Redfin shows that properties in this area are at risk of at least Heat and Wind advisories, some also seem to be highly susceptible to flooding.

The garage was built to work on trucks having 14' ceilings and 2 bay doors heating cooling about 700 sqft.

Windows would be my next check-point (less than R1) and then wall insulation: I would not be surprised if they have no insulation inside, but you can do blow-in, which only requires a small hole.A home looses heat in two ways: heat conduction (which you can slow down with insulation) and drafts, which in old houses is usually the biggest culprit.

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.

“I can’t believe you disconnected the heat.

Upgrades include a fully remodeled kitchen, renovated bathrooms, new durable flooring, contemporary fixtures, and efficient heating and cooling systems.

For example,  providing a heating source for your tenant is your responsibility as the landlord. 

Installing thermostats with regulated heat control (we pay heat) 3.

We ended up replacing the AC unit as well as the heating/gas furnace for 15k in total with TMS.

We heat and keep the doors closed and don't have issues normally.