The utility bill history for a home is very important information to be used in an energy audit. An analysis of the utility bills will help the auditor to determine the biggest users of energy in the home. This will also help in determining the cost-effectiveness of the different solutions that can be recommended.

This chart is an example of the analysis that is performed.  The energy use of the heating and cooling system is identified. 

The baseload is all of the energy used that is not used to heat and cool the home.  This can be considered the 'overhead' energy costs.

Heating and Cooling Costs

This chart tracks energy used to cool the home with the increase in outdoor temperature over the course of a year.  In this example, the amount of energy used very closely correlates with the temperature change of the course of the year.