What does Heat Consumption Index mean?

The heat Consumption Index, “Indice de Consommation de Chaleur” (IDC) in French, is a building’s energy indicator for covering its heating needs.

It represents the annual quantity of final energy consumed for heat production, divided by 1 m2 of heated surface area and corrected according to climatic data.

This index is the measure used by the OCEN (Office Cantonal de l’Energie) to determine whether a building requires renovation work.

How is the index calculated?

L’Etat de Genève provides a calculation tool that can be downloaded online. Owners can either send the ad hoc form directly to the relevant department, the OCEN, or commission an approved dealer to collect and collate the data required for the calculation. We can of course provide you with a list of approved dealers, which can also be found on the link above.

Objectives set by the authorities

Today, the cantonal government has set targets for the next ten years:
2022: maximum “acceptable” IDC set at 800 MJ/m2/year
2027: maximum “acceptable” IDC set at between 650 and 800 MJ/m2/year
2031: maximum “acceptable” CDI set at between 550 and 650 MJ/m2/year

All buildings exceeding the permitted or “acceptable” index must be renovated as soon as possible.

To meet these targets, there are three main options for action:

  1. Improve the thermal envelope of buildings,
  2. Give priority to renewable energies for heat production,
  3. Give priority to electricity consumption for all technical installations.

For both buyers and sellers, a new situation has arisen, requiring even more support from professionals to better understand this new issue.


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