(e.g. nest thermostats, spray foam insulation, or one of Tesla's solar roof systems )  but adding some very basic products that this property was lacking. ( I think a lot of mom & pop C & D properties are in the same There was zero insulation in the attic ( Added R-38)Old Single Strength Wood Windows ( Replaced with low-e replacement windows)HVAC 12 Year Old 10 SEER ( Replaced w/ new 14 SEER HVAC)12- 14 year old appliances ( Adding Energy Efficient Appliances )Definitely the basics, but just making those improvements has definitely directly or indirectly (depends on how you look at it) impacted the NOI and the overall tenant experience.

I show then the digital thermostat they can program.

"Secrets of the Millionaire Mind" - will help you "reset" your financial thermostat."

Also, does the thermostat connect to these or is there something else that controls it?

We also throw in a video doorbell and smart thermostat.

Fix: New $35 thermostat from the hardware store.Everything was running, but the condenser fins on the outside unit were full of dirt, pollen, cottonwood seeds, etc, so the system was blowing warm air. 

Most of my knucklehead contractors always forget to turn it down at night so I am going to program the thermostat on each house.

It is possible to retrofit an apartment with a smart lock, video doorbell, smart thermostat, voice and app controlled lights, smart interconnected smoke alarms etc.,  How much rent premium will your tenants pay?

The new unit had to have "thermostatic control" of their heat (meaning that they could not be at the mercy of whoever lived on the other side.)

I am considering landlord thermostats, but I know there will be complaints.