The Adoption of British Standards in Relation to Issues of Space Separation - Coursework Example

Fire Safety Customer Inserts Name Customer Inserts Tutor’s Name 24th February, 2015 Introduction Fire safety is one of the most important tasks to be undertaken during the construction of buildings. This requirement is observed in several jurisdictions in the globe and therefore it is imperative that we understand these regulations. Several regulations and standards have been adopted for use in the design of buildings and incorporating safety measures within different buildings. This report will analyze the adoption of British standards in relation to issues of space separation, allowable protected areas and other issues as part of the guidelines set within the UK regulations in the Approved Document B (ADB, BS9999, BR 187 etc). This document contains the guidelines and regulations to be followed in utilization of these regulations. Fire safety is one of the most important tasks to be undertaken during the construction of buildings. This requirement is observed in several jurisdictions in the globe and therefore it is imperative that we understand these regulations. Several regulations and standards have been adopted for use in the design of buildings and incorporating safety measures within different buildings. This report will analyze the adoption of British standards in relation to issues of space separation, allowable protected areas and other issues as part of the guidelines set within the UK regulations in the Approved Document B (ADB, BS9999, BR 187 etc). This document contains the guidelines and regulations to be followed in utilization of these regulations. Functional requirements of external fire spread & space separation The major functional requirements for external fire spread within buildings as prescribed by ADB are: a) That the walls external to a building shall sufficiently resist the fire spread over their surfaces from one building to the next considering the height, position or use of the building. b) Moreover, the roof of a building should be able to contain fire spread over the roof from one building to another with considering the position and use of the building. The above provisions and requirements can be adhered to by ensuring that; a) Construction of the external walls is done using a material that ensures heat release within low rates. b) The unprotected sections in the side of the building are constrained to limit the intensity of thermal radiation with capacity to pass through walls factoring the distance between the boundary and the walls (Stationery Office, ADB, p. 91-92). Fire spreads across boundaries of buildings depend on several factors such as; a) The volume and strength of the fire within the building in question b) The distance bordering the buildings c) Amount of fire protection achieved by the facing sides d) Risk present to the occupants in adjacent building(s) Space Separation Space separation provisions are based on assumptions and several factors depending on the situation and circumstances. As a result, the major requirements for space separation should be limited to the extent of unprotected areas such as openings or combustible sides which do not allow adequate protection for occupants against external fire spread from one buildings to next (Stationery Office, ADB, p. 96). Fire spread between buildings are due to; a) Fire spread from one building to another due to distance b) Radiation that can be attributed to burning materials Flame spread is the major fire spread mechanism especially for buildings within 1m from the boundary. Beyond these distances, radiation is assumed as the main cause for fire spread. Fire spreads based on radiation are dependent on; a) The direction and the distance between the original building and the neighbouring building. b) The building surfaces and the extent to which it can transmit heat i.e. an external construction might have fire resistance considered sufficient and thus heat transfer might be limited (BSI British Standards, p. 195). c) The intensity of the source of heat/radiation. In all situations, the radiative energy released from the building with fire origin depends on the volume and severity of the fire. When considering these provisions of BS9999:2008, there are assumptions as outlined; a) The fire spread is not beyond the original compartment b) Fire flashover has been reached in the original compartment c) That entire compartment sections which are unprotected of one compartment could be radiating at the same intensity (Lataille, 2003). d) Moreover, the radiation of unprotected areas will stay at: 84kW/m2 for tenancy whereby characteristic A (open-sided car parks or office based), B(assembly only) and C; 168kW/m2 all other occupancy characteristic. e) That radiation will be reduced drastically through use of an automated sprinkler system. f) That supporting structures or glazers within building that have failed in relation to integrity, or unless glazing systems are fire resistance classified based on BS 476 or BS EN 13501 or to the same standard classified as walls. Since radiation levels differ between insulating and non-insulating class (Wang, 2012). Boundaries Boundaries are relevant in the containment of fire spread since they allow the measurement of separation distances that allow the calculation of allowable proportions of unprotected areas. This is in regardless of adjoining buildings and the unprotected areas a building might have (Stationery Office, 2010, p. 97). In all cases, walls are treated as having a boundary in case it constructs an angle of 80º. In most cases, it is actually the distance to actual boundary that is needed and there are different