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Skyscrapers seem to have reached a historical turning point.

For quite some time, there has been a global competition for skyscrapers, with towering buildings rising from the ground one after another, competing for the commanding heights of the city skyline.

However, in recent years, as the public pays more attention to topics such as sustainable development, environmental protection, and urban quality of life, people have begun to examine the value and significance of skyscrapers more deeply. In particular, the frequent skyscraper disasters in recent years have aroused public concerns about the safety of super-high-rise buildings. In this context, many places have adopted a more cautious attitude towards the construction of skyscrapers.

Recently, the Jiangsu Provincial Department of Housing and Urban-Rural Development, together with the Provincial Department of Natural Resources and the Provincial Fire Rescue Corps, drafted the "Opinions on Strengthening the Planning, Construction and Control of High-Rise Buildings" (hereinafter referred to as the "Draft Opinions"), proposing to strengthen the control of the height of high-rise buildings, strictly control the construction of new super-high-rise buildings, and require that cities with a permanent urban population of more than 3 million should not build new buildings over 500 meters, and strictly limit the construction of new buildings over 250 meters. At the same time, except for those near rivers, lakes, seas and special urban planning areas, new improved residential buildings should not be higher than 60 meters in principle.

The draft opinion also clearly states that if new super-high-rise buildings are indeed needed, they will be subject to major administrative decision-making procedures as major public construction projects, reported to the city party committee at the same level for approval, and the responsibility will be investigated for life. This means that in the future, super-high-rise buildings in Jiangsu will face more stringent planning and approval processes, not only will they be subject to special review and examination, but the relevant responsible parties will also face pressure to be held accountable.

Strictly control new high-rise buildings

In 2022, the National Development and Reform Commission issued the "14th Five-Year Plan for New Urbanization", proposing strict restrictions on the construction of new super-high-rise buildings, prohibiting the construction of new buildings over 500 meters, and imposing strict restrictions on the construction of new buildings over 250 meters.

Compared with the aforementioned implementation plan which focuses more on the overall direction and goal setting, Jiangsu's "Draft Opinion" goes into detail about the height limit standards for cities of different sizes and clarifies the responsible units.

For example, the draft opinion clearly states that cities with a permanent urban population of less than 1 million will strictly limit the construction of new buildings over 100 meters; cities with a permanent urban population of 1 million to 3 million will strictly limit the construction of new buildings over 150 meters; cities with a permanent urban population of more than 3 million will not be allowed to build new buildings over 500 meters, and will strictly limit the construction of new buildings over 250 meters.

At the same time, it is required that new buildings over 150 meters should be reported to the Jiangsu Provincial Department of Housing and Urban-Rural Development for review and filed with the Ministry of Housing and Urban-Rural Development. New buildings over 250 meters should be reported to the Jiangsu Provincial Department of Housing and Urban-Rural Development for strict demonstration and review of special topics such as earthquake resistance of super-high-rise buildings and fire prevention measures for civil buildings, and then reported to the Ministry of Housing and Urban-Rural Development for filing and review.

In addition, the draft opinion requires that super-high-rise buildings should generally not be newly built around important mountains and water bodies, as well as in areas of old cities with high development intensity, dense population and traffic congestion. Disaster prevention and evacuation sites should be concentrated and arranged nearby, with an average area of ​​no less than 1.5 square meters per person.

In addition to the construction height of skyscrapers, the height of residential buildings has gradually become an important issue in the field of urban planning and architectural design in recent years.

In 2021, the Ministry of Housing and Urban-Rural Development and 15 other departments issued the "Opinions on Strengthening Green and Low-Carbon Construction in County Towns", stipulating that newly built residential buildings in county towns should mainly be six-storey buildings, the proportion of residential building area of ​​six floors and below should be no less than 70%, and the height of newly built residential buildings in county towns should not exceed 18 floors.

Nowadays, height restrictions on residential buildings are no longer limited to county towns, but have extended to urban areas.

Recently, the 2024 version of the Shenzhen Building Design Rules was released, proposing to reduce the public area of ​​residential buildings and effectively improveRoom rate, and requires that residences and dormitories have a height limit of 150 meters.

Jiangsu's draft opinion also lists detailed regulations on the height of residential buildings, requiring classification and categorization according to local conditions, and clearly defining the building height,Volume rateEtc. upper limit indicators.

