New York — In advance of the summer solstice (June 21), buildings around the world are turning off their lights for an hour as part of Daylight Hour (, an annual social media campaign organized by the Building Energy Exchange to raise awareness about using natural daylight in lieu of electric lighting, as part of sustainability, conservation and to reduce carbon footprints.

The times when daylight is most available — workday afternoons — coincides with peak demand when business districts demand the most from the grid. That period is also when energy is most expensive and typically the dirtiest and most harmful to the global climate; demand accommodated by older, less efficient plants brought online to meet the surge. The “built” environment accounts for more than two-thirds of greenhouse gas emissions, and a study found that owners and tenants in NYC alone could save $70 million every year by introducing daylight responsive lighting systems.

Daylight Hour occurs on Friday, June 16, for one hour during work hours, usually 12:00 p.m. to 1 p.m. Last year, the overall campaign saved enough energy to power 7,600 homes for a day.

Thornton Tomasetti, an engineering design firm that strives to be one of the most sustainable firms in its industry, will have more than 20 worldwide offices “turning it off” — from its headquarters (in the historic former NY Life building known for its golden top), to offices ranging from Chicago, Denver, Los Angeles, Miami and Washington, D.C., all the way to Mumbai, Shanghai and Christchurch in New Zealand.

Following last year’s participation, some Thornton Tomasetti employees offered the following comments:

  • “I want more daylight-only time. I think most people are in favor, but we give in to the will of a few.” (New York)
  • “We generally have enough natural daylight that we probably don’t need to have the lights on all the time, or as much.” (Washington, D.C.)
  • “I would be interested in doing more ‘natural daylight’ days where we turn off the lights. I prefer the natural daylight in our office to when the lights are turned on. Perhaps this is an option during the summer on sunny days.” (Washington, D.C.)
  • “Our overhead lights in some areas of the office remain on (even overnight). In the future build-out of the office, it would be nice to see this fixed so these lights go off at night. We are looking to start a daylight hour on Fridays…” (Chicago)

Other participants include:

  • 40+ NYC Parks’ recreational and nature centers
  • NY City Hall and other NYC court and municipal buildings
  • Maryland Department of the Environment
  • University of Houston
  • Kansas City (MO) Parks, aviation and City Hall
  • Department of Parks and Recreation, Delray Beach, FL
  • Kumon North America (operates learning centers), IL, TX, NY and NJ
  • Numerous City University of NY and State University of NY schools
  • New York Botanical Garden

A listing of participants is available at