Prosoco, 3741 Greenway Circle, has a new “hurricane in a box” testing chamber that can create wind pressure and rain to simulate up to Category 5 hurricane conditions. Prosoco employees checked out the simulator chamber Friday.

On a sunny Friday afternoon at the East Hills Business Park, the weather took a turn for the worse.

Rain beat against the windows at a speed of 6 gallons of water per hour per square foot. The air pressure rose to what could be compared with 150 mph winds, the same strength as a Category 5 hurricane.

Watching this event unfold were the employees at Prosoco, all of whom remained dry.

The group was testing the Lawrence company’s newest piece of equipment, the Transportable Design Verification Test Chamber, more informally referred to as a hurricane in a box.

The 10-foot-high, 30-foot around, 12,000-pound chamber fills with air pressure that simulates what the winds of a Category 5 hurricane — or higher — would do to the outside of a building.

There are three other chambers like this one in the country. The model that arrived in Lawrence on Thursday came straight from a tour through Florida’s hurricane country.

By Friday afternoon it was whipping up quite a storm in east Lawrence.

The chamber doesn’t actually create 150 mph winds. Instead, blowers fill the chamber with air to produce the pressure that 150 mph winds would create. Then rain starts spraying out of pipes.

On the other side of the wall, spectators watch to see how well the building materials hold up.

On Friday, a sliding glass door, windows and several different building materials in a wall were attached to the chamber.

By seeing where the rain or air leaks are, Prosoco can spot failures in the building materials and how they were assembled.

While testing for the strength of hurricane-like winds is attention-getting, the chamber’s builder and designer Ron Tatley said a more important reason for the chamber is to test for energy efficiency.

“We want to have as tight as a building as possible and this is so precise it can measure how much air flow is penetrating in,” said Tatley, who is with Building Envelope Innovations, a business based in Clackamas, Ore.

Building Envelope Innovations repairs high rises, hospitals and schools and wanted to make sure the materials it was using to put the buildings back together wouldn’t fail.

“We realized the materials weren’t performing the way they should,” Tatley said. “So, we actually started down the path of developing our own materials.”

Most construction materials are built to withstand just 25 mph winds, Prosoco President David Boyer said. But it’s the more extreme weather that often leads to most of the failures in building materials.

Prosoco will use the chamber to test how well its coating materials work within walls. And, it will consult other companies to help determine where the weak link is in their building process.