The Grand Duchy of Luxembourg, at the heart of Europe, continues to gain about 2% in population every year. The South of the country, the former industrial area, is growing especially rapidly, by a quarter since 2010 and in 2021 it hosted a third of all residents. Demand for housing has increased and is one of the most rapidly increasing expenses for Luxembourg households today.

In the already urbanised South, many large-scale development projects for new districts on industrial brownfields are being realised or are in the pipeline. This impacts the urban morphology of the area. Formerly geographically separated urban districts are now connected. But how can new districts interconnect urban fabrics, let alone urban functions? Differdange, the third largest city in Luxembourg, is home to such a brownfield project, ‘Plateau du Funiculaire’.

Rationale for action

The rapid development of the steel industry in Luxembourg during the 19^th and 20^th centuries created a unique urban tissue in the South. Housing was built around steel mills, as in other industrial areas. This resulted in large industrial zones being next to urban centres. In some cases, as in Differdange, these industrial zones are ‘wedges’, impermeable barriers that separate districts functionally.

Steel production in Luxembourg has declined over several crises and steel mills have reduced or entirely stopped production. Around 2000, some 25 hectares became available in the centre of Differdange. The ‘Plateau du Funiculaire’ was formerly a landfill for the adjacent steel mill.

Objective

The Plateau du Funiculaire functionally split several Differdange districts, so plans were drawn up to transform the brownfield site into a new urban district. From 2004, the city has developed urban concepts in cooperation with many local and national players. A new district, providing housing, offices and commercial areas is planned to connect the existing districts of Differdange, Oberkorn and Fousbann.

Some challenges had to be addressed in developing the urban concepts, including pollution of the area due to its use as landfill for the blast furnace. In addition, the river Chiers running through the area was planned to be renaturalised, to provide water retention and flood areas.

Time frame

The first scoping studies were realised as early as 2004. Since then, planning and construction has been ongoing with most of the district being finalised in 2020. Final construction during 2022 will complete the project on the former landfill.

Key players

The key player for developing the new area was the city of Differdange. The urban concept was developed with a Luxembourg planning office as well as an investor.

Implementation steps and processes

Following the first plans to develop the district in 2000, initial research in 2004 assessed the landfill pollution. At the same time, the city of Differdange also outlined strategic objectives for the district. In 2005, a planning office proposed the look and feel of the new district as an urban concept. Development started in 2006 when the historic ‘Villa Hadir’, a former reception and administrative building for the blast furnace was refurbished. Plans to implement the urban concept were submitted for building permits.

A brand was created in 2007 to establish an urban identity to market the new district to future inhabitants, businesses and commerce. Work on the infrastructure started in 2009 and the first bricks for the residential buildings were laid in 2011. In the same year, the recreational park was finalised, allowing neighbourhood residents to get to know the new urban district. Around 2019, a late change to the project integrated a multi-functional tower, called ‘Gravity’, increasing the number of planned housing units from 650 to 728.

Required resources

The resources used are not known.

Results

After a bit more than a decade of construction, the new district will be finalised in 2022. Within 10 years, 728 housing units have been created, providing accommodation for more than 1,600 people. The district also features 15 km² of office and retail area. A school, a section of Luxembourg university, public administrative offices and shops complement the housing so the district is a fully developed urban quarter of Differdange.

A new train station links the area to the national railway network. In addition bus connections as well as bike and pedestrian infrastructure connect the district both internally and to the surrounding areas.

To minimise soil sealing, ‘Plateau du Funiculaire’ is high density. Nevertheless, some polluted parts of the former landfill were sealed with an artificial layer of clay so surface rainwater can drain into the nearby river. Rainwater that penetrates polluted soil layers is collected separately for treatment.

Experiences, success factors, risks

The relatively short construction period of ‘Plateau du Funiculaire’ highlights good preparation. Potential obstacles were identified, and solutions developed to avoid these.

The urban concepts and building permits provided planning security. The late modification to include a multi-functional tower in the district shows the project adapted to changing demands. Such flexibility is important as needs and requirements usually change for decade-long large-scale urban development projects.

Conclusions

‘Plateau du Funiculaire’ is a prime example of a successful large-scale brownfield development project. Such projects can close functional gaps between urban districts, offering new housing and commerce. In addition, interests from multiple public and private stakeholders can be addressed in one go. It also shows innovative approaches to issues like polluted soils that are frequently encountered in brownfield developments.

‘Plateau du Funiculaire’ also underlines that brownfield development offers much more freedom compared to developments in existing urban areas. Measures can be discussed before being realised in detail, helping to avoid conflicts.

In addition, brownfield development projects such as ‘Plateau du Funiculaire’ are testbeds for new approaches and technologies. The size of the district meant that planners faced challenges that could not be solved with existing planning approaches. An example is heating for the residential units where a centralised district heating system was planned as early as 2007 to reduce infrastructure costs and save energy.

Today the district offers a new face for Differdange and combines different urban functions in an optimal way. With multiple housing and commercial possibilities, ‘Plateau du Funiculaire’ will eventually become the new centre for the town.

