Requirements may include egress window, fire rated door etc.. 

In order for me not to be nauseous I have to have my window open with a fan pulling air out with the a/c always on .

In the living room they had a window AC unit, but it didn't drain properly and damaged a good 4'x8' section of the hardwood as well as the subfloor.

Instead of central air and heat, consider window AC units.  

(Note: I should have done a second lien on the property between Justin, Amber, and I for the $4,000 plus interest that I borrowed...but I didn't because we were what I thought at the time, friends) Now fast-forward to November 2019, the house has been completely rehabbed ( new roof, Windows, siding, flooring, doors, HVAC, Electrical, Plumbing ... basically the whole nine yards at a budget that no other contractor in their right mind would have ever remotely considered)  and my realtor performs a new CMA which brought to light a new comp that  brings up our ARV to a new listing price of $54,900!

Click that and a window pops up and gives you multiple sharing options, including Download PDF in the bottom left of the popup window.

Replacement windows in photos... awesome.

These require a properly sized escape window (minimum 5.7 square feet of openable window, 5.0 if your at grade) a smoke detector in the bedroom, a smoke detector outside of the bedroom within 15 feet of the bedroom door, possibly a carbon monoxide detector outside the bedroom (same rule as smoke detector that is outside the bedroom).  

market to someone to move in one of the units (like may be one of your tenants) FHA is 3% down FYIdont forget facebook market place. and never ever forget to put a signfigure out the PITI if some one pays your price, then tell them how much the rent is coming in (on the advertisement) don't forget to offer a seller carried second lien (if its a good price on the sale) 

Without one everything is covered in condensation, the windows, doors, outlet covers, etc..