Mechanical engineer John F. Hennessy III, grandson of the co-founder of the 93-year-old consulting engineer now known as Syska Hennessy Group, died on Feb. 21, after a long illness. He was 65.

In 1989 when he was 33, Hennessy took over as chairman and CEO of Syska & Hennessy Inc. after his father, John F. Hennessy Jr., died suddenly of a heart attack. He remained in that role until 2004, growing the firm into new markets in the U.S. and globally.

Calling him a “genuine fellow,” Cyrus Izzo, co-president of the 480-person Syska Hennessy Group, says Hennessy “installed a strong work ethic but did not take himself too seriously. He was very professional, but he knew how to have fun.”

Voice of Reason

Hennessy offered a voice of reason in the aftermath of 9/11, which triggered a debate about whether building design should be changed in light of the terrorist attacks that destroyed Lower Manhattan’s World Trade Center and damaged the Pentagon. At one public forum at the Center for Architecture in New York City, Hennessy, serving on a panel of experts talking about building security, replied to a question about whether building codes were adequate. He backed up his affirmative answer by saying, “Building codes are based on probabilities not possibilities.”

On another occasion, on the subject of homeland security, he said, "You have to define what threats you're going to defend against. You try to defend against everything and you don't defend against anything (ENR 3/10/03 p. 4).

Hennessy was very active in the profession. In 2000, he was the first chair of the new statewide consulting engineer group, now known as ACEC New York, which combined the state’s eight regions into one organization. “That was challenging,” to join the many voices of all the engineering disciplines into a collective voice, says Hannah O’Grady, senior vice president of ACEC New York.

Hennessy went on to serve as chair of the metro region of ACEC New York and then the national chair, says O’Grady. He had also chaired the New York Building Congress.

Stature in the Industry

“He used his stature in the industry to help move industry organizations forward,” says Izzo.

Hennessy joined Syska in 1978, when the firm was 50 years old, and worked in its Los Angeles, San Francisco and New York City offices. When he took over as chairman, he had been senior vice president of business development and human resources. But he started out as a project mechanical engineer and worked on numerous buildings, including the Jacob Javits Convention Center in New York City.

John Hennessy III earned a B.A. in physics from Kenyon College, a B.S. in mechanical engineering from Rensselaer Polytechnic Institute, and an M.S. in management from MIT Sloan School of Management.

At the time of his death, Hennessy was the managing partner of Hennessy Energy.  He was also a director at the utility, Con Edison and chairman of the advisory board of the Salvation Army.

“John was amazing,” says O’Grady. “And he comes from a family with a tremendous history within design and construction in New York and beyond.”