Contacts

Urban technical service of Differdange: pag@differdange.lu

References

Dewey Muller, 2018: Plateau du Funiculaire project presentation (German): https://www.deweymuller.com/projekte/plateau-du-funiculaire/

Aurea Differdange, 2020: Project developer website (in French): https://www.aurea-differdange.lu/fr/localisation

Many brownfield development projects are under way in the Grand Duchy of Luxembourg. ‘Porte de Hollerich’ in Luxembourg City, ‘Belval’ in Esch-sur-Alzette, ‘Wunne mat der Wooltz’ in Wiltz and ‘NeiSchmelz’ in Dudelange are a few examples. All these are creating new urban districts with living space for many additional inhabitants and businesses. The ‘NeiSchmelz’ project in Dudelange will provide an additional 1,000 housing units on a 40 hectare brownfield site.

Large-scale brownfield development projects present many challenges for their cities, especially energy. In addition, existing infrastructure struggles to satisfy the increased demand. For ‘NeiSchmelz’, an innovative energy concept was developed, to use photovoltaics and deep geothermal energy.

Rationale for action

Because of its size, the ‘NeiSchmelz’ brownfield development poses significant challenges for the existing energy network. This would need to be extended if not complemented with new production facilities. As infrastructure investment significantly increases the cost of such projects, an alternative solution was needed.

‘NeiSchmelz’ was therefore planned as an eco-district. Renewable and carbon-neutral energy will be produced on site, i.e. not relying on fossil resources to supply electricity or heat. There are no centralised renewable energy production facilities in the area, so future energy in the district must be produced on site.

Planners had to develop an energy concept that relies on different energy sources. These will be photovoltaic installations (roofs and open ground) as well as the first deep geothermal drilling in Luxembourg. However, being the first in Luxembourg to drill 2,000 meter down, experience is scarce and the viability and potential had to be determined first.

Objective

Deep geothermal drillings are costly and innovative measures require intensive scoping-studies and test drilling to investigate whether this energy source is financially viable.

The potential for geothermal energy around ‘NeiSchmelz’ is significant. This has led to further investigation to assess drilling for heating in the district.

A first study on geothermal potential in Luxembourg was a doctoral thesis at the German Research Centre for Geosciences and the Luxembourg Geological Service between 2010 and 2015. A more concrete feasibility study included several drillings to test technical details and feasibility.  

https://www.youtube.com/watch?v=vwnVbT8rE2k

Time frame

The first energy concept for the district was developed in 2014. In 2015 important geothermal energy potential in ‘NeiSchmelz’ was identified. A new energy concept was developed in 2017 building on geothermal energy as a primary source for heat. A feasibility study between 2017 and 2019 determined the potential in greater detail.

Key players

The driving force behind the district and the energy concept is the City of Dudelange. It approves the energy concept and the land-use plan as well as following up on implementation of the measures. The district is being developed in cooperation with the Luxembourg Ministry of Housing and the national fund for affordable housing ‘Fonds du Logement’. The Luxembourg Ministry of Environment and its energy department is also a key player for developing and realising the districts’ energy concept. The City of Dudelange can thus rely on the support of national institutions in developing and implementing the plans.

Implementation steps and processes

With little experience of deep geothermal drillings among the involved institutions, preliminary investigations were required. A feasibility study measured the geothermal energy potential including test drillings of 300 to 400 meters between 2017 and 2019 in the area of the future district. The feasibility study determined that deep geothermal energy could supply the entire district with heat. At 2,000 meters temperatures of 70° to 80° Celsius yield enough heat to supply the district with hot water.

Required resources

The preparatory analysis including the feasibility study and test drillings cost about half a million Euros. This was co-funded by 40 % from the Luxembourg European Regional Development Fund (ERDF) programme. The total resources planned for deep geothermal drilling is unknown.

Results

‘NeiSchmelz’ will be equipped with a district heat system powered by a centralised geothermal energy plant. In conjunction with photovoltaic installations and near-surface geothermal energy, ‘NeiSchmelz’ will be an energy self-sufficient development.

Experiences, success factors, risks

Geothermal energy is new to Luxembourg and knowledge of potential, techniques, feasibility and economic viability are still scarce. In developing the concept and the feasibility study, cooperation between specialised players is key to ensuring that knowledge is institutionalised. This will help when implementing similar projects in future.

Conclusions

Geothermal energy means the heat for all ‘NeiSchmelz’ will be from a renewable energy source. In conjunction with extensive photovoltaic installations, the district will have energy self-sufficiency and be a zero-carbon emissions district. As such, it is the first in Luxembourg, offering important experience for future large-scale brownfield developments in the country.

Contact

Mr Patrick Hoss, Director of the ecological department of the City of Dudelange: patrick.hoss@dudelange.lu

References

Tageblatt, 2018: Newspaper article on the planned use of geothermal energy in Dudelange (in German): https://www.tageblatt.lu/headlines/das-heisse-potenzial-von-duedelingen/

City of Dudelange, 2019: Chronology of the development of the brownfield development ‘NeiSchmelz’ (in French): https://www.dudelange.lu/fr/projets-urbains/projet-neischmelz