Sustainable Design  

Extra Edition for the Times

BY ELIZABETH HALL

The energy savings at the recently constructed New York Times building were expected to be great. But the actual results have been even greater. After nearly a year-and-a-half of use, data shows that the 625,000-sq ft portion of the building occupied by the New York Times Company is using 70 percent less lighting-related energy than originally predicted, beating estimates by roughly $1 per sq ft.
  “The building was designed to use 1.28 watts per sq ft, which was New York City code at the time,” says Glenn Hughes, who served as the Times’ director of construction and is now a Times consultant. “Using light level tuning, or target set points, as the primary energy savings strategy as well as occupancy sensors and daylighting” the Times was able to reduce its lighting load to a mere 0.38 watts per sq ft, he notes.
   After extensive testing of potential control systems at a 4,300-sq ft mock-up (LD+A, July 2005), Hughes selected Lutron to produce an integrated control system (Quantum) that would maximize daylight. “The mock-up was a lighting experiment,” explains Hughes. “Initially, we wanted to learn about daylighting. We ended up learning more about lighting control systems, or what we call ‘total light management systems,’ which are where the real energy savings come from.”
   “Total light management” is an integrated approach to controls, which includes dimming, occupancy sensing and automated shading. The major benefit of the system is customizability, says Hughes: “If you have a dimmable, digital system you can tune it to any illuminance level at the work plane you want.” He adopted this strategy at the Times building, where light levels vary according to the tasks employees perform and their preferences. Light levels range from 10-40 footcandles. Areas with workers using backlit computer screens, for example, have lower light levels to avoid glare. “We are finding that you can operate with much lower levels than you could in the past and that produces gigantic savings,” says Hughes. In fact, the reports suggest that 58 percent of the building’s energy savings is achieved by light level tuning.
   An additional 30 percent of the savings came from occupancy sensors in offices and conference rooms, as well as in the open floor plan. To optimize energy use, Hughes played with the “occupancy zones to make them smaller, since 50 people may have occupied a single zone and if 49 had left and one person remained, you still had the lights on,” he explains. Each initial zone was divided into five smaller zones for a more tailored approach. Since Quantum is wireless “there wasn’t a wire or a physical sensor touched,” recalls Hughes. “It took around two hours to rearrange.”
   Helping block and redirect the sun for improved daylighting, MechoShade automated shades were installed in the windows. With the auto-response shades, daylighting makes up 10 percent of the energy savings. The additional 2 percent is from light scheduling.

August 09