Built to House an Inferno The National Fire Research Laboratory aims to make buildings better and safer.

Built to House an Inferno

The National Fire Research Laboratory aims to make buildings better and safer.

When the voice over the intercom announces, “We are clear for ignition,” instead of the deafening roar of a rocket engine, here at the National Fire Research Laboratory (NFRL) in Gaithersburg, Maryland, things stay pretty quiet. 

Inside a 9.1- by 4.6-meter (30- by 15-foot) wood structure furnished like a studio apartment, a firefighter crouches in the corner. He uses a propane torch to light a small gas pilot flame, then leaves to join his colleagues outside, where they will wait…and watch.

The structure sits beside an identical one in the middle of the lab’s massive high-bay. The bay’s precisely engineered floor measures 18 by 27 meters (60 by 90 feet), and its ceiling disappears into shadow more than 12 meters (41 feet) above. What appears to be a giant canvas tent suspended from the ceiling is actually an exhaust hood, ready to guide smoke and gases from the fire into an environmental control system that will scrub toxins from the air before it’s released outside.

“Once the data and video start recording and everyone is in place, I get calm,” says fire scientist Matt Bundy, the NFRL’s director of operations. “All the preparation is done; all the decisions have been made. I am certainly more nervous, more stressed about the whole thing, the day before and the hours leading up.”

The lead-up to a test like this can take years. The NFRL, which is part of the National Institute of Standards and Technology (NIST), got involved in this project in 2016, but the  National Research Council Canada

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 and its partners at the Fire Protection Research Foundation

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 had spent the preceding two years preparing for it. The entire experiment—which involves the construction and burning of six identically furnished rooms over the course of eight weeks—focuses on determining how a new type of construction behaves in a fire. 

Called cross-laminated timber, this type of construction material is currently approved for buildings with up to six stories. Designers would like to use it in taller buildings because it is environmentally sustainable and can speed the construction process. To use it for those taller buildings, the industry needs to understand how the timber would perform during a fire, so these experiments are measuring its structural performance and the amount of energy the timber contributes to the fire.

As Bundy and the project team look on, the fire in the test room spreads from a small gas burner to a side table. It grows to consume a kitchenette, a couch, a bed and eventually climbs the walls of the compartment. Multiple cameras record the fire’s growth, capturing a dramatic scene as the room brightens and then becomes obscured by thick, black smoke descending from the ceiling as a thick mass. The smoke finds the door and pours out and up toward the exhaust hood. About 10 minutes into the test comes the flashover, when all that smoke bursts into flames.

“It’s a very rapid transition,” says Bundy. “The room heats up and all that fuel—the furniture—is going from solid to gas, or pyrolyzing. You can get the conditions where the fuel is pyrolyzing faster than it can burn, so you have more fuel than oxygen in the room. When it finds oxygen, it ignites. It can be quite intense and impressive to watch.”

A History of Fire Research

These fire research experiments are just the latest that NIST has been conducting since the early 1900s.

“NIST has a very long history of conducting problem-oriented and applied research in the area of fire safety,” says Bundy. “For example, the mattresses that you buy now are safer because of the work that was done in our fire laboratory.”

NIST’s research has helped improve product safety codes for fire resistance for a variety of products, including furniture, children's sleepwear, automatic sprinklers and even cigarettes that are less likely to start a fire. The research also has led to modernized building codes and computer models that can predict the behavior of fire, smoke and toxic products. These computer models are now widely used for training firefighters and guiding fire protection engineering.