On a recent Sunday morning at a new pedestrian plaza in the Seaport, men in shorts raced to get inside the Equinox gym and held tight to their baseball caps. Parka-clutching parents struggled to keep strollers upright, and dog walkers equipped their charges in Arctic-caliber outerwear. The barista at La Colombe is used to customers coming through the door with hopelessly tousled hair.
Theirs is a Boston lament both old and familiar and as new as the neighborhood around them: wind tunnels.
Pedestrians, bicyclists, and scooter riders know all the notorious spots where gusts rush down tall buildings and blast down streets — around South Station; on the Freedom Trail at Beacon and Tremont streets; and, perhaps the most infamous, near the base of 200 Clarendon, previously known as the John Hancock Tower (where a fire chief blamed 50-mile-per-hour winds for whipping some concrete debris off scaffolding in January, sending it crashing onto a car below).
These and other face-blasting zones, compiled based on historical records, interviews with architects, and personal experience, come to mind as the Seaport gets developed amid persistent gusts. Is our growing city destined for more of the same?
The answer is yes, almost certainly. Boston, defined by the open sea along its entire eastern edge, consistently records the fastest average wind speeds among major US cities (according to the National Oceanic and Atmospheric Administration). It’s considerably windier than Chicago, notwithstanding the nickname of that metropolis, which originally referred to an alleged penchant for bragging.
Another key factor is the basic nature of urban development in an older city, which creates juxtapositions between new tall buildings and the city’s cozy low-rise neighborhoods — and helps whip up the wind further still.
But have a measure of faith, city planners say. With construction booming and several new towers planned, Boston planners have joined their counterparts from London, Toronto, and San Francisco in paying special attention to street-level wind effects around new development. That means heading off problems early in the design process and making modifications to completed projects when the conditions they help create are too blustery by far for those walking by.
Builders have had to confront all kinds of impacts over the years — shadows, glare, noise, heat effects, energy inefficiency, susceptibility to flooding, and seismic activity. Around the world, wind is now moving up the checklist.
“We’ve seen an increase in awareness,” said Frank Kriksic, principal at RWDI, the go-to global consulting firm for wind studies. No one is suggesting getting rid of tall buildings, he said, but rather “using the technologies that are available, manipulating the architecture to manage the wind … and just be smarter about it.”
Wind tunnels happen because wind travels faster at higher altitudes, hitting the sides of buildings, which act like sails, and rattling down to the street. With nowhere else to go, it finally surges through gaps between buildings, down narrow streets, and around corners, similar to water shooting through the nozzle of a hose. March is historically the city’s windiest month, with speeds averaging around 12.9 miles per hour (again, according to NOAA data). Wind tunnels can easily push gusts beyond 20 miles per hour, which stir up debris, invert umbrellas, and are generally considered uncomfortable. Anything closer to 30 miles per hour and beyond can knock over pedestrians and bicyclists.
Wind effects in urban environments have been around as long as city builders have reached for the sky. After Daniel Burnham’s 21-story Flatiron Building opened in New York City in 1902, police officers shooed away men hoping to glimpse petticoats uplifted by gusts.
Twentieth-century modernism, with its unadorned surfaces from bottom to top, only exacerbated the problem. Along the way, from the 1950s on, development has been pushing into areas adjacent to existing neighborhoods, mixing the low-rise old and skyscraping new. Tall buildings surrounded by other tall buildings actually end up buffering each other. “If the John Hancock were in the downtown core, it would be relatively benign,” Kriksic said.
Fast-growing cities are looking to minimize building-generated wind as much as possible, as a quality-of-life issue for residents and visitors. London recently revamped its standards after complaints of wind tunnels around the base of several skyscrapers that sprouted in the last 20 years — including Rafael Viñoly’s “Walkie Talkie” skyscraper, which also had the dubious distinction of reflecting sunlight so intensely it melted cars parked nearby. San Francisco is reviewing how to best handle street-level wind, as tall buildings such as the Salesforce Tower transform the skyline. A similar update of testing requirements is underway in Toronto, where mountain-climbing ropes were once installed to help people make it through one gale-prone spot.
