The fire department feels it's more effective to use sprinklers to reduce the fire problem than it is to keep increasing its efforts to provide traditional, reactive protection.
We've known for a long time that a major portion of the fire problem in the United States lies in our homes, be they houses, duplexes, manufactured homes, apartments, townhouses, or condominiums. The most recent fire loss figures available from NFPA-those for 1995-indicate that approximately 72 percent of all structure fires occurred in homes. There were an estimated 320,000 fires in one- and two-family homes that year, resulting in an estimated dollar loss of $3.615 billion, and another 94,000 fires in multifamily homes, resulting in an additional $649 million loss. Of the $7.62 billion in structure losses for the year, an estimated 56 percent of the damage occurred in homes.
The injury and fatality statistics for home fires aren't any better. In 1995, 79 percent of all fire deaths occurred in homes. Of these 4,585 fatalities, 66 percent are estimated to have occurred in single-family homes. That means that four of every five people who died in fires in 1995 did so in homes, and two of every three people who died in fires died in one- and twofamily homes. Civilian injuries follow a similar pattern: 72 percent of all fire-related civilian injuries occurred in homes, and 52 percent occurred in one- and two-family structures.
As these statistics indicate, the most dangerous place for most of us is in our own homes.
In 1982, Rural Metro Fire Department, with help from the city of Scottsdale and numerous other organizations, conducted the first fullscale residential fire tests in new residential structures to demonstrate how effective residential sprinkler technology really is. Factory Mutual supplied all the technical support and measured the actual fire conditions, while Sentry Insurance developed the fire loss data and damage estimates. The estimates of losses without sprinklers were based on standard guidelines for fire department response and equipment. The fire damage estimates for sprinkler protection were based on actual damage and structure conditions.
The tests indicated that residential sprinklers could have a positive effect on losses in single-family homes, but they didn't reveal how effective the sprinklers would be if they were installed in all new homes. We didn't have that information until 1996, the 10th anniversary of Scottsdale's sprinkler ordinance, which required sprinkler protection for all new construction, including single-family homes.
Chief Robert Edwards presented the Scottsdale Sprinkler Ordinance to the City Council on June 4,1985, and it passed by a vote of six to one. The requirements for the commercial and multifamily properties went into effect 30 days after the council meeting, and the residential sprinkler portion of the ordinance was implemented on January 1,1986.
A closer look at the Scottsdale statistics
As of January 1, 1996, 19,649, or 35 percent, of Scottsdale's singlefamily homes were sprinklered, as were 13,938, or 49 percent, of the city's multifamily homes.
Between 1986 and 1995, residential sprinklers activated in 44 of the 598 home fires that occurred in Scottsdale. Forty-one of these fires were controlled or contained by one or two sprinklers. Two of the three fires in which more sprinklers were needed to extinguish the blaze were flammable liquid arson fires.
No one died in these 44 fires. If the death rate per fire in the sprinklered homes had matched the rate in unsprinklered homes, however, the fatalities that did occur in home fires during that period might have nearly doubled. As it was,10 people died in 8 fires, all in unsprinklered single-family homes. Smoke detectors had been installed in seven of the homes, and at least four of the detectors were working. The highrisk groups for fire safety were well-represented: three of the victims were elderly, two were impaired, and two were children.
The estimated amount of water discharged when a residential sprinkler system activated was 209 gallons, as opposed to an estimated 3,690 gallons released by firefighters extinguishing a house fire with hoses. The average loss per incident was lower, too: $1,544 in sprinklered properties as opposed to $11,624 in unsprinklered properties.
What did it cost?
Unfortunately, various groups still oppose the widespread installation of residential sprinklers. Among the issues such groups raise, the one most often cited is cost.
To determine whether cost is a legitimate concern, Scottsdale commissioned a study in 1986 to evaluate the impact of cost on residential structures under construction. Using the material costs in effect at the time, the study estimated that the price of the average residential sprinkler system would come to approximately $1.14 per square foot for a 2,000-square-foot home. When design freedom benefits were included, the total costs of installing a residential sprinkler system were $157.24 to the builder and approximately $212.27 to the buyer.
