New research finds that home sprinklers offer dramatic water savings in home fires compared to firefighting operations
NFPA Journal®, March/April 2011
By Fred Durso, Jr.
One of the best defenses against anti-sprinkler legislation is sound research that can be used to convince lawmakers, whether through public outreach or legislative testimony, of the benefits of home fire sprinklers.
Research Foundation Executive Director Kathleen Almand answers questions about the new "Residential Fire Sprinklers -- Water Usage and Water Meter Performance Study."
Moved by a family’s tragic loss, a state lawmaker advocates for residential sprinklers
SPRINKLER WATER USAGE
BY THE NUMBERS
- Sprinkler systems discharge, on average, 280 gallons (1,060 liters) of water during 10 minutes of operation, based on a typical one head design.
- In the 35 home fires without sprinkler systems documented in this study, the amount of water used by responding fire services averaged 3,524 gallons (13,340 liters) per fire, or approximately 12 times the amount of water discharged by a typical home fire sprinkler system per fire.
- In the reported fires in homes without sprinkler systems, an approximate tenfold increase of water used per fire was reported when the fire spread beyond the room of origin or when the degree of fire involvement increased from visible flame and smoke to a fully involved fire.
- The study found that needed community fire flow, and the projected associated infrastructure required to deliver it, could be reduced by 47 percent when homes in a community are protected by sprinklers.
Case in point: Residential Fire Sprinklers — Water Usage and Water Meter Performance Study, a new report that concludes that a home fire sprinkler system uses, on average, only a small fraction of the water used by the fire service in a response to a fire at an unsprinklered home.
The study, commissioned by the Fire Protection Research Foundation (FPRF), found that water conservation of a sprinkler system is significant: the amount of water used to fight fires in homes without sprinkler systems can be many times higher than the amount discharged solely by a sprinkler system. In addition, many of the residential water meters tested met criteria established by NFPA 13D, Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes. The FPRF study found that projected water infrastructure demand could be reduced by 47 percent when homes in a community are protected by sprinklers.
"This report represents yet another piece of research to assist advocates with hard data to support the adoption of sprinklers in one- and two-family dwellings," says Gary Keith, NFPA’s vice-president of Field Operations and Education.
The Foundation’s new study is intended to supplement the FM Global/Home Fire Sprinkler Coalition (HFSC) report, Environmental Impact of Automatic Sprinkler Systems, released last year and available at fmglobal.com. The study compared the environmental effects of large-scale fire tests on identically constructed and furnished residential living rooms, one controlled by sprinklers and the fire service, the other extinguished solely by firefighters. Test results indicated that half the amount of water was used to extinguish the fire in the sprinklered room. By extrapolating the data, researchers determined a potential 1,000 percent increase in water usage for fires in full-sized, unsprinklered buildings.
Rather than perform fire tests for the new study, researchers in the Bowie, Maryland, office of Exponent, a global engineering and scientific consulting firm, conducted a survey to determine the reported amount of water discharged by fire departments during 35 fires in one- and two-family homes in eight U.S. communities from June through October last year.
Using water supply information, calculations were performed on 18 sprinkler system designs for one- and two-family homes that simulated conditions of highest water flow and greatest system pressure demand. Results indicate that sprinkler systems could discharge up to, on average, 280 gallons (1,060 liters) of water per fire during 10 minutes of operation, assuming a single sprinkler operation. Ten minutes was chosen based on the survey’s estimate of an average fire department’s total response time and the NFPA 13D requirements for water supply duration, which gives an occupant enough time to safely evacuate the residence.