boundaries such as; a) Relevant boundary: This is a boundary where the separation distance is measured and in most cases it is the site boundary (Purser, 2009). Although, in some cases where the wall faces a feature or space whereby there is a river, canal or space then there is an assumption that the boundary is a imaginary line flanked by this space. Space Separation & Allowable Unprotected Areas Space separation looks into walls which are either within or extend beyond 100mm from the relevant boundary. The main aim for calculation of acceptable unprotected area is to guarantee that the distance that separates the building from the boundary is at least half the distance from the intensity of thermal radiation received from unprotected areas that should be at 12.6kw/m2 (Simms, 2011, p. 44-47). This calculation assumes that the radiation severity of the unprotected area stands at: i) 84kw/m2, in case the building falls within the inhabited, assembly or general and recreational use or a multi-storey car park. ii) 168kw/m2, in case the building belongs to the commercial, storage or other non-residential categories. In some cases, where sprinkler systems have been installed, the fire severity and degree will be reduced and it may be assumed that the distance will be half that of a normal building (Read, BR 187, p. 4). The methods utilized in the calculation of acceptable unprotected area are outlined as follows; Method 1 The utilization of this method applies to buildings intended for use as a block of apartment or housing purposes in a distance more than 1000mm or more away from any significant boundary. This method utilizes these subsequent rules; a) The building should be at least 24m or less in height with an elevation of less than 3 storeys. b) That each building side should meet the space requirement provisions if: i) Each building side distance from the relevant boundary & extents of unprotected areas are within set limits. c) Any excess parts or sides of the building more than the unprotected area should have fire resisting surfaces (Read, BR 187, p. 8). Method 2 This method applies to buildings meant for any purpose which are not less than 1,000mm from any relevant boundary (Bergstrom, 2008, p. 120-121). Several rules are used for determination of maximum unprotected area based on the following rules; a) A height of 10m should not be exceeded by the building or compartment with the exception of open-sided car park. b) In meeting provisions of space separation, each building side should: i) Each building side distance from the relevant boundary and; ii) Degree of the unprotected area, are within the appropriate limits (Read, 1991, p. 9-11). c) The excesses of the unprotected areas within any parts of the building should be fire resisting. Geometric Method This method is also referred to as the enclosing rectangles since it utilizes the use of viewed elevation whereby the unprotected areas are measured within a drawn rectangle then the minimum boundary is drawn and the proportion of unprotected area is estimated (Nash, 2007, p. 59-62). All these procedures are repeated to obtain a trace for the plan. In case the boundary lies outside the trace then it is appropriate to look into the problem in detail (Purkiss, 2012). The process is quite tedious and it involves five basic steps as outlined; 1) Determination of unprotected areas (parts or sides of the building) that must be considered. 2) Determination of the ‘plane of reference’ through which measurement of boundary distance is undertaken 3) Level of exposure or hazard process due from the side (unprotected areas) of the building. 4) Utilize risk assessment based on previous stage in the determination of the minimum boundary distance. 5) Establish special hazard exposure areas requiring greater or lesser boundary that were obtained in the previous stage. The regulation BS9999 determines the distances and boundaries that are to be considered unprotected and the areas that might be disregarded in the process of calculations (Newman, 2010). In the analysis, the plane of reference might not be considered as a major factor since based on the diagrams (BSI British Standards, 2008, p. 198). The plane of reference is looks at the angle of inclination of the building in relation to the areas that are to be considered protected or unprotected. Aggregate Notational Areas (Protractor Method) This method is well deployed in the implementation of finding the unprotected areas within a building. The system makes use of varied methods which expose a building and allow the viewing of the certain parts of the building from different points on the boundary and to ensure visible effective ‘unprotected areas’ are easily calculated (Newman, 2010). Thus, if an area from the boundary is unprotected then the smaller it’s effective or notational area is. Consequently, this is multiplied by the factor which depends on the distance. This factor is obtained through the placement of a protractor based on a small scale for planning. Meanwhile, ensuring zones corresponding to the different factors fall within the unprotected areas (Ashton, 2010). Therefore, the sum of all the valuable unprotected areas (‘aggregate notional area’) should not be less than an agreed figure. This method involves the following steps; a) Determination of which parts of the building side (expressed ‘unprotected’) should be accounted for. b) Determination of the points on the relevant boundary which should be tested. c) Determination of the unprotected areas that should be taken into account. d) Finally, undertake the calculation of aggregate notional areas of these unprotected areas. Space Separation within Same Site Buildings The space between two sites