resnet.org is another source for an energy rater. we aren't called auditors.
blower door using subtraction method can measure duct leakage.
blower door measures house leakage also. different steps..same equipment.
resnet raters use duct blaster or pressure pans to test
ductwork you would have to request if you chose to test differently.
usually houses are depressurized to get leakage amount.
if you pressurize you can feel the air leaking out of ductwork
so you know exactly where to seal.
sealing house leakage means less of the great outdoors to heat and cool
sealing ducts means all of air you pay to condition comes into the space
where you live. return should also be tested.
sealing both leakage areas (house & duct) can change how many
tons of hvac is required.
manual J would have to reflect reduced infiltration numbers.
best of luck.
The cure of the part should not be attempted without the cure of the whole. ~Plato