High-rise building refers to any building used for human occupancy that exceeds 75 feet (23 m) in height. This definition depends upon the fact that ladders on fire department vehicles mostly do not reach past this point. In this case, the height of the building starts from the lowest ground level a fire truck can access outside the building to the floor of the highest story human can occupy (Harmon and Katherine 62).
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High-rise buildings have occupancy classification to ensure that everyone is safe in a high-rise building. Occupancy classification depends on how the occupants will be using the space. Occupants may use the space for an office now, but later turn it into a conference room for training. As such, we may classify the high-rise building as an assembly instead of business such that the design focuses on stringent code requirements.
The International Code Council (ICC) classification of occupancy may have slight difference in the way the National Fire Protection Association (NFPA) codes define the occupancy type.
There are 10 most common occupancy classifications adopted throughout different buildings and life safety codes. Some of the occupancy types may also have sub-classifications. Occupancy classifications include assembly, business, educational, factory or industrial, hazardous, institutional, mercantile, residential, storage, utility or miscellaneous occupancies.
Before 1970s in the US, there were no rigid criteria for high-rise buildings in the national codes. In 1970s, various codes combined to form the International Building Code (IBC). These codes developed requirements for high-rise buildings. The NFPA Life Safety Code (NFPA 101) provides the requirements for high-rise buildings, which may differ depending on the occupancy classification.
Many jurisdictions in the US have revised the original definition of a high-rise building of at least 75 feet to include a height ranging from 35 feet (11 meters) to 55 feet (17 meters). High-rise building provisions aimed at providing protection in building structures where access rescue was not possible.
The standard height of 75 feet was the longest accessible point that rescuers could access. Therefore, the codes aimed at addressing the safety of the occupant who could not be reached from outside. Apart from stack effect delayed evacuation, all the factors with regard to high-rise building depended on the ladder reach idea.
Provisions regarding high-rise building emerged due to requirements for voice communication, automatic sprinklers, emergency power and pressurized stairs.
Most locations also insisted on smoke control systems. Other codes in other countries referring to the provisions in high-rise buildings are similar to the US provisions such as 75 feet tall. However, some countries have more restrictive provisions regarding the number and locations of elevators for firefighters, width, compartmentation, travel distance to stairs of escapes, and structures of fire resistance.
The US building codes now target new areas, which are addressing the conditions in existing buildings, which do not comply with the new building codes requirements. There are retrofitting sprinkler ordinances in many buildings, in the US cities. However, the challenge is that retrofit laws vary from city to city. NFPA 101 requires that existing high-rise buildings install automatic sprinklers. The public cannot determine the level of protection they have in high-rise buildings due to sporadic application of the new codes requirements.
Another change in code requires additional protection in buildings as high-rise buildings go higher. People may picture a building of a 7-story as a high-rise. However, the level of protection they get is similar to those they get in a 50-story building. The only similarity exists in the exterior rescue measurement of 75 feet.
Factors such as air movement, evacuation viability, staged evacuation, and the information occupants and fire department need are different from tall buildings to mid-level buildings. These are some of the new areas of concern the codes are addressing.
Safety in high-rise buildings is of a paramount concern to its occupants. This is because high-rise buildings pose additional dangers to its occupants due to increased height and characteristics of a high-rise building in the event of a fire. The prominent danger is that it is often impractical to evacuate all the occupants within a reasonable time. Another danger is that fire is more often than not beyond the reach of the fire department equipment.
Fire must be fought in place within the building. Therefore, a need to address safety in high-rise buildings becomes fundamental in relations to compartmentation, means of egress, and the active fire protection systems. The need to pay attention to smoke control is crucial since high-rise buildings have stack effect of smoke in case of fire outbreak. The codes put mandatory requirements such as additional use of automatic sprinkler systems and the overlapping of detection and suppression systems (Moncada 2).
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Let us consider the case of the World Trade Center (WTC) events. The WTC events raise several questions concerning future designs to defend against extreme events and at what costs. There have been several proposals to harden the stairwells.
According to James Quiter, people should not react to one event without fully comprehending the negative consequences as a result of the building’s response to other extreme events. James argue that it is difficult to use collective thinking as we respond to extreme events of security threats, which are unlikely, unpredictable, and dependant on emotions. However, we must apply rigor to improve the overall performance of a building (Quiter 1).
Another concern is the safety of other high-rise buildings like WTC. The issue, which comes out, is whether occupants are comfortable with other high-rise complex. The damages in WTC 1 and 2 spread to other surrounding buildings such as WTC 7. The problem became worse due to inadequate supply of water, presence of fuel, and fire causing the collapse of WTC 7.
