It means that 70% of the energy used is wasted.Landlords don't install a thermostat. 

I also did LED lighting, and looked for efficient appliances, installed a nest thermostat and water sense fixtures, one of the bigger things I did to start was remove and update some of the lead piping in the home and install a whole house water filtration system since the supply lines from the city are still lead.

I also looked for ways to improve the tenants unit at the same time to make them less likely to complain -- for example, adding a video doorbell and a Nest thermostat.4.

We have an ecobee thermostat hooked up to it and love it. 

Tenants had thermostats in their office suites that they had set at 68 degrees. 

If you have thermostats where you can limit temp setting that will save you.Electric LED lights/bulbs. 

I framed in an additional shower, replaced 4000 square feet of flooring with LVP to hold up to rigors of STR, removed 50 gallon electric water heater and replaced with a 75 gallon LP unit, completely renovated both sets of stairs, added additional railings to bring up to code, new trim throughout the house, added automation with thermostats and locks, and also furnished it via secondhand stores with some new items. 

Operating electronics (Wifi password, thermostat settings, TV) 3. 

The only thing I didn't quite get about your post was the "upstairs unit controlling temperature of downstairs unit" part - are you saying that there's one thermostat in this building for 4 units? 

All units have their own thermostat.