By its definition, if something shows excess heat, it is in excess of what can be generated by chemical means.
Good point. Yes, that is the definition in a cold fusion paper. In the context of this field, it means "heat beyond the limits of chemistry" or "heat produced in the absence of chemical fuel, without any chemical changes."
Some cold fusion experiments produce some heat from chemical reactions. Or they produce endothermic reactions. See Fig. 7 here, for example:
http://lenr-canr.org/acrobat/StormsEdescriptioa.pdf
The authors are supposed to point out when this happens, provide graphs of it, and show the maximum amount of heat these reactions can produce (or the maximum endothermic deficit). If an author ignores this, that's a sloppy paper. It is important to show this for several reasons. One reason is that this demonstrates the sensitivity and accuracy of the calorimetry. The heat from chemical reactions is well understood. When you show the calorimeter has detected the expected amount, that is a way of testing and calibrating the instrument.