Boom in skyscraper construction may mean less light for city residents

New skyscrapers add to a city’s skyline and help boost its prestige. But, those same buildings can block light and this is an ongoing concern in New York City and several other major American cities.

For cities, shadows present both a technical challenge — one that can be modeled in 3-D and measured in “theoretical annual sunlight hours” lost — and an ethereal one. They change the feel of space and the value of property in ways that are hard to define. They’re a stark reminder that the new growth needed in healthy cities can come at the expense of people already living there. And in some ways, shadows even turn light into another medium of inequality — a resource that can be bought by the wealthy, eclipsed from the poor.

These tensions are rising with the scale of new development in many cities. As New York’s skyscrapers set height records, Mayor Bill de Blasio has also proposed building 80,000 units of affordable housing over the next 10 years, much of which the city would find room for by rezoning land to build higher. Boston wants to find space for an additional 53,000 units. Toronto in the last five years has built more than 67,000. All of which will inevitably mean more shadow — or even shadows cast upon shadow, creating places that are darker still…

In New York, legislation was introduced in the city council this spring that would create a task force scrutinizing shadows on public parks. Lawmakers in Boston in the last few years have repeatedly proposed to ban new shadows on parkland, though they haven’t succeeded. In San Francisco, the city has tightened guidance on a long-standing law regulating shadows in an era of increasingly contentious development fights. In Washington, where the conflict arises not from luxury skyscrapers but modest apartments and rowhouse pop-ups, the zoning commission voted in April on rules that would prohibit new shadows cast on neighboring solar panels…

As a result, multimillion-dollar apartments in the sky will darken parts of the park [Central Park] a mile away. Enjoyment of the park while actually in the park — a notably free activity in a high-cost city — will be dimmed a little to give millionaires and billionaires views of it from above.

This is an ongoing issue, one that helped prompt zoning laws in the first place and still gets at the basic question of whose city is it anyway? I’m reminded of the suggestion from New Urbanists that there is a proper ratio of building height to the street in order to limit this issue (and also boost street life rather than dwarf it – this is a whole other issue that parts of Manhattan could deal with) but in places where land is incredibly valuable – New York City, Hong Kong, Tokyo, etc. – these design guidelines don’t satisfy the interest in density and the money that can be made.

One drastic thought: shouldn’t all tall buildings in American cities be oriented to the north of major streets or parks or features so as to limit shadows? This is a problem with Central Park: if the tall development was mainly to the east or north, the shadows wouldn’t be as much of an issue (though they would fall elsewhere). Yet, settlement patterns didn’t originally occur with these guidelines in mind.

When the new McMansion next door blocks your solar panels

This is a twist on the issue of a McMansion being built next door: what if it blocks your solar panels?

What happens when the community wants terrace houses and a developer says ”no thanks, I’d prefer 20 storeys”? Which anonymous expert then knocks him back to 18 and compliments himself on his Solomonic even-handedness? Who prevents the new ”complying” McMansion next door from overshadowing your new solar panels? Who decides who gets listened to?

One complaint about teardowns or larger buildings constructed next door is that they can block sunlight. This can be a big deal, particularly in cities where really tall buildings could block sunlight for blocks. Indeed, many cities have restrictions on the footprint and the shadows large buildings can cast.

But, I’ve never seen the argument that it isn’t really about experiencing natural light and is more about solar panels. How many people are affected by this issue? Do homeowners have a right to access direct sunlight so they can power their dwellings? This sounds like a new area for regulations.