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Why must the move be made from lean gas to rich gas?

Natural gas, as its name suggests, is made by nature. Its composition therefore depends on where it comes from in the world.


  • Rich gas (type H) is a natural gas which our country mainly imports from Norway, United Kingdom, Qatar, and Germany.
  • Lean gas (type L) is a natural gas purchased from the Netherlands.

The import of low calorific gas from the Netherlands however, will be suspended in the future (see text below). Until then, some parts of Flanders and Brussels still depend on the supply of L-gas, as indicated by the blue line in the map below.

Both these types of gas are basically made up of methane, but lean gas is diluted with 10% to 15% of nitrogen, a neutral, non-combustible gas.

The following are supplied with lean gas in Belgium:

  • 500,000 Brussels households
  • 1 million Flemish households
  • 100,000 Walloon households

Soon the end of lean gas

Our Dutch neighbours have decided to halt the extraction of gas from the Slochteren sub-soil. The deposit is running out and it seems that drilling is affecting the number of earth tremors in the Groningen region.

The Dutch gas tap is going to start closing in 2024 before being fully closed in 2030.

We are therefore going to have to move to rich gas throughout the country.  This is also called gas L to H conversion.

See Gas changes, the website of the Brussels-Capital Region for more information.
Or take a look at the federal government website (only available in French, Dutch or German).

What should you do for the move to rich gas?

The only thing you'll have to check is whether your devices running on gas, are compatible with rich gas.

  • Theoretically, boilers sold after 1978 should not have a problem. An adjustment or small adaptation may be necessary in a few cases.
  • On the other hand, the necessary adaptations will be difficult or impossible for all pre-1978 equipment and some equipment will have to be replaced.

Only an approved technician will be able to carry out these inspections and adaptations.

In Brussels, conversion to rich gas will be a three-year process, from 2020 to 2022 (see for more information)

How will this affect the bill?

In reality, rich gas has more energy per m3 and therefore less gas is needed to produce the same amount of heat as with lean gas.

Is our bill now going to be reduced? No, because it is based on the energy obtained, not on the volume delivered. This is why the gas price is expressed in kWh, the energy measurement unit, and not in m3.
Moving to rich gas from lean gas will therefore not affect the energy bill.

More info.: "What is the difference between rich gas and lean gas? Will it affect my bill?"

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