Design freedom benefits help offset the cost of mandatory sprinkler protection. In Scottsdale, such benefits include a density increase of 4 percent for single-family communities, a reduction in residential street width from 32 to 28 feet, and an increase in cul de sac lengths from 600 feet to a maximum of 2,000 feet. In the building code, the requirement for one-hour-rated construction was eliminated for separations between multifamily homes, and single-family homes no longer need to separate garages with one-hour-rated construction and rated doors.
In addition, fire hydrant spacing was increased from 330 to 700 feet for developments in which multifamily dwellings predominate, and from 660 feet to 1,200 feet for fully sprinklered single-family developments. Sprinklers reduced the required fire flow demand for structures by 50 percent, typically resulting in a reduction in water main size and the use of smaller water storage tanks. This also made it possible to use reclaimed water in the fire protection systems in commercial structures in communities where the potable water supplies were inadequate.
Since the 1986 study, sprinkler installation costs have declined consistently. By June 1989, the costs for production homes and custom homes had dropped to $.79 per square foot and $.89 per square foot, respectively. By March 1993, the price had dropped again, this time to $.63 per square foot for production homes and $.79 per square foot for custom homes. And those prices dropped even further by January 1996, when automatic sprinklers were being installed in production homes for $.59 per square foot and in custom homes for $.70 per square foot.
Currently, some companies are installing residential sprinklers in Scottsdale for close to $.50 per square foot. This means that a 2,500square-foot house can have residential sprinkler protection for $1,250 to $1,500 initial cost, plus contractor overhead. These figures don't include the savings that accure from the design freedoms identified by the city fire ordinance.
There are three primary reasons for this downward trend in cost. First, residential sprinklers are mandatory in the community, and established standards have been identified. Second, the materials are easier to obtain and use than they used to be. And third, there's open competition among installers for the available business.
Of course, Scottsdale's location has a positive effect on installation costs: The climate is favorable, and the area has experienced dramatic growth, advantages that might not apply in other areas of the country. However, those factors aren't as important as the industry's ability to be innovative, productive, and cost-effective when conditions allow businesses to compete openly for residential sprinkler installations.
Insurance rates and water damage
How have insurance carriers responded to residential sprinklers? A review of the policies of several major carriers across the country identified large variations in the discounts given homeowners who install such systems.
Depending on the design of the system and on the areas protected, discounts range from 5 to 45 percent. The higher discounts are available only when sprinkler protection is combined with other features, such as smoke detectors, system monitoring, fire extinguishers, and deadbolt locks. Surveys of insurers in Scottsdale indicate that most offer some type of discount-about 10 percent on average-for approved residential sprinkler protection.
Those in the building industry, some people in real estate, and individual insurance agents often report that residential sprinklers actually increase insurance costs for residential properties because the sprinklers could leak and cause water damage. Although a survey of local and national insurance providers in Arizona failed to identify any organization that subscribes to this practice, the myth of higher insurance costs due to the possibility of water refuses to go away.
When examined closely, the issue of water damage is full of holes. All new homes already have an extensive network of plumbing for domestic use. Typically, the water and flows required for the domestic water system dictate the connection and size of the water meter for the house, which usually exceed the hydraulic demands for residential sprinklers. Domestic networks are tested for their ability to handle the static pressure from the community distribution system without developing any leaks, not for reliability.
Typical domestic distribution system pressures range from 60 to 100 psi. The most popular sprinkler construction material, CPVC pipe, has a rated burst test pressure of 650 psi, and the typical residential sprinkler is tested at 500 psi. In Scottsdale, the materials used for residential sprinkler installations-usually copper and CPVC piping-are pressure tested at 150 psi for 24 hours to identify weak pipe sections and joints or other installation problems. NFPA 13, Installation of Sprinkler Systems, requires pressure testing for two hours at 200 psi. These tests far exceed the requirements already accepted for domestic water systems and will identify any area of the sprinkler piping network that was installed incorrectly or had material defects.
Because both copper and CPVC are approved potable supply piping materials, backflow shouldn't be an issue, either, particularly since a resilient seat check valve is installed in these systems.