Boston has required wind studies as part of the environmental review process for new developments since the 1990s. The rules apply to any building taller than 150 feet, structures over 100 feet and twice as high as neighboring buildings, or new construction in select places with high-volume pedestrian activity, including along the Rose Kennedy Greenway, located just blocks from the harbor and lined by towers, with more to come.
While in the past some architects and developers may have paid mere lip service to the subject, the city is making it clear they must take wind seriously. The required analysis is getting more thorough, as well: it typically involves not only blasting a big fan at a scale model of a proposed tower, but computer-aided simulations to determine how prevailing winds will behave.
The Chicago-based architectural firm Studio Gang hired RWDI to do scale-model and computational testing for its proposed development at One Kenmore Square, particularly relevant as the project includes a major reconfiguration of streets, bike lanes, and sidewalks at the base of the proposed 300-foot tower. The 42-page report concludes that conditions at grade will be comfortable most of the time, with one to two spots subject to seasonal gusts.
There are a number of steps designers and developers can take to head off a wind-tunnel problem: putting the taller parts of buildings on a podium, which absorbs the downdraft; extending canopies at entrances or building overhead trellises; incorporating fins and other surface modulation to add wind-impeding texture to facades; chamfering, or rounding off corners because wind has a tendency to whip faster around right angles; and landscaping at the street level including marcescent trees, which hold their leaves year-round and thus buffer the breeze.
City planners say they do a lot of follow-up and require further modifications as conditions warrant. After the luxury residential tower at 400 Stuart St., diagonally across from 200 Clarendon, opened in 2009, the developer was asked by the city to beef up both landscaping and the entrance canopy to dampen the wind. Similar monitoring at One Dalton Street — a building by the same architect who designed the John Hancock tower, Henry Cobb of Pei Cobb Freed & Partners — prompted the project team to add a second canopy to the sleek glass facade.
And so what about that breezy pedestrian plaza in the Seaport? The buildings around it aren’t as tall as elsewhere in the city, though they still triggered the city’s wind study requirement. What’s more, several of them are built on protective podiums. A recent environmental impact review concluded that little else could be done to combat the neighborhood’s persistent northeasterly winds, mostly a result of open exposure to the harbor. "Certainly it’s our goal for the public realm to be comfortable for everyone,” said Lauren Shurtleff, acting director of planning at the Boston Planning & Development Agency.
But considering that in some cases windy conditions are more intermittent, judging the intensity of the problem “can be subjective,” Shurtleff said. A certain amount of wind is something Bostonians must put up with. The industry standard, embraced by the city, is to shoot for comfortable conditions — under 20 miles per hour — at least 80 percent of the time.
Architecture has always had a tension between what designers want to create and the practical outcomes of occupancy. No one wants their building to do harm, but there is some danger in over-regulating. That could restrict more creative design, increase development costs (making Boston even more unaffordable), and potentially fix one problem by creating another. A fortress-like podium built to absorb downdrafts will kill street life just as much as any icy blast.
What’s clear is that urban planners and architects have their work cut out for them. It’s an important reminder that the true measure of a building’s success isn’t just aesthetics — it’s the quality of human interaction inside, outside, and all around.
The wind tunnels of Boston
1. Stuart Street between Trinity Place and Clarendon Street (at the base of the former John Hancock Tower)
2. The base of One Beacon Street at the intersection of Beacon, Tremont, and School streets
3. Huntington Avenue at West Newton Street (at the back entrance to the Prudential complex, across from the Christian Science Center)
4. International Village adjacent to Ruggles Station steps (on the Northeastern University campus)
5. Pedestrian plaza between Northern Avenue and Seaport Boulevard (near Farnsworth Street and Courthouse Way)
6. Dewey Square at the base of the Federal Reserve building adjacent to South Station
Wind speeds/Pedestrian comfort criteria (source: City of Boston)
Less than 12 mph: Comfortable for Sitting
13-15 mph: Comfortable for Standing
16-19 mph: Comfortable for Walking
20-27 mph: Uncomfortable for Walking
Greater than 27 mph: Dangerous Conditions