What aspect of home performance is evaluated through utility bills?

The effectiveness of installed energy systems can be evaluated through utility bills because these bills reflect the home’s energy consumption over time. By analyzing the costs associated with heating, cooling, and electricity use, one can assess how well the energy systems are functioning. For example, unusually high utility bills may indicate that systems like heating or cooling are inefficient, poorly maintained, or improperly sized for the space they serve. Conversely, lower than expected utility costs might suggest that the energy systems are operating efficiently, indicating good insulation, proper HVAC system functioning, and effective conservation measures in place.

In contrast, aspects like the quality of construction materials or the age of the residence do not directly correlate with data from utility bills, as these factors do not provide tangible figures of energy performance. Similarly, geography may influence energy consumption patterns but does not offer a straightforward measure of the systems' effectiveness themselves. Therefore, the utilization of utility bills serves as a practical tool for assessing how well the installed energy systems are performing in a real-world context.