New York’s nightscape is as iconic (think film noir street corners and neon glitterati escapades) as it is taken for granted. A city without streetlights is impossible to imagine, but New York’s 396,572 street-side luminaires are as unremarkable as the streets’ paving — invisible until something changes. An initiative to replace sodium and halogen bulbs with energy- and cost-efficient LEDs has thrown the nightscape suddenly into question, as some city residents bemoan the loss of romance (and sleep). Nocturnal animals, too, are finding the conversion hard to take. But the iconic and underappreciated nighttime infrastructure is also essential to the modern city. In New York, “nightlife” generates 300,000 jobs and $10 billion annually, and the recent establishment of an Office of Nightlife and the appointment of a new “night mayor” signals intention to give after-dark the same consideration as the daily grind. LEDs could be a boon for that industry, and for others who prefer to stay out late. SWA’s innovation lab, xl studied New York’s LED conversion for its impacts on the “Urban Sensorium”; below, Emily Schlickman explains what’s going on, what’s to come, and what it all could mean for the night and its many inhabitants.

Artificial light has often shone in scenes from “the city that never sleeps,” from a luminous gas lamppost in Georgia O’Keefe’s New York with Moon to the all-night diner emanating an eerie fluorescent glow in Edward Hopper’s Nighthawks. Artificial light is inextricably linked to our experience of the urban landscape. Five years ago, then-Mayor Michael Bloomberg approved a plan to retrofit all of the streetlights in New York with LEDs for energy and cost savings, prompting the largest municipal lighting system in the United States to become one of the first cities to undergo a municipal conversion. Today, the New York City Department of Transportation (DOT) has completed the conversion process in Brooklyn, Queens, and the Bronx, causing a range of reactions from communities within these boroughs. While some residents laud the transition, citing reduced crime and extended nighttime use of public space, others are more hesitant, given ecological and health concerns. But as the process unfolds, cities across the United States and abroad are looking towards New York to better understand the future of night time design. Lighting the City that Never Sleeps Nighttime illumination has long been a part of New York’s infrastructure, undergoing three major shifts since the city’s founding as a Dutch trading post. First, a 1697 mandate ordered light sources in every seventh Manhattan house to allow for nighttime trading in the streets, often taking the form of simple oil lamp or candle luminaires hung in street-facing windows. Nearly six decades later, city officials established a more formal lighting system by levying a tax to fund the installation of glass lanterns affixed to wooden posts and the oil required to produce light. In the early 1800s a formal infrastructural network began to take shape, made up of underground pipes and cast-iron gas lampposts. Then, in the 1880s, elevated wiring was installed connecting electric arc lamps fixed to 160-foot high towers. One resident described the visual impact of the shift from a gas network to an electric network as going from “pale moonlight” to “brilliantly illuminated avenues.” A few decades later, in the 1930s, incandescent bulbs using tungsten filaments started to replace the remaining gas lamps, making New York a fully electrified city. Following incandescent lights, bulb technology rapidly evolved, producing fluorescent, mercury vapor, high-pressure sodium, and metal halide luminaires, and giving New York its iconic amber glow.

The Bright, White, New World New York may be poised on the brink of another era of illumination. Over the last 15 years, the city has begun building bright white networks out of light emitting diodes (LEDs), an emerging technology that has more in common with smart phones than with traditional streetlights. The digital chips of LEDs, called solid-state semiconductors, produce two to three times more light per watt of energy than traditional light sources, and last up to three to four times longer — 15 to 20 years instead of two to five. Unlike previous evolutions, this new technology requires no new infrastructure: LEDs may be combined into diode panels and retrofitted onto existing poles. In addition to shining longer and for less money overall, LEDs can more efficiently shine light in a specific direction, unlike traditional bulbs than emit light and heat in all directions. And the quality of light emitted from LEDs contains more blue wavelengths than previous technologies, creating a brighter and whiter light.

But no matter how much measurably better light from LEDs might be, ushering in a new era of LED networks is easier said than done. DOT operates the most extensive lighting system in the United States, with approximately 396,572 streetlights in its five boroughs, but the conversion started small, with an LED design competition launched in 2002, followed by a series of pilot projects with the Department of Energy and The Climate Group, an international renewable energy nonprofit. From 2009 to 2012, the team conducted a partial lighting retrofit of Central Park and along FDR Drive, producing energy savings of up to 80 percent compared to traditional lighting. Three years later, those conversions, plus projects on Brooklyn Bridge, Manhattan Bridge, Queens Boulevard, Eastern Parkway, and the Long Island Expressway ramp were all complete. At the end of Mayor Bloomberg’s administration in 2013, the transformation began in earnest: City officials approved a $76 million project to retrofit all traditional municipal luminaires with LEDs. According to the DOT, despite the higher upfront cost for the luminaire technology, the entire conversion project was expected to save the city approximately $6 million in energy and $8 million in maintenance every year. But now that conversion is well underway, does the reality match the pitch?