or buildings presents a greater risk to people or occupants between these buildings. This is because risk is not managed because these buildings might be owned by the same organization leading to ignorance of risk (Canter, 2011). However, in case sprinkler systems have been installed within these buildings then the notional boundary can be ignored. In some circumstances, there could be space flanked by buildings on the same site and thus, distance between these buildings is discounted (Barham, 2006). While in some cases, this distance can be considered since it can be assumed that there existed a boundary linking these buildings. Notional boundary is the reference to this boundary and is understood to be present where; i) Buildings whereby either or both blocks concerned are in the residential, Assembly or recreational groups. ii) Numerous buildings on the same site which are administered by different organizations. Calculations Figure 1 below shows the Maudland and JB Firth buildings and the below the figure are precise calculations using different methods in finding the maximum allowable unprotected areas and the distances from the boundary. Detailed Calculations The process of calculating the allowable unprotected areas within the Maudland building involves a lot of processes and assumptions based on different settings. The Maudland Building is 28m long and 15m high with different rooms within each floor. Moreover, areas such as the stair s are not considered in the calculations since they provide a protected shaft. These scenarios are outlined below; Setting 1 Let us assume that the Maudland building is fully unprotected (walls and windows are not fire resistance). Then the rectangle for the building; = 28 * 15= 420m2 From table 1 on enclosing rectangle; = 15 * 30= 450m2 Therefore, from table 1(BR187), the unprotected percentage =100% As a result, the distance from the relevant boundary for the unprotected area should not exceed; 14m. Setting 2 Let us assume that the rectangle enclosing the unprotected areas is; Enclosing rectangle; = 15 * 28 = 420m2 From table 1, the maximum enclosing rectangle is; = 15 * 30 = 450m2 Therefore, using this table, let us assume that the unprotected areas; = 210.62m2 As a percentage the unprotected area is; =  Since 46.8% is close to 50% we utilize the figures for 50%. Based on the figures in table 1(BR187), the distance from the relevant boundary for the unprotected percentage should not exceed 10m. Setting 3 Let us take the Maudland building into a section of floor which is equally sizeable from the ground to the top floor since it is divided into different floors. Since the building is divided into 4 equal sections from the ground floor to the 3 floor; Consider that rectangle; = 4m * 28m = 112m2 Then we use figures from table 1, enclosing rectangle; = 6m * 30m = 180m2 Assume the unprotected areas = 112m2 Therefore, the unprotected percentage is equal to 100%, Based on table 1, the distance to the boundary should be 8m. Alternatively, we could deploy another method which utilizes a simple function for calculating a section of office block with a height of 4m and width of 28m. We utilize the formula;  Where: h = height of the enclosing rectangle; u = unprotected proportion of the enclosing rectangle; (in case u = 1 or greater, 100% unprotected area is given) w = width of the enclosing rectangle; and g = factor given from Table 3. Therefore, where width exceed height; =  As a result; g=0.54 and therefore; (For non-residential purposes) The above figures and results could be utilized in finding the maximum permitted unprotected area for JB Firth Building as follows; Assume that the JB Firth Building has no compartments and the dimensions of the building are 28m by 15m as illustrated in Figure 1. From the figure 1, we can see that the distance between Maudland and JB Firth buildings is 9.4m and considering the plane of reference and other Maudland Building’s boundary then a distance of 8m is obtained. Thus, we still have 2m which can be used in identifying the maximum unprotected area for JB Firth building as follows; In scenarios where width exceed height; =  Using table 4, we find f = 0.4 and;  =  = 0.02187; Therefore the maximum permitted unprotected area equals 2.18% of the whole section of the JB Firth building. = 0.0218*28*20 = 12.21m2 Setting 4 The Maudland building has different compartments which have different sizes of unprotected areas and thus these areas have different openings. Based on the diagram, the 3 rd floor presents a setting whereby it has the largest unprotected areas among the four compartments. Take the enclosing rectangle; = 3m * 28m = 84m2 Based on BR187 table 1, the maximum for an enclosing rectangle; = 3m * 30m = 90m2 Assume the unprotected areas (openings); = 36.25m2 Therefore, the unprotected percentage; =; we take the 40% Therefore, the distance from the relevant boundary should be 2m minimum. An alternative method using simple function can be used in calculating the distance to the relevant boundary. This is in relation to a section of a building with a height of 3m and a width of 28m can be obtained as follows; We utilize the formula;  Where: h = height of the enclosing rectangle; u = unprotected proportion of the enclosing rectangle; (in case u = 1 or greater, 100% unprotected area is given) w = width of the enclosing rectangle; and g = factor given from Table 3. u=0.556 in our case. Therefore, where width exceed height; =; Using table 5; g=0.74 and therefore; (For non-residential purposes) The above figures and results could be utilized in finding the maximum permitted unprotected area for JB Firth Building as follows; In finding the maximum unprotected area for JB Firth building, we