Lars Peterssen started his professional life working on supercomputers. Then a lecture on design inspired him to change careers. He earned a master's degree in architecture at the University of Minnesota and worked for local firms on commercial projects.

But Peterssen wanted to design homes. He eventually launched his own firm, Domain, and later co-founded the award-­winning Peterssen/Keller Architecture.

"He had a passion for architecture. He got pure joy from it," said P/K architect Kristine Anderson. "He loved the relationship we have with clients — listening to them, getting to know them."

Peterssen cared deeply about his clients and what they wanted in a home, said P/K architect Andrew Edwins. "He saw architecture as about making people's lives better."

Peterssen, 64, died Nov. 3 at home in San Jose del Cabo, Mexico, of complications of frontotemporal degeneration. "He was his easy, sweet, gentle self all the way to the end," said his husband, author R.D. Zimmerman.

Born on Long Island, N.Y., Peterssen moved as a child to Arizona, then to Minnesota to attend Carleton College, where he majored in physics.

During college he spent a year in Leningrad, where he met Zimmerman in a Russian study program. Peterssen was calm, kind, "extraordinarily nonjudgmental" and "fun to be around," Zimmerman said. And "a genius. He never boasted about it. He just was."

The couple were married in 2013, as soon as same-sex marriage became legal in Minnesota. Minneapolis mayor R.T. Rybak started marrying people at midnight, Zimmerman recalled. "We were couple No. 4."

Peterssen and Zimmerman divided their time between homes in Minneapolis and Mexico. They also returned frequently to Russia, where they co-owned businesses.

Peterssen was very social. "He loved being with friends," said Zimmerman. "He would always ask, 'Who's coming for dinner?' "

Often guests included his clients. "He had a habit of becoming friends with his clients," said friend and repeat client Kate Solomonson, who first met him as a colleague at the U, where Peterssen taught architecture and served as assistant head of the department in the 1990s.

"He was very involved in the use of computers in design," Solomonson said, including setting up the department's computer lab.

Her husband, Tom Erickson, a research scientist who taught interdisciplinary classes with Peterssen, admired "the wide-ranging nature of Lars' mind," he said. "He merged technology and design in a very broad way."

As a teacher, Peterssen "knew how to nudge" his students, "but he was always enormously kind," said Erickson.

He brought those qualities to his firm.

"There was something so welcoming about him, especially when you were collaborating with him," said Anderson. "He was very supportive of ideas coming from everybody."

He also had a talent for working well with all the people who come together to build a home, said Erickson. "He could get down to the details, engage with the craftspeople, then zoom out to the big picture."

Earlier this year, Peterssen was awarded the AIA Minnesota Special Award for his contributions to architecture, technology and education.

In addition to Zimmerman, Peterssen is survived by his mother, Virginia Peterssen, and sister Laurie McManus, both of Rochester, N.Y.; sister Kristin Peterssen of Boston; and nieces and nephews. A celebration of life is planned for June.