Though they were born as energy-guzzling behemoths, both the Empire State Building and the Willis Tower (formerly Sears) have become models for energy retrofits in the new century, projects in large part driven by energy-saving lighting technology developed in the past decade. Working with lighting control manufacturer Lutron , the Empire State Building installed wireless vacancy and daylight sensors in 2011, part of ongoing renovations that are estimated to reduce the building's carbon footprint by 105,000 metric tons over 15 years and save its owners around $4.4 million a year on energy bills.
The Chicago-based firm of Adrian Smith and Gordon Gill took its energy retrofit on Willis Tower, which reduced the building's lighting consumption by 40 percent, a step further by using it as a model for a citywide decarbonization plan that would incorporate extensive wind, solar, and energy monitoring technology.
Ironically, today's lighting design practices hinge largely on advances in building envelope design that result in less lighting being used, in part because glass curtain wall fabrication techniques have created larger and more efficient facades that allow more daylight into offices with less solar heat gain.
"It's funny because we're a lighting designer, but half of it is as simple as space planning so that people get to enjoy natural light," says Stephen Iski, principal designer at Studio I Architectural Lighting . The firm is a lighting consultant for the Gensler -designed Tower at PNC Plaza , set to be one of the first naturally ventilated office towers in the United States when it is completed in 2015. The building is targeted to exceed LEED Platinum, and 91 percent of it can be lit with natural daylight thanks to a unique floor plate design.
"The whole green movement has reminded people that daylight is good and natural air is good," says Iski. Today, a lighting designer's knowledge is best spent on the reduction of artificial light, and on understanding of control mechanisms: reprogrammable ballasts, dimmers, and sensors that ensure efficiency. "The technology has allowed us to have benefits from a physiological standpoint," says Iski.
According to a study published last year by Lawrence Berkeley National Laboratory , new lighting systems have the highest potential of any appliance to reduce energy consumption in the United States. When IA Interior Architects began its design of the Mesirow Financial Headquarters in downtown Chicago, Lutron's reprogrammable Quantum system was just hitting the market and the project team pushed the client to approve its use. Once they did, they were able to create a flexible office grid with demountable walls, allowing the client to reconfigure office spaces, and the lighting inside them, without construction or electrical changes.
"In their first year they had a 33 percent energy savings from using this lighting system, and that translated to $230,000 in savings," says Ann Marie Krol, one of the project's designers. Being able to show clients a return on investment keeps designers like Krol looking for the next innovation. "The Lutron system we ended up going with was a pioneer system at the time, but evolution is constantly happening. To always stay at the forefront of that technology is a challenge as a designer."
New energy standards are also keeping designers on their toes. "The energy code for cities is definitely another factor that's playing into lighting controls," says Krol. "When we started Mesirow, it was under the LEED Version 2 rating system, and at the time the city of Chicago's energy compliance was stricter than LEED compliance."