What might high energy bills indicate regarding an HVAC system?

High energy bills typically indicate that an HVAC system may not be operating effectively. When an HVAC system is not functioning at optimal performance, it often consumes more energy than necessary in order to achieve the desired indoor temperature. This inefficiency can be caused by a range of issues, such as improper sizing of the system, lack of maintenance, or malfunctioning components. As a result, homeowners may see their energy costs rise significantly.

In contrast, the other options suggest scenarios that would not align with high energy bills. For example, if the HVAC system were functioning efficiently or all components were working smoothly, one would expect lower energy consumption and, consequently, lower energy bills. Similarly, a well-insulated building typically helps maintain indoor temperatures effectively, reducing the load on the heating and cooling system and also leading to lower energy costs. Thus, high energy bills serve as a strong indicator that something is amiss with the operation of the HVAC system.