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

Your standard electric water heater has basically 2 parts...thermostats and elements.

Technology gadgets like Alexa integrated appliances, Doorbells and thermostat? 

Also these new pumps have ecm motors, plus most have built in timers and thermostats to make operation easy and cost effective.

Here are the expenses on this one:  apartment Vendor Project description Date Amounts Notes house sears 3 stoves/2 refridgerators 5/25/2017 $ 2,111.18 1 right Doug bathroom floor 4/11/2017 $ 500.00 replace floors 2 left David bathroom floors/repair 4/23/2017 $ 400.00 2r/2w Doug bathrooms 4/14/2017 $ 755.00 replace floors 1 right mikes carpet carpet two bedrooms 3/3/2017 $ 532.00 2r/2l amber clean up 5/5/2017 $ 80.00 1r/2r sears cook stoves 4/23/2017 $ 837.41 All Joey dry wall aropund windows 3/27/2017 $ 1,950.00 2 right jesse drywall bedroom wall 4/15/2017 $ 150.00 house Brian Elec elec work 3/24/2017 $ 4,503.00 house Kevin electrian 4/30/2017 $ 100.00 wires 2r/2l Danny floors 5/5/2017 $ 1,000.00 replace with floating floors house libert ut gas bill 6/6/2017 $ 216.44 house David hook up gas stoves 6/1/2017 $ 60.00 house honor captal insurance 2/29/17 $ 209.00 house honor captal insurance 3/19/2017 $ 209.00 house honor captal insurance 4/17/2017 $ 209.00 house honor captal insurance 5/17/2017 $ 209.00 1 right Doug kitchen drywall 4/18/2017 $ 200.00 house Doug labor 6/5/2017 $ 2,200.00 finsh all reoairs and hang doors house jesse locks and light 4/30/2017 $ 150.00 houise walmart mailboxes 5/10/2017 $ 48.88 3 mailboxes remodler outlet materials 2/14/2017 $ 722.50 1 west remodler outlet materials 2/27/2017 $ 134.64 1 west remodler outlet materials 3/27/2017 $ 1,006.91 2 right home depot materials 4/23/2017 $ 280.29 for floor 2r/2l home depot materials 5/5/2017 $ 1,226.08 floors and supplies house home depot materials 5/9/2017 $ 75.52 plug covers/thermostats/mailbox materials 5/23/2017 $ 148.93 for 3rd floor door house home depot materials 5/26/2017 $ 878.22 doors baseboars house home depot materials 5/29/2017 $ 250.37 1 left home depot materials 6/1/2017 $ 247.36 toilt/miscellaneous 1 left jesse miscellaneous 6/19/2017 $ 160.00 house James paint 4/30/2017 $ 1,050.00 house Branco gardner payment $ 1,353.30 house Moniz plumbing 3/27/2017 $ 2,035.07 house mike plumbing 4/11/2017 $ 625.00 hallway put up 3rd floor door 5/23/2017 $ 350.00 to block off attic 1 east Poters repair and prep for paint 3/10/2017 $ 900.00 house Joey roof/siding $ 22,222.00 house smoke isp $ 264.85 1 right Doug tubs/toilt 5/1/2017 $ 135.00 house Joey windows 1/25/2017 $ 4,651.02 house home depot 2/14/2017 $ 1,458.63 lowels 2/14/2017 $ 1,500.85 house u hal 5/26/2017 $ 48.72 to pick up all supplies 1 east home depot materials 6/2/2017 $ 56.78 house ABC dumpster 6/5/2017 $ 587.34 1 east danny floors/ matrial 6/7/2017 $ 1,117.24 railings, 3 floors basement derick clean up all waste 6/7/2017 $ 200.00 1 left jesse last small repairs 6/20/2017 $ 160.00 house ABC dumpster extra feesa 6/16/2017 $ 119.00 1 left amber clean up 4/21/2017 $ 100.00 2 left kevin elec work 5/21/2017 $ 150.00 house home depot light covers/fau 6/3/2017 $ 41.95 1 east national grid elec bill 6/28/2017 $ 68.85 1 west national grid elec 6/28/2017 $ 118.87 house liberty utilies gas bill 5/16/2017 $ 216.44 house national grid elec 4/26/2017 $ 4.54 house city of Faa River taxes 6/29/2017 $ 654.10 house honor captal insurance 6/17/2017 $ 209.00 $ 62,159.28 

I left the house closed up, with the thermostat set on 80 degrees to save electricity.

One thing we just discovered that cut down our expenses big time was installing NEST thermostats in both units since often times people forget to turn them back up when they leave and we can control and program them remotely. 

It taught me a few troubleshooting tips (I already knew how to clean coils and make sure drain lines were clean).Because of this I saved myself several service calls that would have involved a high priced tech replacing; thermostats, exhaust fans and relays.

If this is a boiler system, you can install control valves and thermostats for each unit so they control their own heat.

The heating system is not zoned, but there is evidence (one for each unit) that it was once zoned in each of the 4 units as there are 4 separate pipes and old thermostats in the units that are inaccessible.