Annual Energy Intensity

Intensity calculations are slightly different between the end-use components and the new technology components. For the end use components, Share and Efficiency values that are assigned to the End-Use Set are combined with base year UEC values to generate an end-use energy intensity (EI) value. Within each sector, the results are used to develop annual energy use estimates for the end uses in that sector. These results are later combined with the sector weights to develop total values for the XHeat, XCool and XOther variables which are used as right-hand variables in the SAE regression model.

For the end-use components, it is important that Share and UEC values are defined consistently within each sector. For example, if room air conditioner shares indicate the number of units per home, then the UEC should be in annual kWh per RAC unit. If the room aid conditioner share indicates the fraction of homes that have one or more room air units, then the UEC should be a larger value indicating the average annual consumption of room air conditioners per home.

In the following intensity calculations, sector is indicated by the subscript (sec), end use is indicated by the subscript (use), year is indicated by the subscript (y) and the end-use base year is indicated by the subscript the subscript (by).

In these equations, EI is the annual energy intensity for an end use.

  • The UEC values are a single number that are provided for a base year (by). The units are annual energy use per unit (per appliance, household, MW of connected capacity, or unit density, depending on the end use and sector.
  • Share is the annual fuel share in a year (y), and represents the appliance saturation or device density depending on the end use. Share and UEC must be defined to provide a consistent energy intensity value across end uses within a sector and modeling variable (XHeat, XCool, XOther).
  • Eff is a positive measure of efficiency (a larger value means higher efficiency and lower energy use). The equations index this variable to 1.0 in the base year. For some end uses, this will be a column of 1.0s.
  • For technologies, the Share, Efficiency, and UEC values are combined directly with the base year technology stock values. The result is a direct estimate of monthly energy use and contribution to peak demand and these calculated values combined with system load data using the Add-Back method. With this method, historical solar generation will be added to system load to estimate total end-use consumption. Energy use for new technologies (like electric vehicles) will be subtracted out of the system load, since EV energy use is not modeled in the SAE components.

For new technologies, the calculation is slightly different and depends on the type of technology (GenTech vs. NewTech). For generation technologies, UEC values in all years are set to equal the base year UEC. For these technologies, efficiency improvements imply increased generation capacity and should be embodied in the change in capacity. For other new technologies, the base year UEC is modified by efficiency changes. For example, for electric vehicles, an increase in efficiency will imply reduced KWh per mile driven, and therefore reduced KWh per vehicle. The annual energy intensity per unit for new technologies is computed as follows. In these equations, tby represents the technology base year.

In these equations, EI is the energy production in KWh per KW for generation technologies and in KWh per unit for other new technologies.

  • The UEC value is a single number that is provided for the technology base year (tby). The units are annual KWh per KW of capacity or per unit. Generation technology UECs are positive numbers representing annual generation output per KW of capacity. New technology UECs are positive numbers representing energy requirements per unit (e.g., annual KWh per vehicle).
  • For generation technologies, Efficiency values are not utilized. In the input section, enter a column of 1.0 for these technologies. The reasoning is that more efficient panels will mean that less sunlight is required as an input to generate a KWh, but we are estimating generation output, not solar input requirements. For new end-use technologies, efficiency should be treated like the other end-use components. For example, for EVs, efficiency improvements take the form of improved miles per KWh, which reduces energy use for a given distance traveled.