Specifically, cities with a permanent urban population of less than 1 million will strictly control the construction of new residential buildings over 80 meters. When approving residential buildings over 80 meters and public buildings over 100 meters, relevant local departments should seek the opinions of fire rescue agencies at the same level to ensure that they match the local fire rescue capabilities. In principle, new improved residential buildings should not be higher than 60 meters, except for those near rivers, lakes, and the sea, as well as special urban planning areas.

After the "Draft Opinion" was issued, the term "new improved housing" also attracted attention in the industry.

Li Zimo, vice president of the Nanjing Real Estate Association, said in an interview with China Newsweek that Jiangsu has issued new regulations on improving housing many times this year.

On March 5, Jiangsu Province issued guidelines for the design and construction of improved housing, encouraging the construction of fourth-generation housing with gardens and courtyards in every household; on April 25, Nanjing issued the "Nanjing Housing Quality Improvement Design Guidelines"; on June 13, Nanjing Jiangbei New District issued new housing regulations, which set clear requirements for the quality details of commercial housing and made every effort to improve the quality of commercial housing; on June 26, Nanjing issued new housing regulations, once again emphasizing the improvement of Nanjing's housing quality.

In July this year, the Jiangsu Provincial Department of Housing and Urban-Rural Development issued the "Evaluation Criteria for Improved Housing", which contains more than 100 detailed regulations. It not only sets requirements for building height, floor height, greening rate, decoration standards, etc., but also mentions building materials, sound insulation, intelligent design, etc. It is considered to have redefined improved housing.

For example, the floor height of a residential building shall not be less than 3.1 meters, and the floor height of a residential building with more than three floors shall not be more than 3.6 meters; for residential buildings equipped with floor heating, ducted fresh air or centralized central air-conditioning systems, the floor height shall not be less than 3.15 meters, etc.

Li Zimo believes that the government’s repeated revisions to new housing regulations are not only to strongly support the improvement of demand and to constrain the improvement of housing quality, but more potentially to stimulate the market and stimulate consumers to upgrade their own residences.

He said that according to the draft opinion, the height of Jiangsu's improved housing will be strictly controlled in the future. If calculated based on a floor height of 3.1 meters, the height of Jiangsu's improved housing will not exceed 19 floors. "According to the "Improved Housing Evaluation Rules", overhead floors are not counted, so many new housing projects in Jiangsu now have elevated overhead floors, so the number of floors that can be built in the future will be even smaller," said Li Zimo.

As for why residential buildings are "restricted" to 60 meters, some analysts believe that this may be more from the perspective of fire rescue.

Xu Chuansheng, captain of the Dongying Fire Brigade and one of the top ten fire science workers in the first national fire protection science popularization session, once wrote that the current domestic main fire ladder trucks are generally below 50 meters in height. There are very few particularly tall ladder trucks, and it takes a long time to unfold the ladders, which are easily affected by wind speed. Therefore, if the number of floors is too high, for example, more than 20 floors (about 60 meters), the fire brigade's rescue equipment cannot reach the height when rescuing people, and the water spray height is not high enough when spraying water to extinguish the fire externally. It will also take longer for firefighters to reach the trapped people.

Li Yujia, chief researcher at the Housing Policy Research Center of the Guangdong Provincial Urban and Rural Planning Institute, told China News Weekly that the main reason for Jiangsu's policy to limit building heights is the high maintenance costs of high-rise buildings. With the popularization of the concept of full life cycle management, people have begun to realize that in addition to considering the initial economic costs of a building, they must also pay attention to its maintenance issues 20 to 30 years later, including fire safety and building glass exterior walls, which are very expensive.

new challenge

According to the Council on Tall Buildings and Urban Habitat (CTBUH), as of 2023, there are 2,269 buildings 200 meters or higher and 232 supertall buildings 300 meters or higher built worldwide. Overall, the first 100 of these supertall buildings were completed before 2015, and the other 132 were completed within seven years thereafter.

In fact, China has a considerable number of skyscrapers. In 2023, a total of 177 buildings 200 meters or higher were completed worldwide, more than half of which were in China. Meanwhile, as of 2023, Shenzhen has completed 161 buildings over 200 meters, which means that one out of every 14 such buildings in the world is located in Shenzhen.

