The IEA says[1]:

> For all energy sources, the IEA clearly defines energy production at the point where the energy source becomes a “marketable product” (and not before).

Doesn't that mean if you are burning coal to make electricity, you wouldn't count the heat output because the generated heat is not a marketable product.

[1] https://www.iea.org/commentaries/understanding-and-using-the...