Could a Shadow Review Law Protect New York City Parks from Shadow Impacts?

The New York City CEQR Technical Manual and San Francisco Shadow Analysis Program Provide Templates

One of the major amenities of our great public spaces is sunlight. While a patch of shade is most welcome on a hot July day, we love our parks for the access to sunlight they provide and the feeling of stepping out of the city that the unimpeded sunlight allows. Given our dense environment, new buildings can have the unintended consequence of altering sunlight patterns in our green spaces (not to mention streets, historic resources and even apartments), potentially harming vegetation and decreasing park usage rates. Moreover, sunlight in New York City is almost certainly a diminishing resource; so long as buildings go up at a quicker pace than they come down, shadows will increasingly cover parks, streets and buildings. They’re not easily undone.

Interestingly, New York City does not directly regulate new shadows. Certain zoning requirements are meant to limit the impact of shadows and the 1916 New York City zoning code was initiated, at least in part, in response to the seven-acre shadow cast by the then-new Equitable Building. Though the zoning code has been amended in the intervening years, building height restrictions and design requirements in the current zoning code continue to address shadows indirectly; for example, the height restrictions for buildings on wide avenues in many areas tend to be higher than those for buildings on surrounding side streets, as wider avenues allow for more sunlight relative to building size. Civic groups have also played an indirect and unofficial role in keeping shadows in check. In particular, the successful 1980s fight spearheaded by the Municipal Art Society over the Columbus Circle project that later became the Time Warner Center is now the stuff of city planning lore, thanks to the 800 protesters, Bill Moyers and Jacqueline Kennedy Onassis among them, that used hundreds of black umbrellas to simulate the projected shadow of the planned building.

The world has changed since 1916, and even since the more recent amendments to the zoning code. While zoning regulations aimed at minimizing shadow impact are still in effect, building technology and market mechanisms have evolved to allow taller buildings in places not previously anticipated. As Council Member Mark Levine, Chair of the Parks and Recreation Committee, put it, “in recent years a combination of transferable development rights, zoning lot mergers, and new building technologies have enabled super-tall structures that would have been inconceivable a half century ago--effectively rendering previous zoning laws impotent.”

In light of these developments, as well as a handful of new or planned “supertall” towers on the blocks just south of Central Park, the Municipal Art Society has been active once again. They have done extensive analysis of the impacts of the shadows from these new high-rise buildings in connection with their 2013 “Accidental Skyline” work and provided testimony on behalf of a 2015 New York City Council bill for the creation of a task force to study the effect of shadows cast over public parks (the bill remains in committee as of today). MAS recommends potential solutions to minimize new shadow impacts, including new zoning, height and building setback requirements and a public review process for buildings that would cause new shadows over parks.

Though a review process has the potential to lack teeth (depending on whether the review process is designed to actually prohibit new buildings that would have significant shadow impacts, require or incentivize mitigation in such cases or merely give notice and consideration before allowing construction to proceed), implementing one would be relatively straightforward, as frameworks have been put in place in other contexts or jurisdictions. Moreover, the process is flexible, both on the design end and in allowing for review of projects or types of buildings that we may not be able to foresee today. There are at least two potential models in place for a New York City shadow review process:

  • For one, a New York City Environmental Quality Review (“CEQR”)-like process could be expanded to cover all projects that lead to new shadows, not just those subject to CEQR because they involve a public approval, funding or other “action.” The CEQR Technical Manual already has clear, if case-by-case, thresholds for reviewing shadow impacts and proposes mitigation solutions. As under CEQR, new buildings or other construction projects could be required to perform a shadow assessment (including computer modeling of shadow impacts) if they would result in new or increased structures of greater than 50 feet in height or if they would be located adjacent to or across the street from a public park or other sunlight-sensitive resource. A “significant” shadow impact determination, with its attendant mitigation requirements, could be found for any “incremental shadow of 10 minutes or longer” with impacts to vegetation, open space or other defined sunlight-sensitive resources. The CEQR Technical Manual also suggests potential shadow impact mitigation strategies, including modifications to building height, shape, size, location or orientation and relocation or redesign of sunlight-sensitive resources or features.

  • The San Francisco, California Shadow Analysis Application provides an alternative approach. That program, administered in connection with San Francisco’s zoning code provisions that regulate shadows cast over city parkland, requires any new structure or building addition that will top out over 40 feet to prepare a “shadow fan” diagram showing the maximum reach of building shadows throughout the year. A shadow fan showing that the new building's shadow would reach protected park space would be flagged for further review, including a potential Planning Commission hearing.

In designing a shadow review process, New Yorkers would have to decide certain threshold questions: When do we want to require review? For any building above a certain height? For buildings taking advantage of zoning lot mergers? What resources do we want to protect? Certain, specified parks only? All New York City parks? Other, non-park resources as well? For example, CEQR protects certain historic resources (with sunlight-sensitive features), but not city sidewalks (so that always-used bench outside the local coffee shop with great morning light wouldn’t be protected). And how much new shade is too much? The CEQR Technical Manual puts forth 10 minutes as a relevant, though not determinative, threshold, but perhaps the amount would vary depending on the resource. Any of these parameters could be integrated into a new shadow review process using the CEQR or San Francisco frameworks. Finally, the designers of the shadow review process would need to consider whether and how the process would withstand legal challenges, including due process, takings and vested rights challenges.

It’s worth noting that a shadow review process is not the only way to go -- other jurisdictions regulate shadows more directly. Massachusetts has had a law on the books since 1990 protecting Boston Common and, later, the Boston Public Garden from the impacts of new shadows (though multiple attempts to expand this protection to other public parks have been unsuccessful). And San Francisco’s regulation is more sweeping than just a shadow review process; the zoning code in that city generally prohibits new buildings of greater than 40 feet in height that cast “significant” shadows on park land and has been used to oppose or strike down proposed projects. Moreover, architects have developed new ways to build larger buildings while lessening impacts to light, and it’s possible that some will be codified into future zoning regulations.

New York wouldn’t be New York without an ever-changing skyline. It also wouldn’t be New York without passionate citizens questioning development decisions. A shadow review process would weave together both of those important strands, allowing for development to occur in a way that preserved our access to sunlight in public spaces. New Yorkers are already comfortable with public review processes, and a shadow review is such a process with substantial precedent here and elsewhere. Moreover, the design of the shadow review process would allow for stakeholders to have a voice in articulating what factors matter to them in reviewing shadow impacts going forward.


Note: I would be remiss in not pointing out how helpful I found the Municipal Art Society’s “Accidental Shadows” portal (report found here) and a May 4, 2015 Washington Post article by Emily Badger in understanding this issue.