There was an exterior laundry room that had been added to the house with an interior door to access, but there was no ventilation or air going in there.

If you want any more efficiency you'd be better off with hydronic or forced hot air which can get to 98%. 

I'm seeking a Real Estate Attorney as I have an AIR BNB in Chicago and the HOA is now stating that I can't do short term rentals.

Her ducks were not in a row and ours were air tight.

There was never heat or air in the house. 

The location, however, is somewhat up in the air, fluctuating between a 3-4 cities.

The idea came from letting people sleep on a couch or air mattress.

The heating cost is much lower than forced air or individual units.If you are upgrading, I would definitely look at switching to natural gas.

Thankfully it stopped there and didn't blow up my propane tank or blow into an open window in the units below me and light a unit on fire...anyway...I'm not a lawyer, but my advice to you is to make sure your lease is air tight and spells out the HOA rules.

I'm in a small market (60k people) with a large air force base that is getting a massive investment in the next decade that is expected to be huge for the local area.