Solving the Problem of High-Rise Fires: Why is Rescue so Difficult?
By Zhao Jiaxin, Li Chuanyu, Kong Qianmin, Zhang Xinyue, Zheng Qifang May 20th, 2021
Cities can "grow taller," but safety cannot be neglected. To eliminate "towering fire hazards" from cities, the government, developers, property managers, and residents must work together and make efforts from all sides.
From fire supervision and risk assessment to fire rescue and safety education, China's fire protection industry should adhere to the principle of "prevention as the mainstay, and combining prevention and extinguishment" and use more standardized methods and more perfect measures to protect residents' lives and property.
We cannot wait for a fire to "test" the safety of our high-rise buildings.
At 7:00 pm on May 17th, a large fire broke out on the 24th floor of Building 5, Liwan Plaza, Liwan District, Guangzhou. According to media reports, flames were shooting up and flames fell from time to time. After emergency rescue by the fire brigade, the fire was brought under control within an hour, and no casualties were reported. However, the furniture and other items in the 90-square-meter apartment were burned, causing irreparable property losses.
Liwan Plaza Building 5 has 30 floors and a height of nearly 100 meters. It is a common high-rise building and also a place where fires occur frequently. Although Guangzhou has been continuously carrying out hidden danger investigation, rectification, and training for high-rise building fires in recent years, the occurrence of high-rise fires still catches people off guard.
The fire at Liwan Plaza is not an isolated case. In China, thousands of high-rise fires occur every year. Although in recent years, China has continuously strengthened the comprehensive management of fire safety, effectively curbing most of the fires in various places, and the overall number of fires has shown a downward trend, the number and proportion of high-rise fires continue to rise, causing alarming numbers of casualties and property losses.
In major cities, due to the decreasing availability of urban land for development, buildings are continuously "congregating" and "growing taller," forming clusters of high-rise residential and commercial office buildings.
According to an investigation by the Fire Department of the Ministry of Public Security, as of 2017, there were 619,000 completed and in-use high-rise buildings in China, an increase of 10.6% from the previous year. Among them, buildings over 100 meters can be classified as supertall buildings, of which there are 6,457 in the country, with an annual growth rate of up to 8%, 2.5 times the world average.
Compared with fires in ordinary buildings, fires in high-rise buildings cause greater casualties and property damage. According to statistics from the fire department, in the past decade, fires in high-rise buildings nationwide have caused 474 deaths and direct property losses of 1.56 billion yuan, showing an upward trend year by year. Among them, there were 3 extremely serious fires, 4 major fires, and 24 large fires.
Electrical fires, careless use of fire, smoking, spontaneous combustion, production operations, and arson are the main causes of fires in high-rise buildings, among which electrical fires are the most frequent.
The external rescue dilemma: "smoke is heavy" on the way to firefighting
Rescue operations for high-rise buildings in China mainly follow the principle of "simultaneously fighting fire inside and outside the building." In internal rescue operations, firefighters ride in fire elevators or climb stairs with heavy equipment to enter the building and then open windows for ventilation and activate fire hydrants. External rescue operations rely on firefighters using equipment such as aerial ladder trucks outside the building to fight the fire.
The internal rescue of high-rise building fires has a higher risk factor than that of general building fires. This is because when the fire forms inside the building, the smoke flows upward due to buoyancy, and the vertical passages such as stairwells, elevator shafts, and pipeline spaces in high-rise buildings
Data source: "Technical Specification for Steel Structures of High-rise Civil Buildings (with Article Explanation)"
Data source: Statistics from the Fire Department of the Ministry of Public Security
Data source: Compilation of the "China Fire Yearbook" over the years
provide a channel for the vertical flow of smoke, forming a "chimney effect."
The vertical flow velocity of smoke is extremely fast, reaching 3-4 meters per second, and in super-high-rise buildings over 100 meters, it can reach the top floor in about 20-35 seconds. This means that the time for firefighters to climb and rescue is drastically shortened, and the difficulty of rescue is greatly increased.
In situations where the internal fire is difficult to predict and entering the building is extremely dangerous, using equipment such as aerial fire trucks and helicopters for external rescue is a unique rescue method for high-rise building fires.
