FIU wind machine tests housing sturdiness

It's big, it huffs and puffs, it stands seven feet tall and belts out an earsplitting roar -- and it could yield secrets to keeping your house standing when the next big storm rolls in.

On an overcast morning earlier this month, a team of researchers at Florida International University cranked up this less-than-handsome contraption. Two V-8 engines pushed out winds of more than 100 mph. Thanks to an array of pipes, the engines also pelted a section of wall and roof with water, simulating wind-driven rain.

Known as the ''Wall of Wind,'' it's the first of its kind. Its mission: blow tiles off the roof, shatter windows, bash in doors with hurricane-force winds. In hurricane-prone Florida, studying how actual building materials and construction methods stand up to a massive storm can prevent future damage.

This research is critical because strong homes are now seen as the key to not only saving lives but also helping consumers and the insurance industry reduce costs and emerge from the insurance crisis.

''Until you actually do it, you don't know how these building materials and construction techniques will actually stand up,'' said Stephen Leatherman, professor and director of FIU's International Hurricane Research Center and Laboratory for Coastal Research.

Scientists studying the impact of high winds have worked with mostly small models on individual products, say a window or a door, in wind tunnels. The Wall of Wind allows researchers to work with full-scale models and real materials.

Since insurers, regulators and even homeowners now believe one of the key ways to lowering insurance costs and beginning to alleviate the Florida's current insurance crisis is through mitigation, the Wall of Wind research can provide breakthroughs and valuable insights for real progress.

The bottom line for a flurry of wind-related research is going on at several Florida universities: Build houses that can withstand the onslaught of a Category 3 storm and sustain little damage in even stronger hurricanes.

As he walked the test field and surveyed the broken tiles laying in the grass, Arindam Gan Chowdhury, who is FIU's lead wind engineer and researcher, says he is surprised that 20 percent of the tiles on the roof blew off. ``It goes to show how vulnerable we are to hurricanes.''

But it wasn't surprising that most of the tiles lost were along the edge.

Chowdhury notes wind pressure and pull is greatest along the straight edges and sharp corners of a roof. Part of the problem is that roofs generally aren't aerodynamically designed so wind doesn't flow easily over them.

''Every time we run a test, we learn a new thing. The Wall of Wind will give us information to come up with better building designs and [construction] techniques,'' Chowdhury adds.


The ridge tops on gabled and hip roofs are another problem area because the wind accelerates along these points, according to the researchers. Hurricane Wilma, only a Category 2, ripped off countless ridge roof tiles throughout South Florida. At FIU's West Dade campus, Wilma was responsible for $15 million in damage.

The work at FIU has started to attract notice outside the academic world.

RenaissanceRe Holdings, based in Bermuda, has contributed $387,000 to build the second phase of the Wall of Wind, which will use six fans to produce winds between 155 and 160 mph -- a Category 5 hurricane. The state of Florida has contributed another $600,000 to $700,000 to the project so far.

FIU, which began building the Wall of Wind two years ago, estimates the next phases will cost about $5 million because a permanent structure is needed to house the wind machine and test materials.

Leatherman ultimately expects two facilities, one to house the six-fan machine and a much larger one for an 18-fan model that could be used to pound an entire house with hurricane-force winds.

FIU is negotiating with Miami-Dade County for a donation of five now-vacant acres at the Homestead Air Reserve Base for these facilities.

Earlier this year, the Wall of Wind took a road trip to rural Polk County. Its mission was to pelt 120 mph winds and driving rain on a home built before the first statewide building code was adopted in 1994. The vacant 1970s ranch house didn't hold up well: Shingles and tar paper flew off the roof, and windows buckled and shattered.


Since the majority of homes in Florida were built before the current stronger building codes were adopted, wind research will provide vital information on weaknesses in older homes.

''This work will better define our building codes and building materials in the future,'' said Kurt Gurley, an associate professor of civil engineering at the University of Florida.

Previous research done by Gurley and his UF colleagues has shown that homes built under the most recent building code stood up better to the four 2004 hurricanes than homes built under the first code adopted after Hurricane Andrew hit South Miami-Dade in 1992.

''We want to quantify how much you reduce your vulnerability to wind with various retrofits so that people can weigh their options,'' said Gurley.

FIU graduate student Collette Blessing is researching whether roofs can be modifed in certain ways to make them more aerodynamic. Blessing's research may show that roof corners or edges should be rounded.

Another student, Ivan Canino, who is working on his doctorate in civil engineering, hopes the Wall of Wind will yield some hints on ways to better attach air-conditioning units and other equipment usually stationed on rooftops. Many condo buildings lost A/C units during Wilma.

''It's been a learning experience all around,'' says Leatherman.