However, in the view of many industry insiders, the construction and maintenance costs of super high-rise buildings are high. Due to the need to overcome natural factors such as deadweight and wind load, as well as the need to achieve fast passage, the construction of skyscrapers often requires a large amount of manpower, material and financial resources. Relevant data shows that construction costs do not increase linearly with height, but increase exponentially, which is a huge pressure for local finances and developers.

At the same time, many skyscrapers are often not fully considered in terms of market conditions at the beginning of their construction. In actual operation, due to various factors such as market demand and economic fluctuations, many buildings face difficulties in attracting investment, resulting in a large amount of idle space. In addition, in order to maintain these vacant buildings, energy and manpower must be continuously invested, further resulting in unnecessary waste of resources.

Li Zimo told China Newsweek that, taking Nanjing, Jiangsu as an example, the office market in Nanjing is currently facing certain difficulties, including the old business district Xinjiekou and the new Hexi New Town Science and Technology Park, which are experiencing vacancies and falling rents. He believes that on the one hand, it is related to the overall market environment, and on the other hand, it is because a lot of new skyscrapers have been built in the past few years, resulting in oversupply.

Li Yujia pointed out that many cities build high-rise buildings mainly to enhance the city's image, but this often leads to oversupply. With the changes in housing supply and demand and the reduction in demand for office space by new industries, more attention should be paid to the use of existing buildings and higher quality should be pursued in new buildings.

At the same time, the potential fire safety hazards of high-rise buildings cannot be ignored. Due to factors such as high floors, dense crowds, and limited escape routes, once a fire occurs, the consequences are often disastrous. In addition, natural disasters such as strong winds and earthquakes may also have a serious impact on high-rise buildings.

Although the fire safety responsibilities of super high-rise buildings are more stringent than those of other types of buildings, not all super high-rise buildings are managed and implemented in strict accordance with fire safety requirements.

In March this year, the 18th Comprehensive Inspection Group of the State Council's Safety Committee conducted an open and secret inspection in Hainan and randomly inspected the World Trade Center in Haikou (formerly the Free Trade Zone Times Square), and found a number of safety hazards. For example, the vertical cable shafts more than 200 meters high in the World Trade Center were not horizontally fireproofed and blocked layer by layer, and were basically in a "wide open" state.

He Wenjing, a member of the comprehensive inspection team, said that the cable well itself is a high-risk area prone to fire. The vertical cable well over 200 meters high is not horizontally fireproofed layer by layer, which means that once a disaster occurs, under the blessing of the "chimney effect", the stairwells, pipe wells, and glass curtain wall gaps may become channels for the rapid spread of flames or toxic smoke, and quickly spread vertically to the entire building. In this case, these channels can even be called "death channels" to a certain extent.

It is understood that my country has been implementing a building energy-saving policy since 2005. One of the main measures is to add an insulation layer to the exterior wall. Due to insufficient awareness of the dangers of exterior wall insulation materials and no clear regulations on the combustion performance of the materials, flammable and combustible materials such as polystyrene foam boards or polyurethane rigid foams were mostly used at that time. These materials are extremely easy to ignite and spread rapidly. After burning, they produce a large amount of toxic smoke and pose a great fire hazard.

After a fire occurs in a high-rise building, the "wind helps the fire" and makes it difficult to control the fire. According to measurements, the wind speed at a height of 10 meters is 5 meters per second; at a height of 30 meters, the wind speed is 8.7 meters per second; at a height of 60 meters, the wind speed is 12.3 meters per second; at a height of 90 meters, the wind speed is 15 meters per second. The higher the wind speed is, the faster it is. After a fire occurs, the wind often helps the fire, and the fire uses the wind to burn more and more vigorously.

Therefore, in the face of existing high-rise buildings, many people believe that we should not only pay attention to the challenges of their market operations and the waste of resources, but also deeply reflect on the fire safety hazards behind them and the long-term significance of urban planning.

"How to ensure that every building can become a safe and sustainable urban asset rather than a potential source of disaster while pursuing the city's image and skyline, and how to flexibly adjust the use of buildings to avoid waste of resources and vacant space will be important directions for future exploration." Li Yujia pointed out that as the upsurge in the construction of super-high-rise buildings subsides, how to properly deal with existing high-rise buildings and find a balance between them and urban safety and economic development will become a major challenge facing city managers.

Author: Chen Shulian