Well-equipped firefighting equipment is one of the key factors in improving the rescue rate of high-rise building fires and reducing casualties. Aerial fire trucks are one of the commonly used types of fire trucks, including aerial ladder trucks, elevated platform trucks, and aerial spray trucks.
According to "Measures for Improving the Fire Fighting Capability of High-rise Buildings," cities with 200-500 high-rise buildings need to have 7-10 aerial ladder or elevated platform fire trucks, and cities with more than 500 high-rise buildings should have no less than 10 trucks.
According to data from the 2017 China Fire Yearbook, the allocation of firefighting vehicles in various provinces is already quite sufficient.
However, even if the quantity is sufficient, aerial fire trucks still cannot avoid the limitations of the equipment itself. Taking aerial ladder trucks as an example, the height of the aerial ladder is difficult to exceed 100 meters: due to the limitations of the fire truck's carrying capacity and the impact of strong winds at high altitudes, using a higher aerial ladder poses great risks and its installation and use become extremely difficult.
Moreover, although China's highest aerial ladder fire truck has reached 101 meters, there are many high-rise buildings over 150 meters, and this "peak" is still unreachable. Therefore, rescuing high-rise building fires cannot solely rely on firefighting vehicles.
Nowadays, many developed countries are using firefighting helicopters for fire rescue. Zhu Guoying, a member of the Guangdong Provincial Fire Rescue Corps, stated in his paper "Application of Helicopters in Fire Rescue Operations" that helicopter rescue has obvious advantages such as high efficiency and precision and plays an irreplaceable role in firefighting rescue. According to data from the Prospective Industry Research Institute, the US has about 1,000 forest fire-fighting aircraft, Canada has about 500, and Russia has about 800. Emergency rescue operations are mainly government-operated, and the rescue network is dense. However, China's firefighting helicopter force was established relatively late, with less than 100 helicopters, and the number of firefighting exercises is insufficient, resulting in an overall level gap with developed countries.
However, helicopters are also limited in their application for high-rise rescue due to conditions such as the landing and takeoff site, visibility at disaster sites, and the stability of the aircraft body.
Building designs that hinder rescue efforts require urgent reform
Despite many regions being equipped with complete external firefighting and rescue equipment, rescue efforts become "difficult to execute" in the actual process of responding to high-rise fires. Therefore, taking preventive measures against high-rise fires from the source has become a more feasible option.
Clearing firefighting passages, constructing refuge floors, and using highly fire-resistant exterior insulation materials are all important requirements in China's policies.
Firefighting passages are specialized channels for large fire trucks to enter the fire scene for rescue, ensuring that fire trucks can quickly reach the scene at any time.
China's "Fire Control Law" clearly stipulates that no unit or individual may occupy, block, or seal evacuation passages, safety exits, and fire truck passages. The official WeChat account of the Emergency Management Department's Fire Rescue Bureau, "China Fire Control," conducted a voting survey, and the results showed that although the majority of residents are aware of this law and claim they can strictly comply with it in their daily lives, they do not even know which ones are firefighting passages. In addition, more than 4,000 respondents' firefighting passages in their residential areas are often occupied.
With the widespread dissemination of firefighting knowledge, the topic of "Please Give Way to Fire Trucks" created by Weibo in January 2020 garnered massive attention and support. In the "2020 Firefighting Weibo Big Data Report," terms such as "life channel," "cherish life," and "clear road" were high-frequency words mentioned by netizens.
The refuge floor, also known as the "life-saving floor" during times of crisis by netizens, is a special floor in public buildings with a height exceeding 100 meters, specifically designed for people to evacuate and take refuge, according to China's "Code for Fire Protection Design of High-Rise Civil Buildings." With more than 6,000 high-rise buildings in China exceeding 100 meters in height, Hong Kong, Shanghai, Guangzhou, and Shenzhen alone have more than 1,000 such buildings. Professional fire-fighting equipment is installed on the refuge floor, and no combustible materials are allowed to be stored or decorations to be made, as it is intended for building occupants to seek temporary shelter and wait for rescue during a fire.
Generally, the distance between two refuge floors in a high-rise building does not exceed the height of 15 floors, which is due to the fact that China's fire-fighting ladder can rescue people up to around 50 meters, equivalent to the height of 15 floors.
