A "reading" isn't an energy audit. It could be reading emissions, for instance. A whole house audit is comprehensive. If they didn't pay for an audit, there is no credit for an audit. They likely had an inspection.

Here is HVAC credit info:

https://www.irs.gov/credits-deductions/energy-efficient-home-improvement-credit

Consortium for Energy Efficiency is not the same as Energy Star. The utility provider might rebate against Energy Star. The IRS uses CEE.