A long history of fire safety advances has been shown to save lives, protect property and minimize business interruption losses; however, in todays corporate culture, risk improvement efforts may be cast aside in favor of sustainability efforts. Property risk managers want to earmark money for risk improvement and loss mitigation, while other corporate objectives may drive executives to dedicate resources to sustainability initiatives to improve the corporations image and reduce operating costs. The matter is further complicated by building certification processes, such as Leadership in Energy and Environmental Design (LEED) developed by the U.S. Green Building Council (USGBC) and other international certification organizations. For example, credit for green certification maybe given for items that are difficult to connect with sustainability (such as a bicycle rack), but no benefit is accrued from fire safety measures such as automatic fire sprinkler protection systems and the use of materials certified for their limited flammability characteristics, which may prevent a total loss of resources invested in building construction
Recent studies show that risk management measures and sustainability efforts are not necessarily mutually exclusive.1, 2 In fact, current research demonstrates that, if a building is not properly designed and constructed to withstand potentially catastrophic events due to risk factors posed by fires, floods, earthquakes or hurricanes, such disasters can nullify the benefits gained from green construction. Efforts to improve sustainability solely by increasing energy efficiency (without consideration of risk) have the potential to increase the magnitude of risk factors by a factor of three. Incorporating risk mitigation measures - including construction methods and building materials that can improve a buildings survivability as an integral part of reducing lifecycle environmental impact - represents the next step in making buildings durable, and thus sustainable.
Thus far, the focus of green building research and development has been on reducing the impact on the environment; to that end, green regulations and rating systems that recognize high-performance buildings from an environmental perspective have driven the progress. The USGBC has developed the LEED certification process as a "green" building certification system, providing third-party verification that a building was designed and built using strategies aimed at improving performance across key metrics: energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality, and stewardship of resources and sensitivity to their impacts throughout the world.
One common aspect of most of these certification systems is a lack of consideration for the impact of risks such as fire and natural hazards on sustainability. This approach could result in the selection of materials for their insulating properties but that are deficient in their flammability characteristics.3 Focusing only on improving sustainable aspects of a building under normal operation,without any consideration for off-normal conditions that pose risks to property,can result in unintended consequences and even tragedy.
Gritzo et al.1 supplemented the traditional lifecycle carbon assessments of buildings, taking into account risk factors of events such as fire, wind and flood as well as the use of mitigating technologies such as sprinklers. The impact of risk factors on lifecycle carbon emission is illustrated in Figure 1. The plot indicates the carbon emission of a building as a function of time. The lower curve may be considered the carbon emissions under normal conditions and the upper curve shows the deviation from that due to a fire.
The carbon emission cycle can be divided into three portions: 1) construction, including manufacture of material, transportation and equipment usage; 2) normal operation over the lifetime of the occupancy, i.e., primarily power consumption, utilities and maintenance if applicable; and 3) decommissioning, including equipment usage for demolition and transportation for disposal. Figure 1 reflects additional carbon emissions resulting from the fire and subsequent reconstruction.
Gritzo et al.1defined a risk fraction, indicating the relative importance of carbon emissions due to risk events, such as fire, compared to normal operation over the buildings lifetime. The risk fraction, therefore, represents the increase that risk factors pose to the sustainability posture of a building over its lifetime. A reduction in the risk fraction can be achieved through effective risk management strategies, which can serve to reduce the fire frequency and/or the extent of damage produced and reconstruction required.
This analysis was carried out for four different occupancies: a standard office building, an office building with reduced operating emissions (i.e., a "green" building), a manufacturing facility (where the frequency and severity of fires are greater) and a residential single-family home. The results illustrate that risk factors increase the lifecycle carbon emissions of a standard office building on the order of 1 to 2 percent and as much as 14 percent for light manufacturing facilities. For single-family residential homes, the contribution of fire risk to the total lifecycle carbon emission is between 0.4 and 3.7 percent.2
For the standard office building with an improved sustainability posture achieved by reducing operating emissions, the influence of risk factors increases nominally to 4 percent over the lifetime of the facility. The importance of risk factors will gain increased significance as future efforts progress to reduce the carbon footprint of operating facilities. The impact of a fire in a more "sustainable" building without consideration of risk factors, and the need for risk management, can result in lifetime carbon emissions that are greater than they would be if sustainability had never been considered in the design. This difference is attributed to the higher embodied carbon emission associated with more material and process-intensive components used to achieve energy efficiency.