The fundamental lessons from the WTC events show that it is significant to ensure protection of high-rise buildings and compartmentation are adequate. Buildings should have automatic sprinkler to make them safer. However, the challenge is that sprinklering existing buildings is not simple.
In this case, the government should provide tax breaks and additional time for such buildings to install automatic sprinklers. James sees solutions to high-rise fire issues in the automatic sprinkler. Otherwise, there would be significant risks of fire and safety of occupants.
High-rise buildings have several problems associated with them. There is the life hazard. High-rise building contains more people than ordinary buildings. The occupancy classification determines the people in it. However, these people may be senior citizens, children, physically challenged, transitory or asleep occupants. The nature of height of high-rise buildings may make evacuation time consuming, and to some extent, impossible.
Another problem of high-rise building is the structural deficiencies. There are always possibilities that a high-rise building fire may be confined in the floor of origin, particularly if the building is sprinklered. However, if the renovation or remodeling violated this integrity of fire concern, then the possibilities of fire spreading to other floors are high. Occasionally, strong fire may spread to upper floors through windows.
This increases the intensity and amount of fire causing more danger to the occupant. Open fire doors lead to spread of fire to other areas. At the same time, improper maintenance of firefighting equipment may render them less effective and doubtful. Lastly, high-rise buildings have tactical limitations. Firefighters do not have many options in fighting high-rise buildings fires. Accessing the floor where there is fire outbreak may take time.
These situations aggravate the problem. At the same time, the access ladder is limited to 6th or 7th of high-rise buildings. This will force the firefighters to access the fire using the staircases, which in most cases the occupants of the building are using. These conditions increase the amount of time needed to fight the fire leading to spread of fire to other areas.
Building codes cannot protect occupants of a building in every situation as we witnessed during the 9/11 attacks. Since then, there have been concerns aiming at creating and implementing stricter codes, standards, and federal regulations for the aim of making buildings safe to the occupants. The problem is that we cannot construct all buildings to withstand every an imaginable catastrophe.
Building codes emphasis the construction needs of a whole building and place with strict restrictions on dangerous materials or equipment used in the building. The purposes of these codes are to ensure public safety, health, and welfare of the people using the buildings. Building codes focus on electrical, structural, plumbing, life safety/egress, natural light and air, fire safety (detection and suppression), accessibility standards and energy conservation.
Existing building codes have undergone various changes in the past few decades. Today, we have the ICC and the NFPA building codes which look at the conditions of existing buildings with regard to safety. These codes strive to provide requirements for reasonable upgrade and improvements based on the type and extent of the work.
Occupants of existing buildings must confirm that the International Existing Building Code (IEBC) is in use within the jurisdiction. The IEBC determines the extent of repairs, additions, alteration and any other modification in the building based on the level of code compliance. Some of the requirements in IEBC may be lenient than those in the building code.
Fire codes are present in both the ICC and NFPA. The first fire code the ICC produced was in the year 2000. However, in the year 2003, the NFPA developed a new fire code in partnership with the Western Fire Chief Association (WFCA). The NFPA revises fire codes after every three years. The NFPA develops the standard fire code but makes references to various sources so that users are aware of the origins of the codes.
Fire codes work in conjunction with related building code. Fire code looks at existing high-rise building conditions that are risky and could cause possible fires and explosions. Fires and explosions can occur due to several reasons such as type of occupancy and use of space or storage and handling of some materials.
Fire codes are almost applicable to all buildings. However, building codes may not cover some requirements. Fire code is specific to the kind of material to use in a different section of the building. However, it is necessary to make references to areas such as means of egress, interior finishes, fire-resistant structures, furnishing and decorative materials.
Fire codes have emergency planning to address problems concerning evacuation procedures and fire drills depending on the building occupancy. Fire codes appeal to building owners, occupants and fire departments. Certain fire codes may affect occupancy with regards to signage and other fundamental requirements.
Occupancy codes look into occupancy type, which addresses how the occupants of a building are using the building or space. Occupancy codes address the varied hazardous situations or risk factors associated with different occupancy classifications. Hazardous situations consider both the occupants using the space and the activity they will carry in it.
Any building risk factors focus on spatial characteristics, fuel loads, types of occupants, concentration of occupants and in some cases, the knowledge of the building. Some situations may require additional occupancy code due to varying characteristics of occupants and building use so that the building is safe.
