We have become very familiar with concepts of "green" and low-carbon development. Many Chinese cities have set goals to become low-carbon, ecological cities. But what is a low-carbon city?

While national, provincial and city governments talk about low-carbon development, China's energy consumption per capita has risen from below the world average to above the world average in the past 10-plus years.

If this growth continues Chinese energy consumption per capita and carbon emissions per capita will soon exceed those of the UK. It is not difficult for us to reach and exceed Britain in carbon emissions, but can we build China into a developed country in the same time period? There are some problems.

I found a very interesting phenomenon last year while I was researching Shanghai's low-carbon development blueprint for the years leading up to 2050.

Shanghainese and many other Chinese are living a very simple and low-carbon life. Though the carbon emissions per capita and energy consumption per capita in Shanghai are as high as those of Japan, locals' carbon emissions for daily life is very low, only accounting for 10 percent of the total emissions.

Where do we generate so much carbon emissions? The answer is obvious - steel, concrete and chemical engineering. The same is true for other cities in China.

The energy-intensive industries thrived for so long over the years because of urban construction needs.

Bubbles

Why does China's production in its steel and cement industries account for half of the world's total output? I can't help thinking we have overbuilt.

I call all these the bubbles in the urban construction. If we want to promote construction of ecological cities to slow down the growth of our carbon emissions or make it stable, the core problem is not the technologies, but our guiding concept, development strategy and urban strategy.

The bubbles in urban construction mainly exist in the following three aspects:

First, many buildings have too short a "life." We keep demolishing on a great scale and constructing on a great scale, which causes great waste.

Many industries have very short life cycles. Many local governments nationwide compete for investment by issuing favorable policies as incentives; this leads to short-term investment because investors want to enjoy preferential policies.

This causes frequent capital inflow as projects are launched everywhere. The short life cycle of many industries cause waste in construction projects.

A lot of city infrastructure and buildings have similarly short "lives." For example, I run in Century Park every day, so I pay a lot of attention to the road. It was reconstructed three times before the 2010 World Expo in Shanghai.

System

After the Expo opened, I thought the road would not be rebuilt or repaved for another three to five years. But reconstruction started again this year. What causes this problem? We need to think about it in the system. If we reduce the waste, we can reduce the carbon emissions. The problem cannot be solved by technology, but by management.

Second, population projections are unreasonably high, leading to excessive urban construction.

There is a problem in making reasonable demographic predictions for mid- and long-term urban development. I have read extensively and I am impressed by one thing.

The urban plan made in 1990 is based on an estimated urban population of 2 billion in China by 2010. Though plans should be forward-looking, they should also have a limit.

Overestimated population surely led to lavish construction. There are many under-utilized airports and expressways in China.

The third problem is construction equality, especially in housing.

The per capita housing space for urban Chinese has reached about 40 square meters.

Who owns the 40 square meters? This is a problem.

With such high per capita housing space, there are still lots of people with mediocre or low salaries who do not own a house.

The bubbling in housing exists if we think about the problem from the standpoint of equality. Some people have accumulated lots of houses that are not occupied. Meanwhile, lots of people don't have their own house.

The government should encourage the house leasing market and impose heavy levies on the unoccupied houses, which will be good way to reduce or eliminate the bubble.

Dai Xingyi is a professor in Fudan University's Department of Environmental Science. The excerpts are from his speech last month at an international symposium on low-carbon urban development held at Fudan. Shanghai Daily reporter Liang Yiwen translated Dai's speech from Chinese.