I don’t know how/don’t have the tools to do it myself but if you call up an HVAC company they can come by and check the coolant levels. If it’s too low or too high your system is going to be working overtime to maintain temps. That’s what happened with mine. I set it to 68 but my cooled air output from the HVAC system was only 67. It needs to be lower or it’ll take forever to cool down the house. After the coolant levels were fixed, the HVAC air dropped to 62F

My server rack pulls 650W 24/7. That’s 15.6 kW/day or 468 kW/month. At my current rate of $0.11/kW, that’s $51.50/month. Id definitely look at your HVAC system. At my old place, my HVAC system was 30 years old and overcharged, so it rarely turned off, and my average bill was $400+/month. In my new place, the HVAC system is much more modern and bills hover around $230/month