utilize the following procedures; Let us assume JB Firth building has no compartments and the dimensions of the building based on figure 1 are; 28 m in width, 15 m in height. From the diagram, we can see that the distance between the two buildings is 9.4m and considering the plane of reference a distance of 2.36m is obtained from the boundary. D= 9.4 – 2.36 = 7.04 In scenarios where width exceed height; =  Using table 4, we find f = 0.89 and;  =  = 0.149; Hence the maximum permitted unprotected area equals 14.9% of the whole section of the JB Firth building. = 0.149*28*15 = 62.58m2 Alternative Methods on Increasing UPA There are several methods used in the process of increasing allowable unprotected area as outlined; a) Sprinkler Systems: the utilization of sprinklers has numerous effects on the unprotected area since it can double or half the unprotected area or the distance to the boundary within a given amount of unprotected area (Hasofer, 2010). b) Canopies & Open-sided car parks: these are constructions or scenarios that allow high degree of ventilation and heat dissipation provided that edges of these canopies are 2m from the relevant boundary. This principle also applies to open-sided car parks which allow for necessary heat dissipation and radiation as sprinkled buildings. This is so long as the car park is 1m away from the relevant boundary (Christian, 2011). c) External Walls of portal frame buildings: These structures do not need fire resistance since they only support the roof of buildings. However, buildings with framed entries close to a relevant boundary might require extra protection on the external walls. As a result, these structures can reduced the transmission or the overturning effect due to fire from rafters or roof claddings (Li, 2013). Summary In the case of the Maudland and JB Firth buildings, proper designs were utilized in ensuring fire spread and UPA regulations are adopted. The detailed calculations point out that these buildings offer adequate fire protection but more mechanisms need to be adopted to control fire spread. From the detailed calculations undertaken concerning boundary distances for the two buildings. We realize that the maximum unprotected areas for the two buildings fall within the acceptable ranges and therefore, we can conclude that proper procedures were followed in the design and construction of these buildings. For instance, the maximum areas if no protection as offered shows that the distance between the two buildings should be at least 14m (Brannig, 2008). While, if protection and fire protection was offered then the distance should be at least 10m apart. As a result, we find that proper planning was put into consideration since the two buildings are 10m apart. Moreover, fire protection measures such as installation of sprinkler systems would increase the UPA and thus fire spread shall be decreased sufficiently. From the detailed calculations, we find out that JB Firth building has between 2.18 to 14.9% of unprotected areas (Barham, 2006). These areas are within the allowable unprotected areas according to British regulations and therefore, we can conclude that proper design considerations were made in the design of the two buildings (Wang, 2012). However, fire spread and control should be enhanced by installation of sprinkler systems and other fire protections mechanisms. References Ashton, L and Malhotra, H 2010, “External walls of buildings. Part 1. The protection of openings against spread of fire from storey to storey”, Joint Fire Research Organization, Vol. 12, pp. 78-84. Barham, R 2006, Fire Engineering and Emergency Planning: Research and Methodologies of fighting Fires, Allen & Unwin, New York. Bergstrom, M, Johannesson, P and Marsson, G 2008, “Fire research, some results of investigations”, Statens Provningsanstalt Meddelande, Vol. 34, pp. 120-122. Brannig, F 2008, Building Construction for the Fire Emergencies, Kogan Page Publishers, Chicago. BSI British Standards, 2008, Code of practice for fire safety in the design, management and use of buildings (BS 9999:2008), The Stationery Office, London. Canter, D and Almond, L 2011, The burning issue: research and strategies for fighting Fire, Office of the Deputy Prime Minister, London. Christian, S 2011, A Guide to Fire Safety Engineering, Pelshiver, Manchester. Hasofer, A, Beck, V and Bennetts, D 2010, Risk Analysis in Building Fire Safety Engineering, McGraw Hill Publishing, Newcastle. Lataille, J 2003, Fire Protection Engineering in Building Design, Newnes, Boston. Li, L and Purkiss, J 2013, Fire Safety Engineering Design of Structures, Kogan Page Publishers, Sydney. Nash, P, Pickard R and Hird D 2007, “Automatic heat sensitive fire detection systems”, Fire Protection, Vol. 24, pp. 56-65. Newman, G, Robinson, J and Bailey, C 2010, Fire safe design – A new approach to multi-storey steel-framed buildings, Ascot: Steel Construction Institute, London. Purkiss, J 2012, Fire Safety Engineering Design of Structures, Gower Publishing, London. Purser, D, Fardell, P and Scott, G 2009, Fire safety of occupants within Commercial buildings, Watford: Building Research Establishment, Watford. Read, R, FRICS and MSFSE, 1991, External fire spread: building separation and boundary distances (BR187), Building Research Establishment, Garston, Watford. Simms, D, Hird D and Wraight H 2011, “The temperature and duration of fires. Part 1. Some experiments with models”, Joint Fire Research Organization, Vol. 5, pp. 43-49. Stationery Office, 2010, The Building Regulations 2006, Approved Document B: Fire Safety, The Stationery Office, London. Wang, Y, ‎ Burgess I and ‎ Wald, F 2012, Performance-Based Fire Engineering of Structures, John Wiley & Sons, Lowell. Read More

