David Kohn Architects’ Carrer Avinyó apartment in Barcelona has been crowned the best interior design of  2013 INSIDE: World Festival of Interiors at an awards ceremony in the Marina Bay Sands Hotel in Singapore.

Beating 55 other nominations to the prize, the project is a refurbishment of an apartment in Barcelona’s gothic quarter.

The Carrer Avinyó apartment features an open plan living room, bathroom and three bedrooms – two-stacked one above the other, with the third joined by an elevated mezzanine level.

Kohn remodelled the space, removing the partition walls and harmonising the apartment with the medieval streets beyond to create a pied-à-terre for his clients, two brothers, who had lived there for some time.

The tight, acute floor plan has been maximised, consequently evoking a sense of theatrical delight. Scales have also been cleverly manipulated, with the specially made tiled floor referencing a triangular public square nearby with a tessellated pattern progressively graduating with 25 colours.

Furniture elements, including the library and elevated bedrooms, add to the dynamic architecture inside the room.

“The project has a quality we set out to find, that is the quality of magic. Spanning extremes of scale, it has become a suitcase you can sleep in but also a place for celebration and entertainment. The newly achieved large central room combines simplicity with a sense of space that stimulates curiosity,” explains head judge Nigel Coates on the panel’s decision.

“The jury debated extensively where architecture ends and interiors begin. We thoroughly support the potential for these two worlds to cross into one another’s professional territory, but some of the entries seemed not to capitalise on the special skills that are evident in tonight’s prize-winning scheme.”

London-based David Kohn Architects triumphed over tough competition from world-renowned designers such as Zaha Hadid Architects, as well as Australian practices including HASSELL and FJMT. David Kohn will now join previous winners as a judge at the festival next year.

“We are absolutely delighted to have won the award,” says Kohn.

“The project demonstrates how an interior can be about the city in which it is situated. An homage to Barcelona.”

Full list of INSIDE Category winners

Bars and Restaurants
Ammo Bar + Restaurant by Wang

Creative Re-use
Dardanel Administration Building by Alatas Architecture & Consulting

Culture
Auckland Art Gallery Toi o Tamaki by Francis-Jones Morehen Thorp, fjmt + Archimedia (Architects in Association)

Display
Hublo Pop-up store by Asylum Creative Pte Ltd

Education
DPS Kindergarten School by Khosla Associates

Health
Knowledge Centre, St. Olavs Hospital by Nordic Office of Architecture

Hotels
Parkroyal on Pickering by WOHA

Office
Clemenger BBDO by HASSELL

Residential
Carrer Avinyo by David Kohn Architects

Shopping Centres
Emporia by Wingårdh arkitektkontor

Shops
Tashya by charged voids

Transport
Barrakka Lift by Architecture Project

Photography by Jose Hevia Blach