You ask – we answer!

Customer question: the calorific value of natural gas is indicated on the natural gas invoice. What does it mean and why does it vary from month to month?

In response to the customer’s question, we have prepared an explanation of what the calorific value is and why it appears on the invoice.

The calorific value of natural gas is the energy released as heat by burning 1 m3 of natural gas.

Example. To heat 1 l of water, a certain amount of natural gas is needed. The higher the calorific value of natural gas, the less natural gas is needed to heat the water.

How is the calorific value determined?

Special devices – chromatographs – are installed throughout Latvia to measure the composition of gases, including the calorific value. The calorific value varies from one area of Latvia to another because natural gas in the Baltic region is supplied from different sources, and in Latvia, it comes geographically from Lithuania and Estonia; during the heating season it is taken from storage in the Inčukalns underground gas storage facility, and each gas regulation station (GRS) where a chromatograph is installed has a different gas composition, so each month the calorific value is different. The average calorific value of each zone is published on the GASO website, indicated in the customer’s invoice and in Latvijas Gāze under Meter reading in the measurement unit calculator.

Distribution system operator calorific value zones:

Source: Order of distribution system calorific value zones (

Why is the calorific value included in the invoice?

We include the calorific value in the invoice so that customers have access to information on the exact calorific value used to calculate the kilowatt-hour, as Cabinet Regulation No. 78 “Regulations Regarding the Trade and Use of Natural Gas” states that natural gas invoicing should be done in kilowatt-hours (kWh).  As natural gas is still metered in cubic metres, the calorific value at the object location must be multiplied by the consumption in cubic metres to calculate the kWh. 

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