Classification: UNCLASSIFIED Caveats: NONE For Air Handling Units with VAV boxes Trace calculates the air flows based on loads and outside air requirements. I haven't looked into the program code, but I have noticed that changing interior loads changes the amount of outside air in the system. This makes sense to me since, if the AHU is operating at 30% outside air and a room needs more air for cooling, the total amount of outside air for the building would change. When I model the pretend building, it has different insulation, causing different energy demands, causing different air flows, causing different outside air values. How do I get the two outside air values to match? [On a side note, the outside air values shown on the report give the worst case outside airflow, it wouldn't mean that the baseline and pretend buildings will have identical outside air flows for the total 8760.] Do I go into the pretend building model and manual enter the outside air cfm for each room to make it match the proposed building? John Eurek Classification: UNCLASSIFIED Caveats: NONE