An international design team led by US architects wHY have won the international competition to design the £25m Ross Pavilion and West Princes Street Gardens project in Edinburgh.

The Ross Development Trust together with the City of Edinburgh Council are replacing a bandstand on the site, which has fallen into disrepair, with a new visitor centre, café and flexible platform for cultural programming. The surrounding landscape is also being improved.

Competition organisers Malcolm Reading Consultants led the five-month search for a design team to take the project forward.

In total, there were 125 first-stage submissions. Seven studios were shortlisted, including BIG, Adjaye Associates and William Matthews Associates with Sou Fujimoto Architects, who have been awarded a special commendation by the jury for their proposal.

However, it is wHY’s collective of architects, landscape designers, makers and strategists who have won the unanimous approval of the judges with their vision for “an organic landscape-focused scheme that respects the historic setting but also animates the Gardens through the introduction of a new undulating promenade, transformed access from Princes Street, sculptural seating and dynamic open views.”

The jury praised the team’s concept design as “a beautiful and intensely appealing proposal that complemented, but did not compete with, the skyline of the City and the Castle.”

“We are confident that we have a winning concept that embodies an imaginative ensemble landscape approach, creating a wonderful stage for our iconic Edinburgh Castle,” said jury chair Norman Springford. “The design concept offers a creative energy and a series of unique elements which will all combine to create a new and contemporary landscape.”

Competition director Malcolm Reading added: “wHY is a creative force that has the rare skill of being able to produce design that is exciting yet also sensitive and humane – it is a delight to see them win so exuberantly.

“Their proposal is a landscape scheme that is really more like an energy-field: using animation and drama as well as open vistas, they transform the Gardens and create an experience that is much freer and organic. As is their style, they conscientiously sampled local opinion, and have come up with a design proposal that is engaging and refreshing.

“We would like to thank all the finalists for their hard work and enthusiasm – we were in no doubt over their connection to this wonderful project, and they produced diverse and well-reasoned concept designs.”

The team led by wHY also includes Edinburgh design studio GRAS, Groves-Raines Architects, Arup, Studio Yann Kersalé, O Street, Stuco, Creative Concern, Noel Kingsbury, Atelier Ten and Lawrence Barth.

The group will now work with the Trust, the council, other stakeholders and public to take forward the project. Construction is expected to begin in 2018.

Adjaye, Ingels, Ramstad and Fujimoto in the running to design Edinburgh theatre and gardens