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November 15, 2023

Blog by

Catrin Bates

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Creating a market for net zero multi-storey buildings

The MustBe0 team in Cologne. The top image is the completed primary school in Raismes, France.

The Mustbe0 project funded by Interreg North-West Europe and managed by Energiesprong UK started in 2019, bringing together market development teams from four countries to kick-start a market for net zero multi-storey buildings.


The ambitious project has been one of the biggest in Interreg’s portfolio, with 11 demonstrator retrofit projects in the UK, Germany, France, and the Netherlands aiming to create affordable, comfortable, long-term performance guaranteed zero carbon buildings. The projects are:


As the project draws to a close, here’s a summary of all it has achieved as well as the challenges it’s faced, and the valuable lessons learned along the way.  


  • France, Germany, and the UK carried out design competitions at the start of the project which have supported SMEs to develop and test their solutions for deep retrofits.  
  • The transnational nature of the project has created an open space to collaborate and share innovations across countries and companies. For example, Belgium-based SME Build Up won the design competition in France and their offsite manufactured panels have been installed on an apartment block owned by social housing landlord Vilogia.  
  • The first school in France to undergo an Energiesprong retrofit has been part of the project. The 1960s building has had all classrooms renovated, an elevator installed, fully renovated sanitary facilities and a new enlarged dining room created. As well as the improved internal comfort and carbon savings, attention has been paid to the acoustic comfort of the building and children have been involved in the decision-making process, selecting classroom colours and adding more green space in the yard. The project has overcome significant challenges with unexpected structural concrete issues (echoing current challenges facing some UK schools) and discovering asbestos, causing extra costs and delays.  
  • In Germany, scaffold-free assembly was successfully tested on two pilot projects, saving costs and causing less disruption for residents.  
  • Resident satisfaction surveys issued in the Netherlands by housing provider Woonmeij reported lower energy bills and decreased use of medication by some tenants because of their more comfortable home with constant temperatures and less damp and draughts.  
WGAV project in Germany, before and after the retrofit

Long-term benefits and lessons learned

  • The Vilogia project in France developed an industrially produced technical shaft to house the heat pumps and ventilation units, creating a highly replicable solution.  
  • Vilogia has also gained experience in implementing industrialisation of the building envelope in terms of technology, solutions, processes, contracting, services, and relations with residents. Based on this, Vilogia is now developing a scale-up strategy of industrialisation of the renovation with 4,000 dwellings due to be retrofitted in the coming years.
  • The German Market Development Team introduced and tested the Construction Team Agreement as a supportive tool for project matchmaking between the client and construction company, saving time and money in the design and planning phase.  
  • In the UK, the Treadgold House project in the Royal Borough of Kensington and Chelsea (RBKC) has used a new tender process for the procurement of contractors. The two-stage tender approach will now be used by RBKC for future projects on the estate.  
Woonmeij completed project in the Netherlands

Despite facing many challenges – the Covid pandemic, Brexit, and the war in Ukraine – which have had an impact on material and transportation costs and caused delays, the project has created warm and desirable places to live (or go to school in!) that are future proofed and will leave a legacy for more deep retrofits in the future.  

Moreover, it is estimated that the total energy savings from the project will be 1,320 tonnes of CO2 per year.  

Thank you to all partners involved in the Mustbe0 project, everyone is incredibly proud of what has been achieved. And thank you to Interreg NWE for initiating and funding the project and for all your support.  

> Find out more about Mustbe0

Take a look at a timelapse video of the apartment block in Herford, Germany being retrofitted: