I am attempting to calculate the energy savings of a fan motor after a new runner and inlet cone was installed which claimed to improve fan efficiency. I have logged amp draw before and after the upgrade. The fan is in a large pulp and paper mill and is used for supplying combustion air to a Power Boiler. The site claims to have near unity power factor however I believe the fan motor is very old and probably has a much lower PF. My question is, do I need to take into account the site PF when calculating the energy consumption of the fan? or simply the PF of the fan itself?
Neither you, nor the fan, can tell what the power factor of the site is, just by looking at the electrical socket (or however the fan connects). The supply to the motor is an AC voltage, and the current drawn by the fan motor (and the phase relationship to voltage) is entirely dependent on the motor itself. You are correct that you can ignore the "site power factor".
Note that reading the fan current may not tell you what you expect. It might not change much, but the phase (and thus, the power factor) could, and that reflects the amount of actual work done by the motor.