Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
My opinion: I have prepared models of existing buildings AFTER inspecting the site, noting details about HVAC equipment and lighting and interviewing the occupants.... and was 30-50% "wrong" compared to the utility bills. That resulted in more investigation and interviewing ... and finally the model matched reality.
If your goal is to get a "general idea" of savings, you can get reasonably useful results without the full calibration effort. If someone wants to have a decent idea of their actual return on investment, I think you need to, at minimum, know constructions, occupancy patterns and HVAC types.