By comparison, the average amount of water recorded by fire departments in this study and discharged during fires at unsprinklered homes was 3,524 gallons (13,340 liters), more than 12 times the amount of water discharged by the typical home fire sprinkler system per fire. The actual water usage recorded spanned a range from 100 to 41,000 gallons, reflecting the fire conditions upon the arrival of the fire service. The water used per fire was approximately 10 times greater when the fire extended beyond the room of origin compared to water usage when fires were confined to the room of origin. "The FM Global/HFSC study shows that the established increase in water usage in home fires can be up to 1,000 percent without sprinkler protection," says Yunyong Utiskul, the study’s project manager and a senior associate with Exponent. "What we found in our study was that this figure is [approximately] 1,200 percent. These findings are comparable, even though the methodology and the way we obtained the data are independent and dissimilar. The figure is in line with the fundamental theory of water-based fire suppression. In general, the earlier water is applied to a fire, the less water is needed to [control or] suppress it."
Sprinklers also seem to positively affect a community’s water infrastructure demand. Needed fire flows (NFFs), or the amount of water required for general firefighting operations at select locations throughout a community, were calculated for 17 homes in accordance with industry-recognized methods, including procedures outlined in NFPA 1, Fire Code. These methods incorporate building characteristics into the calculations, including the total floor area of the building, the type of construction, and the occupancy classification, while allowing a reduction in NFFs for buildings protected by sprinklers.The study found that the needed community fire flow, and the projected associated infrastructure required to deliver it, could be reduced by nearly 50 percent when homes in a community are protected by sprinklers.
To analyze water meters used in residential settings, researchers conducted experiments on 16 models from six manufacturers. Water meter size designations are commonly described in terms of the diameter of the pipe connecting the meter to the water supply. Four meter sizes were examined to address performance perceptions. For example, five-eighths-inch (1.5-centimeter) and three-quarters-inch (1.9-centimeter) meters are perceived as inappropriate for use under high flow conditions, whereas meters with a pipe size of an inch (2.5 centimeters) or more in diameter produce less loss, but are believed to be less accurate in measuring low-flow-rate conditions.
Most meters exhibited metering accuracy within industry standards at flow conditions up to approximately 150 percent of their normal operating range. At high flow rates, considered above 35 gallons (132 liters) per minute (gpm), certain five-eighths-inch (1.5-centimeter) meters indicate a "significant decrease" in metering accuracy. "Systems in one- or two-family homes are unlikely to discharge with a flow rate of 35 gpm [132 liters per minute] during operation," Utiskul says. "Nonetheless, in a rare instance when…this flow rate is [exceeded], this temporary reduction [in metering accuracy] is a peripheral concern."
All meters also handled the minimum sprinkler flows outlined in NFPA 13D and the estimated expected flows without failure, and none of the meters failed mechanically during high-flow-rate tests. Ten of the sixteen meters produced pressure loss profiles in "good agreement" with their manufacturers’ reported values based on design criteria that were less than, or similar to, the NFPA 13D suggested flow rate values. The remaining six, five of which were from a single manufacturer, exhibited pressure losses higher than NFPA 13D-suggested values for various flow rates and size meters.
The results "suggest that the unexpected pressure loss characteristic was possibly due to a lack of quality control or lack of standardized testing for pressure loss for meters from this manufacturer," Utiskul says. "Each tested meter was furnished with a unique metering accuracy certificate, but none of them contained any of the test data for pressure loss.
"The unexpected pressure loss from this manufacturer should not be a concern for all…available water meters," he says. "However, additional measures may be necessary to regulate hydraulic performance…through standardized testing and quality control."
Establishing additional conservative pressure values — design parameters that ensure the flow and pressure demands of a sprinkler system don’t exceed water supply capacity — would compensate for losses specific to underperforming water meters, Utiskul adds. However, establishing such comparative values remains a hot topic in the sprinkler design community.
"The choice for fire sprinkler systems ultimately comes down to certain decisions [from lawmakers] regarding [a range of considerations, including] the infrastructure," says Neil Wu, the report’s principal technical contributor for the study and senior managing engineer with Exponent. "This work shows that fire sprinkler systems are compatible with existing water supply infrastructure available throughout the country."
The meter information, combined with the water-usage findings, offer a potent combination of hard data in support of home sprinkler installations, says NFPA’s Keith. "This report demonstrates why water purveyors should not only eliminate existing barriers to sprinkler installations," he says, "but why they should also support sprinkler installations as a means of conserving water and providing cost-effective, efficient water supply infrastructures."