As a result, the major requirements for space separation should be limited to the extent of unprotected areas such as openings or combustible sides which do not allow adequate protection for occupants against external fire spread from one buildings to next (Stationery Office, ADB, p. 96). Fire spread between buildings are due to; a) Fire spread from one building to another due to distance b) Radiation that can be attributed to burning materials Flame spread is the major fire spread mechanism especially for buildings within 1m from the boundary.

Beyond these distances, radiation is assumed as the main cause for fire spread. Fire spreads based on radiation are dependent on; a) The direction and the distance between the original building and the neighbouring building. b) The building surfaces and the extent to which it can transmit heat i.e. an external construction might have fire resistance considered sufficient and thus heat transfer might be limited (BSI British Standards, p. 195). c) The intensity of the source of heat/radiation. In all situations, the radiative energy released from the building with fire origin depends on the volume and severity of the fire.

When considering these provisions of BS9999:2008, there are assumptions as outlined; a) The fire spread is not beyond the original compartment b) Fire flashover has been reached in the original compartment c) That entire compartment sections which are unprotected of one compartment could be radiating at the same intensity (Lataille, 2003). d) Moreover, the radiation of unprotected areas will stay at: 84kW/m2 for tenancy whereby characteristic A (open-sided car parks or office based), B(assembly only) and C; 168kW/m2 all other occupancy characteristic. e) That radiation will be reduced drastically through use of an automated sprinkler system. f) That supporting structures or glazers within building that have failed in relation to integrity, or unless glazing systems are fire resistance classified based on BS 476 or BS EN 13501 or to the same standard classified as walls.

Since radiation levels differ between insulating and non-insulating class (Wang, 2012). Boundaries Boundaries are relevant in the containment of fire spread since they allow the measurement of separation distances that allow the calculation of allowable proportions of unprotected areas. This is in regardless of adjoining buildings and the unprotected areas a building might have (Stationery Office, 2010, p. 97). In all cases, walls are treated as having a boundary in case it constructs an angle of 80º.

In most cases, it is actually the distance to actual boundary that is needed and there are different boundaries such as; a) Relevant boundary: This is a boundary where the separation distance is measured and in most cases it is the site boundary (Purser, 2009). Although, in some cases where the wall faces a feature or space whereby there is a river, canal or space then there is an assumption that the boundary is a imaginary line flanked by this space. Space Separation & Allowable Unprotected Areas Space separation looks into walls which are either within or extend beyond 100mm from the relevant boundary.

The main aim for calculation of acceptable unprotected area is to guarantee that the distance that separates the building from the boundary is at least half the distance from the intensity of thermal radiation received from unprotected areas that should be at 12.6kw/m2 (Simms, 2011, p. 44-47). This calculation assumes that the radiation severity of the unprotected area stands at: i) 84kw/m2, in case the building falls within the inhabited, assembly or general and recreational use or a multi-storey car park. ii) 168kw/m2, in case the building belongs to the commercial, storage or other non-residential categories.

In some cases, where sprinkler systems have been installed, the fire severity and degree will be reduced and it may be assumed that the distance will be half that of a normal building (Read, BR 187, p. 4).

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