Diarmuid Justin McSweeney

Diarmuid Justin McSweeney, 84, of Lakewood Ranch, FL, a leader in lighting at Holophane and Past President of The Illuminating Engineering Society of North America (IESNA), formerly of Granville and New Albany, OH, passed away on February 26, 2025, surrounded by family. Born in Dublin, Ireland, Diarmuid graduated from Trinity College Dublin with Bachelor’s and Master’s degrees in Physics. He also received an MBA from Xavier University in Cincinnati. In addition to his position as Past President of the IESNA, he received the honor of Fellow (FIES) and in 2006 was presented with the prestigious Louis B. Marks award, in recognition of his exceptional service to the society.

Diarmuid began his lighting career at GEC, England, and continued for 40 years at Holophane in Newark. While at Holophane (Acuity Brands), he held the positions of VP and Director of Research and Development, VP International Operations (Australia), VP Sales and Marketing, Director of the Lighting and Vision Center, and Director of Business and Development. He later became a lighting consultant with Relume, Inc. Focusing on education and the future of lighting, he joined the Board of Directors of The Nuckolls Fund for Lighting Education in North America, an endowment fund in support of college-level programs that inspire students with an understanding of light in architecture. He also served as President of the Board of Directors of the McClung Lighting Research Foundation, Inc., which expanded knowledge and emphasized research that explores the effect of light on personal health, safety, productivity, and the environment. After retirement, he co-founded Green Lighting Supply, Inc. with his son, Matthew.

A devout Catholic, Diarmuid was a member of Our Lady of the Angels church in Lakewood Ranch, serving as a head usher for many years. He was previously a member of St. Joseph’s cathedral in Columbus and the Church of St. Edward the Confessor in Granville.

He was a dedicated Rotarian, a Paul Harris Fellow, with almost 50 years of perfect attendance both in Granville and Lakewood Ranch. He was Past President of the Granville Rotary Club and was responsible for creating a new club in Pataskala and in New Albany. In Lakewood Ranch, he served on the New Member Committee, Ways and Means Committee, and for many years was sponsor chair for the annual Lakewood Ranch Suncoast Food and Wine Fest. He received the Service Above Self Award in 2022.

While in Granville and New Albany, he also served on the Board of Directors of First Federal Savings and Loan and the Granville Public Library. He was a member of New Albany Country Club, Lakewood Ranch Country Club, and a 67-year member of the Royal St. George Yacht Club in Dun Laoghaire, Ireland. Diarmuid was also very active in the tennis clubs and platform tennis clubs of Granville and New Albany.

Diarmuid is survived by his loving wife of 40 years, Sydney (Heller) McSweeney of Lakewood Ranch, FL, his three children, Helen (David) Corley of Huntersville, NC, Kristin Lighttiser of San Francisco, CA, and Matthew Lighttiser of DeBary, FL. He is also survived by his six grandchildren, David (Michaela) Corley, Jennifer (Will) Brasington, Sarah (Cole) Tesar, Aidan Corley, Samuel Lighttiser, and Lauren Lighttiser. He was predeceased by his first wife, Jennifer (Leonard) McSweeney, and his parents, Dr. Christopher J. and Evelyn M. (Donegan) McSweeney.

A funeral Mass was held at Our Lady of the Angels in Lakewood Ranch, FL. on March 10. 2025. A Prayer Service will be held at the Church of St. Edward the Confessor in Granville on May 13, 2025 at 10:30 a.m. Interment will be at Maple Grove Cemetery in Granville immediately following the service. All are invited to attend.

In lieu of flowers, the family suggests donations be made to the Fr. Thomas J. Lowery Scholarship Endowment Fund at the Church of St. Edward the Confessor in Granville, Mass General CAA Research (www.angiopathy.org/support-us), or Rotary International (myrotary.org/en/donate).

McPeek Hoekstra Hoskinson Funeral Home is honored to care for Diarmuid and his family.