British gas calorific value

Calorific Value is the heat given out by the combustion of gas. The heat given off is determined by calorimeters that register a reading every eight minutes

Gas supplied to customers’ homes is passed through a testing station where the calorimeter measurements are recorded. There are two stations, located at Elton, near Middlesbrough and Halton in the East Midlands. Either station can be used to take the measurements although one station’s recordings may have a higher Calorific Value than the other. We have provided an undertaking to the Department of Trade and Industry that the lower calorific value will always be used when calculating gas bills

A British/Scottish Gas representative records the readings given by the calorimeters every Thursday. These readings are then used to determine the value we will use on bills to be produced the following week. This is done by calculating a rolling average, using each of the previous thirteen weeks’ lowest recorded values from the calorimeters

Gas passing through the gas pipeline system has a Calorific Value of between 37.5 and 43.0 megajoules per cubic metre, with the exception of Stornaway which receives liquid petroleum gas. The Department of Trade and Industry checks the accuracy of the calorimeters, evaluates and certifies the readings every two weeks. The registered readings are in megajoules and for billing purposes, the number of megajoules is converted into British Thermal Units (BTU’s) by dividing by 0.0373

It is the composition of the gas that changes the calorific value. Generally 90-93% is methane but it is the continual change in the higher hydrocarbons, which causes the value to fluctuate. These include ethane, propane and butane. The higher the content of these three components, the higher the calorific value.

savemoney wrote: »

But why has it changed, it certainly changed from my last bill when I wasnt on energy smart

I thought it was a constant figure

You say it has nothing to do with energy smart but you give no explanation as t why it has changed

Gas passing through the gas pipeline system has a Calorific Value of between 37.5 and 43.0 megajoules per cubic metre, with the exception of Stornaway which receives liquid petroleum gas. The Department of Trade and Industry checks the accuracy of the calorimeters, evaluates and certifies the readings every two weeks. The registered readings are in megajoules and for billing purposes, the number of megajoules is converted into British Thermal Units (BTU’s) by dividing by 0.0373

savemoney wrote: »

I never realised it did, I been trying to working out billing for my own peace of mind in excel and I found discrepancy hence why I found the calorific value had changed.