Gas furnaces are far more efficient than 30%, I think mine is 95%? Irrelevant anyway, as the link I provided said this about it:
Quote:
Global primary energy consumption by source
Primary energy is calculated based on the 'substitution method' which takes account of the inefficiencies in fossil fuelproduction by converting non-fossil energy into the energy inputs required if they had the same conversion losses as fossilfuels.
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