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  • Feature Story

The evolution of fire

house fire in the hot weather.

October 17, 2017

Fifty years ago, the materials used to furnish and decorate a home were comprised of wood, wool, cotton and steel. Houses were generally smaller with compartmentalized rooms and lower ceilings while kitchens were traditionally set away from the main living areas.

Changing consumer taste and the drive for sustainable practices pushed manufacturers, architects and the construction industry to adopt new designs, building techniques and decorative materials. Today, homes are on average 56 times larger with open floor plans, increased ceiling height and architectural details like arches that create large living spaces.

Home materials have also changed from more natural materials to synthetics made of chemicals derived from coal, oil or natural gas. Synthetic materials can be found in practically everything from furniture padding, which is typically polyurethane foam, to engineered products that allow for faster construction and increased cost efficiencies.

The use of synthetic materials and the design of beautiful living spaces may have aesthetically and financially improved lives but at what cost?

Synthetic materials burn faster and hotter than traditional products while an open floorplan stokes the fire due to the increased volume of air. Flames require oxygen-rich air to burn. Absent it; ignition cannot occur. Minimize access, and the fire will be either slow to burn or may self-extinguish.

Additionally, lightweight structural components, such as engineered floor systems have the potential to collapse very quickly under well-ventilated fire conditions.

Bottom line? The time people have to exit a building has been dramatically reduced, from an average egress time of 17 minutes to four or five minutes today.

Related, What you need to know about smoke alarms

UL’s research group, along with industry stakeholders, began a decade-long inquiry into the changing dynamics of residential fires, examining everything from room configurations and average emergency response time to the role of smoke alarms in the modern structural fire.

Completed in 2007, the Smoke Characterization Project, conducted by the Research Foundation of the National Fire Protection Association, discovered a need for additional research into polyurethane foam and expansion of the range of smoke colors and particle sizes currently recognized by smoke alarms. The third area of research revolved around nuisance alarms and how to differentiate between cooking fumes and the smoke given off by a fire.

Over 250 revisions were made to the Standard for Smoke Alarms, UL 217, and the Standard for Smoke Detectors, UL 268, because of the project. Many of the revisions reflect updates to keep pace with the technological advancements of smoke alarms and detectors, plus a new smoldering polyurethane foam fire test, a new flaming foam fire test and a cooking nuisance alarm test.

UL is accredited by the American National Standards Institute (ANSI), an organization that coordinates the U.S. voluntary consensus standards system. Under the UL Standards ANSI approved process, the UL Standard is governed by a Standards Technical Panel (STP). The revised standards, which led to the development of new smoke alarms and detectors, are expected to have a significant impact on public safety by providing smoke detection that is well attuned to the modern materials found in buildings today.