Louis Armstrong Stadium, a new 14,069-seat venue located at the National Tennis Center in Queens, New York, will host its first official matches when the 138th U.S. Open begins on Monday, Aug. 27. The new stadium replaces the original venue named in honor of the legendary jazz musician, which hosted tournament matches from 1978 until its demolition in 2016.

One of the signature features of the new stadium is its retractable roof. On behalf of the United States Tennis Association (USTA), and together with ROSSETTI Architects, WSP provided the design and structural engineering services of the retractable roof for the Arthur Ashe project.

With the successful opening of the Arthur Ashe Stadium retractable roof in 2016, USTA moved on to its next stadium project, the new Louis Armstrong Stadium. ROSSETTI continued as the design architect, and together with the USTA, selected WSP to provide the mechanical, electrical, plumbing (MEP) and fire protection engineering design, along with conceptual design and analysis of a naturally ventilated stadium.

“In collaboration with ROSSETTI, our team designed the world’s first naturally ventilated retractable roof tennis stadium,” said Matthew Payne, WSP project manager for the ventilation system. The WSP team also included Dennis Burton, MEP project manager; Mark Powasnik, mechanical design lead; Joe DeGrazio, plumbing and fire protection lead; and Jacob Denner, mechanical engineering.

When the weather is clear, Louis Armstrong Stadium functions as it always has as an outdoor venue. The challenge comes when inclement weather forces closure of the roof to eliminate game delays and postponement.

“If a stadium is simply enclosed without thought for passive design, it will either need air conditioning or conditions will become intolerable inside the structure,” Payne said.

One of USTA’s priorities was that the new stadium maintains an outdoor feel, even when the roof was closed.

“Fundamentally, the US Open is an outdoor tournament, so the USTA wanted to explore ways they could provide rain protection to allow play to continue, but for the tournament to retain its outdoor feel,” Payne said. “Once you close a stadium roof, you are limiting the amount of airflow into the stadium and there is a risk of heat building up and you get that stuffy feeling. With the new Louis Armstrong Stadium, we were focused on making sure that wouldn’t happen.”

The idea of using natural ventilation was first considered when a retractable roof was built over Arthur Ashe Stadium, but it was determined to not be a viable option, given the constraints of the existing building.

“For Arthur Ashe, a natural ventilation analysis showed that it was going to be too difficult to get air into a stadium that was, for the most part, a large concrete bowl with very few permeations, and now a large roof on top — which is very present, even when the roof is open,” Payne said. “At the time we said, ‘If only there was a way to bring air into the stadium at lower levels, natural ventilation might have a shot.’ When the decision was made to design and build Louis Armstrong Stadium with a retractable roof, it seemed like the perfect opportunity.”

While temperatures might not be as cool as it would be with air conditioning, he believes the design maintains spectator expectations for an outdoor summer sporting event.

“Fans come to these matches with an understanding that temperatures and conditions can be unpredictable; they don’t expect it to feel like they are sitting in a climate-controlled building,” Payne said.

The resulting design encourages air flow throughout the stadium, while keeping the playing surface dry enough to continue tournament play. Since the venue is never completely sealed shut, the presence of outdoor conditions is still felt by everyone inside, and the temperature inside will usually be within a few degrees of what it is outside.

“Think of the roof as having an effect similar to standing underneath an umbrella during a rain shower,” Payne said. “It protects the spectators from the rain, but you are still aware that it is raining.”

The design process began with analytical models that demonstrated how the wind in the area around the stadium typically behaves — such as seasonal wind directions and wind speeds — and how the air would ultimately flow through different configurations of the stadium. It was also critical that the air had a pathway to flow through the stadium without influencing conditions on the tennis court.

The stadium seating consists of a lower bowl, with an open concourse on its upper level to allow breeze to pass through from all directions. Additionally, the upper seating is built only on the east and west edges, with the north and south faces featuring an impressive terra cotta-louvered façade. This façade has been carefully designed to allow cross ventilation of the stadium, but keep out most rain and direct sun.

In addition, an underground air pathway was developed that will passively cool the courtside seating without impacting gameplay.

“Since the ground temperature is typically a few degrees cooler than the ambient temperature, it is used as a passive cooling system as the air flows through the chamber, keeping the temperatures at court level more comfortable,” Payne said.

The system requires wind speeds of at least 5-7 miles per hour to maintain the desired temperature levels. If wind speeds fall below that threshold when the roof is closed, fans will operate to provide the required air movement within the stadium.

“Although the fans will be operational at the USTA’s discretion, they will not be needed most of the time for the system to work as intended,” Payne said.

Payne said that WSP also demonstrated how the retractable roof and the ventilation system could be used to improve game-time climate conditions even when games aren’t being played, such as closing the roof between sunrise and when play starts to protect the thermal mass of the stadium from the direct sun.

Payne is a leader in WSP’s Built Ecology team, a national practice of sustainability and high-performance design specialists. In addition to helping strategize the natural ventilation concept, the Built Ecology team leveraged the analytical capability of computational fluid dynamics (CFD) and bulk air flow modeling to understand and communicate air speeds and to model human comfort expectations.

An avid tennis fan himself, Payne said he is looking forward to the US Open … and while he wishes for good weather throughout the two-week tournament, he wouldn’t mind if there is a day or two where a rain shower creates the need to test out the retractable roof.

“I think it will be very exciting to experience the natural ventilation system in action," Payne said.

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