HKU Bulletin April 2010 (Vol. 11 No. 2)

If greening is good for our health, it’s also good for our pockets. Research shows that a natural view – ocean, park or mountain – adds value to a property beacuse home- buyers place it high on their list of desires. Dr Wendy Chen, a Research Assistant Professor in the Department of Geography, has been exploring the financial advantage of ocean views in comparison with mountain views and neighbourhood parks. “We try to use some ecometric methods to separate the value of different natural landscapes so we can inform residential developers,” she says. “Then they can assess the value of including a nature landscape in their residential developments.” What she’s found is that homebuyers attach greater value to ocean or harbour views, but that any natural landscape is desirable. In high density urban areas, where a natural view has already been built out, developers can add value to their properties, and attract potential buyers, by incorporating green elements, like a garden or a pond. “This sort of research is useful to developers,” she explains, “but also to the government, because we need to evaluate the quality of urban life. In addition to education and income, green accounting is a very important element to evaluate the quality of urban life. Green places are good, not just because of the views they provide, but also because of their effect on air quality. In addition they allow room for recreational activities that can enhance the cohesion of a community. We need to encourage the development of more neighbourhood parks, which are important not only to improve the quality of urban life in Hong Kong, but also offer other benefits that people can enjoy.” “People like to be close to nature, they like to hear birdsong and to experience the wildlife that parks attract. Scientific evidence shows that natural landscapes are very beneficial to human mental health and also to physical recovery in hospital patients.” “For a city to be successful long term it needs to attract creative types, and evidence shows that creative people choose green, clean environments. Unless Hong Kong makes more of an effort to improve air quality and increase green spaces it may lose its creative workforce over the long term.” Open, natural landscapes also help alleviate urban heating. But, says Dr Chen, there is still a gap between the research and the application in Hong Kong. “I know that the government is trying to develop more green areas, with roof gardens and vertical greening, which are good options in such a dense city, but the economic index is still widely applicable here. Also, developers are not entirely open to greening because land here is very very expensive.” “Research shows that a natural view adds value to a property.” 8 The University of Hong Kong Bulletin 9 April 2010 Professor Li Yuguo of the Department of Mechanical Engineering is similarly concerned with urban heat and pollution, but from the perspective of dispersal. By improving the movement of air through the city, it may be possible to reduce localized heat and pollution, he says. “Scientists, when they look at cities, don’t talk about ventilation or air cleaning, they talk about emissions. But historically, all the bad air pollution episodes are not due to a sudden increase in emissions, they are due to the reduced ability of ventilation,” he says. Cities, like buildings, need regular injections of fresh air to flush out heat and pollutants. Professor Li estimates Hong Kong itself is ventilated at 500-1,500 litres per person per second – only 20 per cent of that in Helsinki. He has constructed computer simulation models for ventilation and hopes to get funding to test them in field experiments in smaller environments, such as around HKU or Mong Kok. Knowing the ideal ventilation rate is one thing, though. How to ventilate is another. Smoothing the way for natural air flows could make a difference. Preliminary work by Professor Li’s team shows air travels up buildings and mountain slopes during the day and down at night, bringing fresh air to street level. Urban design could take advantage of this process. Alternating buildings of different heights can create more turbulent air flow at the top and increase the movement of air to the lower levels. Creating open spaces Cover Story at ground level, such as that in the HSBC Building, also increases a city’s ventilation rate by two to five times. “These may not always be realistic but you can find tricks to improve ventilation. Certainly you could remove some of the signs hanging over the streets. Everybody can see the names on them but the wind is blocked at street level,” he says. Ultimately, he thinks sorting out ventilation could help in Hong Kong’s development. “High-rise compact cities have the potential to be the most energy efficient places. Hong Kong is doing well, but it could do better. What we learn here could apply to other cities in Mainland China, India and so on, where most of the future growth in the world’s cities will happen.” Creating open spaces at ground level, such as that in the HSBC Building, also increases a city’s ventilation rate by two to five times. AIRING OUT the problem THE ECONOMIC VALUE OF green landscapes