An hour south of Charlotte, N.C., two forks in the road beyond suburbia, a freshly constructed house sits in a wind tunnel waiting to be set on fire.
To the left of the house is a brick wall with a hole in the middle, made by a 2-by-4 propelled at 70 miles per hour.
In front of the house is a metal staircase five stories tall. At the top are the hail guns.
More than 100 fans begin to turn, slowly at first and then faster. The ember generators flicker on. The fire is about to begin.