HVAC question
 

Not sure this can be answered but would it take more energy to get House from 60 degrees to 70 or 90 to 75? My electricity bill has more than doubled, almost tripled. I’m trying to figure out if it’s the tenant just usimg more electricity running other things or the HVAC is likely the culprit. Any help appreciated.
The place is in SC and is my first year of ownership so I don’t really know the trend or the impact of weather on my bill.

Also, I’m getting a new HVAC system soon since getting on the old side. Hopefully tech has gotten more efficient. I’ll call electricity co today.

Unusually cold winter?
Consumption tripled or just the price that you're paying tripled?

Here it isn't the cost of nat gas, it is the service and delivery fees that hurt. Plus the old carbon tax that puts the squeeze on homeowners and small businesses.

The "aux heat" (auxiliary heating) coils cost you big when they kick in.

Yep . If you have an aging low SEER heat pump with electric strip auxillary heat your electric meter will spin like a router . If you have access to natural gas or propane you would be better off with a dual fuel heat pump system .

Put solar on the roof. Charge the Tennant for their electric. Take the tax write off

How do you even correlate a 10º rise to a 15º drop in temperature especially when they are in different ranges?

That drop in temperature isn't just reducing the sensible temperature 15 F degrees. Reducing the temperature of the air will require a latent heat change when removing moisture from the air.
Condensing moisture from the air on the coil is a huge load on an A/C system.

Put a smart stat in so you can monitor what the tenant is setting heat and a/c setpoints at.
With many programmable stats, you can install setpoint limits that cannot be exceeded high or low.

Some people treat thermostats like a gas pedal. They think the further above or below setpoint they are set, the quicker they will get to the desired temperature.

Yep, I've never understood that.

Look into Accustat's. You can install whatever heat/cool bulb in them that you want. Their covers lock and the tenant would have to unlock cover and jump contacts to override the system. Other than that, too many factors to take into consideration for the increase in energy consumption to address online. Could have a short, dirty coils (reduced air flow that would cause unit to run longer to reach desired temps) or could have an open circuit on your secondary heat strip that would cause the first strip to run constantly. Hope this helps and that you get the problem resolved. If you are able to lock in a rate on your electrical consumption per kwh that can help when rates get volatile.

Those systems have gotten more efficient, and the tech will be able to answer your questions.