In all cases, the use of automatic fire sprinkler systems provides an order of magnitude reduction in the fire risk factor contribution to lifecycle emissions.
Environmental Impact of Automatic Fire Protection Sprinkler Systems
In addition to reducing the risk factor contribution to lifecycle emissions of a building, automatic fire sprinklers have environmental benefits by reducing the levels of air and water pollution, water usage and overall fire damage. To quantify these environmental impacts, large-scale fire tests were conducted using identically constructed and furnished residential living rooms.2 In the non-sprinklered test, fire extinguishment was achieved only by fire service intervention, while in the sprinklered test, a single residential sprinkler was used to control the fire until final extinguishment was achieved by the fire service. In the tests, the fire service initiated water application 10 minutes after the fire was detected.
Quantification of the environmental benefit was based on comparisons between the two tests, including total greenhouse gas production, quantity of water required to extinguish the fire, quality of water runoff, potential impact of wastewater runoff on ground water and surface water, and mass of materials requiring disposal.
The use of automatic fire sprinklers reduced the peak heat release rate from 13,200 kW to 300 kW and reduced total energy generated by a factor of 76. The amount of combustible material consumed in the fire was less than 3 percent in the sprinklered test and between 62 and 95 percent in the non-sprinklered test.
The total air emissions generated from the sprinklered test were lower than those from the non-sprinklered test. Of the 123 species analyzed in the air emissions, only 76 were detected in either the sprinklered or non-sprinklered tests. Of the species detected, the ratio of non-sprinklered to sprinklered levels for 24 of the species was in excess of 10:1. Eleven were detected at a ratio in excess of 50:1, and of those, six were detected at a ratio in excess of 100:1. The remaining species were detected at the same order of magnitude. The use of automatic fire sprinklers reduced the greenhouse gas emissions - consisting of carbon dioxide, methane and nitrous oxide - reported as equivalent mass of carbon dioxide, by 97.8 percent.
Comparing the water usage between the two tests, it was found that, in order to extinguish the fire, the combination of sprinkler and hose stream discharge from the fire-fighters for final extinguishment was 50 percent less than the hose stream alone. Extrapolation to a full-size house indicated that the reduction in water usage achieved by using sprinklers could be as much as 91 percent.
A new study independently confirmed this result, stating that the increase in water usage in full-size homes without sprinkler protection can be as much as 1,200 percent.4 Furthermore, fewer persistent pollutants, such as heavy metals, and fewer solids were detected in the wastewater sample from the sprinklered test compared to that of the non-sprinklered test. The pH value of the non-sprinklered test wastewater exceeded the allowable discharge range of 5.5 to 9.0 required by most environmental agencies and was four orders of magnitude higher in alkalinity than the wastewater from the sprinklered test. The non-sprinklered test wastewater represents a serious environmental concern.5
Analysis of the solid waste samples indicated that the ash/charred materials from neither the sprinklered nor the non-sprinklered test would be considered "hazardous waste," and that the wastes are not anticipated to significantly leach once disposed of in landfills.
In the sprinklered room, flashover never occurred; however, in the nonsprinklered test, flashover occurred at approximately five minutes after ignition. The occurrence of flashover prior to fire service intervention is an indication that the fire would have propagated to adjacent rooms, resulting in greater production of greenhouse gases, greater water demand to extinguish the fire, and additional materials to be disposed of in landfills. However, in the sprinklered test where the fire was confined to the area of origin, the damage, greenhouse gas production and water consumption represent maximum values independent of additional rooms.
The greater fire damage in the nonsprinklered test has a direct impact on the carbon emissions of the building. This is due to the embodied carbon associated with the building materials necessary for reconstruction and that associated with the manufacture of furnishings and contents.
