I read we could add TRVs (Thermostatic Radiator Values) to each radiator so the tenants can control the temperature and we could track how much hot water is flowing through the radiator.

If you have smart speakers, TVs, thermostat, etc. that you want guests to be able to access, it probably won't work because of compatibility issues.

This is an example of why people in the field aren’t worried about it: https://finance.yahoo.com/news...Billionaire tech investor calls programmers 'the most scarce commodity on the planet' It is hard to mention to some grandpas here in BP is that EE/CS/SW graduates already secured six-digit salaries even before they allowed to buy alcohol. 

Your hvac contractor should be able to setup a controls package to allow the two systems to interact with one another.Be advised many heat pump thermostats are more expensive then usual thermostats because they’re specially designed for that piece of equipment and you cannot use something like a nest or an ecobee.

For me, the key would be to use property management software that allows you to do your property management and accounting, and store documents all in the same place (rather than using 3 different programmes for each unique purpose).

To me, this is not an option because the room is just a few degrees warmer than the thermostat. 

I think most tenants that come from a shared wall apartment building keep their thermostat in 60's.

Last week the A/C in our unit fried from a power surge and required a new thermostat and tablet piece.

It connects to the Emerson Sensi thermostat as well.Z Wave radios use far less energy than WiFi which mean battery life is much better.

Also, if you have some kind of green energy saving thermostat that micro manages the temperature throughout the day, that might be an issue.An old school Honeywell with no adjustments might be worth a try.Even a low IQ renter should be able to handle these.