There are two levels at which energy costs can be analyzed in WaterGEMS. The tool called Scenario Energy Costs calculates energy use and cost for a single scenario while Energy Management uses the results of multiple Energy Cost scenarios to determine energy costs at a higher level of aggregation to determine the energy cost for pump stations (not just pump-by-pump) for multiple scenarios that can occur over a billing period and determine economic costs such as net present worth of pumping energy.

The scenario energy cost analysis determines the energy cost by pump for all pumps selected by the user. Pricing for energy cost is set up in the Pricing button in energy costing. Price functions are assigned to individual pumps in energy costing. See Scneario Energy Cost for detailed steps in running Energy Costs.

For users interested in a more complete energy analysis, running a single scenario may not be sufficient as block rate charges must be determined based on energy use over a complete billing cycle which may contain low, average and high water use periods which should be modeled as separate scenarios. In addition, the scenario corresponding to the setting of a peak demand charge is usually not an average day but some kind of peak condition that should be modeled in a separate scenario. In order to deal with the complexities of block rates, multiple scenarios, aggregation of pumps within a station, and performing present worth calculation, the user needs to use the Energy Management analysis. Such calculations are usually required because of complex tariffs for electric power.

An important concept in energy management analysis is that of a "Power meter". A Power Meter is the basic unit that is billed by an electric utility. A Power Meter usually corresponds to a pump station. However, in WaterGEMS, a pump station is a collection of pumps serving a single pressure zone. Therefore, if a pump station building has a single electric service but has a set of Low, Medium and High service pumps, for WaterGEMS hydraulic calculations, it is three Pump Station elements but for energy management, it corresponds to a single Power Meter. The figure below shows how a single power meter can include multiple pumps and pump stations in a single building.

Because there may be other energy uses at the pump station besides pumping, the user can specify non-pumping energy costs to account four uses such as lighting, HVAC, control systems, chemical feed equipment, etc. These costs are added in on a Power Meter basis. There may also be charges on the power bill that are not associated with individual pumping operations such as taxes, discounts, lump sum surcharges, etc. These can be added in to the overall cost and are referred to as "other costs".

The usual work flow for using the energy cost and energy management analyses may be followed as shown below:

The energy manager analysis provides a way to combine the energy use and peak demands from multiple scenarios and multiple pumps associated with a power meter to display energy and peak demand cost based on pump, pump station, power meter, scenario or system wide. See Energy Management for detailed steps. Values reported in Energy Management Analysis are aggregated over time. To view time series energy use, it is necessary to use the Scenario Energy Cost Analysis.