High rise net zero retrofit – the Netherlands

After a successful start bringing the Dutch Energiesprong approach for affordable, desirable, long-term performance guaranteed net zero energy (NZE) retrofits to Europe for single family homes (E=0), the coming three years we will see Energiesprong develop a market for apartment buildings in North West Europe under project: Mustbe0, funded by Interreg NWE. The UK, France, Germany and the Netherlands will join forces to create a viable path to scale.

Utrecht – “Flat with a future”

An ambitious project:

The complete renovation of an outdated Intervam flat on the Camera Obscuradreef in Utrecht, the Netherlands.
After a successful pilot with 8 homes that were made net zero in 10 weeks, construction company VIOS refurbished a total of 252 apartments and 15 new homes in the same neighbourhood to net zero energy homes. This was just the starting point for the Housing Organisation Mitros.


In addition, all homes also included a new kitchen, bathroom and toilet. New stucco, interior paintwork, interior doors, H&S work, switchgear, and new interior installations throughout. Asbestos must be remediated and we completed 15 new homes.

The successful project has received a lot of media attention and, at the end of 2019, it received an award at the prestigious Green Solutions Awards in the Sustainable Renovation category.

Technical specifications:

  • Performance guarantee: 10 years
  • Energy use before the renovation: 225 kWh/m2 per year
  • Energy use after the renovation: 50 kWh/m2 per year
  • Divided over energy use:
  • Heating: 10,9 kWh/m2 (including ventilation)
  • Warm Water: 14,2 kWh/m2
  • Cooling: 0 kWh/m2
  • Household consumption: 24,8 kWh/m2
  • Energy savings: 175 kWh/m2 per year
  • Production of energy through solar panels to achieve net zero energy: around 50 kWh/m2 per year

Most important elements:

  • Ventilation by means of balanced ventilation with a Heat Recovery Unit
  • CO2 controlled (system D)
  • Air-water heat pump
  • PV (solar panel) Insulation
  • Entire shell thermally insulated:
    roof: Rc= 6
    closed façade: Rc = 4,5
    open façade, triple glas: U-value = 0,5
    ground floor: Rc = 4,5
    cold bridges removed by local insulation and thermal breaks


Click here for the complete photoalbum

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