The fire protection engineering industry views smoke and heat venting in warehouse type occupancies as a waste of money and a hindrance to the performance of an automatic sprinkler system. Why do building codes constantly recommend heat and smoke venting?
In the fire protection industry Factory Mutual (FM) and the National Fire Protection Association (NFPA) are the two most recognized standards because of their research, testing and prescriptive codes that are developed for our application.
FM Research & Engineering
The most recent version of FM Global Property Loss Prevention Data Sheets 8-9, Storage of Class 1, 2, 3, 4 and Plastic Commodities, states in Section 2.1.3.1, Heat and Smoke Venting, to refer to FM Global Data Sheet 1-10, Smoke and Heat Venting in Sprinklered Buildings. The following is direct from FM DS 1-10 under the Venting for Specific Storage Occupancies section:
Smoke and heat vents have been used for many years in an effort to aid in controlling storage fires. However, recent testing shows that, for sprinklered storage fires, vents are at best of limited value. In many cases they can be detrimental. Although the vents may delay the time of smoke obscuration by up to 10 minutes, they accomplish this at the expense of increased fuel consumption. If draft curtains are installed, water demand will increase, with more surrounding sprinklers operating. This is the result of fresh air rushing into the building through all available openings to offset the volume of gases discharged by the vents. The oxygen content of the air, therefore, remains high enough to encourage efficient burning. The venting achieved during a sprinklered fire is quite inefficient…
In the second & third sentences of FM DS Sheet 8-9 within the Section 2.1.3.1 Heat and Smoke Venting, it states as follows:
The protection options provided in this data sheet are based on automatic heat and smoke vents not being provided. Fire tests have shown that automatic heat and smoke vents are not cost effective and can increase the sprinkler water demand.
NFPA Research & Engineering
NFPA 13, Standard for the Installation of Sprinkler Systems, has been adopted in 46 states in the United States. Some states have not adopted the most current version, which was written in 2002. Within the 2002 version of NFPA 13 in Chapter 12, Storage, it states the following:
12.1.1 Roof Vents and Draft Curtains. Sprinkler protection criteria are based on the assumption that roof vents and draft curtains are not being used. (See Section C.6.)
C.6 [12.1.1] Tests were conducted as a part of this program with eave line windows or louvers open to simulate smoke and heat venting. These tests opened 87.5 percent and 91 percent more sprinklers than did comparative tests without windows or louvers open. Venting tests that have been conducted in other programs were without the benefit of sprinkler protection and, as such, are not considered in this report, which covers only buildings protected by sprinklers. The design curves are based upon the absence of roof vents or draft curtains in the building. During mop-up operations, ventilating systems, where installed, should be capable of manual exhaust operations.
Building Code Requirement for Heat and Smoke Venting
The United States is slowly conforming from the three building codes (UBC, SBC, BOCA) to the International Building Code (IBC). It is estimated that most municipalities in the USA will adopt the IBC within three years. The IBC refers to the International Fire Code (IFC) to meet the needs of the building code. The IBC also has identical sections copied from NFPA 13.
The IFC states in Section 910 Smoke and Heat Vents that smoke and heat vents or mechanical smoke exhaust systems and curtain boards are required based on the following:
910.2.1 Groups F-1 and S-1. Buildings and portions thereof used as a Group F-1 orS-1 occupancies having more than 50,000 square feet in undivided area.
910.2.2 Group H. Buildings and portions thereof used as Group H occupancy as follows:
1. In Group H-1, H-2 or H-3, any of the following more than 15,000 sq. ft. in single floor area.
2. In areas of buildings in Group H used for storing Class 2, 3 and 4 liquid and solid oxidizers, Class 1 and unclassified detonatable organic peroxides, Class 3 and 4 unstable (reactive) materials, or Class 2 or 3 water reactive materials as required for a Class V hazard Classification.
910.2.3 High-piled combustible storage. Buildings and portions thereof containing high-piled combustible stock or rack storage in any occupancy group in accordance with Section 2306.7.
910.2.4 Exit access travel distance increase. Buildings and portions thereof used as Group F-A or S-1 occupancy were the maximum exit access travel distance is increased in accordance with Section 1004.2.4.1.
The IFC also contains Section 2306 General Fire Protection and Life Safety Features. This section contains Table 2306.2 General Fire Protection and Life Safety Requirements. This table contains a column on smoke and heat removal and curtain boards and when they are required by code. For commodity classes’ I-IV and High Hazard (Plastics) they are required for storage areas greater than 2,500 sq. ft. with some exceptions.
This code is mandated throughout the Unites States and is required to be met in order to gain a Certificate of Occupancy. Why is it that the IFC picks and chooses what sections of NFPA they use? The IFC is not based on engineering and science and prescriptive codes like NFPA and FM. The purpose of the IFC is a political topic and this article is not meant to tackle that quagmire. Let’s just ask a simple question, “Why does the IFC require Heat and Smoke Venting in sprinklered warehouses?” Based on the IFC Section 2306 General Fire Protection and Life Safety Features, it must be for Life Safety Purposes. How many people really die each year in a sprinklered warehouse? Does the IFC or IBC or any building code offer facts on that? No, they don’t.
NFPA Statistics on Fire Fighter and Civilian Fatalities and Injuries
NFPA provides annual statistics of fire fighter fatalities and injuries. The most recent 2005 statistics were as follows:
– Approximately 100 on duty fire fighter fatalities have occurred annually in recent years in the United States.
– The primary cause of the fire fighter fatalities is not fire, smoke, heat or building collapse but heart attacks.
– Approximately 50% of fire fighters have died of heart attacks
– Traffic accidents followed with 20-25%
– Approximately 10 fire fighter fatalities were caused by smoke, fire and building collapse
– None of the structures involved in fatal fires were reported to have sprinklers installed
– 75,840 fire fighters were injured in 2004. Approximately 36,840 or 48.6% occurred during fire fighting.
– Of the 36,840 injuries during fire fighting the following is a breakdown by injury during fire fighting operations:
– Muscle Strains/Sprains = 48.6%
– Wounds / Cuts / Bruises = 17.2%
– Burns = 7.8%
– Smoke / Gas Inhalation = 5.5%
The statistics provided by the NFPA are for all structural fires and not just warehouses. They encompass 50 states or 3141 counties and approximately 30,400 fire departments or 1.1 million fire fighters.
The NFPA adds that there is no record of a fatality in a fully sprinklered building outside the point of fire origin. The NFPA states that it “has no record of a fire killing more than two people in a completely sprinklered building where a sprinkler system was properly operating, except in an explosion or flash fire or where industrial fire brigade members or employees were killed during fire suppression operations.”
The statistics above are directly from NFPA and can be accessed at www.nfpa.org.
Conclusion
As a fire protection engineer we take great pride in the education, engineering, science and research that are the principals and backbone of our field. NFPA and FM standards provide the most current and accurate standards for fire protection engineering.
The facts show that heat and smoke venting under the design and installation guidelines of the building code will introduce oxygen to the fire in a warehouse thereby opening more automatic sprinklers. NFPA cites testing and research that 87.5 to 91% more sprinklers opened during a fire with heat and spoke venting introduced. FM indicated that venting achieved during a sprinklered fire is quite inefficient and that fire tests have shown that automatic heat and smoke vents are not cost effective and can increase the sprinkler water demand. In some cases heat and smoke venting can cost more than sprinkler systems.
There are too many instances where a building code will require smoke and heat venting. There are no facts or data on why it is needed. In most cases the code official is knowledgeable about facets of the building code but are they educated and trained in the fire protection field? Do they know the facts? In comparison a fire protection engineer has an engineering degree and is familiar with the NFPA and FM standards. So many times it comes down to a negotiation on smoke and heat venting between a fire marshall/code official and a code consultant? Why do building owners have to spend thousands of dollars investing in code consultants so they can negotiate a deal with a fire marshall or a code official for a variance to remove smoke and heat venting? Fire protection engineers with a background in FM and NFPA knowing the facts realize that smoke and vent venting in a fully sprinklered warehouse is detrimental to the proper design and control of a fire.
In conclusion fire protection engineering research has provided data so that FM and NFPA agree as to why heat and smoke venting should not be installed in sprinklered buildings. We are in no way minimizing the loss of life in sprinklered warehouses. However knowing the facts about fire fighter and civilian fatalities and injuries in warehouses begs the question of code development activities, “Why is smoke and heat venting a life safety requirement?”
Today there are so many warehouses with automatic sprinkler systems that are not adequately protected to meet FM or NFPA standards. Usually they meet the minimum code requirement, which in most cases is inferior to the FM and NFPA standards. Wouldn’t it make sense for building codes to remove the smoke and heat venting requirement so building owners can spend there money wisely on upgrading their sprinkler systems to meet NFPA or FM standards? Statistics have shown that sprinkler systems that are designed properly to prescriptive standards are controlled by several sprinklers; thereby the fire department would only have to extinguish a controlled or smoldering fire. Doesn’t it make sense to concentrate on providing adequate protection of your automatic sprinkler system, versus installing smoke and heat venting?
For questions on heat and smoke venting and warehouse protection, please contact Risk Logic.