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Author Topic: Calorific Value of Gas in SAP  (Read 3347 times)

Malcolm Maclean

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Calorific Value of Gas in SAP
« on: September 16, 2013, 12:17:58 PM »
I'm trying to compare actual gas consumption data in m3 with modeled gas consumption in SAP 2005 and SAP 2009 given in kWh.
In order to do this accurately it seems that I need to know what assumption SAP makes in terms of the calorific value of gas. 
The equation transco give is
energy (kWh) = corrected volume of gas X calorific value / 3.6
I cannot find this in SAP 2005 rev 1 and NHER were unable to help.
Anyone know the answer?

Dave Howorth

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Re: Calorific Value of Gas in SAP
« Reply #1 on: September 16, 2013, 07:40:03 PM »
I'm trying to compare actual gas consumption data in m3 with modeled gas consumption in SAP 2005 and SAP 2009 given in kWh.
In order to do this accurately it seems that I need to know what assumption SAP makes in terms of the calorific value of gas. 
The equation transco give is
energy (kWh) = corrected volume of gas X calorific value / 3.6
I cannot find this in SAP 2005 rev 1 and NHER were unable to help.
Anyone know the answer?

Are you sure that SAP makes any assumption? It's an energy model, as I understand it, so modelling in kWh is reasonable and it doesn't need to know anything about the calorific value of gas.

The calorific value of the particular gas that you have used is printed on the bill that your gas supplier sends you. So you can work out how many kWh correspond to the m you have used. It may even be worked out for you on the bill, I don't remember.

Malcolm Maclean

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Re: Calorific Value of Gas in SAP
« Reply #2 on: September 17, 2013, 04:34:37 PM »
Hi Dave

Thanks for the reply, I'm not sure whether SAP does assume anything for calorific values. My thinking was that maybe SAP makes an assumption on calorific vale or else how is CO2 accurately calculated? Natural gas contains varying amounts of methane, ethane and CO2 according to National grid.

 I am still waiting to hear back from BRE to see if they know.

If SAP doesn't account for it I will have to use Transco figures for calorific values. I don't have any gas bills as its a project monitoring energy use of social housing tenants.