John F. Hennessy, III passed away on Sunday February 21, 2021 after a long illness at the age of 65. John was born on November 27th, 1955 in New York City to THE LATE John F. Hennessy, Jr. and Barbara McDonnell Hennessy.
John grew up in New Canaan, CT graduating from St. Luke’s School in 1973, Kenyon College in 1977, Rensselaer Polytechnic Institute in 1978 and MIT Sloane School of Management in 1988. He began his career in the New York Office of Syska Hennessy as a project mechanical engineer and worked on numerous projects including the Jacob Javits Convention Center in New York. Following the death of his father in 1989, John assumed the position of CEO of Syska Hennessy Group. He led the firm to become one of the largest Building Services Engineer Firms. He was widely respected in the profession, with active involvement and leadership positions in the Building Congress, ACEC and Con Edison. He was actively involved in numerous philanthropic and charitable organizations, including 31 years of support and leadership at The Salvation Army.
John had many friends and interests, from playing golf around the world to attending the Kentucky Derby, the Indianapolis 500 and the World Series, but nothing was more important than his family. He is survived by his five siblings and their spouses, Kathleen, Jim & Janis, Kevin & Elaine, Peter & Lisa and David & Jackie. His 10 nieces and nephews, Brian, Hannah, James “Jake”, Kerry, Kelly, Will, Erin, Andrew, Brooks & Bradley. He will always BE remembered for his kindness and generosity.
