Published: December 17, 2015

Eco City


For those passionate about energy efficient buildings and mobility, eco-territory Alzette-Belval, France is a dream coming true – thanks in part to the imagination, innovation and responsible approach by Tractebel Engineering’s experts who helped define how it could, and should, happen.


The community of small towns in the Pays Haut Val d’Alzette is in North-East France, 3 km across the border from the Luxembourg town of Belval. Opportunities for the re-dynamisation of an entire territory, social upliftment and large-scale climate change action justified Alzette-Belval as one of 19 eco-city projects chosen by the Ministry of Ecology, Sustainable Development, Transport and Housing in France. Read more.


Central to the Alzette-Belval eco-territory, starting with the greenfield Micheville zone, will be an eco-centre with clusters of BEPOS (Energy Positive Buildings) mixed with regulation and passive buildings. The BEPOS “islands”, sharing energy resources and a mix of energy saving programmes to achieve zero-energy goals, contribute to the overall energy efficiency of the whole development. Read more.


Extending beyond the new eco-city, the major mobility task in Alzette-Belval is to facilitate the re-dynamisation of the whole territory by; connecting existing towns to the new eco-city centre so everyone can benefit from the new facilities; and providing new mobility options for current and future daily commuters to Luxembourg with multimodal, eco-friendly transport options and routes. This has resulted in 10 core mobility solutions being identified. Read more.


“Dealing with an entire territory, not just an “eco-district” within a city, makes this a special eco-project and one of national interest for France – both for its social upliftment potential and as a tangible demonstration of innovative climate change action on a large-scale.”

Sebastien Rodesch, Project Manager Lot 3 Alzette-Belval – Tractebel Engineering

Alzette Belval



Beyond an important investment in the environment, the Alzette-Belval eco-territory project ticks all the boxes by bringing social and economic benefits to the region too.

1. MORE HOUSING = MORE EMPLOYMENT: Once a steel and mining hub, the Pays Haut Val d’Alzette has suffered closure of all of its mines in the last 30 years. In contrast, across the frontier, Luxembourg is economically strong and offers high employment for “les frontaliers” living on its borders. Today 75% of 25,000 people in the territory work in Luxembourg; but there is room for even more if new housing and infrastructure makes it possible.

2. WELL PLACED FOR DEVELOPMENT: Key to choosing Alzette-Belval for eco-city development, just across the border urban-renewal of Luxembourg’s old Belval steelworks district was already underway – promising 20,000 job opportunities; with a new railway station on the connecting line to Luxembourg City, shopping centres and a University for 7,000 students. Together the joint projects make for a good Eco-Agglomeration Trans Frontier effort.


Leading the French development, a public institution Etablissement Public d’Aménagement Alzette-Belval (EPA-Alzette-Belval) was established in 2012. It is responsible for implementing all operations to effect the eco- and economic development of the OIN territory, with the goal to house 20,000 new residents and create 8,000 local jobs, via:

  • A new eco-city development on 50 hectares of industrial wasteland between existing towns Audun-le-Tiche and Belval; namely sites 1. Micheville and 2. Portes de Belval.
  • Energy-efficient construction of: 119.000 m2 new housing, 145.000 m2 business facilities, shops and 13.000 m2 schools and sports centres
  • An eco-friendly, multi-modal mobility network connecting the entire 5.285 ha OIN territory and facilitating commuter access to Belval and the City of Luxembourg.


With many new concepts to consider, EPA first called for engineering deployment and feasibility studies to outline the possible approaches and technologies ahead of any binding investments. The engineering missions were divided into 4 lots; proving a growing “City of Tomorrow” reputation, Tractebel Engineering was awarded 2 of them!

  • Lot 1: Feasibility study for the construction of “islands” of Positive Energy Buildings contributing to a global neutral energy balance of the zone.
  • Lot 2: Heating network.
  • Lot 3: Mobility, eco-mobility and innovative public transport.
  • Lot 4: Smart City Services (smart grid and smart metering).