The installation of automatic sprinkler systems usually allows for a reduction in the requirements for standby and fire flow water of up to 50 percent, since it's generally accepted that the calculated flows from sprinkler systems are much more effective early in a fire than the larger fire suppression hose lines and master stream devices.
In the early 1980s, flows from residential sprinklers were calculated at 18 gallons per minute (gpm) for a maximum coverage area of 144 square feet. Recent improvements in sprinklers have resulted in water flows of 16 gpm to cover an area of 400 square feet. Compare this figure with standard fire suppression interior hose lines, which flow an average of 100 to 200 gpm. This translates to an estimated average total water demand of 3,000 to 5,996 gallons to control a fire. Residential sprinklers, on the other hand, use an average of 209 gallons.
An in-depth study of the first 40 structural fires of 1986 in which sprinklers activated supports these calculations. Of these 40 properties, 28 were commercial occupancies, 8 were multifamily homes, and 4 were single-family homes. Definitive times and flows couldn't be established in two of the fires, but the study used the 38 identifiable activations to compare sprinkler activation and flows to estimated fire flows from fire suppression handlines.
The actual flow times for the sprinklers, as recorded on activation records, were used as a baseline. Residential sprinkler flow calculations were set at 18 gpm for a single sprinkler and 26 gpm for two sprinklers, the original base guidelines established in NFPA 13D, Sprinklers Systems in One- and Two-Family Dwellings and Manufactured Homes. Commercial sprinkler flows were set at an average of 25 gpm for each sprinkler, while fire flows were based on two 13/4-inch handlines flowing 200 gpm each.
The sprinkler flow calculations for all 38 fires came to 13,573 gallons of water, or an average of 357 gallons of water per fire. In the suppression operations, 185,600 gallons of water were used, for an average discharge of 4,884 gallons of water per fire. We at the Scottsdale Fire Department estimate that the suppression flow times to control all 38 fires were the same as the sprinkler control times. This exercise illustrates that smaller amounts of water, distributed earlier in a fire by built-in protection, limit the spread of fire and minimize water damage.
Can they control flammable liquid fires?
It's been reported that automatic sprinkler systems can't control fast, flaming, flammable liquid fires or protect people who are intimate with ignition. However, this hasn't been the case in Scottsdale. In residential applications alone, residential sprinkler technology has been extremely effective in numerous cases.
Take the three separate arson fires in which gasoline was used as an accelerant. In the first, a sleeping 21-year-old man was doused with gasoline and set on fire. The blaze activated a single quick response sprinkler, which saved the victim's life and limited damage to the structure. In the second fire, 13 sprinklers activated when an arsonist tried to burn down a two-story house using gasoline. The sprinklers controlled the fire and saved the structure. Gasoline was also used as an accelerant in the third fire, in which an arsonist tried to destroy a house under construction. Fortunately, the residential sprinkler system had already been installed, and two sprinklers controlled the fire. There were also two instances in which residential sprinkler systems controlled fires ignited by flammable gas vapors. In the first, an LP-gas tank stored in a utility closet developed a leak, and the leaking gas came in contact with the pilot light of the water heater. A single sprinkler controlled the resulting fire, which did only $40 worth of damage. The second fire occurred when a natural gas water heater developed a leak. When the gas vapors ignited, a single sprinkler activated and controlled the fire. Damage was so minimal that the fire department wasn't even called. Obviously, residential sprinklers are effective on all types of fires, including the kitchen grease fires common in homes.
Several years ago, Operation Life Safety published an article asking what the mission of a fire department really was. Does a fire department best serve its community by suppressing fires quickly and efficiently? Or does it do so by keeping fires from occurring? Clearly, it's more economical and effective to use available technology to reduce the impact of fire than it is to continually increase one's efforts to provide traditional, reactive protection. Can the fire service afford to concentrate its available resources on activities that make up a smaller and smaller percentage of the requests it gets for emergency services every year?
The Scottsdale Fire Department believes that Scottsdale's experience over the last 10 years has proven to be more than just an experiment. There's no question that all the major players in the fire protection industry in the United States can do more to promote better fire protection for our homes.
Copyright National Fire Protection Association Jul/Aug 1997
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