Why High-Rise Buildings for Climate Change Adaptation?
Population and Migration Trends
Among the most pressing issues that have encouraged tall buildings development and will likely continue is the colossal increase in urban population worldwide in conjunction with wealth accumulation. Currently, almost half of the world lives in urban areas while 20 years ago only one-third did. It is estimated that by 2030 approximately 60 % of the world’s population will be living in urban areas. In 2050, over 80 % of the world population will live in urban areas at a time when the world’s population is expected to reach nine billion. At that time, all major cities of the world, particularly those in Africa, Asia, and Latin America will have enormous populations, probably ranging from 30 to 50 million, or more (Tall & Green 2008). Accommodating such a large population in cities will be a huge challenge and will put severe pressure on shelter and energy; with land prices on the increase, high-rise buildings may be the solution to house this high increase of urban population.
Horizontal scale of cities is continually being strained with no alternative except to build upward to accommodate people. Rural-to-urban migration is one of the causes of urban population increase. Between 1945 and 1985, the urban population of South Korea grew from 14.5 to 65.4 %, and to 78.3 % of the total population by 2000. In China, it is projected that by 2025, 350 million people will migrate from a rural to an urban environment (Tall & Green 2008). According to Marcos Fava Neves estimation, it is predicted that five million buildings will be needed—an equivalent of ten cities the size of New York (Neves 2010). In contrast, Chinese cities need to be built to accommodate a population increase equivalent to the US population in just 15 years. Thus, high-rise development is the way forward to address this challenge. As urbanisation rates explode around the globe, governments and urban planners increasingly see more high-rise as the answer to reducing urban sprawl and creating more sustainable cities, for example. In China, Shanghai is a mega-city which houses 19.21 million people, mostly living in high-rise buildings (http://www.ee-highrise.eu/index.php/en/). Hong Kong and other mega-cities of China such as Macau, two of the most densely populated places on the planet (http://www.ee-highrise.eu/index.php/en/) are considered a means of vertical living. Australia is also no exception, both federal and state government policies have targeted high-density development, particularly along transport nodes. Nonetheless, questions are being raised about the sustainability of this approach—the amount of energy used by tall buildings and the energy embodied in their materials through to the social impacts of living and working in them. It is vital however that these high- rises must be sustainable.