Carbon Footprint of Automatic Fire Protection Systems
The manufacture and installation of an automatic fire protection system is not a "carbon zero" process and thus a potential concern regarding sprinklers being considered sustainable. Although, to date, no cradle-to-grave analysis of an automatic fire sprinkler system has been conducted, an order-of-magnitude evaluation can be made by noting that the major carbon emission contribution is associated with the steel pipe. The carbon dioxide emissions associated with the manufacture of steel pipe is known. Buchanan and Honey state that, for steel pipes, the carbon dioxide emissions incorporate "the energy required to make the machines that make the machines."6 For steel pipes, the carbon emissions are reported as 1.96 kg C/kg steel; the equivalent carbon dioxide value would be 7.2 kg CO2/kg steel.5
Making the assumption that for an industrial occupancy the typical sprinkler system consists of a 3 in. (80 mm), schedule 10 (3 mm thick) steel pipe, the weight per unit length is 6.44 kg/m.7, 8 A 3m (10 ft.) length of pipe is necessary for a 9.29 m2 (100 ft.2) coverage area; thus, there would be 2.11 kg steel per square meter protected. Based on these values, the carbon emission contribution of a sprinkler system in an industrial occupancy is 15.2 kg CO2/m2. For office buildings and manufacturing facilities, the total carbon emission of the building, over a 40- to 60-year lifetime, can range between 2,000 and 4,500 kg CO2 /m2;1 therefore,the installation of a sprinkler system would result in a 0.34 to 0.76 percent increase in total carbon emissions.
Although this analysis neglects the carbon emissions associated with the sprinklers, sprinkler risers, pumps, fittings, etc., the analysis was based on the partially off setting assumption that the steel pipe manufacturing was achieved with machines operating only on fossil fuels.5 This is a conservative assumption, since many current manufacturing processes use sustainable practices that reduce reliance on fossil fuels.
For residential occupancies, a similar analysis can be conducted assuming a 1 in. (25 mm) diameter, schedule 10 (2.8 mm thick) pipe and would result in a carbon emission contribution from the sprinkler system of 4.91 kg CO2 /m2.9 Based on 1998 and 2008 U.S. census data, the average single-family home was 164 m2 (1,765 ft.2); thus, for a typical home, the sprinkler system will add 806 kg CO2. This would result in an increase of 0.29 percent to total carbon emission over the buildings lifetime, i.e., 278,000 kg CO2.2
It should be noted that for residential homes, plastic pipe would be more typical than steel pipe. A recent study indicates that the carbon dioxide emission of a plastic pipe is between 63 and 80 percent lower than that of a steel pipe.10 Therefore, the carbon emission of a residential sprinkler system is equivalent to the carbon dioxide emission from the combustion of 18 to 33 gallons (68 to 125 liters) of gasoline.
Christopher Wieczorek is with FM Global.
- Gritzo, L.A., Doerr, W., Bill, R., Ali, H., Nong, S., and Krasner, L., "The Influence of Risk Factors on Sustainable Development," FM Global, Johnston, RI, 2009.
- Wieczorek, C.J., Ditch, B., and Bill, R., "Environmental Impact of Automatic Fire Sprinklers," FM Global, Johnston, RI, 2010.
- Bill, R.G., Jr., Meredith, K., Krishnamoorthy, N., Dorofeev, S., and Gritzo, L.A., "The Relationship of Sustainability to Flammability of Construction Material," 12th International Fire Science & Engineering Conference, interFLAM 2010 Interscience, London: 2010.
- Durso, Jr., Fred, "Meter Says," NFPA Journal, March/April, Vol. 105, No. 2, 2011, pp.54-57.
- Moore, S., Burns, B., OHalloran, K., Booth, L., Impact of Fire Service Activity on the Environment, Landcare Research, Prepared for New Zealand Fire Service Commission. Wellington, New Zealand, 2007.
- Buchanan, A.H., and Honey, B.G., "Energy and Carbon Dioxide Implications of Building Construction," Energy and Buildings, Vol. 20, 1994, pp. 205-217.
- FM Global Property Loss Prevention Data Sheets 2-0, Installation Guidelines for Automatic Sprinklers, Johnston, RI, April 2011.
- "Piping Properties," The SFPE Handbook of Fire Protection Engineering, 4th Edition, Appendix E, National Fire Protection Association, Quincy, MA, 2008.
- NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, National Fire Protection Association, Quincy, MA, 2010.
- Aumonier, S., Collins, M., Hartlin, B., Penny, T., "Streamlined Life Cycle Assessment (LCA) of BlazeMaster Fire Sprinkler System in Comparison to PPR and Steel Systems," Final Report, The Lubrizol Corp., July 2010.