A "proper wind analysis"? Brutally cold wind around Sixth Ave. raises questions about 2006 study, plus impact of (unstudied) larger proposed towers.

It's another cold, windy day today, so windy there's a gale warning, with winds up to 19 mph and gusts up to 39 mph in Brooklyn.

Approaching Dean St. and Sixth Ave. Not much variety

So it's likely to be another brutally cold and windy day around certain portions of the Atlantic Yards/Pacific Park project. 

After all, as longtime Brooklynites know, the area has its risks: in 2003, the New York Times suggested that then-solitary Williamsburgh Savings Bank Tower, aka One Hanson Place, might be the coldest and windiest place in the city, partly due to its location and partly due to its solo status.

It's no longer the sole tall building in the area, but others nearby are channeling wind gusts.

On Jan. 4, resident Rodrigo Solé asked, "Do you know if proper wind analysis was conducted for AY development? The wind tunnel that runs on 6th Ave from Atlantic onto Flatbush Av makes street life unbearable. There’s a lack of mitigation elements such as proper bldng setbacks / street trees / etc."

The answer is yes, I responded, but the big focus in 2006 was on the (never built) flagship tower. Moreover, as I wrote, the report (also at bottom) didn't try to pin down whether uncomfortable winds would be more likely in the winter, when they’d exacerbate wind chill.

As shown in the photo above, a screenshot from a video below, there aren't many setbacks visible at the buildings on Sixth Avenue. (One more is coming.)

A proper analysis?

Actually, whether it was a "proper wind analysis" was debatable, since the document was belatedly produced in response to comments, rather than as part of the main project documents, and never subject to scrutiny. 

Whether it remains a "proper wind analysis" is even more dubious, since the project configuration has changed, and taller and bulkier proposed buildings--at both the six railyard sites and Site 5, catercorner to the arena--should exacerbate wind.

Obviously. larger trees are a long way off, I responded, asking Solé, who's an architect and urban planner, what he thought should be done. 

His reply: "Besides landscaping, recessed sections and setbacks in the lower façades could have helped reduce the force of the downwash effect. Additionally, the implementation of canopies/awnings are good buffers against the downdrafts."

In 2006, I quoted a 2005 report by Ezra Goldstein in the Park Slope Civic Council’s Civic News on a visit by Danish urban planner Jan Gehl, who suggested a mix of building sizes:

B5, center-left, plus (built) B4. Dattner Architects

On the walk, Gehl talked about how, at street level, a solid wall of high rise buildings blocks the sun and creates a wind tunnel effect. He told his listeners how Vancouver, British Columbia, has surrounded skyscrapers with lower buildings that let in light and deflect down-currents of air from the towers.

What next?

On tap, across Sixth Ave., between Pacific St. and Atlantic Ave., from 18 Sixth Ave. (B4) is the B5 tower, 700 Atlantic Ave. (or 698), which also looks to be very vertical.

Solé's comment: "B5 does not look great either judging from the elevations/renderings provided. That first section of the building podium facing the [Sixth Ave.] sidewalk is 165' tall before the first setback. That’ll do little to nothing."

On video

Before I go deeper into the documents, let's take a look. Later that day, I walked along Sixth Avenue from Flatbush Avenue to Pacific Street. A flapping awning and a yielding street sign attested to the wind.

    

My ungloved hand got so cold I had to give up filming, but, yes, some young people proceeded without hats.

I then filmed along the Pacific Street open space corridor from Vanderbilt Avenue to Carlton Avenue, which seemed to have wind channeled from both the east and the north. You can see the wind blowing a canvas motorcycle cover.

 

I then walked along Pacific Street and started filming not far east of Sixth Avenue, then walked to the west side of Sixth, and up a short way toward Atlantic Avenue. You can hear the wind interfering with my narration.

 

Crossing Sixth Avenue made me unsteady. 

See the buildings (18 Sixth, 38 Sixth, 662 Pacific) with basically blank walls? Note that the B5 tower (l.) is planned to flank Sixth Ave btw Pacific St. & Atlantic Ave., once a platform is built.

The comments and the response

In the Response to Comments documents (Part 1, Part 2) Chapter of the November 2006 Final Environmental Impact Statement (EIS), various commenters raised the wind issue.

For example, the Council of Brooklyn Neighborhoods suggested that various qualitative impacts on surrounding public spaces had been underestimated in the DEIS, including impacts of shadows, wind, pollution, noise, and traffic. 

Regarding wind, the response from the Empire State Development Corporation (ESDC, now ESD), was that was: "In response to comments, an evaluation of wind conditions was conducted and indicated that the proposed project would not result in adverse wind conditions in or around the project site."

A number of residents and organizations either asked about a wind analysis or warned that the buildings would create a wind tunnel, citing the existing extreme conditions. Pratt Institute academic Brett Porter said similar projects in Canada require a wind analysis. (It's colder there, of course.)

"A supplemental EIS is required because the DEIS ignored wind impacts," the Fort Greene Association warned.

The study

Likely to avoid that issue coming up in ligitation, and/or forcing a supplemental study that would delay project approval, ESDC then hired Minneapolis-based Newmerical Technologies International via AKRF, the consultancy that conducted most of the environmental impact analysis. 

Newmerical's conclusion was benign:

In general, while ground-level wind speeds in the area are projected to increase with the addition of the proposed Atlantic Yards Arena project for all locations identified, these increases would not cause significant hardship to pedestrians.

