Fire Safety and Possible Building Construction Methods and Materials - Assignment Example

University of Central Lancashire School of Engineering FV2003 Report Assignment Brief Name: Course: Professor: Date: Part 1: Engineering Innovation Center Building Possible building construction methods and materials One of the objectives of BREEAM is to support innovation and its supply chain through additional credits for recognizing sustainability benefits that are currently not recognized by standard assessment criteria. To achieve this, the construction methods and materials must meet certain criteria set by BREEAM. Building materials are normally manufactured and consume energy in the process, especially fossil fuel. It is known that the use of fossil fuels directly contributes to the levels of CO2 emissions into the atmosphere. Furthermore, chemicals released into the atmosphere during the manufacture of building products contribute to the damage on the ozone layer and other harmful effects both to human health and the environment (Brebbia, 2011). Some materials like steel contain high embodied carbon and should be minimized. Others like timber, low carbon bricks, green tiles and recycled materials have a relatively low embodied carbon, low emission factors and even a lower environmental carbon footprint, and should be used more on the building. The timber must be legally harvested and sustainably sourced. Cement replacements, such as PFA, have lower carbon intensities and can be suitable alternatives to Portland cement. Fixing components and facades should be made of materials with longer lifespan and low-through-life maintenance, such as wood. The supply of these materials should be as close to the building site as possible to reduce carbon emissions due to material transport (Kibert, 2012). The building design and construction should consider the use of renewable energy sources e.g. solar and wind energy to reduce electricity consumption, on-site solid and waste-water treatment and other emissions that may result from processes in the building. After construction of the building, all wastes should be taken to waste recycling centers for recycling. Strategies of design for fire safety The EIC building must meet some design measures to prevent or reduce damages that may result in case of a fire in the building. Fire Detection and Fire alarm systems Automatic fire detector systems should be incorporated in the building design to provide building protection. Optical smoke detectors should be throughout all corridors, staircases and escape routes, and all rooms that can be accessed directly through these routes as well as areas with high fire risk or areas with expensive or sensitive equipment. Manual call devices with sufficient alarm sounders should be installed adjacent to the building’s exit points to meet the fire safety requirements. All rooms within which naked flames, smoke, dust, aerosol or steam will be expected as part of normal ambient conditions should be provided heat detecting systems. One key design characteristics is the inclusion of voids in the upper floors to provide light and ventilation. However, this may provide a pathway for spreading of combustion products such as flames, fire gases and smoke from floor to floor. The building design should provide enhanced level of automated fire detection system and life-safety sprinkler system to ensure that the fire alarm rings whilst the fire is still under incipient growth stage. This will suppress fire spread and mitigate the potential for fire spread from floor to floor. Means of escape from the building The evacuation strategy in the building design should be based on simultaneous evacuation. This is whereby the activation of the fire detection and alarm system in the building will lead to immediate and safe evacuation from the building. The horizontal exits should be wide enough to carry the maximum expected building occupancy. The same approach can be used in determining a storey capacity and major exits from the building. Exit widths designs are normally based on 3.3 – 3.6 mm/person in sprinkler protected buildings. The door widths are to be at least 800mm irrespective of how many people it serves. Protection of the building In terms of insulation, load bearing capacity and integrity, structural elements of the building require at least one hour of fire resistance. Walls enclosing protected stairs should be provided with at least 30 minutes of fire resistance. The doors used should be FD30S fire doors (Morgan & Eric, 2015). Conclusion and recommendations for development of sustainable construction The construction industry faces the challenge of safeguarding the world’s rich natural resources for future use. Sustainable construction incorporates elements such as environmental performance, economic efficiency and social responsibility in contribution to architectural quality, transferability and technical innovation. It involves issues such as materials performance, building design and management, construction technology and methods, operation and maintenance, energy and resource efficiency, long-term monitoring, occupational health and safety, function and change and many more. A construction project must therefore, demonstrate very innovative approaches to achieve sustainable development. It should adhere to a high level of ethical standards, taking care of social inclusion and promoting social realm at every construction stage to ensure that the communities endure a positive impact. Construction projects must also demonstrate a sensible use and proper management of resources throughout their life cycle integrated in the design philosophy. In addition, they must be proved to be economically