OpenStudio: Heating vs Interior Equipment NG

edit

Using OpenStudio, I am modeling a building with a packaged rooftop air handler. When I run the analysis, the majority of the NG being consumed in my building I am told is due to interior equipment. Yet, the only thing I am running in the building that uses NG is the AHU. To top it off, I am modeling in moderate SoCal, and the Interior Equipment NG use is much higher than the heating value.

The total value of NG is actually quite close to the monthly bills I have for the existing building, so I believe the total value is right. Just uncertain as to why OS says the interior equipment is using so much NG.

Any idea as to why?