For instance, assembly occupancy may require more exits because of the large number of people using the space. Hospitals may require alternate exiting methods due to the characteristics of patients such as age, health, or security reasons. These various characteristics define occupancy codes of high-rise buildings.
Occupancy codes address these various characteristics, so that occupants may feel safe in every high-rise building, or any other space they occupy. Occupancy codes also influence the occupant load (the number of people assumed safely occupying a building or a space) and occupancy classification. Conversely, occupant loads influence the occupancy code a building requires and other code requirements.
Life safety code (LSC) or NFPA 101 was among the first codes NFPA published. This code is subject to revision after every three years. LSC is not a building code rather it concentrates on the evacuation and removal of all persons in the building during an emergency situation.
LSC establishes and provides the minimum requirements that give a reasonable degree of safety from fire in buildings and structures. LSC does not address all the issues concerning construction of a building. It leaves out issues concerning accessibility, plumbing and glazing. This is because it is not a building code.
LSC focuses on occupancies, fire protection and means of egress. Means of egress may include stairwells, horizontal exits, exit passageways, and other exit enclosures. Sometimes, fire-resistance rating is available both horizontally and vertically and get strict towards the exit.
LSC provides a table of fire-resistance ratings. LSC provisions for stairs are that they must meet similar requirements as vertical shafts. Normally, the stairs have a 1-hour rating in 3-stories or less and provision for 2-hours in more than four stories. At the same time, there are also provisions for smoke.
LSC provision for an exit stair needs a fire-related enclosure if it links more than two floors. A rated stairwell must be vertically continuous through each floor and fully enclose the stair. In order to protect the fire ratings, only a minimum number of penetrations are necessary and allowed.
Large high-rise buildings may require smoke-proof to serve as an area of refuge during fire. LSC provision for an exit stair needs a fire-related enclosure if it links more than two floors. A rated stairwell must be vertically continuous through each floor and fully enclose the stair. In order to protect the fire ratings, only a minimum number of penetrations are necessary and allowed. Large high-rise buildings may require smoke-proof to serve as an area of refuge during fire (Puchovsky 4).
Horizontal exits provide alternative exit routes within a building. They also have fire barriers to provide an exit within the same floor. High-rise buildings have exit corridors leading to an exit or an exit stairwell. Buildings, which are sprinklered, are easy to determine the rating of a corridor.
Business occupancy, which has no sprinkler and has an occupant load of more than 30, requires rating of an hour. On the other hand, if business occupancy has less than a 30 occupant load, then we do not need to rate an exit corridor. Occasionally, corridors, which serve small tenant space, do not require a rating. Exit access corridors, which serve the whole floor must be rated, more so in non-sprinklered buildings. An IBC provision for an exit access corridor is that they serve as a type of fire partition.
Evacuation may involve fire, explosions, toxic release, and other events of extreme danger in high-rise buildings. Occupants of the high-rise story buildings should take safety precautions to avoid incidences of fire. However, we must note that we cannot prevent and control some events like the terrorists attack of 9/11 on WTC.
Therefore, uncontrollable fire is likely to occur in high-rise buildings. In this case, the assigned authority must order for evacuation of the building occupants in order to save lives and avert destruction of property. Evacuation starts at where there is an emergency fire, then it can spread to several other floors or the whole building.
The best method to complete an evacuation process is through the fire stairwells. In cases of fire or smoke penetrating stairwells, then alternative routes and stairwells should be used. Some cases of evacuation require a joint effort of the police, fire department, building management and tenants.
Elevators are only safe for bomb-threat emergency evacuation but not for fire. Instead, fire stairwells should be used to assist the occupants to safe floors. When fire emergency occur, all elevators should return to the lobby floor as per the American National Standard Elevator Code. Elevators should have installed automatic devices to allow them pass through all the fire-affected floors. Elevators should never be stopped at the floor of the fire incidence.
Evacuation should be a controlled and coordinated process. Therefore, an emergency rescue team must take into account the number of occupants per floor, emergency fire stairwells available, and the number of floors directly under threat of a fire. Evacuation priority should focus on directly notifying the occupants to leave the building. At the same time, a priority must focus on the occupants who are directly under threat of fire (Colonna 1).
Methods of evacuation depend on the building control systems. This is responsible for determining efficient and safe methods of evacuating the building with attention to the nature of the fire and extent of the damage. People must be controlled during emergencies. Therefore, the floor personnel must control the number of occupants exiting through a single stairwell. At the same time, alternate floors should have different stairwells to provide for full flight between two floors to safe grounds (Blackley 1).
Disabilities in people manifest themselves through mobility, hearing, speech, visual and cognitive impairments. These various degrees of impairments and other functional issues are essential in emergency evacuation processes. There should be a plan of evacuation to cater for all manner of disabilities listed above.
People with disabilities should be moved down the fire stairwell to an upper part of the building where there is unengaged elevator bank, and then taken by the elevator to the fire rescue officials. In cases of seriously physically handicapped persons, the floor evacuation coordinator should assist them exit the building (NFPA 1).
We must acknowledge the fact that it is impossible to plan for every possible emergency that might occur in high-rise buildings. However, preparation is possible in crucial emergency situations. Preparation for evacuations must involve the input of different occupants including people with disabilities in the building. Evacuation guides must address the needs of people with disabilities in the high-rise buildings during emergencies.
The Fair Housing Act Design Manual has general guidelines and provisions for people with disabilities, which new buildings must adhere to as provided for in the building codes and LSC. The manual addresses four areas of evacuating five types of people with disabilities. Therefore, accessibility and evacuations standards must adhere to these five categories.
There are several factors design and code people should focus on when high-rise buildings are in consideration. Risk evaluations in high-rise buildings must be given first priority. Designing of high-rise buildings must be integrated, rational and holistic with regard to engineering approach.
Risks in high-rise buildings increases as its height increases. Increase in the number of occupants results into an increase in potential hazard to the occupants. Engineering decisions must take such factors as occupant load, potential target to threats, space and its uses, suppression efforts, and other building facilities.
These analyses must be present so that the standards meet the building rigor and public safety. The rigor must enable the engineers to make informed designs. High-rise buildings must meet this specification of rigor, instead of putting pieces in the codes together in order to meet engineering requirements and safety standards (Goode 5).
There should be some thresholds of protections in all buildings. Codes have gaps particularly where old high-rise buildings are concerned. High-rise buildings also have varied degrees of height. The standard height of 75 feet based on access of fire ladder may not help to fight fire at 20 stories high.
At the same time, time to evacuate occupants may vary depending on the height of the building. There are thresholds where elevators may not be useful in evacuation processes and where there is smoke stack effect. At these stages of varying thresholds in emergency responses, the prescriptive code may no longer apply, and the rescuers must use the performance code approach as an alternative.
The existing code procedures for evaluating the building fire structural resistance are out-of-date. The system codes should abandon the hour rating and implement the simulation techniques which can give accurate response of building behavior in cases of emergency. Building codes should use simulation techniques to determine the structural and fire resistance ability of the structures.
Likewise, the focus should also shift to how much time a high-rise building can withstand an event of fire. The current code provisions only match the structural fire-resistance with a reasonable full-time evacuation in medium height buildings. However, very high buildings do not have such provisions.
The changes in the energy sector have shifted to energy use in high-rise buildings. There is a voluntary system for evaluating the energy consumptions of a building. Modern building constructions adopt the techniques of building energy friendly buildings.
While this may not be important in fighting fire in high-rise buildings, it is necessary to show how such buildings can save both costs and energy usage for the occupants. This new development has ignited the NFPA and the Tall Building Council to search for similar potential system for life safety. The method tries to influence the building owners to improve safety in high-rise buildings with little financial incentives.
Blackley, William F. “High-Rise Fire and Life Safety: Hazards and Education for Older People.” National Fire Academy 1.5 (2006): 1-46. Print.
Colonna, Guy. “Introduction to Employee Fire and Life Safety.” National Fire Protection Association 4.2 (2001): 1-31. Print.
Goode, Michael G. “Fire Protection of Structural Steel in High-Rise Buildings.” Building and Fire Research Laboratory 3.4 (2004): 5-86. Print.
Harmon, Sharon Koomen and Katherine E. Kennon. The Codes Guidebook for Interiors, 3rd Edition. New Jersey: John Wiley & Sons, Inc., 2005. Print.
Moncada, Jaime A. “Fire Unchecked.” NFPA Journal 1.1 (2005): 2-4. Print.
NFPA, (National Fire Protection Association). “Emergency Evacuation Planning Guide For People with Disabilities.” NFPA Journal 5.3 (2007): 1-60. Print.
Puchovsky, Milosh. “High concept: Proposed NFPA code changes for high-rise buildings.” NFPA Journal 5.4 (2007): 4-6. Print.
Quiter, James. “High-Rise Buildings: What Should We Do About Them?” Fire Protection Engineering 1.2 (2011): 1-1. Print.