viable with the highest standards of architectural quality. Part 2: Fire Case Studies Case Study 1: Southwest Inn Hotel Fire in Houston, Texas (May 31, 2013) Fire safety engineering issues The building had a means of egress consisting of a number of exit discharge doors. The exit doors, provided with panic type exit hardware, were placed around the building perimeter swinging towards the exit travel path. Exit signs were properly illuminated with clear emergency lighting units. There was no a fire sprinkler equipment or an automated fire alarm in the complex, and according to the Houston Fire Inspection Division (HFID), the building was compliant under the code record for these features. The fire alarm system equipped in the building was manually operated with manual pull stations and alarm devices (visual and audio) installed throughout the structure. The fire alarm system control panel was in a location inside the offices in the main building. The building’s fire protection was limited to a fixed suppression system for vent hood and kitchen appliances, and portable fire extinguishers. The vent hood and the cooking line in the kitchen were protected from fire by an automatic fire suppression system. In 2012, the system had been used twice, one manual operation and one automatic operation. The service contract company had restored the equipment to service after each operation. According to HFID, the building was not required to comply under the current codes, unless it underwent renovations affecting 50% of the complex (Southwest Inn Recovery Committee, 2014). As with the Life Safety Code (LSC), the use of building and occupancy were classified as an existing assembly occupancy. Under the LSC provisions, existing assembly occupancies should have a fire alarm when the occupant load exceeds 300 persons, unless the concerned authority identifies adequate alternative provisions for promptly alerting building occupants in case fire is discovered. Occupant load exceeding 300 persons can be determined based on the building classification using the occupant load factor and total floor area. In accordance with LSC provisions, assembly occupants need a fire sprinkler system when occupant load exceeds 100 persons in occupancies classified as dance hall or nightclub. The primary use of the incident building was banquet space and restaurant. Lessons Learnt A report released about the Southwest Inn fire incidence revealed that some fire fighters from the Houston Fire Department abandoned radio procedures. This lead to a confusion as for who was in charge of radio channels and cluttering them with non-essential transmissions. There was limited planning and delayed response. The disorganization was further fuelled by technical challenges from a newly put radio system. Firefighting respondents need to develop better response plans for big structures, including addressing challenges to finding appropriate space for arriving firefighting units. Following procedures such as proper radio discipline, and clarity of who is to issue commands during emergency can prevent a re-occurrence such fire incidences. Having bar codes that link every piece of equipment to an individual firefighter can be part of advance planning. The radio system should also be improved at the station. Case Study 2: Fire at Hunts Waste Recycling Centre, Dagenham (13, August 2012) Fire safety Engineering Issues The fire incident took place at a waste recycling company known as Hunts Waste located on Chequers Lane, Dagenham. The facility measured 50m by 100m and used to process materials including: plasterboard recycling, wood recycling, refuse derived fuel (RDF), plastic, paper and cardboard, and carpet and carpet tiles (COCKERTON, 2012). The cause of this fire incident is still unclear up to date. However, recycling centers like this one have a number of potential risks that are likely to cause fire. One common risk is the kind of waste materials they deal with; most of them are flammable and combustible materials. Paper, cardboard, carpet and RFD can ignite at relatively low temperatures and can pose a catastrophic risk of explosion if ignited. Handling such materials require special care. Flammable and combustible materials handled at Hunts Waste Recycling Center can be categorized into two classes: Class A combustibles and Class B combustibles. Class A combustibles include materials such as paper, cardboard, wood and plastics. These materials act as fuel and accelerate the spread of fire. These materials have to be kept away from ignition sources such as spark devices, hot plates and heat producing devices. Water and ABC multi-purpose dry chemical are some of the fire extinguishing agents approved for fighting fires resulting from Class A combustibles. Class B combustible include flammable and combustible liquids such as oils, tars, and greases, flammable gases, and flammable aerosols. All these materials are common in an industrial setting. Water cannot be used to extinguish Class B fires as it can cause the spread of the burning liquid, worsening the situation. Lessons Learnt Recycling centers receive, store and process large amounts of combustible materials. This is enough assurance that there will always be a risk of fire, even at well managed recycling centers. A small fire that can be thought to be easily handled can burn the entire facility, calling for the need of response agencies. Recycling facility operators need to design an effective fire protection plan as the first step towards reducing fire incidences. A well designed fire protection plan will ensure that potential fire hazards are identified and reduced through facility design, proper operating practices and fire protection