EPI Calculation
Contents
• Energy Performance Index
• Aggregate output selection
• Weighted output example
• EPI calculation
• EPI report
Energy Performance Index
• A company’s Energy Performance Index (EPI) is based on the ratio of annual primary energy consumption to aggregate product output
• This output is developed individually by each company to reflect their unique mix of products and processes
• For a member’s first year of joining the LIEN, their EPI is normalised to 100
• Subsequent improvements or deteriorations in energy performance are reflected in a decrease or increase of EPI
Aggregate Output Selection
• For a single commodity manufacturer, the output unit is simply their base production unit
• However, most firms have more than one product therefore an aggregate output must be selected
• It is necessary to look at the relative energy intensity of each product and assign a weighting if appropriate
• Must be a measure which can be meaningfully compared year-on-year
Weighted Output Example – Company XYZ
Product A
Product B
Product C
Total
Tonnes 2001
1000 100 10 1110
GWh 2001
20 20 20 60
Tonnes 2002
1000 150 20 1170
GWh 2002
20 30 40 90
Energy per unit output
If tonnes is used as output measure:
• Energy/output 2001 = 60/1110= 0.054 GWh/tonne= 54 MWh/tonne
• Energy/output 2002 = 90/1170= 0.077 GWh/tonne= 77 MWh/tonne
Weighted Output Example
• It would not be representative to simply add the various quantities of Products A, B and C due to their different energy intensities
• A more representative approach is to assign a weighting to each output relative to the amount of energy it takes to produce
• In order to do this it must be possible to monitor the varying energy consumptions of each product e.g. meter each product line separately
Weighted Output Example – Company XYZ
Product A Product B Product C Total
Tonnes 2001 1000 100 10 1110
GWh 2001 20 20 20 60
Weighting 1 10 100
Weighted output 2001 (output x weighting)
1000 1000 1000 3000
Tonnes 2002 1000 150 20 1170
GWh 2002 20 30 40 90
Weighting 1 10 100
Weighted output 2002 (output x weighting)
1000 1500 2000 4500
Energy per unit output
If weighted output is used as output measure:
• Energy/output 2001 = 60/3000
= 0.02 GWh/wt output
= 20 MWh/wt output
• Energy/output 2002 = 90/4500
= 0.02 GWh/wt output
= 20 MWh/wt output
Output selection
Consider;
• Weighted output may give a more representative indication if appropriate e.g. varying product mix and concentration
• Value chosen much be comparable year-on-year e.g. is product line constantly changing
EPI calculation
• Information is provided annually and must be reported in a manner that is confidential
• LIEN members come from 13 different sectors with thousands or varying products
• It is not possible to compare varying energy intensity units e.g. kWh/gallon, GWh/tonne, MWh/weighted production unit
• Need to make comparison in energy intensity trends
• Energy Performance Index developed
EPI calculation
EPI = Energy x FOutput
where F is a factor used to set the EPI to 100 for a firm’s base year (i.e. the year they joined the LIEN or started reporting)
F then is fixed for subsequent years
EPI example
EPI example
EPI Report
• EPI report contains 5 pages of information specific to your site
• Details trends in primary energy per unit of output since a company joined the LIEN
• Gives information on estimated CO2 emissions as a result of energy use
• Estimates how these specific emissions have changed from the previous year as a result of a firm’s energy performance
EPI Calculation
Fiona Murray
LIEN Project Manager
