E2REBUILD Site Voiron

Country & City: 
  • France
  • Voiron
Contact Information: 

The French demonstration site is a multi-storey building in Voiron in the Isère Department. The building was made of concrete with no insulation. The windows were first generation PVC double-glazing 4-6-4. The building had natural ventilation. All dwellings had an individual gas boilers for the domestic hot water production, but each dwelling had its own different heat production - either electric heaters (ca. 29 dwellings with an energy demand of 529 kWh/m² year) or fossil fuel boilers (c. 43 dwellings with an energy demand of 202 kWh/m² year). The building’s average consumption was 330 kWh/m²/year.

The retrofitting program reduced the energy consumption down to 60 kWh/m²/year and created a structured heat and domestic hot water production through a collective heating system (gas boiler) and solar panels for hot water. Mechanical ventilation was installed and the roof, floor and walls were insulated. Furthermore, balconies were closed using prefabricated elements.

Financial & Economic: 



Problem description

Monitoring failures caused lack of monitoring values for the first 12 months.

Data filling gap process based on indirect means.


Difficulties were encountered when implementing prefabrication: unfavourable regulations, as well as problems discovered on site (e.g. need for reinforcement of the balconies) 

A better preparation during the design phase was necessary, possibly using BIM modelling as in some other demonstration projects. In Voiron, the use of prefabrication was too limited and the site didin’t fully benefit from its added-values.