This article explores the difficulties in evacuating occupants from high rise fires. This subject has received careful attention, with many international conferences to determine optimum systems and codes that help developers and stake holders to comply with their responsibility towards the tenants occupying high rise buildings. When balancing Economy with Responsibility, greater weight must be given to RESPONSIBILITY. It is imperative that Building Management accept responsibility for the safety of all occupants, and fulfil their duty by providing redundant Supplemental Evacuation that will be put to use when normal evacuation has failed or compromised. This article addresses the same issues with solutions and suggestions in adopting the concept of Supplemental Evacuation in enhancing fire safety and in getting more people out of danger more quickly.
In the event of high эпицентр сайт rise fires, building occupants are commonly faced with danger from the rapid spread of flames and heat, smoke and toxic fumes, confusions and disorientations. In the absence of adequate care in either design or construction or maintenance of a tall building, a fire emergency may occur on a single floor and then spread to upper floors, and sometimes to neighbouring lower floors. Hence, Building designers and Building Managements must explore ways of minimizing such hazards and risks.
Modern high rise building must be designed and constructed such that any fire is either contained within one apartment or at the worst within one floor. This is a prime requirement that is assumed when designing for evacuating a building during a local or general emergency. Secondly, the premises must comply with safety standards by providing adequate smoke and heat detectors, alarms, sprinklers, water storage tanks with adequate pumping capacity at the required pressure, connected to adequate stand pipes and hoses distributed throughout the premises. Thirdly, adequate ventilation system with automatic baffles need to be put in place that will isolate the areas where a fire may have started and smoke and toxic fumes are being generated. If these systems are in place and kept in good operating condition, it is possible to control the spread of fire and heat sufficiently to allow occupiers to safely pass through to designated exit points.
Emergency Escape Routes are typically limited to the stairs. Most codes for high rise buildings requires multiple hardened stairwells that are to be fitted with fire doors and fire walls with a rating of two hours, and provided with adequate emergency lighting as well as pressurised clean air for ventilation. The assumption for evacuation by stairs is that persons can be evacuated from each stairwell, provided there are no blockages or hindrances, and the occupants have the physical stamina to walk down from the upper floors to ground. However, evacuating people from above 50 storey building through the stairwells will exceed the physical capacity of most persons, and will also take too much time to get down and out, thus enhance risks to those who need assistance.
Refuge Areas or Refuge Floors that are similarly hardened to stairwells, and placed at intervals of 5 to 8 floors, are also specified in most Code. The assumption is that residents will access the hardened stairwells, walk down without panic to the nearest Refuge Area, and await further orders for evacuation or rescue. With a travel distance limited to about 5 floors, using a hardened stairwell, it would be reasonable to assume that the physically fit will assist those with disabilities, and that the others will be patient and courteous despite their own anxieties. The occupants will stay put in that safe area and wait for further instructions by the Fire department.
Fire Lifts are designated Lifts that are totally enclosed and pressurized to prevent smoke entering, and also provided with special fire retardant sheathed cabling, fire suppressors, communication systems, independent power for lighting and motor operation, (also with standby power source), and operated by specially trained operators. The recent changes to the NFPA Life Safety Code for high rise buildings encourage developers to provide a bank of hardened Fire Lifts with similarly hardened Lift Lobbies & Shafts, which are connected to the hardened Stairwells. In theory, these lifts are allocated for the used by the Fire Department for evacuating the handicapped, but there is no practical way to control crowds to separate the physically fit from those needing special attention. Most individual lifts descend only 100m, with all passengers switching to the next bank of lifts descending a further 100m. It would be convenient to provide a fire lift at each Refuge Floor.
If there is a fire in your building you want to get everyone out quickly. It is the Management’s responsibility to evacuate ALL people from the building in an emergency before the fire engines arrives. It is NOT the Fire Department responsibility to evacuate building users. The fire-fighters will assist in the evacuation if people are still in the building when they arrive.
It is the responsibility of the Building Management to come up with a Building Evacuation Plan in ensuring smooth evacuation of everyone inside the building in every emergency prior to the arrival of the Fire Department. A building evacuation plan is of limited use if half of the people it is designed for do not understand their respective roles and responsibilities. Planning for building evacuation and conducting periodic fire drill/evacuation drill is important because, when confronted with a dire situation, many people simply do not know what to do or where to start. However, having contingency plans with self help that account for multiple ‘what if’ scenarios including alternative escape routes and modes of evacuation would minimize evacuation hazards and allowing more people to be evacuated in difficult conditions. Once the emergency is announced, it likely is too late to start a back-up plan. If the Building Management has in place a building evacuation plan and shares it with occupiers through dedicated cable TV, meetings and mock drills, it enables occupiers to become familiar with evacuation risks, evacuation routes, equipment, a list of Do’s and Don’ts, and allows delegation of share responsibilities and duties.
With self help the key, building occupants, tenants and residents must take equal responsibility to become familiar with the logistics of evacuation, and possibly, also control of fires, smoke and fumes. With this knowledge, the potential for panic is lowered and evacuation can be efficiently executed. Appropriate selection and placement of smoke and heat detectors, along with automatic and manual alarms, and adequate exit markings visible in all lighting conditions, will provide the critical early warning necessary to safely evacuate the building. While Management must be proactive in maintaining safety systems to prevent malfunction, however, occupiers must not do anything that would hinder prompt fire detection, fire fighting and rapid mass evacuation.
When occupiers are aware of the building evacuation plan that are essential for self help, have experience from mock drills, training in the use of evacuation systems and equipment that the building management provided, sharing responsibilities and duties, and information on the numbers and location of persons that may require assistance in evacuation, it is possible to estimate the time for occupants would take to reach safe zones. Typical evacuation strategy for high rise building is evacuating occupiers of the affected floors and those immediately below and those above first, and follow by the other floors if is required. The evacuees are to be evacuated via the stairwell to the nearest Refuge Area and where necessary are to be evacuated to a level about 5 floor below the fire or even to the ground. Adequate systems can then be specified to ensure that the time taken to reach safe zones is within reasonable practical limits. With self help, the risk of evacuees confusion, disorientation, panic, delay reaching safe zones, and some people may succumb to either smoke or become trapped in the fire zone would be minimized.