It’s never a good idea to leave exterior shading systems deployed during very windy conditions. Even with products like the FlexShade ZIP, which are designed to stay put in windy conditions, we stress that the product should not be in the open position during high winds.
However we were still interested to know just how much wind our ZIP design could take so we decided to conduct wind tunnel testing to find out.
At first we had some trouble finding a suitable location. Either the testing facilities we approached didn’t generate high enough wind speeds, or used a closed system that led to fears of damage from flying debris. Finally we found what we wanted at Florida International University’s (FIU) Wall of Wind (WOW), an open jet wind tunnel with an excellent reputation.
“We are the only North American manufacturer of zip systems to carry out such wind tunnel testing in North America,” said Clint Childress, LEED®AP, solar control solutions product manager for Draper. “We have set the bar for the industry to follow.”
We were very pleased with the results of the testing, and have prepared a white paper on the subject, which you can read here:
When a shade system is being used outdoors it’s important that it be as resistant as possible to wind and weather. Draper’s FlexShade ZIP is often used to protect outdoor spaces from wind and insects. Its wind resistance comes from extruded aluminum side channels that incorporate plastic inner channels. Cushioning pads dampen fabric movement, and “zip” details attached to the fabric’s edges keep it in place.
Because the FlexShade ZIP is used in some especially windy areas of the world, Draper wanted to see how much wind the product could withstand.
“We wanted to understand the limits of our product better,” said Childress. “With exterior shading, end users and designers want to know the performance in the elements. The testing helps us know the limits and communicate that to potential customers.”
For the testing, Draper used Florida International University’s (FIU) Wall of Wind (WOW). Other wind testing facilities couldn’t generate the wind speeds we wanted to observe, plus they recycled their air and were concerned about flying product pieces damaging their equipment. However, the FIU Wall of Wind is an open jet wind tunnel, capable of generating wind speeds of 150 mph at 10.5 feet above the ground.
The test shades were mounted to a metal support structure custom-built of 3” x 3” square steel tubing. Two different sizes of frames were provided to accommodate three different shade sizes.
The three sizes tested were (width x height) 79-3/8″ x 56-13/16″, 100″ x 71-1/2″, and 126″ x 90″. For each size, fabrics with three different openness factors were used: Soltis B92, which is an opaque blackout fabric, and 3% and 10% Mermet E screen.
According to the test report from FIU, “The WOW was configured to produce a wind profile representative of Open Terrain Exposure (ASCE 7 Exposure Category C).” That essentially means wind that would be experienced in flat, open ground with few obstructions.
Ten tests were conducted with the wind flowing perpendicular to the front of the shade and one with the flow perpendicular to the back side of the shade. The exterior shades were all in the fully down position (rolled-down to cover the entire opening that they are meant to enclose).
Testing started at low speeds and wind was increased at 5 mph increments. Each wind speed was held constant for one minute before being increased to the next level. This process was repeated for each shade until the unit or one of its components flew off, or until maximum wind speed was reached.
Based on our examination of the data from the tests, we are confident in the FlexShade ZIP’s ability to withstand wind speeds of up to 100 mph when in the down position.
But that’s not the whole story. Want to see how the testing came out? Click here to download a PDF copy of the complete white paper!
You can also watch a short video by clicking here!
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