On Jan. 15,interested parties gathered at the New York Times building to hear the latest findings concerning the energy savings potential of advanced lighting controls for commercial office buildings. The event was organized by Green Light New York, an independent nonprofit formed in 2011 whose mission is to promote quality, energy-efficient lighting in New York City while involving the design and real estate communities in this effort. The nonprofit has recently released its first major report, “Retrofitting Daylight Controls in NYC Office Buildings.”
New York, more than any other major metropolitan U.S. city, has the largest concentration of commercial office space: 542 million square feet. Chicago comes in at a distant second with 110 million square feet of commercial office space followed by Washington, D.C., with 90; Boston with 50; San Francisco with 30; and Seattle with 25. Consequently, New York has a tremendous opportunity to implement a strategy for incorporating daylighting controls that could, according to the Green Light report, “result in electric peak demand reduction of as much as 160 megawatts and 340 gigawatt hours (GWh) of electricity savings.” This would save New York City building owners and tenants more than $70 million annually.
Since a relatively small group of real estate firms control the majority of the city’s commercial real estate, it is easier in New York to introduce a comprehensive plan for retrofit strategies while keeping with the city’s overall sustainability goals, as outlined in 2009’s “Greener, Greater Buildings Plan.” According to the report, Lighting & Submetering law (Local Law 88 of 2009) requires that all large, nonresidential buildings in New York City retrofit their lighting by 2025. Green Light’s analysis found that there is currently 114 million square feet of office space in the city that can accommodate a daylighting controls retrofit.
Interior lighting represents 26 percent of a commercial building’s electricity usage in New York City. Exterior lighting, by comparison, represents only 6 percent. Over the past decade, a number of high-profile, newly constructed commercial office buildings have led the charge in implementing an advanced lighting strategy that incorporates natural and electric light with daylighting and shading control. The new Times headquarters, completed in 2007, is one such project.
Green Light’s report indicates that the 1.5-million-square-foot office tower has been able to achieve a savings of $600,000 annually through its shading system coupled with its dimmable lighting system. The New York Times Co. occupies approximately 600,000 square feet in the building, and although the spaces were designed for a connected lighting load of 1.28W per square foot, due to the lighting control system the offices only use 0.396W per square foot, just one-third of their connected load.
But implementing daylighting and lighting control strategies is not easy, or inexpensive, a point reinforced by Stephen Selkowitz of Lawrence Berkeley National Laboratory during Green Light’s presentation. Selkowitz noted that no single solution is appropriate for every building, but if the will exists for the investment, the return can be substantial. The Green Light report is available online at greenlightny.org.