His specialty was turning around underperforming commercial buildings, including several downtown Minneapolis office towers, and he launched five startup businesses, including an energy transportation company in the Bakken oil fields of North Dakota.

Hempel died April 5 of brain cancer at age 47.

"Jon always had really high aspirations," said Josh Krsnak, who met Hempel while both were studying for their real estate licenses. "He'd have a vision but wouldn't know how he'd get there. But he knew where he wanted to go."

Hempel wasn't just good with numbers, he could swing a hammer. He helped his dad build the family house and in his early 20s built a cabin on Blue Lake in Zimmerman. He studied economics at Hamline University, helped start the construction division at the Cunningham Group and then worked for the commercial real estate company that's now called NTH.

Krsnak joined Hempel Cos. in 2002, a year after Hempel founded it, and the two were involved in more than 80 commercial properties, including several challenging and complicated ones.

One of their first big acquisitions was the 25-story UBS Plaza in downtown St. Paul, which they bought on the cusp of the recession in 2006. In the years since, they tackled several other high-profile projects, including the former Macy's building in downtown St. Paul, which they recently transformed into a mixed-use building with retail, restaurants and the Minnesota Wild training facility.

Logistically, Hempel's biggest business challenge was the acquisition of several buildings — the Rand Tower, One Financial Plaza and the Soo Line building — on the same block in downtown Minneapolis.

Those purchases happened in the midst of the recession and were complicated when several hundred Canadian Pacific employees in the Soo Line building had to be relocated to the nearby 26-story One Financial Plaza building, which was renamed Canadian Pacific Plaza, after the Soo Line building was sold to a Michigan developer. The move was challenging because it had to happen without disrupting the operation of the railroad company headquarters and employees' oversight of its U.S. system.

If that series of transactions was the most complicated for Hempel, one of the most gratifying was the Hotel Minneapolis, which opened in 2008 after Hempel Cos. acquired the century-old Midland Bank Building and teamed with Morrissey Hospitality to transform it into a 222-room hotel.

"Jon accomplished an incredible amount in his short 47 years," Krsnak said. "He left his mark wherever he went. Jon defined optimism and was the most courageous person I knew."

Office buildings weren't Hempel's only interest. In 2013, the duo purchased several hundred acres along a rail line and developed a transfer operation that supported providers of sand used in oil exploration in North Dakota. In 2013, Hempel stepped aside and Krsnak, who had partnered with Hempel for 16 years on real estate ventures, took over the company and later acquired it.

Hempel's wife, Heidi, said that outside of work, Jon loved golf, snowmobiles and Kenny Chesney's music. When word spread of his death, Heidi came across a note from a worker in the kitchen of the Hotel Minneapolis praising Jon for always treating the staff with respect.

"Everybody was an equal to Jon," Heidi Hempel said. "No matter who you were, he made people feel important."

In addition to his wife, Hempel is survived by sons Jack and Eli and daughter Della. Services will be held at 1 p.m. Wednesday at Mount Olivet Church in Minneapolis.