areas that ensure the issue of air flow is a major consideration. Architects should be encouraged to develop street-level designs with features such as archways that allow the air to pass through.
In older urban areas there is a need for a more innovative planning approach to open them up to more fresh air. For example when leases expire there could be an option for swapping land-use rights in another part of the territory and putting the sites to more environmentally-friendly use, such as urban parks. Only with such initiatives can we thin out population density as well as address the wall and urban canyon effect of past development.
The KCRC is to be commended for setting a good example. It is hoped the move by the rail operator will encourage other developers to take a socially responsible attitude to the long-term benefits of ensuring that we do not wall off our city from cleansing sunlight and breezes.