Sorry, for some reason the additional context field didn't post originally.
For personal taxes under home energy credits there is a section for qualifying products including insulation, but I cannot seem to find where "insulation" is defined. From an engineering perspective, I'd assume this translates to anything that mitigates unwanted heat transfer into/out of a home. Which is why I'd think HVAC ductwork + supply/return ducts would count.
Thanks!