Energy efficient buildings are at the heart of eco-city development. But there are 3 levels of energy-efficient buildings:

  • REGULATION – conforming to acceptable low energy consumption standards
  • PASSIVE – achieving ultra-low energy consumption
  • ENERGY POSITIVE (BEPOS) – a building or group of buildings that produce more energy than they consume globally – targeting 0 kWh consumption in primary energy.

In an ideal eco-city all buildings would be BEPOS. In reality, it’s not viable from a total cost point of view, so BEPOS “islands” are a way to go – the question being how best to achieve the BEPOS clusters in terms of: the mass plan, energy network opportunities, renewable energy potential, localised building material opportunities, innovative solutions; new or being successfully utilised in other eco-city developments – and costs.

Alzette Belval


For Alzette-Belval, with many different design options, concepts and interconnections impacting a positive result, every detail was considered with investigations covering all possible means for energy savings in individual homes and the urban context. Starting in February 2014, the studies, reports, consultation with developers, homeowners and manufacturers took almost 1½ years to complete, covering:

BENCHMARKING – A full review of what is being done in other eco-city developments.

RENEWABLE ENERGY POTENTIAL – Assessment of local renewable energy potential: Biomass (wood, agri- and waste); Geothermal; Wind (small urban turbines); Solar PV.

THE BLOCK PLAN Building placement and orientation impacts energy use, requiring modelling of:

  • Bioclimatic impacts
  • Building width and window placements – to benefit from natural ventilation and light, building widths cannot exceed 20 m or a “dead” space is created in the centre.
  • Energy network plan
  • Building schedule – Building construction will be in 3 phases over almost 20 years. As the energy network is a phase 1 development, it was critical to schedule which buildings are built first to make efficient use of the network from the start.

MATERIALS & GREY ENERGY – When targeting a zero-energy balance, the energy consumed in material creation (grey energy) is also taken into account. Building material options are rated for efficacy, innovation, sustainability, locality (dynamising employment in the area), cost – and grey energy. If fabricating a material for walling, roofing, flooring, plumbing etc., uses high energy or creates high levels of CO2, it’s not for BEPOS.

DECENTRALISED ELECTRICITY PRODUCTION Available technologies for decentralised electricity, heat and mixed production are also compared against the same criteria.

OTHER ENERGY SAVING OPTIONS – Solutions for water, for waste, for everything from cogeneration using vegetal oil to supermarkets that no longer stock packaged products (customers bring in containers and fill them in store) are evaluated.


The resulting studies and recommendations were submitted to the EPA, and the drafting of the technical requirements and specifications of the approved projects achieved to enable developers to take the various assignments forward. BEPOS building in Alzette Belval will be a reality. Between 2016 when the first building is achieved to +- 2030 when the full project is set to complete, technical developments may allow for even more BEPOS opportunities in the city. But with BEPOS already becoming a household name in Alzette-Belval, it’s been an extremely positive start.


Jean-Baptise Débonnaire

Jean-Baptiste Débonnaire

“The interest of this project is not only working on BEPOS building on a huge scale, which is ambitious and unusual, but we get to apply new ways of thinking about energy efficiency and sustainability because we are creating a whole system from scratch. Knowing that one day an exemplary eco-city will exist on those empty fields and we were at the start of it is inspiring and motivating.”

Jean-Baptiste Débonnaire, Project Manager Lot 1 Alzette-Belval – Tractebel Engineering


Alzette Belval Mobility


First eco-mobility steps for the Alzette-Belval territory required diagnosis of both the existing (infrastructure, governance, transport costs) and future mobility use considering people’s means and motive for daily movements, mornings, evenings, weekends etc. At the same time, all possible “innovative” mobility solutions associated with eco-city environments; from circulating automatic vehicles to an overhead cable car connection to Belval were assessed – innovation being important to the EPA in its vision of Alzette-Belval as a leading, pilot territory for new mobility technologies.


