I need to clarify that $15k is not my FI number, it's an ideal goal I'd like to reach!

You clearly have factored this in already.

Then, I typically see them take about a half to a third of that number for the adjustment factor.

., the 2006 or 2009 IECC — International Energy Conservation Code).Cost Considerations for a 90-unit or 112-unit Project:The actual cost of qualifying for the 45L tax credit depends on various factors, including:Energy Efficiency Compliance: The primary cost will come from ensuring that each unit meets the required energy efficiency standards, which typically involve energy modeling, certification from third-party energy raters, and potentially upgrading insulation, HVAC systems, windows, and other components of the building to meet the necessary performance levels.Energy Modeling: Typically, you'll need to pay for an energy consultant or engineer to model the building's energy performance and ensure it qualifies for the credit.

Ideally I’d like to get to $10,000-$15,000.

When evaluating markets for rental properties, there are a lot of factors to consider: population growth, employment rates, rent to price ratio/GRM/Cap Rate, rent trends, vacancy rates, etc. 

Recently, a lot of the market factors that kept people away, are the same that are drawing attention.

I live in a rural market and this type of issue with technology may not be as big a factor in urban areas.

Do you have an ideal type of and location within TX/Dallas for a flip?

An audit could be triggered by a number of factors that don't line up when run through the IRS's system, and create an exception.