There is more than one way to generate the annual energy use breakdown by end-use, and in most buildings it will require a combination of strategies. Start by identifying the major end-uses, and then consider which of the following strategies will work best for each end-use.

Submeters

If you have submeters installed in your building for one or more end-uses, simply track this data over a year. For end-uses that are the sole sources of consumption of a given energy type, the main building readings can be uses (e.g., if natural gas is only used for space heating).

Consumption Analysis

Generating a bar graph of consumption over the course of the year can be used to evaluate end-uses that only occur during certain months.

Spot Metering

Consider using spot meters to measure end-use energy consumption at the system level and extrapolate the information for a year, taking into account operational and seasonal variations. This works especially well for loads that follow a constant or regular schedule—for example, exhaust fans that run continuously all year at a constant speed.

Calculations

A final option is to determine the rated demand of equipment and estimate energy use based on run time, hours of operation, and operational and seasonal variations. You can cross-reference your results against your utility bills to confirm that your estimates are accurate (even if your bills only provide monthly totals).