The Mid-Conversion Lightbulb Moment The city-wide conversion is proceeding in three phases, moving first through Brooklyn, then Queens, and then to Manhattan, the Bronx, and Staten Island in the final phase. According to a DOT spokesperson, about 60,000 fixtures have been upgraded in Brooklyn, 81,000 in Queens, 33,000 in the Bronx, and 16,500 in Manhattan, leaving only 36,500 in Manhattan and Staten Island. It may be too soon to assess whether the conversion has succeeded in reducing energy use and maintenance demands — DOT is currently collecting data and will publish the findings after all three phases are complete — but New Yorkers aren’t waiting to register their impressions of the project. Brooklyn residents submitting comments through a recent grassroots petition, which advocated revising the conversion plan, likened their newly LED-lit neighborhood to a “football stadium,” “Times Square,” a “Walmart parking lot,” a “zombie picnic,” the “Close Encounters Mothership,” and a “prison yard.” Ghanshyam Patel, a Project Director for the NYC Department of Design and Construction, noted that the DOT does not officially collect survey information on neighborhood impacts, but said anecdotal reports suggest geographically divided support. Some residents in Brooklyn dislike the “trespassing” light, possible negative health impacts, and changes to the borough’s historical atmosphere because of the brighter streetlights. In Queens, on the other hand, residents tend to laud the project, crediting brighter lights with reduced crime and increased visibility and surveillance. In both Brooklyn and Queens, the DOT used standard 4000K LED luminaires. But in light of community feedback, the final phase of the conversion project will use a lower kelvin temperature luminaire – 3000K in lieu of 4000K – with the hopes of reducing glare, discomfort, and overall brightness. This decision also came on the heels of a 2016 American Medical Association study tying high intensity street lights to circadian rhythm disruption. But placating the community may mean risking the majority of LEDs’ benefits. According to the DOT, the new, lower-kelvin luminaires are comparable in cost to the original fixtures and only yield a three percent reduction in energy savings.

The Future, Lighted By 2019, it is expected that the full conversion project in New York City will be completed, with all 396,572 street lights in the five boroughs retrofitted with LEDs. With this change on the horizon, what can we speculate about the future of illumination in New York? In one hypothetical scenario, the future is bright. In 2016, a team of researchers from the National Oceanic and Atmospheric Administration and the Light Pollution Science and Technology Institute created a model of global light pollution called the “Atlas of Artificial Night Sky Brightness.” They stitched more than 300 regional maps together and analyzed altitude, the angle that urban light hits the atmosphere, and the reflection of that light back to the Earth’s surface. The study revealed that light pollution has increased about six percent each year over the past half century; more than 99 percent of Americans now experience light-polluted night skies. Their study also predicted an increase in worldwide light pollution if LEDs continue to be adopted globally. Blue wavelengths, which are present in LEDs to a greater degree than in traditional streetlights, are more easily scattered by the earth’s atmosphere and more easily perceived by the human eye. A bright future for New York City could have a number of city-wide implications. While it is difficult to make a direct correlation between lighting and crime, some academics speculate that the retrofit project could mean improved pedestrian security and reduced criminal offenses such as burglaries and vandalism. Better illumination could also make increased economic and recreational activity during nighttime hours possible: Business hours and public space programming could shift later or last longer. On the other hand, this brighter future could negatively impact the city in various ways. Researchers from China and the Netherlands speculate that this new lighting system could result in increased roadway glare and impair nighttime vision. LEDs could also impact the health of those in contact with them, interrupting circadian sleep rhythms, reducing sleep time and quality, and potentially exacerbating serious conditions like cancer and cardiovascular diseases. And for the 30 percent of vertebrates and 60 percent of invertebrates that are nocturnal, this new illumination could create confusion and collisions, impacting typical migration and mating patterns. In New York City, nighttime brightness is already impacting nocturnal species — in 2015, Governor Andrew Cuomo announced that state-owned and managed buildings will participate in the Audubon “Lights Out” program, to protect a dark route for migrating songbirds. But in another potential scenario, New York City’s future night sky is dark. Community groups and international dark-sky proponents are pushing for LEDs that reduce light pollution but remain energy- and cost-efficient. With LED technology rapidly advancing, new luminaires boast lower Kelvin ratings, and fewer blue wavelengths. They produce a warmer, softer glow, similar to traditional light sources, while maintaining the same energy efficiency levels as their brighter, whiter counterparts. Furthermore, some cities like Cambridge, Massachusetts and Los Angeles are exploring smart and responsive street lighting networks that could result in a reduction of light pollution; the streetlights function as nodes in a larger network, that can be dimmed or brightened based on environmental change, traffic flows, or municipal schedules. Beyond luminaire technology, streetlight fixtures could also be modified to better control light directionality. Simple improvements in shielding hardware could yield darker skies: by encasing the luminaire from above, the streetlights can minimize the amount of light they project up into the sky, reducing light pollution overall.

How can cities truly begin to value the night? Our cities need new models for illumination infrastructure, ones that reach beyond issues of cost, energy, safety, and even functionality. Municipal governments must include night scenes in their visions for vibrant, inclusive, and resilient urban landscapes. With its unparalleled network and early start, New York could model the future at night.

This article is an extension of a project which explores the future of cities through the lens of sensory experience. Using sight, smell, touch, sound, and taste, Urban Sensorium anticipates potential energy, ecology, climate, transit, and food scenarios for five major cities, chosen for their projected growth and international influence. The project was researched and designed by Emily Schlickman and Anya Domlesky of XL: Experiments in Landscape and Urbanism and supported by SWA Group and Noah Christman, SPUR Public Programming Manager. It was exhibited at SPUR Urban Center in 2017-2018.

Emily Schlickman is a landscape and urban designer at SWA, where she co-leads the firm-wide research and innovation lab, XL. She has worked on a number of large-scale planning and urban design projects, both domestic and international, and has served as an adjunct faculty member at UC Davis. She holds an M.L.A. from the Graduate School of Design at Harvard and a B.A. from Washington University in St. Louis.