I have 2-story house and 2 AC units (4-ton for 1st floor and 2 ton for 2nd floor... each AC unit independent of each other ).
2 Bedrooms, Game room, 1 bathroom, and large storage closet (AC'd) Upstairs. 2nd-Floor Game room is open to the stairs and entry-way on the 1st floor. Most of the 1st-floor open floor plan.
We are in south-central Texas. Outside temps June-Sept are routinely 96-103 every day.
As an energy savings approach, my wife tells my son to shut-off the 2nd-floor AC when he comes down. Of course the 2nd-floor temp rises over time and of course the warm air from the 1st-floor rises up to there too. Then, my son goes back upstairs to play video games and the temp is 86+. So he turns on the AC and it is set to 80-81.
Now my wife says the 2nd-floor AC is running non-stop and never automatically shuts off.
In addition, on the 1st-floor, my wife wants to set the temp to 84 or 85 (to keep the electric bill down). I have a home-office. Eventually, that becomes too hot (uncomfortable) for me, so I set down to 80-81. Then my wife sets the Temp back up to 85, then I set it down to 80.
I know this scenario sounds silly. I applaud my wife's interest in energy-saving and therefore cost savings. But, I need some additional information from all of you HVAC-Talk forum experts to help support my argument that maintaining a consistent balanced temp is more energy efficient and cost-effective than the repeated running the temp up and down or AC unit off and on approach.
In the long-run is all this yo-yoing of the temp on the AC units actually causing the AC units to actually work hard and longer (using more electricity) to re-cool the house than if the 1st-floor and 2nd-floor temps were set to maintain some type of balanced temperature ?
If so, How can I achieve an optimized balance between the two floors, given that most of 1st Floor, Stairs, and 2nd-Floor Game Room are open to each other?