Problem: The value for the Energy Use Index (EUI) for a building in EnergyCAP may differ from the value for the same building in ENERGY STAR's Portfolio Manager. What are the reasons why?
- Timing of bills. The bills that make up the usage total may not be exactly the same, i.e. PM may be looking at May 2012 to April 2013 and EnergyCAP could be June 2012 to May 2013. Depends on exactly what you’re looking at and when the data last was submitted to PM.
- ECAP EUI data is weather normalized. PM may or may not be, depending upon which value you are looking at.
- Weather normalization base years are different. ECAP allows you to explicitly set it, PM doesn’t.
- Weather normalization calculations are slightly different. PM’s weather calcs are a black box, I have never seen documentation on exactly how it’s done and doubt that the info is posted anywhere.