The answer to 'why is my HVAC system high energy bills' is that there are several common causes, including improper insulation, air leaks, old or inefficient equipment, and thermostat issues. These can lead to your HVAC system working harder than necessary to maintain your desired temperature, resulting in higher energy usage and costs.
Some key signs of these issues include uneven heating/cooling, frequent cycling of the HVAC system, and unexpectedly high utility bills. Addressing problems like air leaks, upgrading to more efficient equipment, and properly programming your thermostat can help reduce energy consumption and lower your bills.