Fred Durso, Jr. is staff writer for NFPA Journal.
Moved by a family’s tragic loss, a state lawmaker advocates for residential sprinklers
Irv and Cathy Bailey don’t need sound science to convince them of the benefits of fire sprinklers—they experienced firsthand the tragedy sprinklers could have prevented. Their story of losing two grandchildren in a fire in 2009 is part of NFPA’s Faces of Fire Campaign, which humanizes NFPA’s Fire Sprinkler Initiative promoting home fire sprinkler provisions.
It should have been a perfect holiday. But when an early morning fire broke out, Irv and Cathy's young grandsons were trapped in an upstairs bedroom. The two boys died, three firefighters were injured, and the house was destroyed.
Moved by the Baileys’ tragedy, Kentucky State Representative Jim Wayne filed legislation in February that would allow certain cities and counties to require sprinkler systems in new homes. A similar measure introduced in Indian Hills, Kentucky, included sprinkler provisions for new construction in its building code.
Helping the mayor of Indian Hills with the legislation was Russ Sanders, NFPA regional director and former fire chief of Louisville, Kentucky. The ordinance was challenged by the Kentucky Office of Housing, Buildings, and Construction and the Home Builders Association of Kentucky, which argued that local governments couldn’t adopt building requirements more stringent than the state’s. Fire safety groups appealed, but the Kentucky Court of Appeals upheld the challengers’ position.
At press time, legal measures prohibiting mandatory installation of residential sprinklers have been filed in 12 states this year. Similar legislation was introduced in 17 states last year, including Pennsylvania, where the state’s Builders Association also filed an injunction to delay the state sprinkler adoption now in effect; the Commonwealth Court of Pennsylvania dismissed the lawsuit. In February, Pennsylvania legislators introduced a new bill that would nix the sprinkler requirement now in effect. Sprinkler supporters are encouraged by other statewide sprinkler provisions that have taken effect in California and Maryland, as well as requirements in other jurisdictions.
Despite the setback in his neighboring town, Wayne was immediately on board when Sanders contacted him about introducing a similar bill in the state legislature. "What I’m advocating for is elected officials to decide what is best for their communities," Wayne says. "The bill gives them the authority to choose if this sprinkler provision is right for them. In terms of where I live, I would strongly recommend an adoption of sprinkler provisions for all new buildings. We have a large number of deaths and injuries by fires."
The Baileys’ story began Christmas morning, 2009, when a fire erupted in their Louisville home as the family slept. Awakened by smoke alarms, Irv discovered a rapidly spreading fire in the dining room. His family left the house as he frantically tried to reach his grandchildren — William, 10, and Solon, 12 — who were trapped upstairs. The flames were too intense, and Irv only got halfway up the stairs before retreating. Once outside, he could hear the boys’ screams. With help from neighbors, they hoisted a ladder to the bedroom and shattered a window. By then, however, flames had rushed through the home so quickly that oxygen from the broken window caused the fire to flash over, leaving no chance of rescue.
"Our smoke alarms worked, and the fire department was automatically summoned by our security system," says Irv in a video at firesprinklerinitiative.org. "Even with our alert systems working properly, we couldn’t save the boys. The experts tell us that there would have been no loss of life if we had fire sprinklers."
Complementing the Baileys’ story are two new Faces of Fire videos. Stuart Tom, a building official in Glendale, California, discusses how provisions his town passed in 1986 have prevented significant fire-related injuries and deaths. And dispelling sprinkler myths is Meredith Hawes, a public educator for the Grand Traverse Metro Fire Department in Traverse City, Michigan.
Wayne equates NFPA’s campaign with initiatives that prompted automobile safeguards. "Many of these safeguards — airbags, seatbelts, cushioning — have been adopted by law and have increased the cost of the automobile, but we reduced the number of fatalities and injuries," he says. "There’s a parallel here with regard to building safety and construction."