I focused on the plan to make the Urban Room, the atrium attached the flagship tower, the "front stoop," noting that it could frequently be too windy (above 11 mph) for sitting (as opposed to walking).

Of course, the Urban Room was never built, nor was that tower.

Just not too often?

The report stated: "No locations were found to be in the uncomfortable range, greater than 20 mph, more than 1% of the time - well within the normal occurrence level for the area."

That may well remain true, in terms of percentage, but wind greater than 20 mph in the cold can be brutal, and design can help.

The garden's warning

The Brooklyn Bear's Community Garden, located at Pacific Street and Flatbush Avenue adjacent to Site 5, warned:

With towers proposed literally on the Bear’s Garden’s door step, we will definitely feel the effects of winter and summer blasts of air, and everything else that entails: dust, garbage, damage to trees and plants, hazards to pedestrians, homes and business. Increased wind speeds at the ground level created by the proposed towers would produce significantly dryer conditions for the garden, damaging plants and requiring increased irrigation. It would cause adverse effects for existing street trees surrounding the garden, exacerbating conditions they already struggle to overcome. Wind shear and wind chill would cause further damage and could potentially compromise the safety of members working in the garden.

The response:

At the Brooklyn Bear’s Community Garden, the wind conditions would be suitable for the type of activity expected in such a space, i.e., sitting, standing, gardening, and leisurely walking. In the area of the garden as a whole, the evaporative capability of the winds above the vegetation would increase somewhat, but since plants draw the needed amount of water from the surrounding soil, and the soil, when irrigated, usually contains more water than actually used by the plants, additional irrigation may not be necessary.

However, the report suggested that, for 14 percent of the time, roughly one day a week, the garden would not be “suitable for sitting, walking, and general gardening activities.” Still, the increase in wind was “not considered significant.”

From the report

The report noted:

New York City does not have wind-related pedestrian comfort criteria. The criteria used in this project follow general design guidelines used throughout the U.S. and Canada, which define wind speeds determined to be comfortable for different expected uses at least 80% of the time. Results are presented for annual wind directional probabilities to determine comfort levels of pedestrian wind speeds around the vicinity of the proposed Atlantic Yards Arena and Redevelopment Project.

Among the highlights: 

• No locations were found to be in the uncomfortable range, greater than 20 mph, more than 1% of the time - well within the normal occurrence level for the area; 
• Conditions at all locations are expected to be within the acceptable comfort levels for the existing uses and for the potential uses within the proposed project; 
• All locations had predicted wind speeds suitable for general pedestrian activities (<20 mph) ranging from 91% to 100% of the time; 
•  With the exception of several locations near the intersection of Flatbush and Atlantic Avenues and a few narrow passages between the proposed buildings, all locations had predicted wind speeds suitable for short term sitting, leisurely walking, and waiting, such as bus stops (<16 mph) ranging from 92% to 100% of the time; 
• near the intersection of Flatbush and Atlantic Avenues and within some narrow passages mentioned above such conditions would be expected at least 84% of the time; 
•  Locations that may have more extended use, such as parks and open space, would experience suitable conditions (<11 MPH) at least 91% of the time, with the exception of the Brooklyn Bears Community Garden where such conditions would be expected at least 86% of the time; 

The comfort criteria used in this study are summarized as follows: 

• Leisure Sitting, Dining (L): Wind speeds below 7 MPH would be acceptable for leisure sitting for extended periods of time and is suitable for outdoor dining. 
• Sitting (S): Wind speeds 0 - 11 MPH. This range of wind speeds is suitable for short term sitting at outdoor cafes, standing, or strolling. These are light to gentle breezes where wind is felt on face, leaves rustle, small branches and twigs are in constant motion. 
• Standing (T): Wind speeds 0 - 16 MPH. This range of wind speeds is suitable at building entrances, bus stops, short term sitting, window shopping, and leisurely walking. These are moderate breezes where, at the higher end of this range, dust, loose paper and small branches are in motion. 
• Walking (W): Wind speeds 0 - 20 MPH. This range of wind speeds is suitable for brisk walking, parks, and general pedestrian activities. At the higher end of this range, small leafed trees begin to sway, crested wavelets form on inland waterways, and umbrella usage becomes difficult. 
• Uncomfortable (U): Wind speeds > 20 MPH. These winds are generally considered uncomfortable and begin to become a nuisance for most activities. 
• Dangerous (D): Wind speeds > 45 MPH. At these speeds, whole trees are in motion,

Again, wind chill went unmentioned.

About Sixth Avenue

The report acknowledged that the Sixth Avenue corridor was of concern, because winds from "the North and South have a higher annual probability of occurrence and therefore blockage, downwash from buildings, and the channeling effect of the corridor may cause an increase in wind speeds."

It analyzed the proposed buildings, acknowledging that "the building massings did not include detailed architectural features which could reduce the effects of downwash and channeling, such as canopies, street furniture and signs, and other landscaping features." (They don't have many.)

The conclusion:

Wind speeds along the Sixth Avenue corridor would be highest near the intersection with Atlantic Avenue. The speeds could approach the 16 MPH wind threshold. The winds would be reduced proceeding southward along Sixth Avenue. These wind levels indicate comfort conditions suitable for walking, and general activities near the Atlantic Avenue intersection.

Except not always.