If you're going to produce "pants on pants" for the cold weather, Minnesota is a logical place to start.

Aeronautical engineer Jeffrey Xu (Xu Junfeng) moved to Duluth, Minnesota, from Shanghai in November 2015, after he was hired to design planes for Cirrus Aircraft.

Duluth, which sits on the shore of Lake Superior in northeastern Minnesota, gets cold, real cold in the winter.

Upon arriving, Xu, 48, wondered why Minnesotans would layer their upper bodies against the cold but wouldn't bother with their lower extremities.

"Feeling cold in the legs outdoors is a universal problem worldwide, especially in high-latitude places," Xu told China Daily.

"Most people take the 'suffer and tolerate' approach to the cold here. However, my body reacted to the cold weather by gaining a lot of weight during the winter season," he said.

"This compelled me to devise a solution that can guarantee warmth for the legs and butt, so my body would not try to accumulate a layer of fat insulation," Xu bluntly put it.

"Pants-on-Pants|World's Only Convenient Snow Pants" exclaims Xu's page on crowdfunding kickstarter.com. "Keep both feet on the ground, just wrap around the waist and zip up, like a jacket for legs."

So far, Xu has raised close to $15,000 on kickstarter, with a goal of $30,000. The project will be funded by kickstarter only if it reaches the funding goal by Jan 28.

On Xu's e-commerce website, pantsonpants.com, a 40-second video shows how to, well, wear the pants. They wrap around like a sarong at first, but when zippered up from the ankles to the waist, they resemble ski pants.

Xu started with an old pair of pajamas and went through about 20 iterations before the pants had the desired composition. Xu said he consulted many suppliers to find the right fabrics.

And Xu isn't flying by the seat of his pants when it comes to thermal protection.

"My personal experience told me the coldest moment was sitting on the seat of a cold-soaked car. We doubled the insulation in the butt area."

For the lining, he chose 3M Thinsulate, an insulated material common in winter gear, made by the Minnesota corporate giant.

Long, diagonal openings on the sides are a key feature of the pants, he said.

"We knew we did not need pockets for pants-on-pants, because everything is in the pockets of inner pants. I did not have these openings on my first prototype," he says. "Every time it was a struggle to reach the keys, cellular phone and wallets in the pockets of my khakis."

He said the openings also serve as vents when indoors, and "we also have two openings at the back for men because many men put their wallets in back pockets".

Another key feature is the "waist-adjustment mechanism", which also is used to lower one's pants when going to the bathroom.

Xu grew up in Quanzhou city, Fujian province, where his mother was a primary school teacher and his father a math teacher in normal school. An outstanding student, Xu skipped a grade in primary school and another in senior high school.

"I did not see snow until I went to college in Hefei city, Anhui province," Xu said.

He was 16 then and enrolled in a gifted and young class at the University of Science and Technology of China.

Xu went on to earn master's degrees in materials science and engineering, and in aeronautics and astronautics, along with a PhD in electrical engineering - all from Stanford University in temperate Palo Alto, California. He also has a private pilot's license.

Xu is selling five sizes for men and five for women in the initial production run of about 500 pairs. The pants, which are stitched together in Jiangsu province, sell for $179.99; discounts are available to first movers on kickstarter.

Contact the writer at williamhennelly@chinadailyusa.com