systems. Part 3: Modelling Problems Question 1 Halon refers to halogenated hydrocarbon gas that is liquefied and compressed and is used to stop spreading of fire by chemically disrupting the process of combustion. It is termed as a “Clean Agent” i.e. “an electrically non-conducting, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation.” The gas is an effective fire extinguishing agent even at very low concentrations. Freon is a brand name associated with chlorofluorocarbon (CFC), a compound that consists of carbon, chlorine and fluorine, manufactured as a volatile derivative of ethane, methane and propane. CFCs have been used as solvents, refrigerants and propellants because of their low reactivity, low flammability and low toxicity. Halon is a CFC, and as far as CFCs are concerned, they have two major effects – greenhouse effect and ozone-depletion effect. Halons act as greenhouse gases in the atmosphere and have been considered as major contributors of the greenhouse effect. They are not easily destroyed within the lower atmosphere, but slowly waft towards the stratosphere where they breakdown. Furthermore, there has been no cost-effective way of safely disposing the Halon. Because of these effects, there has been a need to replace halon. Exceptional uses of halon are in the aviation industry and suppression systems (Committee on Assessment of Fire Suppression Substitutes and Alternatives to Halon, 1997). Based on a personal opinion, halon replacement was a right decision on the international level because it was found to contribute to the greenhouse effect – a problem that largely contributes to global warming, one of the biggest environmental problems experienced on earth today. Question 2 Solution: Thermal radiation emission can be calculated using Stefan-Boltzmann Law, which states: Where: q - - T – A full cherry red flame burns at a temperature of about 900oC (1173.15 Kelvin) q / A = σ T4 = (0.855.6703 10-8 W/m2K4) (1173.15 K)4 = 9.129 kW/m2 The maximum indefinite skin exposure has a radiant heat flux of 1 kW/m2. At a thermal radiation of 9.129 kW/m2, the human skin will start paining after 3 seconds and start showing second-hand degree burn blisters when 9 seconds elapse. Question 3 Rankine temperature scale has an absolute zero, a point below which temperatures do not exist. The scale uses the same degree size as that used by the Fahrenheit temperature scale. Based on the definition of the Fahrenheit temperature scale, the absolute zero or 0oR is equivalent to -459.67oF. Fahrenheit/Rankine temperature scales have 180 equal degree intervals between the freezing point (32°F corresponding to 491.67°Ra) and the boiling point (212°F corresponding to 671.67°Ra ) of water. The Kelvin/Celsius temperature scales have the same magnitude. In this scales, the interval between the freezing point and the boiling point of water is 100 degrees interval unlike in the Rankine/Fahrenheit scales. Question 4 Solution: Lower Flammable Limit = Where: P1, P2 and P3 are volume fractions of methane, carbon monoxide and hydrogen respectively. LFL1, LFL2 and LFL3 are lower flammable limits of methane, carbon monoxide and hydrogen respectively. Lower Flammable Limit = Question 5 Solution: Flame height under normal atmospheric conditions is given by: Where: L – mean flame height (m) D – diameter of pan (m) A – typical area (0.235) Q – heat release intensity (kW) So, Q = 500 475.17 kW Question 6 Solution: Using Arrhenius Equation relating the natural logarithm of the rate constant ( and the absolute temperature (T) Where: – rate constant – activation energy (kJ/mole) – ideal gas constant (8.314 J / mol. K) Case 1: Case 2: Case 3: Conclusion: The reaction rate constant changes with increase in temperature, which is the varying factor in Arrhenius Equation. This shows that temperature has an effect on the rate of reaction. Generally, chemical reaction rates increase as temperature increases. Increasing the temperature increases the rate of collision of the reactant molecules, ions or atoms, thus, increasing the rate of reaction process. Question 7 Solution: c =  So,  = c/ Visible radiation has a wavelength range of 750 nm - 400 nm. This range is shorter compared to . On the other hand, radio waves have a wavelength of > 1 mm, which is far longer than that of the infrared radiation obtained above. Question 8 Figure 1: Fire exit Solution: Using the sin rule to find BD: So, AB = = 5.45 m Time taken to move from point A to B = From point B to C, Deceleration = = Where vf is the final velocity and t is the time taken for velocity change. Therefore, (Equation 1) We know that, (Equation 2) Substituting in equation 1 with the value ( , we have the quadratic equation below: (Equation 3) Solving the quadratic equation 3 above, t = 9.01 sec. Total time needed to achieve the exit = 4.54 + 9.01 = 13.55 seconds. Question 9 Figure 2: Fire exit through a corridor Solution: The resultant velocity (R) can be calculated using the Pythagorean Theorem. = R = = 1.35m/sec The shortest distance to the fire exit is via route AC. Using the sin rule: So, BC = 15(sin 30 sin 60) = 6.50 m Time required to reach the fire exit = The resulting velocity of the person is the vector sum of his velocity and the velocity of the wind. The person’s velocity relative to air must be added to the velocity of the wind to determine this resultant velocity. The right direction that would take the shortest time is via route AB. Question 10 Solution: If the air changes direction, then the resultant velocity, R is calculated as: = = -0.25 + 1.5625 = 1.3125 R = = 1.15m/s Time required to reach the fire exit = It would take 0.84 seconds longer to reach the fire exit point if wind reverses its direction. References Read More