A CONSCIOUS TOMORROW: Belval urban development project illustrates new sustainability

In our search for projects that fit the theme of ‘Thoughtful tomorrow’, we cannot possibly stay away from the Grand Duchy of Luxembourg. There, an ambitious urban development project has been underway for many years in Belval, between Esch-Alzette and Sanem, a project for which the description ambitious is actually an understatement.

To situate Belval first: this is a former mineral water spring that later became the home of one of the Grand Duchy's most important steelworks. Since industrial production ceased in 1997, this location has been subjected to a number of landscape-changing renovations that have been ongoing for many years.

The development is being led by Agora, a company that was jointly founded by steel giant ArcelorMittal and the state to build a new neighbourhood at the start of the 21st century. A master plan defined the future of Belval around five sites: the Blast Furnace (which houses the University of Luxembourg, the Rockhal and Belval Plaza), the Belval-Nord and Belval-Sud residential areas, the Park and the Square Mile. In the heart of the Square Mile, the construction of Central Square on a former brownfield site that was previously transformed into a car park is now in full swing and it is here that we will look at two projects that can serve as examples of how to tackle such a mega project in the most sustainable way.

We are specifically focusing on Place des Bassins, where development work began in 2023 and which is to become a remarkable public space. Five different projects are being built around this heart of the neighbourhood, symbolised by the project to transform the former sinter basins according to a concept proposed by the firm Metaform, in collaboration with Latz+Partners and HLG. The five in a row: The Roots, Lot 44, Idesya, Kyklos and The Nest. Of these five, we will take a closer look at the approach of Kyklos and The Roots.

Kyklos: the lowest possible carbon footprint

Kyklos has a bold design, made entirely of glass, by the offices of HYP & UNStudio. Kyklos (the Greek word for circle) will be the last to complete the Central Square project and should become a symbol of this Central Square. Here, Atenor and the ARHS group (as co-investor and future user) are developing a project consisting of eight floors of offices covering more than 7,513 square metres. There is 283 m² of retail space available on the ground floor.

An interesting aspect of Kyklos is that the building proposal by UNStudio aims for the smallest possible carbon footprint. The design team, with local partner HYP Architects, used the early prototype of the so-called Carbon Builder. This is a tool that is being developed as part of a fully-fledged sustainable design framework. It reduced the carbon footprint of the design concept for this building by approximately 80% compared to a traditional office building in Luxembourg.

The building uses recycled, locally produced steel and there is a collaboration with concrete producers to improve the performance of the material. This resulted in the choice of a hybrid steel-concrete construction because it was determined that this hybrid solution offered better carbon performance in the long term. The goal: a huge reduction in the carbon footprint compared to a typical Luxembourg office building, with the Kyklos building aspiring to achieve at least BREEAM Excellent and Well Gold.

Kyklos connects two basins, remnants of the former steel factory site on which the neighbourhood was developed, in the form of a unique ‘infinity loop’. This loop symbolises the alliance of the industrial site and its revitalisation as an urban space. Due to its proximity to the square, the building is seen as the third loop in this equation: it is a sustainable connection that represents the future of urban development.

The design takes into account the master plan, the main pedestrian path and the existing central square, to create a building that is inspired by and complements the surroundings. The result is a combination of the circular geometry of the square with the orthogonal geometry of the surrounding buildings.

The Roots: mixed-use complex

The Roots, which has already started, is also ambitious. This mixed-use complex will be built on a concrete foundation and consists of four main parts: a residential area, offices, retail and a Food Market.

The project has a total surface area of 34,800 square metres and consists of a communal basement of 9,200 square metres with 253 parking spaces and a mixed commercial/office base in traditional reinforced concrete. On this base are three buildings with a wooden structure, including CLT floors. One will be used as office space and the other two will contain the 102 apartments. The Roots is being realised using a circular economy approach.

It is worth noting that the wood used comes exclusively from sustainably managed and PEFC-certified forests. In these forests, one felled tree is replaced by one or two others. Based on these strengths, The Roots is the pilot project for the new LCBI (Low Carbon Building Initiative) certification, which aims to reduce the carbon footprint of buildings by 30% to 50%. In addition, we see how the homes and communal areas directly benefit from the production of more than 120 photovoltaic panels. The Roots also collects rainwater to water the green spaces and a communal vegetable garden. Through these actions, The Roots is striving for the BREEAM Excellent certificate.

Perhaps most importantly, The Roots wants to bring nature back into the heart of the city. A hanging garden and various shared green spaces will become perfect relaxation areas that require little maintenance. According to the initiators, these spaces are crucial for well-being, because we know that people have a spontaneous and unconscious need to connect with nature. This biophilic design integrates natural elements into the built environment in such a way that the well-being of the residents is improved. The Roots focuses on the WELL Building Standard® Gold certification, which assesses ten concepts that contribute to health and well-being, such as air quality, water quality, natural light, choice of materials, thermal and acoustic comfort, and so on.