In the midst of an ecological transition, with sustainable building becoming ever more central to the world of construction, the bar is gradually being raised higher. So everyone is now paying close attention to the most sustainable building projects in the world, starting, for example, with the list produced by the American Institute of Architects for 2022. But there are not only lists of the most sustainable houses: there are also the most sustainable museums, stations, airports, districts and cities, with new examples to follow each year. In the field of sports buildings, for example, the new benchmark for the construction and redevelopment of stadiums is the Qatar Showcase Stadium in Doha, built in the lead up to the 2022 UEFA World Cup: one the of the key factors helping to make it a model of sustainability is a photovoltaic park twice as large as the structure itself, as well as the construction of a mobile roof that exploits natural ventilation. However, since 2021 the main example to look to in the world of sports stadiums and buildings is definitely the Climate Pledge Arena, that is the central arena in the city of Seattle, in the state of Washington.
Before the Climate Pledge Arena
Until recently, the site where the Climate Pledge Arena stands today was home to an arena called the Key Arena. From the time it was first built, this sports centre has changed name several times, in fact: first it was the Washington State Pavilion, then the Washington State Coliseum, then the Seattle Center Coliseum, and finally, in 1995, the KeyArena at Seattle Center. The building was opened for the first time in 1962, on the occasion of the Century 21 Exposition. The architect who designed the Pavilion was Paul Thiry, considered the father of modernism in the western United States. Having been acquired by the city of Seattle for 2.9 million dollars at the end of the Exposition, it underwent rapid redevelopment to become a “multi-purpose arena”, that is, a building designed to host events of various kinds, starting with sports events: it became the home of the Seattle SuperSonics basketball team that was active until 2008, and it was thanks to the SuperSonics that the arena hosted two NBA finals, in 1978 and 1979.
After a decade of slow decline, the arena underwent substantial renovations between 1994 and 1995, bringing the building up to the NBA standards of the day.
Amazon and Climate Pledge
Before we take a look at the construction of the Climate Pledge Arena, we should explain the reasons for the new name. As we can see, the new Seattle arena was not given the name of a corporate sponsor in the traditional sense, as often happened in that period. In fact, the name Climate Pledge was chosen after Amazon – in collaboration with Global Optimism – acquired the naming rights to the new Seattle arena, currently home to the NHL Seattle Kraken and the WNBA Seattle Storm. The name was not chosen at random: Climate Pledge is the name of an initiative launched by Amazon in 2019 together with Global Optimism: their concrete commitment is to achieve zero carbon dioxide emissions by 2040, 10 years earlier than the date set by the Paris Agreement. So the name of the new Seattle arena evokes a sustainable future, with the new building becoming one of the first realizations of this.
The construction of the Climate Pledge Arena
The announcement of the redevelopment of the Key Arena was made in 2016 by the then mayor, of Seattle, Ed Murray. The Request for Proposal was launched in 2017 and the works started in 2018, overseen by Mortenson, a general contractor based in Minneapolis. The works were completed in 2021, demonstrating the speed with which the building was redeveloped.
The redevelopment increased the arena’s capacity, so that it can now accommodate 17,100 spectators for ice hockey matches, 18,100 for basketball matches and 17,200 for concerts. Among the most unusual aspects of the project, which was designed by Populous and carried out by the Oak View Group, is the preservation of the original roof from 1962. In order to preserve the original roof it was necessary to construct a temporary structure to support the roof while the new arena was built underneath.
In close observance of the principles of circular building, the glass from the original windows was recycled as well as the steel window posts, and the original elements of the continuous facade.
The enlargement of the building, which had to take place downwards in order to maintain the original roof, also made it necessary to construct a tunnel leading to the loading dock in the deepest underground part of the arena: the tunnel was 10 metres tall and 10 metres wide.
The new arena was inaugurated on 19 October 2021 with a benefit concert by the Foo Fighters and Death Cab for Cutie, although the official opening took place 3 days later with a sold-out concert by Coldplay.
The features that make the Seattle arena highly sustainable
From the description of the construction process, it is already easy to see why the Seattle arena is considered the most sustainable arena in the world. However, it is worth noting some other important features of this sports stadium.
For example, there is a rainwater harvesting system so that the process of creating the ice surface for hockey matches has the least possible impact on the environment. And urban greenery has not been overlooked either, with the cultivation of about 12,500 plants, including trees.
Every watt of energy used by the building comes from renewable sources, and the entrance tickets are designed to include free public transport to and from the arena. Particular attention has been paid to the restaurants in the arena: the food served is always sourced locally, and any unused portions are automatically donated to local charitable organizations.