Findings showed a territory hugely reliant on private cars, with little organised local public transport and extreme North–South rush-hour supercharging of the road and rail systems to and from Luxembourg. Key questions were then; how to add even more future commuters to the Luxembourg route without overwhelming the system; how best to access the Belval rail connection and university; and how to enhance territorial circulation while reducing the need for private vehicles.


As heavy traffic flows are not a constant and most people remaining in the territory by day are dispersed over a large rural/peri-urban area, it became clear that “extraordinary” mobility ideas weren’t the answer. More pragmatic solutions responding to the actual territory needs and realities were needed. Using the eco-development of Micheville as a springboard, a responsible, integrated and organised multimodal mobility system developed:


  • Tying in with the eco-city smart grid and energy networks – a high-quality Rapid Bus Service using hybrid/electric vehicles – linking 3 main territory centres Villerupt, Micheville and Audun-le-Tiche to Luxembourg City via a dedicated highway bypass route.
  • Drawn down from the commuter service; better local bus services also using hybrid/electric vehicles.
  • Transport on demand, for pensioners or “stranded” people in outlying areas into the city.
  • In Micheville – a high-level Park & Ride centre, envisaged as a mobility hub, with frequent bus (local and commuter)  and bus to train (Belval) connections, bicycle hire or storage facilities for students (Belval University is just 3 km away), lockers, electric-car charging facilities, as well as practical amenities; banks, restaurants, laundrettes, shopping, postal services etc.
  • Dedicated bicycle highways crossing the territory and connecting to the Micheville Park & Ride centre; promoting this mode of transport as a credible alternative to most private car trips.
  • A supported Bike Services Centre for short and long term hiring, repairs, etc.
  • A system facilitating electric-shared-cars and long distance car hire.
  • A digitalised multi-modal mobility platform (app for smart phones, iPad etc.).
  • A mobility shop allowing physical interface between suppliers and transport users to inform about the different existing options and to help the user to choose the most adapted solution
  • A central “Neighbourhood Concierge” service centre assisting commuters leaving and returning to Micheville with parcel, dry-cleaning, etc. delivery and collection (notably through the high development of  e-commerce).


Yasmine Merad

Yasmine Merad

“That the EPA was willing to embrace the most innovative ideas possible was an unusual freedom, but we still had to answer the real needs – the best concepts being those that deliver eco-friendly mobility that is useful. The changes won’t be overnight, but when everything is in place, Alzette-Belval could be one of the best places to live – or at least move around in – in France!” 

Yasmine Merad – Studies Engineer – Mobility – Tractebel Engineering


With EPA approval of the proposals received in September 2014, further dimensioning, combining the technical and spatial solutions, planning and cost of investment, was achieved to define how the complete mobility system will work in detail: where bus stops will be placed, exact bus routes, the cycle highway routes, operation and governance of the different programmes, schedules etc. down to the number of electric-cars that need to be available for hire! With a long list of specifications to follow, all that remains now is for developers to put the entire system into action – making eco-mobility a reality for tomorrow’s Alzette-Belval.

Project drivers

2009 the French Ministry of Ecology, Sustainable Development, Transport and Housing launched a programme to encourage eco-city projects in France. 19 eco-city projects were chosen.

2012 a public institution Etablissement Public d’Aménagement Alzette-Belval (EPA-Alzette-Belval) was established to lead the French development of Alzette-Belval.

Future mobility

Shining a light on mobility for the future – Tractebel Engineering mobility experts recently investigated and imagined all the ways that Brussels could be moving by 2040; establishing benchmarks, data and a valuable global view for eco-city mobility worldwide.

More information

Jean-Baptiste Débonnaire, Project Manager Lot 1 Alzette-Belval – Tractebel Engineering

Sebastien Rodesch, Project Manager Lot 3 Alzette-Belval – Tractebel Engineering

Yasmine Merad Studies Engineer – Mobility – Tractebel Engineering