Occupancy Inspection - heating

[Doug Spartz]

I just received the results from the occupancy inspection of my triplex in Houston.  The most significant issue noted is a requirement that "...heating facilities capable of maintaining a room temperature of 70 degrees..." be provided.  The triplex was built in 1963 without air conditioning or heating.  Since then window units have been supplied by the tenenats.  Each unit has  2 bedrooms and is 700 SF in size.  Standalone heaters are not an option.  I'm looking for advice on how others have met this requirement in Houston.  I see only two real options: upgrade to central air and heat or provide multiple heating/cooling windows units per apartment.  Both are expensive and the latter is a theft/maintenance headache.  Any other suggestions?