Image source: Code for Fire Protection in the Design of High-rise Civil Buildings
However, according to a report by the Zhejiang Daily, although there is no comprehensive statistics, the phenomenon of using refuge floors for other purposes does exist; and the lack of obvious warning signs and low awareness among residents regarding refuge floors is even more common.
In the investigation, more than 90% of residents did not know whether their community had a refuge floor,
and over 95% of people did not know the location of the refuge floor. Even if the refuge space is nearby, many people may miss the chance to survive due to a lack of understanding.
In addition, refuge floors are often used as offices or temporary storage, which violates regulations and reduces the effectiveness of the refuge floor system. After the completion of high-rise buildings, they must be inspected and approved by the fire department in the administrative area (generally the housing and urban-rural development department of local governments at or above the county level) before they can be put into use. However, due to the high cost of constructing a refuge floor in a competitive real estate market, management units often ignore regulations and illegally occupy refuge floors for other purposes.
To truly benefit residents, the implementation of the "life-saving floor" system requires further exploration in policy-making by the government.
According to Chinese regulations, only super-high-rise buildings exceeding 100 meters in height are required to have refuge floors, and there is no mandatory requirement for other high-rise buildings below this threshold.
The formula for calculating building height is as follows: Building height = height of the first floor + floor height (approximately 3 meters) x number of floors + height of the top equipment room. Usually, a 32-story building is close to 100 meters in height. Therefore, developers often limit the number of floors to 32 or less to avoid the cost of building a refuge floor.
This problem is not limited to China's high-rise buildings. Zhao Jinjing, the executive vice president of the Henan Real Estate Chamber of Commerce, pointed out in an interview with Dahe Daily that by the end of 2010, there were more than 3,000 high-rise buildings exceeding 24 meters in Zhengzhou, but there were no refuge floors in nearly 100 super-high-rise buildings with more than 30 floors. And the rescue height of the fire ladder is only more than 50 meters. As a result, residents on or above the 16th floor would have to rely on self-rescue in the event of a fire. Therefore, the construction of refuge floors should not be limited to super-high-rise buildings, and high-rise buildings should also be taken into consideration.
Constructing an exterior wall insulation layer involves placing the insulation layer outside the main wall material. This insulation method has the advantages of being lightweight, providing good insulation and heat resistance, and having a low price. It has been vigorously promoted by the government and has become the most widely used building insulation measure. However, exterior insulation materials have become one of the culprits of high-rise building fires.
Exterior insulation materials are mainly divided into four grades: A (non-combustible), B1 (hard to ignite), B2 (combustible), and B3 (flammable). Different types of high-rise buildings should use different grades of exterior insulation materials, and current policies have made clear provisions for this.
However, in practice, implementation of the regulations is not optimistic. Ji Guangqi, a researcher at the Building Fire Research Institute of
China Academy of Building Research, stated in a CCTV program "Combustible Insulation Materials in Building" that many common insulation materials are substandard B3 grade products, which are flammable materials that easily catch fire. For example, extruded polystyrene insulation board that meets fire protection standards costs more than twice as much as the flammable variety.
In 2017, the Ministry of Public Security led six departments to deploy a special action for comprehensive treatment of fire safety in high-rise buildings (referred to as "comprehensive treatment"), investigating the use of combustible/flammable exterior insulation materials in 42,000 high-rise buildings, involving 6,206 buildings that illegally used exterior wall insulation materials.
In addition, the exterior insulation layer of old buildings is in need of renovation. Most of China's high-rise building exterior wall decoration uses a full wall laying grid cloth technology. This technology can easily overload the wall surface, causing the exterior insulation layer to fall off. Even if the grid cloth exterior insulation layer does not fall off, it is easy to crack and damage if regular inspections and renovations are lacking. The comprehensive treatment investigation found that 11,000 of the 42,000 high-rise buildings had damaged, cracked, or fallen exterior insulation layer protective layers.
On July 20, 2020, the General Office of the State Council issued the "Guiding Opinions on Comprehensive Promotion of Renovation of Urban Old Residential Areas," which requires all regions to focus on the renovation of urban old residential areas built before the end of 2000, with a focus on fire inspection and renovation of old buildings.
How to implement this policy and renovate the exterior insulation layer of old buildings is a topic that deserves continued attention from society.
Reference materials
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