How does Loop convert from m3 of gas to kWh?

Gas meters measure volume of gas used, but you're billed for the energy. How does Loop convert from one to the other?

Gas meters measure the volume of gas that your home uses. This volume is measured in metres cubed. However, you are not billed for the volume of gas you use, but rather the energy in the gas you use. This requires a conversion from the volume of gas in metres cubed, to the energy of the gas in kWh. 

The energy density of gas varies from location-to-location and changes over time depending on the source of the gas. The calorific value is the parameter that determines this.

Loop uses a calorific value of 39.5 MJ/m3. This has been calculated by taking the average of the daily Calorific Values in each of the 13 regions on the national gas grid over the first 3 months of 2022. We update this value periodically but it is unlikely to exactly match the value used by your utility for your meter which you can find on your latest bill. For this reason there are often small discrepancies between your bill and Loop’s gas measurements. Typically these differences are less than 2%.

There are more details on how the calorific values are calculated here.